From 6c349d83b607cfe20a685a5f66a4fa0e24dbe458 Mon Sep 17 00:00:00 2001 From: Michael Paquier Date: Wed, 26 Feb 2025 09:49:59 +0900 Subject: Re-add GUC track_wal_io_timing This commit is a rework of 2421e9a51d20, about which Andres Freund has raised some concerns as it is valuable to have both track_io_timing and track_wal_io_timing in some cases, as the WAL write and fsync paths can be a major bottleneck for some workloads. Hence, it can be relevant to not calculate the WAL timings in environments where pg_test_timing performs poorly while capturing some IO data under track_io_timing for the non-WAL IO paths. The opposite can be also true: it should be possible to disable the non-WAL timings and enable the WAL timings (the previous GUC setups allowed this possibility). track_wal_io_timing is added back in this commit, controlling if WAL timings should be calculated in pg_stat_io for the read, fsync and write paths, as done previously with pg_stat_wal. pg_stat_wal previously tracked only the sync and write parts (now removed), read stats is new data tracked in pg_stat_io, all three are aggregated if track_wal_io_timing is enabled. The read part matters during recovery or if a XLogReader is used. Extra note: more control over if the types of timings calculated in pg_stat_io could be done with a GUC that lists pairs of (IOObject,IOOp). Reported-by: Andres Freund Author: Bertrand Drouvot Co-authored-by: Michael Paquier Discussion: https://postgr.es/m/3opf2wh2oljco6ldyqf7ukabw3jijnnhno6fjb4mlu6civ5h24@fcwmhsgmlmzu --- src/backend/access/transam/xlogreader.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'src/backend/access/transam/xlogreader.c') diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c index 995e4f7c26f..5483d4f0dd2 100644 --- a/src/backend/access/transam/xlogreader.c +++ b/src/backend/access/transam/xlogreader.c @@ -1557,7 +1557,7 @@ WALRead(XLogReaderState *state, #ifndef FRONTEND /* Measure I/O timing when reading segment */ - io_start = pgstat_prepare_io_time(); + io_start = pgstat_prepare_io_time(track_wal_io_timing); pgstat_report_wait_start(WAIT_EVENT_WAL_READ); #endif -- cgit v1.2.3