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[PATCH v3] Introduce ternary reloptions 52+ messages / 2 participants [nested] [flat]
* [PATCH v3] Introduce ternary reloptions @ 2026-01-16 15:04 Álvaro Herrera <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Álvaro Herrera @ 2026-01-16 15:04 UTC (permalink / raw) Introduce ternary reloption as a replacement for current `vacuum_truncate` implementation. Remove the `vacuum_truncate_set` separate flag and use TERNARY_UNSET instead. This could also be used for other options such as `vacuum_index_cleanup` and `buffering`, but lets get the scaffolding in first. Discussion: https://postgr.es/m/3474141.usfYGdeWWP@thinkpad-pgpro --- src/backend/access/common/reloptions.c | 137 ++++++++++++++++++----- src/backend/commands/vacuum.c | 4 +- src/include/access/reloptions.h | 27 ++--- src/include/postgres.h | 15 +++ src/include/utils/rel.h | 3 +- src/test/regress/expected/reloptions.out | 36 ++++++ src/test/regress/sql/reloptions.sql | 21 ++++ src/tools/pgindent/typedefs.list | 2 + 8 files changed, 202 insertions(+), 43 deletions(-) diff --git a/src/backend/access/common/reloptions.c b/src/backend/access/common/reloptions.c index 0b83f98ed5f..6f1f577581a 100644 --- a/src/backend/access/common/reloptions.c +++ b/src/backend/access/common/reloptions.c @@ -40,9 +40,9 @@ * * To add an option: * - * (i) decide on a type (bool, integer, real, enum, string), name, default - * value, upper and lower bounds (if applicable); for strings, consider a - * validation routine. + * (i) decide on a type (bool, ternary, integer, real, enum, string), name, + * default value, upper and lower bounds (if applicable); for strings, + * consider a validation routine. * (ii) add a record below (or use add_<type>_reloption). * (iii) add it to the appropriate options struct (perhaps StdRdOptions) * (iv) add it to the appropriate handling routine (perhaps @@ -147,15 +147,6 @@ static relopt_bool boolRelOpts[] = }, false }, - { - { - "vacuum_truncate", - "Enables vacuum to truncate empty pages at the end of this table", - RELOPT_KIND_HEAP | RELOPT_KIND_TOAST, - ShareUpdateExclusiveLock - }, - true - }, { { "deduplicate_items", @@ -170,6 +161,25 @@ static relopt_bool boolRelOpts[] = {{NULL}} }; +static relopt_ternary ternaryRelOpts[] = +{ + { + { + "vacuum_truncate", + "Enables vacuum to truncate empty pages at the end of this table", + RELOPT_KIND_HEAP | RELOPT_KIND_TOAST, + ShareUpdateExclusiveLock + }, + TERNARY_UNSET + }, + /* list terminator */ + { + { + NULL + } + } +}; + static relopt_int intRelOpts[] = { { @@ -609,6 +619,13 @@ initialize_reloptions(void) boolRelOpts[i].gen.lockmode)); j++; } + for (i = 0; ternaryRelOpts[i].gen.name; i++) + { + Assert(DoLockModesConflict(ternaryRelOpts[i].gen.lockmode, + ternaryRelOpts[i].gen.lockmode)); + j++; + } + for (i = 0; intRelOpts[i].gen.name; i++) { Assert(DoLockModesConflict(intRelOpts[i].gen.lockmode, @@ -649,6 +666,14 @@ initialize_reloptions(void) j++; } + for (i = 0; ternaryRelOpts[i].gen.name; i++) + { + relOpts[j] = &ternaryRelOpts[i].gen; + relOpts[j]->type = RELOPT_TYPE_TERNARY; + relOpts[j]->namelen = strlen(relOpts[j]->name); + j++; + } + for (i = 0; intRelOpts[i].gen.name; i++) { relOpts[j] = &intRelOpts[i].gen; @@ -809,6 +834,9 @@ allocate_reloption(bits32 kinds, int type, const char *name, const char *desc, case RELOPT_TYPE_BOOL: size = sizeof(relopt_bool); break; + case RELOPT_TYPE_TERNARY: + size = sizeof(relopt_ternary); + break; case RELOPT_TYPE_INT: size = sizeof(relopt_int); break; @@ -892,6 +920,57 @@ add_local_bool_reloption(local_relopts *relopts, const char *name, add_local_reloption(relopts, (relopt_gen *) newoption, offset); } +/* + * init_ternary_reloption + * Allocate and initialize a new ternary reloption + */ +static relopt_ternary * +init_ternary_reloption(bits32 kinds, const char *name, const char *desc, + pg_ternary default_val, LOCKMODE lockmode) +{ + relopt_ternary *newoption; + + newoption = (relopt_ternary *) + allocate_reloption(kinds, RELOPT_TYPE_TERNARY, name, desc, lockmode); + newoption->default_val = default_val; + + return newoption; +} + +/* + * add_ternary_reloption + * Add a new ternary reloption + */ +void +add_ternary_reloption(bits32 kinds, const char *name, const char *desc, + pg_ternary default_val, LOCKMODE lockmode) +{ + relopt_ternary *newoption; + + newoption = + init_ternary_reloption(kinds, name, desc, default_val, lockmode); + + add_reloption((relopt_gen *) newoption); +} + +/* + * add_local_ternary_reloption + * Add a new ternary local reloption + * + * 'offset' is offset of ternary-typed field. + */ +void +add_local_ternary_reloption(local_relopts *relopts, const char *name, + const char *desc, pg_ternary default_val, + int offset) +{ + relopt_ternary *newoption; + + newoption = + init_ternary_reloption(RELOPT_KIND_LOCAL, name, desc, default_val, 0); + + add_local_reloption(relopts, (relopt_gen *) newoption, offset); +} /* * init_real_reloption @@ -1626,6 +1705,19 @@ parse_one_reloption(relopt_value *option, char *text_str, int text_len, option->gen->name, value))); } break; + case RELOPT_TYPE_TERNARY: + { + bool b; + + parsed = parse_bool(value, &b); + option->values.ternary_val = b ? TERNARY_TRUE : TERNARY_FALSE; + if (validate && !parsed) + ereport(ERROR, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("invalid value for ternary option \"%s\": %s", + option->gen->name, value))); + } + break; case RELOPT_TYPE_INT: { relopt_int *optint = (relopt_int *) option->gen; @@ -1789,17 +1881,6 @@ fillRelOptions(void *rdopts, Size basesize, char *itempos = ((char *) rdopts) + elems[j].offset; char *string_val; - /* - * If isset_offset is provided, store whether the reloption is - * set there. - */ - if (elems[j].isset_offset > 0) - { - char *setpos = ((char *) rdopts) + elems[j].isset_offset; - - *(bool *) setpos = options[i].isset; - } - switch (options[i].gen->type) { case RELOPT_TYPE_BOOL: @@ -1807,6 +1888,11 @@ fillRelOptions(void *rdopts, Size basesize, options[i].values.bool_val : ((relopt_bool *) options[i].gen)->default_val; break; + case RELOPT_TYPE_TERNARY: + *(pg_ternary *) itempos = options[i].isset ? + options[i].values.ternary_val : + ((relopt_ternary *) options[i].gen)->default_val; + break; case RELOPT_TYPE_INT: *(int *) itempos = options[i].isset ? options[i].values.int_val : @@ -1923,8 +2009,8 @@ default_reloptions(Datum reloptions, bool validate, relopt_kind kind) offsetof(StdRdOptions, parallel_workers)}, {"vacuum_index_cleanup", RELOPT_TYPE_ENUM, offsetof(StdRdOptions, vacuum_index_cleanup)}, - {"vacuum_truncate", RELOPT_TYPE_BOOL, - offsetof(StdRdOptions, vacuum_truncate), offsetof(StdRdOptions, vacuum_truncate_set)}, + {"vacuum_truncate", RELOPT_TYPE_TERNARY, + offsetof(StdRdOptions, vacuum_truncate)}, {"vacuum_max_eager_freeze_failure_rate", RELOPT_TYPE_REAL, offsetof(StdRdOptions, vacuum_max_eager_freeze_failure_rate)} }; @@ -2004,7 +2090,6 @@ build_local_reloptions(local_relopts *relopts, Datum options, bool validate) elems[i].optname = opt->option->name; elems[i].opttype = opt->option->type; elems[i].offset = opt->offset; - elems[i].isset_offset = 0; /* not supported for local relopts yet */ i++; } diff --git a/src/backend/commands/vacuum.c b/src/backend/commands/vacuum.c index aa4fbec143f..696eab9bd97 100644 --- a/src/backend/commands/vacuum.c +++ b/src/backend/commands/vacuum.c @@ -2224,9 +2224,9 @@ vacuum_rel(Oid relid, RangeVar *relation, VacuumParams params, { StdRdOptions *opts = (StdRdOptions *) rel->rd_options; - if (opts && opts->vacuum_truncate_set) + if (opts && opts->vacuum_truncate != TERNARY_UNSET) { - if (opts->vacuum_truncate) + if (opts->vacuum_truncate == TERNARY_TRUE) params.truncate = VACOPTVALUE_ENABLED; else params.truncate = VACOPTVALUE_DISABLED; diff --git a/src/include/access/reloptions.h b/src/include/access/reloptions.h index 2f08e1b0cf0..dfbef2babf2 100644 --- a/src/include/access/reloptions.h +++ b/src/include/access/reloptions.h @@ -29,6 +29,7 @@ typedef enum relopt_type { RELOPT_TYPE_BOOL, + RELOPT_TYPE_TERNARY, /* on, off, unset */ RELOPT_TYPE_INT, RELOPT_TYPE_REAL, RELOPT_TYPE_ENUM, @@ -80,6 +81,7 @@ typedef struct relopt_value union { bool bool_val; + pg_ternary ternary_val; int int_val; double real_val; int enum_val; @@ -94,6 +96,12 @@ typedef struct relopt_bool bool default_val; } relopt_bool; +typedef struct relopt_ternary +{ + relopt_gen gen; + int default_val; +} relopt_ternary; + typedef struct relopt_int { relopt_gen gen; @@ -152,19 +160,6 @@ typedef struct const char *optname; /* option's name */ relopt_type opttype; /* option's datatype */ int offset; /* offset of field in result struct */ - - /* - * isset_offset is an optional offset of a field in the result struct that - * stores whether the option is explicitly set for the relation or if it - * just picked up the default value. In most cases, this can be - * accomplished by giving the reloption a special out-of-range default - * value (e.g., some integer reloptions use -2), but this isn't always - * possible. For example, a Boolean reloption cannot be given an - * out-of-range default, so we need another way to discover the source of - * its value. This offset is only used if given a value greater than - * zero. - */ - int isset_offset; } relopt_parse_elt; /* Local reloption definition */ @@ -195,6 +190,9 @@ typedef struct local_relopts extern relopt_kind add_reloption_kind(void); extern void add_bool_reloption(bits32 kinds, const char *name, const char *desc, bool default_val, LOCKMODE lockmode); +extern void add_ternary_reloption(bits32 kinds, const char *name, + const char *desc, pg_ternary default_val, + LOCKMODE lockmode); extern void add_int_reloption(bits32 kinds, const char *name, const char *desc, int default_val, int min_val, int max_val, LOCKMODE lockmode); @@ -214,6 +212,9 @@ extern void register_reloptions_validator(local_relopts *relopts, extern void add_local_bool_reloption(local_relopts *relopts, const char *name, const char *desc, bool default_val, int offset); +extern void add_local_ternary_reloption(local_relopts *relopts, + const char *name, const char *desc, + pg_ternary default_val, int offset); extern void add_local_int_reloption(local_relopts *relopts, const char *name, const char *desc, int default_val, int min_val, int max_val, int offset); diff --git a/src/include/postgres.h b/src/include/postgres.h index 7d93fbce709..47c88780776 100644 --- a/src/include/postgres.h +++ b/src/include/postgres.h @@ -543,6 +543,21 @@ Float8GetDatum(float8 X) * ---------------------------------------------------------------- */ +/* + * pg_ternary + * Boolean value with an extra "unset" value + * + * This enum can be used for values that want to distinguish between true, + * false, and unset. +*/ + +typedef enum pg_ternary +{ + TERNARY_FALSE = 0, + TERNARY_TRUE = 1, + TERNARY_UNSET = -1 +} pg_ternary; + /* * NON_EXEC_STATIC: It's sometimes useful to define a variable or function * that is normally static but extern when using EXEC_BACKEND (see diff --git a/src/include/utils/rel.h b/src/include/utils/rel.h index d03ab247788..5feb18a5373 100644 --- a/src/include/utils/rel.h +++ b/src/include/utils/rel.h @@ -347,8 +347,7 @@ typedef struct StdRdOptions bool user_catalog_table; /* use as an additional catalog relation */ int parallel_workers; /* max number of parallel workers */ StdRdOptIndexCleanup vacuum_index_cleanup; /* controls index vacuuming */ - bool vacuum_truncate; /* enables vacuum to truncate a relation */ - bool vacuum_truncate_set; /* whether vacuum_truncate is set */ + pg_ternary vacuum_truncate; /* enables vacuum to truncate a relation */ /* * Fraction of pages in a relation that vacuum can eagerly scan and fail diff --git a/src/test/regress/expected/reloptions.out b/src/test/regress/expected/reloptions.out index 9de19b4e3f1..1c99f79ab01 100644 --- a/src/test/regress/expected/reloptions.out +++ b/src/test/regress/expected/reloptions.out @@ -98,6 +98,42 @@ SELECT reloptions FROM pg_class WHERE oid = 'reloptions_test'::regclass; {fillfactor=13,autovacuum_enabled=false} (1 row) +-- Tests for future (FIXME) ternary options +-- behave as boolean option: accept unassigned name and truncated value +DROP TABLE reloptions_test; +CREATE TABLE reloptions_test(i INT) WITH (vacuum_truncate); +SELECT reloptions FROM pg_class WHERE oid = 'reloptions_test'::regclass; + reloptions +------------------------ + {vacuum_truncate=true} +(1 row) + +DROP TABLE reloptions_test; +CREATE TABLE reloptions_test(i INT) WITH (vacuum_truncate=FaLS); +SELECT reloptions FROM pg_class WHERE oid = 'reloptions_test'::regclass; + reloptions +------------------------ + {vacuum_truncate=fals} +(1 row) + +-- preferred "true" alias is used when storing +DROP TABLE reloptions_test; +CREATE TABLE reloptions_test(i INT) WITH (vacuum_index_cleanup=on); +SELECT reloptions FROM pg_class WHERE oid = 'reloptions_test'::regclass; + reloptions +--------------------------- + {vacuum_index_cleanup=on} +(1 row) + +-- custom "third" value is available +DROP TABLE reloptions_test; +CREATE TABLE reloptions_test(i INT) WITH (vacuum_index_cleanup=auto); +SELECT reloptions FROM pg_class WHERE oid = 'reloptions_test'::regclass; + reloptions +----------------------------- + {vacuum_index_cleanup=auto} +(1 row) + -- Test vacuum_truncate option DROP TABLE reloptions_test; CREATE TEMP TABLE reloptions_test(i INT NOT NULL, j text) diff --git a/src/test/regress/sql/reloptions.sql b/src/test/regress/sql/reloptions.sql index 24fbe0b478d..f5980dafcbc 100644 --- a/src/test/regress/sql/reloptions.sql +++ b/src/test/regress/sql/reloptions.sql @@ -59,6 +59,27 @@ UPDATE pg_class ALTER TABLE reloptions_test RESET (illegal_option); SELECT reloptions FROM pg_class WHERE oid = 'reloptions_test'::regclass; +-- Tests for future (FIXME) ternary options + +-- behave as boolean option: accept unassigned name and truncated value +DROP TABLE reloptions_test; +CREATE TABLE reloptions_test(i INT) WITH (vacuum_truncate); +SELECT reloptions FROM pg_class WHERE oid = 'reloptions_test'::regclass; + +DROP TABLE reloptions_test; +CREATE TABLE reloptions_test(i INT) WITH (vacuum_truncate=FaLS); +SELECT reloptions FROM pg_class WHERE oid = 'reloptions_test'::regclass; + +-- preferred "true" alias is used when storing +DROP TABLE reloptions_test; +CREATE TABLE reloptions_test(i INT) WITH (vacuum_index_cleanup=on); +SELECT reloptions FROM pg_class WHERE oid = 'reloptions_test'::regclass; + +-- custom "third" value is available +DROP TABLE reloptions_test; +CREATE TABLE reloptions_test(i INT) WITH (vacuum_index_cleanup=auto); +SELECT reloptions FROM pg_class WHERE oid = 'reloptions_test'::regclass; + -- Test vacuum_truncate option DROP TABLE reloptions_test; diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index 3f3a888fd0e..1c8610fd46c 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -3952,6 +3952,7 @@ pg_sha512_ctx pg_snapshot pg_special_case pg_stack_base_t +pg_ternary pg_time_t pg_time_usec_t pg_tz @@ -4079,6 +4080,7 @@ relopt_kind relopt_parse_elt relopt_real relopt_string +relopt_ternary relopt_type relopt_value relopts_validator -- 2.47.3 --c36t3fndxhkzbl5z-- ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
* [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic @ 2026-07-09 19:20 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 52+ messages in thread From: Nathan Bossart @ 2026-07-09 19:20 UTC (permalink / raw) --- src/backend/storage/ipc/sinvaladt.c | 51 ++++++++++------------------- 1 file changed, 17 insertions(+), 34 deletions(-) diff --git a/src/backend/storage/ipc/sinvaladt.c b/src/backend/storage/ipc/sinvaladt.c index 37a21ffaf1a..17e98c9efdc 100644 --- a/src/backend/storage/ipc/sinvaladt.c +++ b/src/backend/storage/ipc/sinvaladt.c @@ -24,7 +24,6 @@ #include "storage/procsignal.h" #include "storage/shmem.h" #include "storage/sinvaladt.h" -#include "storage/spin.h" #include "storage/subsystems.h" /* @@ -87,19 +86,10 @@ * has no need to touch anyone's ProcState, except in the infrequent cases * when SICleanupQueue is needed. The only point of overlap is that * the writer wants to change maxMsgNum while readers need to read it. - * We deal with that by having a spinlock that readers must take for just - * long enough to read maxMsgNum, while writers take it for just long enough - * to write maxMsgNum. (The exact rule is that you need the spinlock to - * read maxMsgNum if you are not holding SInvalWriteLock, and you need the - * spinlock to write maxMsgNum unless you are holding both locks.) - * - * Note: since maxMsgNum is an int and hence presumably atomically readable/ - * writable, the spinlock might seem unnecessary. The reason it is needed - * is to provide a memory barrier: we need to be sure that messages written - * to the array are actually there before maxMsgNum is increased, and that - * readers will see that data after fetching maxMsgNum. Multiprocessors - * that have weak memory-ordering guarantees can fail without the memory - * barrier instructions that are included in the spinlock sequences. + * We deal with that by making maxMsgNum an atomic variable. (The exact rule + * is that you need to use a barrier-providing accessor to read maxMsgNum if + * you are not holding SInvalWriteLock, and you need a barrier-providing + * accessor to write maxMsgNum unless you are holding both locks.) */ @@ -169,11 +159,9 @@ typedef struct SISeg * General state information */ int minMsgNum; /* oldest message still needed */ - int maxMsgNum; /* next message number to be assigned */ + pg_atomic_uint32 maxMsgNum; /* next message number to be assigned */ int nextThreshold; /* # of messages to call SICleanupQueue */ - slock_t msgnumLock; /* spinlock protecting maxMsgNum */ - /* * Circular buffer holding shared-inval messages */ @@ -244,11 +232,10 @@ SharedInvalShmemInit(void *arg) { int i; - /* Clear message counters, init spinlock */ + /* Clear message counters */ shmInvalBuffer->minMsgNum = 0; - shmInvalBuffer->maxMsgNum = 0; + pg_atomic_init_u32(&shmInvalBuffer->maxMsgNum, 0); shmInvalBuffer->nextThreshold = CLEANUP_MIN; - SpinLockInit(&shmInvalBuffer->msgnumLock); /* The buffer[] array is initially all unused, so we need not fill it */ @@ -306,7 +293,7 @@ SharedInvalBackendInit(bool sendOnly) /* mark myself active, with all extant messages already read */ stateP->procPid = MyProcPid; - stateP->nextMsgNum = segP->maxMsgNum; + stateP->nextMsgNum = pg_atomic_read_u32(&segP->maxMsgNum); stateP->resetState = false; stateP->signaled = false; stateP->hasMessages = false; @@ -402,7 +389,7 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) */ for (;;) { - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs + nthistime > MAXNUMMESSAGES || numMsgs >= segP->nextThreshold) SICleanupQueue(true, nthistime); @@ -413,17 +400,15 @@ SIInsertDataEntries(const SharedInvalidationMessage *data, int n) /* * Insert new message(s) into proper slot of circular buffer */ - max = segP->maxMsgNum; + max = pg_atomic_read_u32(&segP->maxMsgNum); while (nthistime-- > 0) { segP->buffer[max % MAXNUMMESSAGES] = *data++; max++; } - /* Update current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - segP->maxMsgNum = max; - SpinLockRelease(&segP->msgnumLock); + /* Update current value of maxMsgNum using barrier */ + pg_atomic_write_membarrier_u32(&segP->maxMsgNum, max); /* * Now that the maxMsgNum change is globally visible, we give everyone @@ -509,10 +494,8 @@ SIGetDataEntries(SharedInvalidationMessage *data, int datasize) */ stateP->hasMessages = false; - /* Fetch current value of maxMsgNum using spinlock */ - SpinLockAcquire(&segP->msgnumLock); - max = segP->maxMsgNum; - SpinLockRelease(&segP->msgnumLock); + /* Fetch current value of maxMsgNum using barrier */ + max = pg_atomic_read_membarrier_u32(&segP->maxMsgNum); if (stateP->resetState) { @@ -598,7 +581,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * backends here it is possible for them to keep sending messages without * a problem even when they are the only active backend. */ - min = segP->maxMsgNum; + min = pg_atomic_read_u32(&segP->maxMsgNum); minsig = min - SIG_THRESHOLD; lowbound = min - MAXNUMMESSAGES + minFree; @@ -644,7 +627,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) if (min >= MSGNUMWRAPAROUND) { segP->minMsgNum -= MSGNUMWRAPAROUND; - segP->maxMsgNum -= MSGNUMWRAPAROUND; + pg_atomic_fetch_sub_u32(&segP->maxMsgNum, MSGNUMWRAPAROUND); for (i = 0; i < segP->numProcs; i++) segP->procState[segP->pgprocnos[i]].nextMsgNum -= MSGNUMWRAPAROUND; } @@ -653,7 +636,7 @@ SICleanupQueue(bool callerHasWriteLock, int minFree) * Determine how many messages are still in the queue, and set the * threshold at which we should repeat SICleanupQueue(). */ - numMsgs = segP->maxMsgNum - segP->minMsgNum; + numMsgs = pg_atomic_read_u32(&segP->maxMsgNum) - segP->minMsgNum; if (numMsgs < CLEANUP_MIN) segP->nextThreshold = CLEANUP_MIN; else -- 2.50.1 (Apple Git-155) --Ot5x3ffkWEuxilWO Content-Type: text/plain; charset=us-ascii Content-Disposition: attachment; filename=v1-0002-convert-ParallelBitmapHeapState-state-to-an-atomi.patch ^ permalink raw reply [nested|flat] 52+ messages in thread
end of thread, other threads:[~2026-07-09 19:20 UTC | newest] Thread overview: 52+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2026-01-16 15:04 [PATCH v3] Introduce ternary reloptions Álvaro Herrera <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]> 2026-07-09 19:20 [PATCH v1 1/8] convert SISeg->maxMsgNum to an atomic Nathan Bossart <[email protected]>
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