From 168603c7f9dc1852c2e5a927da3b7b31baf65eb2 Mon Sep 17 00:00:00 2001 From: Jakub Wartak Date: Thu, 8 Jan 2026 12:18:03 +0100 Subject: [PATCH v3 3/4] wait_event_arg: implement SLRU type reporting for IO/Slru* wait events pg_stat_activity.wait_event_arg now can be used to pinpoint exact SLRU type in case of backends performing lots of SLRU I/O. Author: Jakub Wartak Reviewed-by: Discussion: https://www.postgresql.org/message-id/flat/CAKZiRmyKcTaeSGzMYDN6aRR-BwYGPeZbzDRKvGkJhxAghfb4LQ%40mail.gmail.com --- src/backend/access/transam/clog.c | 2 +- src/backend/access/transam/commit_ts.c | 11 ++++++----- src/backend/access/transam/multixact.c | 4 ++-- src/backend/access/transam/slru.c | 11 ++++++----- src/backend/access/transam/subtrans.c | 7 ++++--- src/backend/commands/async.c | 7 ++++--- src/backend/storage/lmgr/predicate.c | 2 +- src/include/access/slru.h | 17 ++++++++++++++++- src/test/modules/test_slru/test_slru.c | 2 +- 9 files changed, 41 insertions(+), 22 deletions(-) diff --git a/src/backend/access/transam/clog.c b/src/backend/access/transam/clog.c index b5c38bbb16..6a42ce239a 100644 --- a/src/backend/access/transam/clog.c +++ b/src/backend/access/transam/clog.c @@ -807,7 +807,7 @@ CLOGShmemInit(void) Assert(transaction_buffers != 0); XactCtl->PagePrecedes = CLOGPagePrecedes; - SimpleLruInit(XactCtl, "transaction", CLOGShmemBuffers(), CLOG_LSNS_PER_PAGE, + SimpleLruInit(XactCtl, SLRU_TYPE_CLOG, "transaction", CLOGShmemBuffers(), CLOG_LSNS_PER_PAGE, "pg_xact", LWTRANCHE_XACT_BUFFER, LWTRANCHE_XACT_SLRU, SYNC_HANDLER_CLOG, false); SlruPagePrecedesUnitTests(XactCtl, CLOG_XACTS_PER_PAGE); diff --git a/src/backend/access/transam/commit_ts.c b/src/backend/access/transam/commit_ts.c index 082b564da8..8fedf839a7 100644 --- a/src/backend/access/transam/commit_ts.c +++ b/src/backend/access/transam/commit_ts.c @@ -551,11 +551,12 @@ CommitTsShmemInit(void) Assert(commit_timestamp_buffers != 0); CommitTsCtl->PagePrecedes = CommitTsPagePrecedes; - SimpleLruInit(CommitTsCtl, "commit_timestamp", CommitTsShmemBuffers(), 0, - "pg_commit_ts", LWTRANCHE_COMMITTS_BUFFER, - LWTRANCHE_COMMITTS_SLRU, - SYNC_HANDLER_COMMIT_TS, - false); + SimpleLruInit(CommitTsCtl, SLRU_TYPE_COMMIT_TS, + "commit_timestamp", CommitTsShmemBuffers(), 0, + "pg_commit_ts", LWTRANCHE_COMMITTS_BUFFER, + LWTRANCHE_COMMITTS_SLRU, + SYNC_HANDLER_COMMIT_TS, + false); SlruPagePrecedesUnitTests(CommitTsCtl, COMMIT_TS_XACTS_PER_PAGE); commitTsShared = ShmemInitStruct("CommitTs shared", diff --git a/src/backend/access/transam/multixact.c b/src/backend/access/transam/multixact.c index b2a04e34b2..85ad857bf0 100644 --- a/src/backend/access/transam/multixact.c +++ b/src/backend/access/transam/multixact.c @@ -1738,14 +1738,14 @@ MultiXactShmemInit(void) MultiXactOffsetCtl->PagePrecedes = MultiXactOffsetPagePrecedes; MultiXactMemberCtl->PagePrecedes = MultiXactMemberPagePrecedes; - SimpleLruInit(MultiXactOffsetCtl, + SimpleLruInit(MultiXactOffsetCtl, SLRU_TYPE_MULTIXACT_OFFSET, "multixact_offset", multixact_offset_buffers, 0, "pg_multixact/offsets", LWTRANCHE_MULTIXACTOFFSET_BUFFER, LWTRANCHE_MULTIXACTOFFSET_SLRU, SYNC_HANDLER_MULTIXACT_OFFSET, false); SlruPagePrecedesUnitTests(MultiXactOffsetCtl, MULTIXACT_OFFSETS_PER_PAGE); - SimpleLruInit(MultiXactMemberCtl, + SimpleLruInit(MultiXactMemberCtl, SLRU_TYPE_MULTIXACT_MEMBER, "multixact_member", multixact_member_buffers, 0, "pg_multixact/members", LWTRANCHE_MULTIXACTMEMBER_BUFFER, LWTRANCHE_MULTIXACTMEMBER_SLRU, diff --git a/src/backend/access/transam/slru.c b/src/backend/access/transam/slru.c index 549c7e3e64..434c07e031 100644 --- a/src/backend/access/transam/slru.c +++ b/src/backend/access/transam/slru.c @@ -249,7 +249,7 @@ SimpleLruAutotuneBuffers(int divisor, int max) * long_segment_names: use short or long segment names */ void -SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns, +SimpleLruInit(SlruCtl ctl, SlruType type, const char *name, int nslots, int nlsns, const char *subdir, int buffer_tranche_id, int bank_tranche_id, SyncRequestHandler sync_handler, bool long_segment_names) { @@ -345,6 +345,7 @@ SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns, ctl->long_segment_names = long_segment_names; ctl->nbanks = nbanks; strlcpy(ctl->Dir, subdir, sizeof(ctl->Dir)); + ctl->type = type; } /* @@ -862,7 +863,7 @@ SlruPhysicalReadPage(SlruCtl ctl, int64 pageno, int slotno) } errno = 0; - pgstat_report_wait_start(WAIT_EVENT_SLRU_READ); + pgstat_report_wait_start(WAIT_EVENT_SLRU_READ | ctl->type); if (pg_pread(fd, shared->page_buffer[slotno], BLCKSZ, offset) != BLCKSZ) { pgstat_report_wait_end(); @@ -1014,7 +1015,7 @@ SlruPhysicalWritePage(SlruCtl ctl, int64 pageno, int slotno, SlruWriteAll fdata) } errno = 0; - pgstat_report_wait_start(WAIT_EVENT_SLRU_WRITE); + pgstat_report_wait_start(WAIT_EVENT_SLRU_WRITE | ctl->type); if (pg_pwrite(fd, shared->page_buffer[slotno], BLCKSZ, offset) != BLCKSZ) { pgstat_report_wait_end(); @@ -1038,7 +1039,7 @@ SlruPhysicalWritePage(SlruCtl ctl, int64 pageno, int slotno, SlruWriteAll fdata) if (!RegisterSyncRequest(&tag, SYNC_REQUEST, false)) { /* No space to enqueue sync request. Do it synchronously. */ - pgstat_report_wait_start(WAIT_EVENT_SLRU_SYNC); + pgstat_report_wait_start(WAIT_EVENT_SLRU_SYNC | ctl->type); if (pg_fsync(fd) != 0) { pgstat_report_wait_end(); @@ -1865,7 +1866,7 @@ SlruSyncFileTag(SlruCtl ctl, const FileTag *ftag, char *path) if (fd < 0) return -1; - pgstat_report_wait_start(WAIT_EVENT_SLRU_FLUSH_SYNC); + pgstat_report_wait_start(WAIT_EVENT_SLRU_FLUSH_SYNC | ctl->type); result = pg_fsync(fd); pgstat_report_wait_end(); save_errno = errno; diff --git a/src/backend/access/transam/subtrans.c b/src/backend/access/transam/subtrans.c index c0987f43f1..bc50e3e7ab 100644 --- a/src/backend/access/transam/subtrans.c +++ b/src/backend/access/transam/subtrans.c @@ -240,9 +240,10 @@ SUBTRANSShmemInit(void) Assert(subtransaction_buffers != 0); SubTransCtl->PagePrecedes = SubTransPagePrecedes; - SimpleLruInit(SubTransCtl, "subtransaction", SUBTRANSShmemBuffers(), 0, - "pg_subtrans", LWTRANCHE_SUBTRANS_BUFFER, - LWTRANCHE_SUBTRANS_SLRU, SYNC_HANDLER_NONE, false); + SimpleLruInit(SubTransCtl, SLRU_TYPE_SUBTRANS, + "subtransaction", SUBTRANSShmemBuffers(), 0, + "pg_subtrans", LWTRANCHE_SUBTRANS_BUFFER, + LWTRANCHE_SUBTRANS_SLRU, SYNC_HANDLER_NONE, false); SlruPagePrecedesUnitTests(SubTransCtl, SUBTRANS_XACTS_PER_PAGE); } diff --git a/src/backend/commands/async.c b/src/backend/commands/async.c index 40c42f572e..1c2d07af18 100644 --- a/src/backend/commands/async.c +++ b/src/backend/commands/async.c @@ -534,9 +534,10 @@ AsyncShmemInit(void) * names are used in order to avoid wraparound. */ NotifyCtl->PagePrecedes = asyncQueuePagePrecedes; - SimpleLruInit(NotifyCtl, "notify", notify_buffers, 0, - "pg_notify", LWTRANCHE_NOTIFY_BUFFER, LWTRANCHE_NOTIFY_SLRU, - SYNC_HANDLER_NONE, true); + SimpleLruInit(NotifyCtl, SLRU_TYPE_NOTIFY, "notify", + notify_buffers, 0, + "pg_notify", LWTRANCHE_NOTIFY_BUFFER, LWTRANCHE_NOTIFY_SLRU, + SYNC_HANDLER_NONE, true); if (!found) { diff --git a/src/backend/storage/lmgr/predicate.c b/src/backend/storage/lmgr/predicate.c index fe75ead350..11cc9cf6ac 100644 --- a/src/backend/storage/lmgr/predicate.c +++ b/src/backend/storage/lmgr/predicate.c @@ -811,7 +811,7 @@ SerialInit(void) * Set up SLRU management of the pg_serial data. */ SerialSlruCtl->PagePrecedes = SerialPagePrecedesLogically; - SimpleLruInit(SerialSlruCtl, "serializable", + SimpleLruInit(SerialSlruCtl, SLRU_TYPE_SERIAL, "serializable", serializable_buffers, 0, "pg_serial", LWTRANCHE_SERIAL_BUFFER, LWTRANCHE_SERIAL_SLRU, SYNC_HANDLER_NONE, false); diff --git a/src/include/access/slru.h b/src/include/access/slru.h index 4cb8f478fc..a94df291bf 100644 --- a/src/include/access/slru.h +++ b/src/include/access/slru.h @@ -37,6 +37,18 @@ typedef enum SLRU_PAGE_WRITE_IN_PROGRESS, /* page is being written out */ } SlruPageStatus; +/* Used only for pg_stat_activity.wait_event_arg for Slru* wait events */ +typedef enum { + SLRU_TYPE_UNKNOWN, + SLRU_TYPE_NOTIFY, + SLRU_TYPE_CLOG, + SLRU_TYPE_SUBTRANS, + SLRU_TYPE_COMMIT_TS, + SLRU_TYPE_MULTIXACT_OFFSET, + SLRU_TYPE_MULTIXACT_MEMBER, + SLRU_TYPE_SERIAL +} SlruType; + /* * Shared-memory state * @@ -113,6 +125,9 @@ typedef struct SlruCtlData { SlruShared shared; + /* Type of SLRU that is later passed pgstat_report_wait_start() */ + SlruType type; + /* Number of banks in this SLRU. */ uint16 nbanks; @@ -167,7 +182,7 @@ SimpleLruGetBankLock(SlruCtl ctl, int64 pageno) extern Size SimpleLruShmemSize(int nslots, int nlsns); extern int SimpleLruAutotuneBuffers(int divisor, int max); -extern void SimpleLruInit(SlruCtl ctl, const char *name, int nslots, int nlsns, +extern void SimpleLruInit(SlruCtl ctl, SlruType type, const char *name, int nslots, int nlsns, const char *subdir, int buffer_tranche_id, int bank_tranche_id, SyncRequestHandler sync_handler, bool long_segment_names); diff --git a/src/test/modules/test_slru/test_slru.c b/src/test/modules/test_slru/test_slru.c index 4dc74e1962..c817629fa2 100644 --- a/src/test/modules/test_slru/test_slru.c +++ b/src/test/modules/test_slru/test_slru.c @@ -245,7 +245,7 @@ test_slru_shmem_startup(void) } TestSlruCtl->PagePrecedes = test_slru_page_precedes_logically; - SimpleLruInit(TestSlruCtl, "TestSLRU", + SimpleLruInit(TestSlruCtl, SLRU_TYPE_UNKNOWN, "TestSLRU", NUM_TEST_BUFFERS, 0, slru_dir_name, test_buffer_tranche_id, test_tranche_id, SYNC_HANDLER_NONE, long_segment_names); -- 2.43.0