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Re: ReadRecentBuffer() doesn't scale well 2+ messages / 2 participants [nested] [flat]
* Re: ReadRecentBuffer() doesn't scale well @ 2023-06-27 03:44 Peter Geoghegan <[email protected]> 0 siblings, 0 replies; 2+ messages in thread From: Peter Geoghegan @ 2023-06-27 03:44 UTC (permalink / raw) To: Thomas Munro <[email protected]>; +Cc: Andres Freund <[email protected]>; pgsql-hackers On Mon, Jun 26, 2023 at 8:34 PM Thomas Munro <[email protected]> wrote: > Yeah. Aside from inherent nastiness of user-space spinlocks, this new > use case is also enormously more likely to contend and then get into > trouble by being preempted due to btree root pages being about the > hottest pages in the universe than the use case I was focusing on at > the time. They're not just the hottest. They're also among the least likely to change from one moment to the next. (If that ever failed to hold then it wouldn't take long for the index to become grotesquely tall.) -- Peter Geoghegan ^ permalink raw reply [nested|flat] 2+ messages in thread
* [PATCH v1 1/1] remove WaitEventCustomCounterData @ 2026-07-09 02:50 Nathan Bossart <[email protected]> 0 siblings, 0 replies; 2+ messages in thread From: Nathan Bossart @ 2026-07-09 02:50 UTC (permalink / raw) --- src/backend/utils/activity/wait_event.c | 29 ++++++------------------- src/tools/pgindent/typedefs.list | 1 - 2 files changed, 7 insertions(+), 23 deletions(-) diff --git a/src/backend/utils/activity/wait_event.c b/src/backend/utils/activity/wait_event.c index 95635c7f56c..7ee6f99fb50 100644 --- a/src/backend/utils/activity/wait_event.c +++ b/src/backend/utils/activity/wait_event.c @@ -81,14 +81,7 @@ typedef struct WaitEventCustomEntryByName /* dynamic allocation counter for custom wait events */ -typedef struct WaitEventCustomCounterData -{ - int nextId; /* next ID to assign */ - slock_t mutex; /* protects the counter */ -} WaitEventCustomCounterData; - -/* pointer to the shared memory */ -static WaitEventCustomCounterData *WaitEventCustomCounter; +static int *WaitEventCustomCounter; /* first event ID of custom wait events */ #define WAIT_EVENT_CUSTOM_INITIAL_ID 1 @@ -110,8 +103,8 @@ const ShmemCallbacks WaitEventCustomShmemCallbacks = { static void WaitEventCustomShmemRequest(void *arg) { - ShmemRequestStruct(.name = "WaitEventCustomCounterData", - .size = sizeof(WaitEventCustomCounterData), + ShmemRequestStruct(.name = "WaitEventCustomCounter", + .size = sizeof(int), .ptr = (void **) &WaitEventCustomCounter, ); ShmemRequestHash(.name = "WaitEventCustom hash by wait event information", @@ -134,9 +127,8 @@ WaitEventCustomShmemRequest(void *arg) static void WaitEventCustomShmemInit(void *arg) { - /* initialize the allocation counter and its spinlock. */ - WaitEventCustomCounter->nextId = WAIT_EVENT_CUSTOM_INITIAL_ID; - SpinLockInit(&WaitEventCustomCounter->mutex); + /* initialize the allocation counter */ + *WaitEventCustomCounter = WAIT_EVENT_CUSTOM_INITIAL_ID; } /* @@ -221,19 +213,12 @@ WaitEventCustomNew(uint32 classId, const char *wait_event_name) } /* Allocate a new event Id */ - SpinLockAcquire(&WaitEventCustomCounter->mutex); - - if (WaitEventCustomCounter->nextId >= WAIT_EVENT_CUSTOM_HASH_SIZE) - { - SpinLockRelease(&WaitEventCustomCounter->mutex); + if (*WaitEventCustomCounter >= WAIT_EVENT_CUSTOM_HASH_SIZE) ereport(ERROR, errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), errmsg("too many custom wait events")); - } - - eventId = WaitEventCustomCounter->nextId++; - SpinLockRelease(&WaitEventCustomCounter->mutex); + eventId = (*WaitEventCustomCounter)++; /* Register the new wait event */ wait_event_info = classId | eventId; diff --git a/src/tools/pgindent/typedefs.list b/src/tools/pgindent/typedefs.list index ffb413ab612..3174e0e4ab8 100644 --- a/src/tools/pgindent/typedefs.list +++ b/src/tools/pgindent/typedefs.list @@ -3418,7 +3418,6 @@ WaitEvent WaitEventActivity WaitEventBuffer WaitEventClient -WaitEventCustomCounterData WaitEventCustomEntryByInfo WaitEventCustomEntryByName WaitEventIO -- 2.50.1 (Apple Git-155) --65l7A33W789+zwjF-- ^ permalink raw reply [nested|flat] 2+ messages in thread
end of thread, other threads:[~2026-07-09 02:50 UTC | newest] Thread overview: 2+ messages (download: mbox mbox.gz follow: Atom feed) -- links below jump to the message on this page -- 2023-06-27 03:44 Re: ReadRecentBuffer() doesn't scale well Peter Geoghegan <[email protected]> 2026-07-09 02:50 [PATCH v1 1/1] remove WaitEventCustomCounterData Nathan Bossart <[email protected]>
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