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* [PATCH v1] Use open file description locks for data directory lockfile
@ 2025-12-18 17:21 Dmitrii Dolgov <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Dmitrii Dolgov @ 2025-12-18 17:21 UTC (permalink / raw)
When starting up, postmaster checks for an existing data directory lockfile. If
this file contains current process PID, it's assumed to be stale. Turns out
there is another possibility: we might be running in a PID namespace, and there
is another postgres running inside another PID namespace using the same data
directory. The result is that we don't see another process due to namespace
isolation and start concurrently with the other.
To prevent such situations, at startup use fcntl to get an exclusive open file
description lock for data directory lockfile. Since such locks are associated
with open file descriptors, meaning they're not affected by PID namespace
isolation. It's a "best effort" locking, intended to work with already existing
mechanism, not replace it.
This approach was discussed multiple times in the past, and usually was
rejected as the main work horse for the data directory lockfile due to:
* Portability issues. Open file description lock was a non-POSIX extension in
Linux and similar flock is from BSD standard. But looks like everybody agrees
that such locks make more sense than a typical advisory locks, and
F_OFD_SETLK made its way into POSIX.1 2024 [1].
* Issues with NFS. The current state of things here looks like this:
- NFSv3 doesn't implement open file description locks, they're converted to
advisory locks instead. Advisory locks are subject to namespace isolation,
meaning that processes in different PID namespaces will not see each other
advisory lock, and it's still possible to run multiple postgres
instances on the same data directory.
- NFSv4 uses a lease system for locking, I haven't found any mention of
conversion to advisory locks neither in the man page nor in RFC [2].
To summarize, the approach is now considered POSIX and should fix the described
problem everywhere, except NFSv3.
[1]: https://pubs.opengroup.org/onlinepubs/9799919799/functions/fcntl.html
[2]: https://www.rfc-editor.org/rfc/rfc7530
---
configure | 14 ++++
configure.ac | 3 +
meson.build | 1 +
src/backend/utils/init/miscinit.c | 107 +++++++++++++++++++++++++-----
src/include/pg_config.h.in | 4 ++
5 files changed, 111 insertions(+), 18 deletions(-)
diff --git a/configure b/configure
index 14ad0a5006f..b176ac39799 100755
--- a/configure
+++ b/configure
@@ -16177,6 +16177,20 @@ cat >>confdefs.h <<_ACEOF
_ACEOF
+# Linux open file descriptor locks
+ac_fn_c_check_decl "$LINENO" "F_OFD_SETLK" "ac_cv_have_decl_F_OFD_SETLK" "#include <fcntl.h>
+"
+if test "x$ac_cv_have_decl_F_OFD_SETLK" = xyes; then :
+ ac_have_decl=1
+else
+ ac_have_decl=0
+fi
+
+cat >>confdefs.h <<_ACEOF
+#define HAVE_DECL_F_OFD_SETLK $ac_have_decl
+_ACEOF
+
+
ac_fn_c_check_func "$LINENO" "explicit_bzero" "ac_cv_func_explicit_bzero"
if test "x$ac_cv_func_explicit_bzero" = xyes; then :
$as_echo "#define HAVE_EXPLICIT_BZERO 1" >>confdefs.h
diff --git a/configure.ac b/configure.ac
index 01b3bbc1be8..d6cf1f27771 100644
--- a/configure.ac
+++ b/configure.ac
@@ -1838,6 +1838,9 @@ AC_CHECK_DECLS([memset_s], [], [], [#define __STDC_WANT_LIB_EXT1__ 1
# This is probably only present on macOS, but may as well check always
AC_CHECK_DECLS(F_FULLFSYNC, [], [], [#include <fcntl.h>])
+# Linux open file descriptor locks
+AC_CHECK_DECLS([F_OFD_SETLK], [], [], [#include <fcntl.h>])
+
AC_REPLACE_FUNCS(m4_normalize([
explicit_bzero
getopt
diff --git a/meson.build b/meson.build
index d7c5193d4ce..ad9ecad829f 100644
--- a/meson.build
+++ b/meson.build
@@ -2667,6 +2667,7 @@ decl_checks = [
['strnlen', 'string.h'],
['strsep', 'string.h'],
['timingsafe_bcmp', 'string.h'],
+ ['F_OFD_SETLK', 'fcntl.h'],
]
# Need to check for function declarations for these functions, because
diff --git a/src/backend/utils/init/miscinit.c b/src/backend/utils/init/miscinit.c
index fec79992c8d..78bb7df543e 100644
--- a/src/backend/utils/init/miscinit.c
+++ b/src/backend/utils/init/miscinit.c
@@ -68,6 +68,11 @@ static List *lock_files = NIL;
static Latch LocalLatchData;
+#ifdef HAVE_DECL_F_OFD_SETLK
+/* File descriptor for data directory lock file. */
+static int DataDirLockFD;
+#endif
+
/* ----------------------------------------------------------------
* ignoring system indexes support stuff
*
@@ -1117,6 +1122,45 @@ RestoreClientConnectionInfo(char *conninfo)
*-------------------------------------------------------------------------
*/
+/*
+ * Flock the data directory lockfile.
+ *
+ * Lock the data directory lockfile with an open file description lock. If the
+ * lock is already taken, it's a hard stop. It's only a best effort test, and
+ * any other errors are ignored. On succes the file descriptor is duplicated,
+ * to make sure there will be at least one open copy of it to keep the lock.
+ *
+ * filename is used only for reporting purposes.
+ */
+static void
+FlockDataDirLockFile(int fd, const char *filename)
+{
+
+#ifdef HAVE_DECL_F_OFD_SETLK
+ struct flock lock;
+
+ lock.l_type = F_WRLCK;
+ lock.l_whence = SEEK_SET;
+ lock.l_start = 0;
+ lock.l_len = 0;
+ lock.l_pid = 0;
+
+ if (fcntl(fd, F_OFD_SETLK, &lock) == -1)
+ {
+ if (errno == EAGAIN)
+ ereport(FATAL,
+ (errcode(ERRCODE_LOCK_FILE_EXISTS),
+ errmsg("cannot lock the lock file \"%s\"", filename),
+ errhint("Another server is starting.")));
+ else
+ elog(WARNING, "Failed locking file \"%s\", %m", filename);
+ }
+ else
+ DataDirLockFD = dup(fd);
+#endif
+
+}
+
/*
* proc_exit callback to remove lockfiles.
*/
@@ -1125,6 +1169,11 @@ UnlinkLockFiles(int status, Datum arg)
{
ListCell *l;
+#ifdef HAVE_DECL_F_OFD_SETLK
+ /* Close the file descriptor, which keeps the open file description lock */
+ close(DataDirLockFD);
+#endif
+
foreach(l, lock_files)
{
char *curfile = (char *) lfirst(l);
@@ -1171,22 +1220,32 @@ CreateLockFile(const char *filename, bool amPostmaster,
const char *envvar;
/*
- * If the PID in the lockfile is our own PID or our parent's or
- * grandparent's PID, then the file must be stale (probably left over from
- * a previous system boot cycle). We need to check this because of the
- * likelihood that a reboot will assign exactly the same PID as we had in
- * the previous reboot, or one that's only one or two counts larger and
- * hence the lockfile's PID now refers to an ancestor shell process. We
- * allow pg_ctl to pass down its parent shell PID (our grandparent PID)
- * via the environment variable PG_GRANDPARENT_PID; this is so that
- * launching the postmaster via pg_ctl can be just as reliable as
- * launching it directly. There is no provision for detecting
- * further-removed ancestor processes, but if the init script is written
- * carefully then all but the immediate parent shell will be root-owned
- * processes and so the kill test will fail with EPERM. Note that we
- * cannot get a false negative this way, because an existing postmaster
- * would surely never launch a competing postmaster or pg_ctl process
- * directly.
+ * If we find an already existing lockfile containing our own PID,
+ * there are few options:
+ *
+ * - There is another process, that we don't see due to PID namespace
+ * isolation, which is already running in this data directory.
+ *
+ * To prevent two concurrent processes working with the same data
+ * directory, we first try to lock the lockfile exclusively.
+ *
+ * - The file must be stale, probably left over from a previous system boot
+ * cycle. The same if the lockfile contains our parent's or grandparent's
+ * PID.
+ *
+ * We need to check this because of the likelihood that a reboot will
+ * assign exactly the same PID as we had in the previous reboot, or one
+ * that's only one or two counts larger and hence the lockfile's PID now
+ * refers to an ancestor shell process. We allow pg_ctl to pass down its
+ * parent shell PID (our grandparent PID) via the environment variable
+ * PG_GRANDPARENT_PID; this is so that launching the postmaster via
+ * pg_ctl can be just as reliable as launching it directly. There is no
+ * provision for detecting further-removed ancestor processes, but if the
+ * init script is written carefully then all but the immediate parent
+ * shell will be root-owned processes and so the kill test will fail with
+ * EPERM. Note that we cannot get a false negative this way, because an
+ * existing postmaster would surely never launch a competing postmaster
+ * or pg_ctl process directly.
*/
my_pid = getpid();
@@ -1222,7 +1281,11 @@ CreateLockFile(const char *filename, bool amPostmaster,
*/
fd = open(filename, O_RDWR | O_CREAT | O_EXCL, pg_file_create_mode);
if (fd >= 0)
- break; /* Success; exit the retry loop */
+ {
+ /* Success; lock and exit the retry loop */
+ FlockDataDirLockFile(fd, filename);
+ break;
+ }
/*
* Couldn't create the pid file. Probably it already exists.
@@ -1236,8 +1299,12 @@ CreateLockFile(const char *filename, bool amPostmaster,
/*
* Read the file to get the old owner's PID. Note race condition
* here: file might have been deleted since we tried to create it.
+ *
+ * We're going to use the same fd for flock, and want to create a write
+ * lock for the latter one. Since both fd and the lock have to be of
+ * the same type, open the file for read and write.
*/
- fd = open(filename, O_RDONLY, pg_file_create_mode);
+ fd = open(filename, O_RDWR, pg_file_create_mode);
if (fd < 0)
{
if (errno == ENOENT)
@@ -1247,6 +1314,10 @@ CreateLockFile(const char *filename, bool amPostmaster,
errmsg("could not open lock file \"%s\": %m",
filename)));
}
+
+ /* Try to lock the file. We stop here, if it's already locked. */
+ FlockDataDirLockFile(fd, filename);
+
pgstat_report_wait_start(WAIT_EVENT_LOCK_FILE_CREATE_READ);
if ((len = read(fd, buffer, sizeof(buffer) - 1)) < 0)
ereport(FATAL,
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 92fcc5f3063..c19a50f108e 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -83,6 +83,10 @@
don't. */
#undef HAVE_DECL_F_FULLFSYNC
+/* Define to 1 if you have the declaration of `F_OFD_SETLK', and to 0 if you
+ don't. */
+#undef HAVE_DECL_F_OFD_SETLK
+
/* Define to 1 if you have the declaration of
`LLVMCreateGDBRegistrationListener', and to 0 if you don't. */
#undef HAVE_DECL_LLVMCREATEGDBREGISTRATIONLISTENER
base-commit: 44f49511b7940adf3be4337d4feb2de38fe92297
--
2.49.0
--n6t6hie3zne7u6vd--
^ permalink raw reply [nested|flat] 14+ messages in thread
* [PATCH v8 3/3] Make use of pg_popcount() in more places.
@ 2026-01-22 17:16 Nathan Bossart <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Nathan Bossart @ 2026-01-22 17:16 UTC (permalink / raw)
This replaces some loops over word-length popcount functions with
calls to our perhaps-over-optimized pg_popcount() function. Since
pg_popcount() uses a function pointer for inputs with sizes >= a
Bitmapset word, this produces a small regression for the common
one-word case in bms_num_members(). To deal with that, this commit
adds an inlined fast-path for that case. This fast-path could
arguably go in pg_popcount() itself (with an appropriate alignment
check), but that is left as a future exercise.
Suggested-by: John Naylor <[email protected]>
Reviewed-by: John Naylor <[email protected]>
Discussion: https://postgr.es/m/CANWCAZY7R%2Biy%2Br9YM_sySNydHzNqUirx1xk0tB3ej5HO62GdgQ%40mail.gmail.com
---
src/backend/nodes/bitmapset.c | 29 +++++++----------------------
src/include/lib/radixtree.h | 4 ++--
2 files changed, 9 insertions(+), 24 deletions(-)
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c
index a4765876c31..786f343b3c9 100644
--- a/src/backend/nodes/bitmapset.c
+++ b/src/backend/nodes/bitmapset.c
@@ -553,14 +553,8 @@ bms_member_index(Bitmapset *a, int x)
bitnum = BITNUM(x);
/* count bits in preceding words */
- for (int i = 0; i < wordnum; i++)
- {
- bitmapword w = a->words[i];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- }
+ result += pg_popcount((const char *) a->words,
+ wordnum * sizeof(bitmapword));
/*
* Now add bits of the last word, but only those before the item. We can
@@ -749,26 +743,17 @@ bms_get_singleton_member(const Bitmapset *a, int *member)
int
bms_num_members(const Bitmapset *a)
{
- int result = 0;
- int nwords;
- int wordnum;
-
Assert(bms_is_valid_set(a));
if (a == NULL)
return 0;
- nwords = a->nwords;
- wordnum = 0;
- do
- {
- bitmapword w = a->words[wordnum];
+ /* fast-path for common case */
+ if (a->nwords == 1)
+ return bmw_popcount(a->words[0]);
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- } while (++wordnum < nwords);
- return result;
+ return pg_popcount((const char *) a->words,
+ a->nwords * sizeof(bitmapword));
}
/*
diff --git a/src/include/lib/radixtree.h b/src/include/lib/radixtree.h
index b223ce10a2d..1425654a67c 100644
--- a/src/include/lib/radixtree.h
+++ b/src/include/lib/radixtree.h
@@ -2725,8 +2725,8 @@ RT_VERIFY_NODE(RT_NODE * node)
/* RT_DUMP_NODE(node); */
- for (int i = 0; i < RT_BM_IDX(RT_NODE_MAX_SLOTS); i++)
- cnt += bmw_popcount(n256->isset[i]);
+ cnt += pg_popcount((const char *) n256->isset,
+ RT_NODE_MAX_SLOTS / BITS_PER_BYTE);
/*
* Check if the number of used chunk matches, accounting for
--
2.50.1 (Apple Git-155)
--dIDo5IfS/hVe25hD--
^ permalink raw reply [nested|flat] 14+ messages in thread
* [PATCH v10 3/3] Make use of pg_popcount() in more places.
@ 2026-01-22 17:16 Nathan Bossart <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Nathan Bossart @ 2026-01-22 17:16 UTC (permalink / raw)
This replaces some loops over word-length popcount functions with
calls to our perhaps-over-optimized pg_popcount() function. Since
pg_popcount() uses a function pointer for inputs with sizes >= a
Bitmapset word, this produces a small regression for the common
one-word case in bms_num_members(). To deal with that, this commit
adds an inlined fast-path for that case. This fast-path could
arguably go in pg_popcount() itself (with an appropriate alignment
check), but that is left as a future exercise.
Suggested-by: John Naylor <[email protected]>
Reviewed-by: John Naylor <[email protected]>
Discussion: https://postgr.es/m/CANWCAZY7R%2Biy%2Br9YM_sySNydHzNqUirx1xk0tB3ej5HO62GdgQ%40mail.gmail.com
---
src/backend/nodes/bitmapset.c | 29 +++++++----------------------
src/include/lib/radixtree.h | 6 +++---
2 files changed, 10 insertions(+), 25 deletions(-)
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c
index a4765876c31..786f343b3c9 100644
--- a/src/backend/nodes/bitmapset.c
+++ b/src/backend/nodes/bitmapset.c
@@ -553,14 +553,8 @@ bms_member_index(Bitmapset *a, int x)
bitnum = BITNUM(x);
/* count bits in preceding words */
- for (int i = 0; i < wordnum; i++)
- {
- bitmapword w = a->words[i];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- }
+ result += pg_popcount((const char *) a->words,
+ wordnum * sizeof(bitmapword));
/*
* Now add bits of the last word, but only those before the item. We can
@@ -749,26 +743,17 @@ bms_get_singleton_member(const Bitmapset *a, int *member)
int
bms_num_members(const Bitmapset *a)
{
- int result = 0;
- int nwords;
- int wordnum;
-
Assert(bms_is_valid_set(a));
if (a == NULL)
return 0;
- nwords = a->nwords;
- wordnum = 0;
- do
- {
- bitmapword w = a->words[wordnum];
+ /* fast-path for common case */
+ if (a->nwords == 1)
+ return bmw_popcount(a->words[0]);
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- } while (++wordnum < nwords);
- return result;
+ return pg_popcount((const char *) a->words,
+ a->nwords * sizeof(bitmapword));
}
/*
diff --git a/src/include/lib/radixtree.h b/src/include/lib/radixtree.h
index b223ce10a2d..e6c9a591c17 100644
--- a/src/include/lib/radixtree.h
+++ b/src/include/lib/radixtree.h
@@ -2721,12 +2721,12 @@ RT_VERIFY_NODE(RT_NODE * node)
case RT_NODE_KIND_256:
{
RT_NODE_256 *n256 = (RT_NODE_256 *) node;
- int cnt = 0;
+ int cnt;
/* RT_DUMP_NODE(node); */
- for (int i = 0; i < RT_BM_IDX(RT_NODE_MAX_SLOTS); i++)
- cnt += bmw_popcount(n256->isset[i]);
+ cnt = pg_popcount((const char *) n256->isset,
+ RT_NODE_MAX_SLOTS / BITS_PER_BYTE);
/*
* Check if the number of used chunk matches, accounting for
--
2.50.1 (Apple Git-155)
--rlwGoOKBy5dABfM4--
^ permalink raw reply [nested|flat] 14+ messages in thread
* [PATCH v4 1/4] Make use of pg_popcount() in more places.
@ 2026-01-22 17:16 Nathan Bossart <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Nathan Bossart @ 2026-01-22 17:16 UTC (permalink / raw)
---
src/backend/nodes/bitmapset.c | 27 ++++-----------------------
src/include/lib/radixtree.h | 4 ++--
2 files changed, 6 insertions(+), 25 deletions(-)
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c
index a4765876c31..23c91fdb6c9 100644
--- a/src/backend/nodes/bitmapset.c
+++ b/src/backend/nodes/bitmapset.c
@@ -553,14 +553,8 @@ bms_member_index(Bitmapset *a, int x)
bitnum = BITNUM(x);
/* count bits in preceding words */
- for (int i = 0; i < wordnum; i++)
- {
- bitmapword w = a->words[i];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- }
+ result += pg_popcount((const char *) a->words,
+ wordnum * sizeof(bitmapword));
/*
* Now add bits of the last word, but only those before the item. We can
@@ -749,26 +743,13 @@ bms_get_singleton_member(const Bitmapset *a, int *member)
int
bms_num_members(const Bitmapset *a)
{
- int result = 0;
- int nwords;
- int wordnum;
-
Assert(bms_is_valid_set(a));
if (a == NULL)
return 0;
- nwords = a->nwords;
- wordnum = 0;
- do
- {
- bitmapword w = a->words[wordnum];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- } while (++wordnum < nwords);
- return result;
+ return pg_popcount((const char *) a->words,
+ a->nwords * sizeof(bitmapword));
}
/*
diff --git a/src/include/lib/radixtree.h b/src/include/lib/radixtree.h
index b223ce10a2d..1425654a67c 100644
--- a/src/include/lib/radixtree.h
+++ b/src/include/lib/radixtree.h
@@ -2725,8 +2725,8 @@ RT_VERIFY_NODE(RT_NODE * node)
/* RT_DUMP_NODE(node); */
- for (int i = 0; i < RT_BM_IDX(RT_NODE_MAX_SLOTS); i++)
- cnt += bmw_popcount(n256->isset[i]);
+ cnt += pg_popcount((const char *) n256->isset,
+ RT_NODE_MAX_SLOTS / BITS_PER_BYTE);
/*
* Check if the number of used chunk matches, accounting for
--
2.50.1 (Apple Git-155)
--u/0bDz5KPuHk2IF+
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
filename=v4-0002-Remove-unnecessary-32-bit-optimizations-and-align.patch
^ permalink raw reply [nested|flat] 14+ messages in thread
* [PATCH v5 1/3] Make use of pg_popcount() in more places.
@ 2026-01-22 17:16 Nathan Bossart <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Nathan Bossart @ 2026-01-22 17:16 UTC (permalink / raw)
---
src/backend/nodes/bitmapset.c | 27 ++++-----------------------
src/include/lib/radixtree.h | 4 ++--
2 files changed, 6 insertions(+), 25 deletions(-)
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c
index a4765876c31..23c91fdb6c9 100644
--- a/src/backend/nodes/bitmapset.c
+++ b/src/backend/nodes/bitmapset.c
@@ -553,14 +553,8 @@ bms_member_index(Bitmapset *a, int x)
bitnum = BITNUM(x);
/* count bits in preceding words */
- for (int i = 0; i < wordnum; i++)
- {
- bitmapword w = a->words[i];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- }
+ result += pg_popcount((const char *) a->words,
+ wordnum * sizeof(bitmapword));
/*
* Now add bits of the last word, but only those before the item. We can
@@ -749,26 +743,13 @@ bms_get_singleton_member(const Bitmapset *a, int *member)
int
bms_num_members(const Bitmapset *a)
{
- int result = 0;
- int nwords;
- int wordnum;
-
Assert(bms_is_valid_set(a));
if (a == NULL)
return 0;
- nwords = a->nwords;
- wordnum = 0;
- do
- {
- bitmapword w = a->words[wordnum];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- } while (++wordnum < nwords);
- return result;
+ return pg_popcount((const char *) a->words,
+ a->nwords * sizeof(bitmapword));
}
/*
diff --git a/src/include/lib/radixtree.h b/src/include/lib/radixtree.h
index b223ce10a2d..1425654a67c 100644
--- a/src/include/lib/radixtree.h
+++ b/src/include/lib/radixtree.h
@@ -2725,8 +2725,8 @@ RT_VERIFY_NODE(RT_NODE * node)
/* RT_DUMP_NODE(node); */
- for (int i = 0; i < RT_BM_IDX(RT_NODE_MAX_SLOTS); i++)
- cnt += bmw_popcount(n256->isset[i]);
+ cnt += pg_popcount((const char *) n256->isset,
+ RT_NODE_MAX_SLOTS / BITS_PER_BYTE);
/*
* Check if the number of used chunk matches, accounting for
--
2.50.1 (Apple Git-155)
--a4C7SGgzwrPm67dM
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
filename=v5-0002-Remove-unnecessary-32-bit-optimizations-and-align.patch
^ permalink raw reply [nested|flat] 14+ messages in thread
* [PATCH v3 1/2] Make use of pg_popcount() in more places.
@ 2026-01-22 17:16 Nathan Bossart <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Nathan Bossart @ 2026-01-22 17:16 UTC (permalink / raw)
---
src/backend/nodes/bitmapset.c | 27 ++++-----------------------
src/include/lib/radixtree.h | 4 ++--
2 files changed, 6 insertions(+), 25 deletions(-)
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c
index a4765876c31..23c91fdb6c9 100644
--- a/src/backend/nodes/bitmapset.c
+++ b/src/backend/nodes/bitmapset.c
@@ -553,14 +553,8 @@ bms_member_index(Bitmapset *a, int x)
bitnum = BITNUM(x);
/* count bits in preceding words */
- for (int i = 0; i < wordnum; i++)
- {
- bitmapword w = a->words[i];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- }
+ result += pg_popcount((const char *) a->words,
+ wordnum * sizeof(bitmapword));
/*
* Now add bits of the last word, but only those before the item. We can
@@ -749,26 +743,13 @@ bms_get_singleton_member(const Bitmapset *a, int *member)
int
bms_num_members(const Bitmapset *a)
{
- int result = 0;
- int nwords;
- int wordnum;
-
Assert(bms_is_valid_set(a));
if (a == NULL)
return 0;
- nwords = a->nwords;
- wordnum = 0;
- do
- {
- bitmapword w = a->words[wordnum];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- } while (++wordnum < nwords);
- return result;
+ return pg_popcount((const char *) a->words,
+ a->nwords * sizeof(bitmapword));
}
/*
diff --git a/src/include/lib/radixtree.h b/src/include/lib/radixtree.h
index b223ce10a2d..1425654a67c 100644
--- a/src/include/lib/radixtree.h
+++ b/src/include/lib/radixtree.h
@@ -2725,8 +2725,8 @@ RT_VERIFY_NODE(RT_NODE * node)
/* RT_DUMP_NODE(node); */
- for (int i = 0; i < RT_BM_IDX(RT_NODE_MAX_SLOTS); i++)
- cnt += bmw_popcount(n256->isset[i]);
+ cnt += pg_popcount((const char *) n256->isset,
+ RT_NODE_MAX_SLOTS / BITS_PER_BYTE);
/*
* Check if the number of used chunk matches, accounting for
--
2.50.1 (Apple Git-155)
--1Cwfhs/B30EIRjWN
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
filename=v3-0002-Remove-unnecessary-32-bit-optimizations-and-align.patch
^ permalink raw reply [nested|flat] 14+ messages in thread
* [PATCH v6 1/3] Make use of pg_popcount() in more places.
@ 2026-01-22 17:16 Nathan Bossart <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Nathan Bossart @ 2026-01-22 17:16 UTC (permalink / raw)
---
src/backend/nodes/bitmapset.c | 27 ++++-----------------------
src/include/lib/radixtree.h | 4 ++--
2 files changed, 6 insertions(+), 25 deletions(-)
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c
index a4765876c31..23c91fdb6c9 100644
--- a/src/backend/nodes/bitmapset.c
+++ b/src/backend/nodes/bitmapset.c
@@ -553,14 +553,8 @@ bms_member_index(Bitmapset *a, int x)
bitnum = BITNUM(x);
/* count bits in preceding words */
- for (int i = 0; i < wordnum; i++)
- {
- bitmapword w = a->words[i];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- }
+ result += pg_popcount((const char *) a->words,
+ wordnum * sizeof(bitmapword));
/*
* Now add bits of the last word, but only those before the item. We can
@@ -749,26 +743,13 @@ bms_get_singleton_member(const Bitmapset *a, int *member)
int
bms_num_members(const Bitmapset *a)
{
- int result = 0;
- int nwords;
- int wordnum;
-
Assert(bms_is_valid_set(a));
if (a == NULL)
return 0;
- nwords = a->nwords;
- wordnum = 0;
- do
- {
- bitmapword w = a->words[wordnum];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- } while (++wordnum < nwords);
- return result;
+ return pg_popcount((const char *) a->words,
+ a->nwords * sizeof(bitmapword));
}
/*
diff --git a/src/include/lib/radixtree.h b/src/include/lib/radixtree.h
index b223ce10a2d..1425654a67c 100644
--- a/src/include/lib/radixtree.h
+++ b/src/include/lib/radixtree.h
@@ -2725,8 +2725,8 @@ RT_VERIFY_NODE(RT_NODE * node)
/* RT_DUMP_NODE(node); */
- for (int i = 0; i < RT_BM_IDX(RT_NODE_MAX_SLOTS); i++)
- cnt += bmw_popcount(n256->isset[i]);
+ cnt += pg_popcount((const char *) n256->isset,
+ RT_NODE_MAX_SLOTS / BITS_PER_BYTE);
/*
* Check if the number of used chunk matches, accounting for
--
2.50.1 (Apple Git-155)
--vgXyZptCXHDBThGI
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
filename=v6-0002-Remove-unnecessary-32-bit-optimizations-and-align.patch
^ permalink raw reply [nested|flat] 14+ messages in thread
* [PATCH v11 3/4] Make use of pg_popcount() in more places.
@ 2026-01-22 17:16 Nathan Bossart <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Nathan Bossart @ 2026-01-22 17:16 UTC (permalink / raw)
This replaces some loops over word-length popcount functions with
calls to pg_popcount(). Since pg_popcount() uses a function
pointer for inputs with sizes >= a Bitmapset word, this produces a
small regression for the common one-word case in bms_num_members().
To deal with that, this commit adds an inlined fast-path for that
case. This fast-path could arguably go in pg_popcount() itself
(with an appropriate alignment check), but that is left as a future
exercise.
Suggested-by: John Naylor <[email protected]>
Reviewed-by: John Naylor <[email protected]>
Discussion: https://postgr.es/m/CANWCAZY7R%2Biy%2Br9YM_sySNydHzNqUirx1xk0tB3ej5HO62GdgQ%40mail.gmail.com
---
src/backend/nodes/bitmapset.c | 29 +++++++----------------------
src/include/lib/radixtree.h | 6 +++---
2 files changed, 10 insertions(+), 25 deletions(-)
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c
index a4765876c31..786f343b3c9 100644
--- a/src/backend/nodes/bitmapset.c
+++ b/src/backend/nodes/bitmapset.c
@@ -553,14 +553,8 @@ bms_member_index(Bitmapset *a, int x)
bitnum = BITNUM(x);
/* count bits in preceding words */
- for (int i = 0; i < wordnum; i++)
- {
- bitmapword w = a->words[i];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- }
+ result += pg_popcount((const char *) a->words,
+ wordnum * sizeof(bitmapword));
/*
* Now add bits of the last word, but only those before the item. We can
@@ -749,26 +743,17 @@ bms_get_singleton_member(const Bitmapset *a, int *member)
int
bms_num_members(const Bitmapset *a)
{
- int result = 0;
- int nwords;
- int wordnum;
-
Assert(bms_is_valid_set(a));
if (a == NULL)
return 0;
- nwords = a->nwords;
- wordnum = 0;
- do
- {
- bitmapword w = a->words[wordnum];
+ /* fast-path for common case */
+ if (a->nwords == 1)
+ return bmw_popcount(a->words[0]);
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- } while (++wordnum < nwords);
- return result;
+ return pg_popcount((const char *) a->words,
+ a->nwords * sizeof(bitmapword));
}
/*
diff --git a/src/include/lib/radixtree.h b/src/include/lib/radixtree.h
index b223ce10a2d..e6c9a591c17 100644
--- a/src/include/lib/radixtree.h
+++ b/src/include/lib/radixtree.h
@@ -2721,12 +2721,12 @@ RT_VERIFY_NODE(RT_NODE * node)
case RT_NODE_KIND_256:
{
RT_NODE_256 *n256 = (RT_NODE_256 *) node;
- int cnt = 0;
+ int cnt;
/* RT_DUMP_NODE(node); */
- for (int i = 0; i < RT_BM_IDX(RT_NODE_MAX_SLOTS); i++)
- cnt += bmw_popcount(n256->isset[i]);
+ cnt = pg_popcount((const char *) n256->isset,
+ RT_NODE_MAX_SLOTS / BITS_PER_BYTE);
/*
* Check if the number of used chunk matches, accounting for
--
2.50.1 (Apple Git-155)
--mih0IfQp6StcW7xc
Content-Type: text/plain; charset=us-ascii
Content-Disposition: attachment;
filename=v11-0004-Remove-uses-of-popcount-builtins.patch
^ permalink raw reply [nested|flat] 14+ messages in thread
* [PATCH v9 3/3] Make use of pg_popcount() in more places.
@ 2026-01-22 17:16 Nathan Bossart <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Nathan Bossart @ 2026-01-22 17:16 UTC (permalink / raw)
This replaces some loops over word-length popcount functions with
calls to our perhaps-over-optimized pg_popcount() function. Since
pg_popcount() uses a function pointer for inputs with sizes >= a
Bitmapset word, this produces a small regression for the common
one-word case in bms_num_members(). To deal with that, this commit
adds an inlined fast-path for that case. This fast-path could
arguably go in pg_popcount() itself (with an appropriate alignment
check), but that is left as a future exercise.
Suggested-by: John Naylor <[email protected]>
Reviewed-by: John Naylor <[email protected]>
Discussion: https://postgr.es/m/CANWCAZY7R%2Biy%2Br9YM_sySNydHzNqUirx1xk0tB3ej5HO62GdgQ%40mail.gmail.com
---
src/backend/nodes/bitmapset.c | 29 +++++++----------------------
src/include/lib/radixtree.h | 4 ++--
2 files changed, 9 insertions(+), 24 deletions(-)
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c
index a4765876c31..786f343b3c9 100644
--- a/src/backend/nodes/bitmapset.c
+++ b/src/backend/nodes/bitmapset.c
@@ -553,14 +553,8 @@ bms_member_index(Bitmapset *a, int x)
bitnum = BITNUM(x);
/* count bits in preceding words */
- for (int i = 0; i < wordnum; i++)
- {
- bitmapword w = a->words[i];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- }
+ result += pg_popcount((const char *) a->words,
+ wordnum * sizeof(bitmapword));
/*
* Now add bits of the last word, but only those before the item. We can
@@ -749,26 +743,17 @@ bms_get_singleton_member(const Bitmapset *a, int *member)
int
bms_num_members(const Bitmapset *a)
{
- int result = 0;
- int nwords;
- int wordnum;
-
Assert(bms_is_valid_set(a));
if (a == NULL)
return 0;
- nwords = a->nwords;
- wordnum = 0;
- do
- {
- bitmapword w = a->words[wordnum];
+ /* fast-path for common case */
+ if (a->nwords == 1)
+ return bmw_popcount(a->words[0]);
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- } while (++wordnum < nwords);
- return result;
+ return pg_popcount((const char *) a->words,
+ a->nwords * sizeof(bitmapword));
}
/*
diff --git a/src/include/lib/radixtree.h b/src/include/lib/radixtree.h
index b223ce10a2d..1425654a67c 100644
--- a/src/include/lib/radixtree.h
+++ b/src/include/lib/radixtree.h
@@ -2725,8 +2725,8 @@ RT_VERIFY_NODE(RT_NODE * node)
/* RT_DUMP_NODE(node); */
- for (int i = 0; i < RT_BM_IDX(RT_NODE_MAX_SLOTS); i++)
- cnt += bmw_popcount(n256->isset[i]);
+ cnt += pg_popcount((const char *) n256->isset,
+ RT_NODE_MAX_SLOTS / BITS_PER_BYTE);
/*
* Check if the number of used chunk matches, accounting for
--
2.50.1 (Apple Git-155)
--oEt0RkbzovU82iL7--
^ permalink raw reply [nested|flat] 14+ messages in thread
* [PATCH v12 4/4] Make use of pg_popcount() in more places.
@ 2026-02-10 18:40 Nathan Bossart <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Nathan Bossart @ 2026-02-10 18:40 UTC (permalink / raw)
This replaces some loops over word-length popcount functions with
calls to pg_popcount(). Since pg_popcount() uses a function
pointer for inputs with sizes >= a Bitmapset word, this produces a
small regression for the common one-word case in bms_num_members().
To deal with that, this commit adds an inlined fast-path for that
case. This fast-path could arguably go in pg_popcount() itself
(with an appropriate alignment check), but that is left for future
study.
Suggested-by: John Naylor <[email protected]>
Reviewed-by: John Naylor <[email protected]>
Discussion: https://postgr.es/m/CANWCAZY7R%2Biy%2Br9YM_sySNydHzNqUirx1xk0tB3ej5HO62GdgQ%40mail.gmail.com
---
src/backend/nodes/bitmapset.c | 29 +++++++----------------------
src/include/lib/radixtree.h | 6 +++---
2 files changed, 10 insertions(+), 25 deletions(-)
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c
index a4765876c31..786f343b3c9 100644
--- a/src/backend/nodes/bitmapset.c
+++ b/src/backend/nodes/bitmapset.c
@@ -553,14 +553,8 @@ bms_member_index(Bitmapset *a, int x)
bitnum = BITNUM(x);
/* count bits in preceding words */
- for (int i = 0; i < wordnum; i++)
- {
- bitmapword w = a->words[i];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- }
+ result += pg_popcount((const char *) a->words,
+ wordnum * sizeof(bitmapword));
/*
* Now add bits of the last word, but only those before the item. We can
@@ -749,26 +743,17 @@ bms_get_singleton_member(const Bitmapset *a, int *member)
int
bms_num_members(const Bitmapset *a)
{
- int result = 0;
- int nwords;
- int wordnum;
-
Assert(bms_is_valid_set(a));
if (a == NULL)
return 0;
- nwords = a->nwords;
- wordnum = 0;
- do
- {
- bitmapword w = a->words[wordnum];
+ /* fast-path for common case */
+ if (a->nwords == 1)
+ return bmw_popcount(a->words[0]);
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- } while (++wordnum < nwords);
- return result;
+ return pg_popcount((const char *) a->words,
+ a->nwords * sizeof(bitmapword));
}
/*
diff --git a/src/include/lib/radixtree.h b/src/include/lib/radixtree.h
index b223ce10a2d..e6c9a591c17 100644
--- a/src/include/lib/radixtree.h
+++ b/src/include/lib/radixtree.h
@@ -2721,12 +2721,12 @@ RT_VERIFY_NODE(RT_NODE * node)
case RT_NODE_KIND_256:
{
RT_NODE_256 *n256 = (RT_NODE_256 *) node;
- int cnt = 0;
+ int cnt;
/* RT_DUMP_NODE(node); */
- for (int i = 0; i < RT_BM_IDX(RT_NODE_MAX_SLOTS); i++)
- cnt += bmw_popcount(n256->isset[i]);
+ cnt = pg_popcount((const char *) n256->isset,
+ RT_NODE_MAX_SLOTS / BITS_PER_BYTE);
/*
* Check if the number of used chunk matches, accounting for
--
2.50.1 (Apple Git-155)
--AFLuD1w+kMRlv6Zk--
^ permalink raw reply [nested|flat] 14+ messages in thread
* [PATCH v15 2/2] Make use of pg_popcount() in more places.
@ 2026-02-10 18:40 Nathan Bossart <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Nathan Bossart @ 2026-02-10 18:40 UTC (permalink / raw)
This replaces some loops over word-length popcount functions with
calls to pg_popcount(). Since pg_popcount() uses a function
pointer for inputs with sizes >= a Bitmapset word, this produces a
small regression for the common one-word case in bms_num_members().
To deal with that, this commit adds an inlined fast-path for that
case. This fast-path could arguably go in pg_popcount() itself
(with an appropriate alignment check), but that is left for future
study.
Suggested-by: John Naylor <[email protected]>
Reviewed-by: John Naylor <[email protected]>
Discussion: https://postgr.es/m/CANWCAZY7R%2Biy%2Br9YM_sySNydHzNqUirx1xk0tB3ej5HO62GdgQ%40mail.gmail.com
---
src/backend/nodes/bitmapset.c | 29 +++++++----------------------
src/include/lib/radixtree.h | 6 +++---
2 files changed, 10 insertions(+), 25 deletions(-)
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c
index a4765876c31..786f343b3c9 100644
--- a/src/backend/nodes/bitmapset.c
+++ b/src/backend/nodes/bitmapset.c
@@ -553,14 +553,8 @@ bms_member_index(Bitmapset *a, int x)
bitnum = BITNUM(x);
/* count bits in preceding words */
- for (int i = 0; i < wordnum; i++)
- {
- bitmapword w = a->words[i];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- }
+ result += pg_popcount((const char *) a->words,
+ wordnum * sizeof(bitmapword));
/*
* Now add bits of the last word, but only those before the item. We can
@@ -749,26 +743,17 @@ bms_get_singleton_member(const Bitmapset *a, int *member)
int
bms_num_members(const Bitmapset *a)
{
- int result = 0;
- int nwords;
- int wordnum;
-
Assert(bms_is_valid_set(a));
if (a == NULL)
return 0;
- nwords = a->nwords;
- wordnum = 0;
- do
- {
- bitmapword w = a->words[wordnum];
+ /* fast-path for common case */
+ if (a->nwords == 1)
+ return bmw_popcount(a->words[0]);
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- } while (++wordnum < nwords);
- return result;
+ return pg_popcount((const char *) a->words,
+ a->nwords * sizeof(bitmapword));
}
/*
diff --git a/src/include/lib/radixtree.h b/src/include/lib/radixtree.h
index b223ce10a2d..e6c9a591c17 100644
--- a/src/include/lib/radixtree.h
+++ b/src/include/lib/radixtree.h
@@ -2721,12 +2721,12 @@ RT_VERIFY_NODE(RT_NODE * node)
case RT_NODE_KIND_256:
{
RT_NODE_256 *n256 = (RT_NODE_256 *) node;
- int cnt = 0;
+ int cnt;
/* RT_DUMP_NODE(node); */
- for (int i = 0; i < RT_BM_IDX(RT_NODE_MAX_SLOTS); i++)
- cnt += bmw_popcount(n256->isset[i]);
+ cnt = pg_popcount((const char *) n256->isset,
+ RT_NODE_MAX_SLOTS / BITS_PER_BYTE);
/*
* Check if the number of used chunk matches, accounting for
--
2.50.1 (Apple Git-155)
--PPBl4GgF05zqfOFU--
^ permalink raw reply [nested|flat] 14+ messages in thread
* [PATCH v14 2/2] Make use of pg_popcount() in more places.
@ 2026-02-10 18:40 Nathan Bossart <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Nathan Bossart @ 2026-02-10 18:40 UTC (permalink / raw)
This replaces some loops over word-length popcount functions with
calls to pg_popcount(). Since pg_popcount() uses a function
pointer for inputs with sizes >= a Bitmapset word, this produces a
small regression for the common one-word case in bms_num_members().
To deal with that, this commit adds an inlined fast-path for that
case. This fast-path could arguably go in pg_popcount() itself
(with an appropriate alignment check), but that is left for future
study.
Suggested-by: John Naylor <[email protected]>
Reviewed-by: John Naylor <[email protected]>
Discussion: https://postgr.es/m/CANWCAZY7R%2Biy%2Br9YM_sySNydHzNqUirx1xk0tB3ej5HO62GdgQ%40mail.gmail.com
---
src/backend/nodes/bitmapset.c | 29 +++++++----------------------
src/include/lib/radixtree.h | 6 +++---
2 files changed, 10 insertions(+), 25 deletions(-)
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c
index a4765876c31..786f343b3c9 100644
--- a/src/backend/nodes/bitmapset.c
+++ b/src/backend/nodes/bitmapset.c
@@ -553,14 +553,8 @@ bms_member_index(Bitmapset *a, int x)
bitnum = BITNUM(x);
/* count bits in preceding words */
- for (int i = 0; i < wordnum; i++)
- {
- bitmapword w = a->words[i];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- }
+ result += pg_popcount((const char *) a->words,
+ wordnum * sizeof(bitmapword));
/*
* Now add bits of the last word, but only those before the item. We can
@@ -749,26 +743,17 @@ bms_get_singleton_member(const Bitmapset *a, int *member)
int
bms_num_members(const Bitmapset *a)
{
- int result = 0;
- int nwords;
- int wordnum;
-
Assert(bms_is_valid_set(a));
if (a == NULL)
return 0;
- nwords = a->nwords;
- wordnum = 0;
- do
- {
- bitmapword w = a->words[wordnum];
+ /* fast-path for common case */
+ if (a->nwords == 1)
+ return bmw_popcount(a->words[0]);
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- } while (++wordnum < nwords);
- return result;
+ return pg_popcount((const char *) a->words,
+ a->nwords * sizeof(bitmapword));
}
/*
diff --git a/src/include/lib/radixtree.h b/src/include/lib/radixtree.h
index b223ce10a2d..e6c9a591c17 100644
--- a/src/include/lib/radixtree.h
+++ b/src/include/lib/radixtree.h
@@ -2721,12 +2721,12 @@ RT_VERIFY_NODE(RT_NODE * node)
case RT_NODE_KIND_256:
{
RT_NODE_256 *n256 = (RT_NODE_256 *) node;
- int cnt = 0;
+ int cnt;
/* RT_DUMP_NODE(node); */
- for (int i = 0; i < RT_BM_IDX(RT_NODE_MAX_SLOTS); i++)
- cnt += bmw_popcount(n256->isset[i]);
+ cnt = pg_popcount((const char *) n256->isset,
+ RT_NODE_MAX_SLOTS / BITS_PER_BYTE);
/*
* Check if the number of used chunk matches, accounting for
--
2.50.1 (Apple Git-155)
--rjsRYmGG7r/fFdxn--
^ permalink raw reply [nested|flat] 14+ messages in thread
* [PATCH v13 5/5] Make use of pg_popcount() in more places.
@ 2026-02-10 18:40 Nathan Bossart <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Nathan Bossart @ 2026-02-10 18:40 UTC (permalink / raw)
This replaces some loops over word-length popcount functions with
calls to pg_popcount(). Since pg_popcount() uses a function
pointer for inputs with sizes >= a Bitmapset word, this produces a
small regression for the common one-word case in bms_num_members().
To deal with that, this commit adds an inlined fast-path for that
case. This fast-path could arguably go in pg_popcount() itself
(with an appropriate alignment check), but that is left for future
study.
Suggested-by: John Naylor <[email protected]>
Reviewed-by: John Naylor <[email protected]>
Discussion: https://postgr.es/m/CANWCAZY7R%2Biy%2Br9YM_sySNydHzNqUirx1xk0tB3ej5HO62GdgQ%40mail.gmail.com
---
src/backend/nodes/bitmapset.c | 29 +++++++----------------------
src/include/lib/radixtree.h | 6 +++---
2 files changed, 10 insertions(+), 25 deletions(-)
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c
index a4765876c31..786f343b3c9 100644
--- a/src/backend/nodes/bitmapset.c
+++ b/src/backend/nodes/bitmapset.c
@@ -553,14 +553,8 @@ bms_member_index(Bitmapset *a, int x)
bitnum = BITNUM(x);
/* count bits in preceding words */
- for (int i = 0; i < wordnum; i++)
- {
- bitmapword w = a->words[i];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- }
+ result += pg_popcount((const char *) a->words,
+ wordnum * sizeof(bitmapword));
/*
* Now add bits of the last word, but only those before the item. We can
@@ -749,26 +743,17 @@ bms_get_singleton_member(const Bitmapset *a, int *member)
int
bms_num_members(const Bitmapset *a)
{
- int result = 0;
- int nwords;
- int wordnum;
-
Assert(bms_is_valid_set(a));
if (a == NULL)
return 0;
- nwords = a->nwords;
- wordnum = 0;
- do
- {
- bitmapword w = a->words[wordnum];
+ /* fast-path for common case */
+ if (a->nwords == 1)
+ return bmw_popcount(a->words[0]);
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- } while (++wordnum < nwords);
- return result;
+ return pg_popcount((const char *) a->words,
+ a->nwords * sizeof(bitmapword));
}
/*
diff --git a/src/include/lib/radixtree.h b/src/include/lib/radixtree.h
index b223ce10a2d..e6c9a591c17 100644
--- a/src/include/lib/radixtree.h
+++ b/src/include/lib/radixtree.h
@@ -2721,12 +2721,12 @@ RT_VERIFY_NODE(RT_NODE * node)
case RT_NODE_KIND_256:
{
RT_NODE_256 *n256 = (RT_NODE_256 *) node;
- int cnt = 0;
+ int cnt;
/* RT_DUMP_NODE(node); */
- for (int i = 0; i < RT_BM_IDX(RT_NODE_MAX_SLOTS); i++)
- cnt += bmw_popcount(n256->isset[i]);
+ cnt = pg_popcount((const char *) n256->isset,
+ RT_NODE_MAX_SLOTS / BITS_PER_BYTE);
/*
* Check if the number of used chunk matches, accounting for
--
2.50.1 (Apple Git-155)
--5NNwvjHYUnRaoEDo--
^ permalink raw reply [nested|flat] 14+ messages in thread
* [PATCH v16 2/2] Make use of pg_popcount() in more places.
@ 2026-02-10 18:40 Nathan Bossart <[email protected]>
0 siblings, 0 replies; 14+ messages in thread
From: Nathan Bossart @ 2026-02-10 18:40 UTC (permalink / raw)
This replaces some loops over word-length popcount functions with
calls to pg_popcount(). Since pg_popcount() uses a function
pointer for inputs with sizes >= a Bitmapset word, this produces a
small regression for the common one-word case in bms_num_members().
To deal with that, this commit adds an inlined fast-path for that
case. This fast-path could arguably go in pg_popcount() itself
(with an appropriate alignment check), but that is left for future
study.
Suggested-by: John Naylor <[email protected]>
Reviewed-by: John Naylor <[email protected]>
Discussion: https://postgr.es/m/CANWCAZY7R%2Biy%2Br9YM_sySNydHzNqUirx1xk0tB3ej5HO62GdgQ%40mail.gmail.com
---
src/backend/nodes/bitmapset.c | 29 +++++++----------------------
src/include/lib/radixtree.h | 6 +++---
2 files changed, 10 insertions(+), 25 deletions(-)
diff --git a/src/backend/nodes/bitmapset.c b/src/backend/nodes/bitmapset.c
index a4765876c31..786f343b3c9 100644
--- a/src/backend/nodes/bitmapset.c
+++ b/src/backend/nodes/bitmapset.c
@@ -553,14 +553,8 @@ bms_member_index(Bitmapset *a, int x)
bitnum = BITNUM(x);
/* count bits in preceding words */
- for (int i = 0; i < wordnum; i++)
- {
- bitmapword w = a->words[i];
-
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- }
+ result += pg_popcount((const char *) a->words,
+ wordnum * sizeof(bitmapword));
/*
* Now add bits of the last word, but only those before the item. We can
@@ -749,26 +743,17 @@ bms_get_singleton_member(const Bitmapset *a, int *member)
int
bms_num_members(const Bitmapset *a)
{
- int result = 0;
- int nwords;
- int wordnum;
-
Assert(bms_is_valid_set(a));
if (a == NULL)
return 0;
- nwords = a->nwords;
- wordnum = 0;
- do
- {
- bitmapword w = a->words[wordnum];
+ /* fast-path for common case */
+ if (a->nwords == 1)
+ return bmw_popcount(a->words[0]);
- /* No need to count the bits in a zero word */
- if (w != 0)
- result += bmw_popcount(w);
- } while (++wordnum < nwords);
- return result;
+ return pg_popcount((const char *) a->words,
+ a->nwords * sizeof(bitmapword));
}
/*
diff --git a/src/include/lib/radixtree.h b/src/include/lib/radixtree.h
index b223ce10a2d..e6c9a591c17 100644
--- a/src/include/lib/radixtree.h
+++ b/src/include/lib/radixtree.h
@@ -2721,12 +2721,12 @@ RT_VERIFY_NODE(RT_NODE * node)
case RT_NODE_KIND_256:
{
RT_NODE_256 *n256 = (RT_NODE_256 *) node;
- int cnt = 0;
+ int cnt;
/* RT_DUMP_NODE(node); */
- for (int i = 0; i < RT_BM_IDX(RT_NODE_MAX_SLOTS); i++)
- cnt += bmw_popcount(n256->isset[i]);
+ cnt = pg_popcount((const char *) n256->isset,
+ RT_NODE_MAX_SLOTS / BITS_PER_BYTE);
/*
* Check if the number of used chunk matches, accounting for
--
2.50.1 (Apple Git-155)
--/1paUjurV8mGDyTY--
^ permalink raw reply [nested|flat] 14+ messages in thread
end of thread, other threads:[~2026-02-10 18:40 UTC | newest]
Thread overview: 14+ messages (download: mbox mbox.gz follow: Atom feed)
-- links below jump to the message on this page --
2025-12-18 17:21 [PATCH v1] Use open file description locks for data directory lockfile Dmitrii Dolgov <[email protected]>
2026-01-22 17:16 [PATCH v8 3/3] Make use of pg_popcount() in more places. Nathan Bossart <[email protected]>
2026-01-22 17:16 [PATCH v10 3/3] Make use of pg_popcount() in more places. Nathan Bossart <[email protected]>
2026-01-22 17:16 [PATCH v4 1/4] Make use of pg_popcount() in more places. Nathan Bossart <[email protected]>
2026-01-22 17:16 [PATCH v5 1/3] Make use of pg_popcount() in more places. Nathan Bossart <[email protected]>
2026-01-22 17:16 [PATCH v3 1/2] Make use of pg_popcount() in more places. Nathan Bossart <[email protected]>
2026-01-22 17:16 [PATCH v6 1/3] Make use of pg_popcount() in more places. Nathan Bossart <[email protected]>
2026-01-22 17:16 [PATCH v11 3/4] Make use of pg_popcount() in more places. Nathan Bossart <[email protected]>
2026-01-22 17:16 [PATCH v9 3/3] Make use of pg_popcount() in more places. Nathan Bossart <[email protected]>
2026-02-10 18:40 [PATCH v12 4/4] Make use of pg_popcount() in more places. Nathan Bossart <[email protected]>
2026-02-10 18:40 [PATCH v15 2/2] Make use of pg_popcount() in more places. Nathan Bossart <[email protected]>
2026-02-10 18:40 [PATCH v14 2/2] Make use of pg_popcount() in more places. Nathan Bossart <[email protected]>
2026-02-10 18:40 [PATCH v13 5/5] Make use of pg_popcount() in more places. Nathan Bossart <[email protected]>
2026-02-10 18:40 [PATCH v16 2/2] Make use of pg_popcount() in more places. Nathan Bossart <[email protected]>
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