From 3c501ebbb63c591688546b1e3ff62aaf30b05bc0 Mon Sep 17 00:00:00 2001 From: Andres Freund Date: Tue, 31 Dec 2024 13:25:56 -0500 Subject: [PATCH v2.4 28/29] WIP: Use MAP_POPULATE For benchmarking it's quite annoying that the first time a memory is touched has completely different perf characteristics than subsequent accesses. Using MAP_POPULATE reduces that substantially. --- src/backend/port/sysv_shmem.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/src/backend/port/sysv_shmem.c b/src/backend/port/sysv_shmem.c index 197926d44f6..a700b02d5a1 100644 --- a/src/backend/port/sysv_shmem.c +++ b/src/backend/port/sysv_shmem.c @@ -620,7 +620,7 @@ CreateAnonymousSegment(Size *size) allocsize += hugepagesize - (allocsize % hugepagesize); ptr = mmap(NULL, allocsize, PROT_READ | PROT_WRITE, - PG_MMAP_FLAGS | mmap_flags, -1, 0); + PG_MMAP_FLAGS | MAP_POPULATE | mmap_flags, -1, 0); mmap_errno = errno; if (huge_pages == HUGE_PAGES_TRY && ptr == MAP_FAILED) elog(DEBUG1, "mmap(%zu) with MAP_HUGETLB failed, huge pages disabled: %m", -- 2.48.1.76.g4e746b1a31.dirty