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 <and...@anarazel.de> Author: Bertrand Drouvot <bertranddrouvot...@gmail.com> Co-authored-by: Michael Paquier <mich...@paquier.xyz> Discussion: https://postgr.es/m/3opf2wh2oljco6ldyqf7ukabw3jijnnhno6fjb4mlu6civ5h24@fcwmhsgmlmzu Branch ------ master Details ------- https://git.postgresql.org/pg/commitdiff/6c349d83b607cfe20a685a5f66a4fa0e24dbe458 Modified Files -------------- doc/src/sgml/config.sgml | 32 +++++++++++++++++++++++++-- doc/src/sgml/monitoring.sgml | 31 +++++++++++++++++++++----- doc/src/sgml/wal.sgml | 4 ++-- src/backend/access/transam/xlog.c | 9 ++++---- src/backend/access/transam/xlogreader.c | 2 +- src/backend/access/transam/xlogrecovery.c | 2 +- src/backend/storage/buffer/bufmgr.c | 10 ++++----- src/backend/storage/buffer/localbuf.c | 4 ++-- src/backend/storage/smgr/md.c | 4 ++-- src/backend/utils/activity/pgstat_backend.c | 3 ++- src/backend/utils/activity/pgstat_io.c | 14 +++++++----- src/backend/utils/misc/guc_tables.c | 9 ++++++++ src/backend/utils/misc/postgresql.conf.sample | 1 + src/include/access/xlog.h | 1 + src/include/pgstat.h | 2 +- 15 files changed, 96 insertions(+), 32 deletions(-)
