diff options
Diffstat (limited to 'src')
| -rw-r--r-- | src/backend/storage/ipc/shmem.c | 12 |
1 files changed, 10 insertions, 2 deletions
diff --git a/src/backend/storage/ipc/shmem.c b/src/backend/storage/ipc/shmem.c index 81506eaffd0..1ad68cda4e5 100644 --- a/src/backend/storage/ipc/shmem.c +++ b/src/backend/storage/ipc/shmem.c @@ -171,9 +171,17 @@ ShmemAlloc(Size size) void *newSpace; /* - * ensure all space is adequately aligned. + * Ensure all space is adequately aligned. We used to only MAXALIGN this + * space but experience has proved that on modern systems that is not good + * enough. Many parts of the system are very sensitive to critical data + * structures getting split across cache line boundaries. To avoid that, + * attempt to align the beginning of the allocation to a cache line + * boundary. The calling code will still need to be careful about how it + * uses the allocated space - e.g. by padding each element in an array of + * structures out to a power-of-two size - but without this, even that + * won't be sufficient. */ - size = MAXALIGN(size); + size = CACHELINEALIGN(size); Assert(ShmemSegHdr != NULL); |