From 74604a37f2f9eb6e626a4ff3cedd02aef5a2ad59 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Fri, 27 Oct 2023 11:16:39 +0900 Subject: Remove buffers_backend and buffers_backend_fsync from pg_stat_checkpointer Two attributes related to checkpointer statistics are removed in this commit: - buffers_backend, that counts the number of buffers written directly by a backend. - buffers_backend_fsync, that counts the number of times a backend had to do fsync() by its own. These are actually not checkpointer properties but backend properties. Also, pg_stat_io provides a more accurate and equivalent report of these numbers, by tracking all the I/O stats related to backends, including writes and fsyncs, so storing them in pg_stat_checkpointer was redundant. Thanks also to Robert Haas and Amit Kapila for their input. Bump catalog version. Author: Bharath Rupireddy Reviewed-by: Bertrand Drouvot, Andres Freund Discussion: https://postgr.es/m/20230210004604.mcszbscsqs3bc5nx@awork3.anarazel.de --- src/backend/postmaster/checkpointer.c | 32 ++------------------------------ 1 file changed, 2 insertions(+), 30 deletions(-) (limited to 'src/backend/postmaster/checkpointer.c') diff --git a/src/backend/postmaster/checkpointer.c b/src/backend/postmaster/checkpointer.c index ace9893d957..4fe403c9a89 100644 --- a/src/backend/postmaster/checkpointer.c +++ b/src/backend/postmaster/checkpointer.c @@ -91,17 +91,11 @@ * requesting backends since the last checkpoint start. The flags are * chosen so that OR'ing is the correct way to combine multiple requests. * - * num_backend_writes is used to count the number of buffer writes performed - * by user backend processes. This counter should be wide enough that it - * can't overflow during a single processing cycle. num_backend_fsync - * counts the subset of those writes that also had to do their own fsync, - * because the checkpointer failed to absorb their request. - * * The requests array holds fsync requests sent by backends and not yet * absorbed by the checkpointer. * - * Unlike the checkpoint fields, num_backend_writes, num_backend_fsync, and - * the requests fields are protected by CheckpointerCommLock. + * Unlike the checkpoint fields, requests related fields are protected by + * CheckpointerCommLock. *---------- */ typedef struct @@ -125,9 +119,6 @@ typedef struct ConditionVariable start_cv; /* signaled when ckpt_started advances */ ConditionVariable done_cv; /* signaled when ckpt_done advances */ - uint32 num_backend_writes; /* counts user backend buffer writes */ - uint32 num_backend_fsync; /* counts user backend fsync calls */ - int num_requests; /* current # of requests */ int max_requests; /* allocated array size */ CheckpointerRequest requests[FLEXIBLE_ARRAY_MEMBER]; @@ -1095,10 +1086,6 @@ ForwardSyncRequest(const FileTag *ftag, SyncRequestType type) LWLockAcquire(CheckpointerCommLock, LW_EXCLUSIVE); - /* Count all backend writes regardless of if they fit in the queue */ - if (!AmBackgroundWriterProcess()) - CheckpointerShmem->num_backend_writes++; - /* * If the checkpointer isn't running or the request queue is full, the * backend will have to perform its own fsync request. But before forcing @@ -1108,12 +1095,6 @@ ForwardSyncRequest(const FileTag *ftag, SyncRequestType type) (CheckpointerShmem->num_requests >= CheckpointerShmem->max_requests && !CompactCheckpointerRequestQueue())) { - /* - * Count the subset of writes where backends have to do their own - * fsync - */ - if (!AmBackgroundWriterProcess()) - CheckpointerShmem->num_backend_fsync++; LWLockRelease(CheckpointerCommLock); return false; } @@ -1270,15 +1251,6 @@ AbsorbSyncRequests(void) LWLockAcquire(CheckpointerCommLock, LW_EXCLUSIVE); - /* Transfer stats counts into pending pgstats message */ - PendingCheckpointerStats.buf_written_backend - += CheckpointerShmem->num_backend_writes; - PendingCheckpointerStats.buf_fsync_backend - += CheckpointerShmem->num_backend_fsync; - - CheckpointerShmem->num_backend_writes = 0; - CheckpointerShmem->num_backend_fsync = 0; - /* * We try to avoid holding the lock for a long time by copying the request * array, and processing the requests after releasing the lock. -- cgit v1.2.3