diff options
| author | Thomas Munro | 2020-07-31 05:27:09 +0000 |
|---|---|---|
| committer | Thomas Munro | 2020-07-31 05:49:58 +0000 |
| commit | 84b1c63ad41872792d47e523363fce1f0e230022 (patch) | |
| tree | cc9ecdfd4f66edbcc5a1382598de5ba502023be9 /src/backend/utils/misc/guc.c | |
| parent | 7b1110d2fd3da3d7536530d14952d4f4d9c25438 (diff) | |
Preallocate some DSM space at startup.
Create an optional region in the main shared memory segment that can be
used to acquire and release "fast" DSM segments, and can benefit from
huge pages allocated at cluster startup time, if configured. Fall back
to the existing mechanisms when that space is full. The size is
controlled by a new GUC min_dynamic_shared_memory, defaulting to 0.
Main region DSM segments initially contain whatever garbage the memory
held last time they were used, rather than zeroes. That change revealed
that DSA areas failed to initialize themselves correctly in memory that
wasn't zeroed first, so fix that problem.
Discussion: https://postgr.es/m/CA%2BhUKGLAE2QBv-WgGp%2BD9P_J-%3Dyne3zof9nfMaqq1h3EGHFXYQ%40mail.gmail.com
Diffstat (limited to 'src/backend/utils/misc/guc.c')
| -rw-r--r-- | src/backend/utils/misc/guc.c | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/src/backend/utils/misc/guc.c b/src/backend/utils/misc/guc.c index c20885e97b2..6c6bb220149 100644 --- a/src/backend/utils/misc/guc.c +++ b/src/backend/utils/misc/guc.c @@ -2231,6 +2231,17 @@ static struct config_int ConfigureNamesInt[] = NULL, NULL, NULL }, + { + {"min_dynamic_shared_memory", PGC_POSTMASTER, RESOURCES_MEM, + gettext_noop("Amount of dynamic shared memory reserved at startup."), + NULL, + GUC_UNIT_MB + }, + &min_dynamic_shared_memory, + 0, 0, Min(INT_MAX, SIZE_MAX / 1024 / 1024), + NULL, NULL, NULL + }, + /* * We sometimes multiply the number of shared buffers by two without * checking for overflow, so we mustn't allow more than INT_MAX / 2. |