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| author | Melanie Plageman <melanieplageman@gmail.com> | 2025-03-12 15:56:59 -0400 |
|---|---|---|
| committer | Melanie Plageman <melanieplageman@gmail.com> | 2025-03-12 15:57:44 -0400 |
| commit | ff79b5b2aba02d720f9b7fff644dd50ce07b8c6e (patch) | |
| tree | 4591f073288d14e04bb2e5b000ab496a55669bf4 /src | |
| parent | af717317a04f5217728ce296edf4a581eb7e6ea0 (diff) | |
| download | postgresql-ff79b5b2aba02d720f9b7fff644dd50ce07b8c6e.tar.gz postgresql-ff79b5b2aba02d720f9b7fff644dd50ce07b8c6e.zip | |
Increase default effective_io_concurrency to 16
The default effective_io_concurrency has been 1 since it was introduced
in b7b8f0b6096d2ab6e. Referencing the associated discussion [1], it
seems 1 was chosen as a conservative value that seemed unlikely to cause
regressions.
Experimentation on high latency cloud storage as well as fast, local
nvme storage (see Discussion link) shows that even slightly higher
values improve query timings substantially. 1 actually performs worse
than 0 [2]. With effective_io_concurrency 1, we are not prefetching
enough to avoid I/O stalls, but we are issuing extra syscalls.
The new default is 16, which should be more appropriate for common
hardware while still avoiding flooding low IOPs devices with I/O
requests.
[1] https://www.postgresql.org/message-id/flat/FDDBA24E-FF4D-4654-BA75-692B3BA71B97%40enterprisedb.com
[2] https://www.postgresql.org/message-id/CAAKRu_Zv08Cic%3DqdCfzrQabpEXGrd9Z9UOW5svEVkCM6%3DFXA9g%40mail.gmail.com
Reviewed-by: Andres Freund <andres@anarazel.de>
Discussion: https://postgr.es/m/CAAKRu_Z%2BJa-mwXebOoOERMMUMvJeRhzTjad4dSThxG0JLXESxw%40mail.gmail.com
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/utils/misc/postgresql.conf.sample | 2 | ||||
| -rw-r--r-- | src/include/storage/bufmgr.h | 2 |
2 files changed, 2 insertions, 2 deletions
diff --git a/src/backend/utils/misc/postgresql.conf.sample b/src/backend/utils/misc/postgresql.conf.sample index d2bd329a587..36cb64d7ebc 100644 --- a/src/backend/utils/misc/postgresql.conf.sample +++ b/src/backend/utils/misc/postgresql.conf.sample @@ -198,7 +198,7 @@ # - I/O - #backend_flush_after = 0 # measured in pages, 0 disables -#effective_io_concurrency = 1 # 1-1000; 0 disables prefetching +#effective_io_concurrency = 16 # 1-1000; 0 disables prefetching #maintenance_io_concurrency = 10 # 1-1000; 0 disables prefetching #io_combine_limit = 128kB # usually 1-32 blocks (depends on OS) diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h index 7c1e4316dde..b204e4731c1 100644 --- a/src/include/storage/bufmgr.h +++ b/src/include/storage/bufmgr.h @@ -152,7 +152,7 @@ extern PGDLLIMPORT bool track_io_timing; /* only applicable when prefetching is available */ #ifdef USE_PREFETCH -#define DEFAULT_EFFECTIVE_IO_CONCURRENCY 1 +#define DEFAULT_EFFECTIVE_IO_CONCURRENCY 16 #define DEFAULT_MAINTENANCE_IO_CONCURRENCY 10 #else #define DEFAULT_EFFECTIVE_IO_CONCURRENCY 0 |