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| author | Thomas Munro <tmunro@postgresql.org> | 2025-03-19 11:40:56 +1300 |
|---|---|---|
| committer | Thomas Munro <tmunro@postgresql.org> | 2025-03-19 15:23:54 +1300 |
| commit | 10f6646847515b1ab02735c24b04abaf1996f65f (patch) | |
| tree | e49ca63aec12d99997f4fa91a6d4e3a11dbbe858 /src/include/storage/bufmgr.h | |
| parent | 17d8bba6dad12e14a7cafca9ef5eef21e577e9c3 (diff) | |
| download | postgresql-10f6646847515b1ab02735c24b04abaf1996f65f.tar.gz postgresql-10f6646847515b1ab02735c24b04abaf1996f65f.zip | |
Introduce io_max_combine_limit.
The existing io_combine_limit can be changed by users. The new
io_max_combine_limit is fixed at server startup time, and functions as a
silent clamp on the user setting. That in itself is probably quite
useful, but the primary motivation is:
aio_init.c allocates shared memory for all asynchronous IOs including
some per-block data, and we didn't want to waste memory you'd never used
by assuming they could be up to PG_IOV_MAX. This commit already halves
the size of 'AioHandleIov' and 'AioHandleData'. A follow-up commit can
now expand PG_IOV_MAX without affecting that.
Since our GUC system doesn't support dependencies or cross-checks
between GUCs, the user-settable one now assigns a "raw" value to
io_combine_limit_guc, and the lower of io_combine_limit_guc and
io_max_combine_limit is maintained in io_combine_limit.
Reviewed-by: Andres Freund <andres@anarazel.de> (earlier version)
Discussion: https://postgr.es/m/CA%2BhUKG%2B2T9p-%2BzM6Eeou-RAJjTML6eit1qn26f9twznX59qtCA%40mail.gmail.com
Diffstat (limited to 'src/include/storage/bufmgr.h')
| -rw-r--r-- | src/include/storage/bufmgr.h | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/src/include/storage/bufmgr.h b/src/include/storage/bufmgr.h index 7f5def6bada..ecc1c3a909b 100644 --- a/src/include/storage/bufmgr.h +++ b/src/include/storage/bufmgr.h @@ -163,7 +163,9 @@ extern PGDLLIMPORT int maintenance_io_concurrency; #define MAX_IO_COMBINE_LIMIT PG_IOV_MAX #define DEFAULT_IO_COMBINE_LIMIT Min(MAX_IO_COMBINE_LIMIT, (128 * 1024) / BLCKSZ) -extern PGDLLIMPORT int io_combine_limit; +extern PGDLLIMPORT int io_combine_limit; /* min of the two GUCs below */ +extern PGDLLIMPORT int io_combine_limit_guc; +extern PGDLLIMPORT int io_max_combine_limit; extern PGDLLIMPORT int checkpoint_flush_after; extern PGDLLIMPORT int backend_flush_after; |