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Fix thinko in huge_tlb_pages patch.

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We calculated the rounded-up size for the allocation, but then failed to
use the rounded-up value in the mmap() call. Oops.

Also, initialize allocsize, to silence warnings seen with some compilers,
as pointed out by Jeff Janes.
This commit is contained in:
Heikki Linnakangas 2014-01-29 21:33:56 +02:00
parent 626a120656
commit 699b1f40da
1 changed files with 7 additions and 4 deletions
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11
src/backend/port/sysv_shmem.c
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@ -329,7 +329,7 @@ PGSharedMemoryIsInUse(unsigned long id1, unsigned long id2)
static void * static void *
CreateAnonymousSegment(Size *size) CreateAnonymousSegment(Size *size)
{ {
Size allocsize; Size allocsize = *size;
void *ptr = MAP_FAILED; void *ptr = MAP_FAILED;
#ifndef MAP_HUGETLB #ifndef MAP_HUGETLB
@ -358,11 +358,10 @@ CreateAnonymousSegment(Size *size)
*/ */
int hugepagesize = 2 * 1024 * 1024; int hugepagesize = 2 * 1024 * 1024;
allocsize = *size;
if (allocsize % hugepagesize != 0) if (allocsize % hugepagesize != 0)
allocsize += hugepagesize - (allocsize % hugepagesize); allocsize += hugepagesize - (allocsize % hugepagesize);
ptr = mmap(NULL, *size, PROT_READ | PROT_WRITE, ptr = mmap(NULL, allocsize, PROT_READ | PROT_WRITE,
PG_MMAP_FLAGS | MAP_HUGETLB, -1, 0); PG_MMAP_FLAGS | MAP_HUGETLB, -1, 0);
if (huge_tlb_pages == HUGE_TLB_TRY && ptr == MAP_FAILED) if (huge_tlb_pages == HUGE_TLB_TRY && ptr == MAP_FAILED)
elog(DEBUG1, "mmap with MAP_HUGETLB failed, huge pages disabled: %m"); elog(DEBUG1, "mmap with MAP_HUGETLB failed, huge pages disabled: %m");
@ -372,8 +371,12 @@ CreateAnonymousSegment(Size *size)
if (huge_tlb_pages == HUGE_TLB_OFF || if (huge_tlb_pages == HUGE_TLB_OFF ||
(huge_tlb_pages == HUGE_TLB_TRY && ptr == MAP_FAILED)) (huge_tlb_pages == HUGE_TLB_TRY && ptr == MAP_FAILED))
{ {
/*
* use the original size, not the rounded up value, when falling
* back to non-huge pages.
*/
allocsize = *size; allocsize = *size;
ptr = mmap(NULL, *size, PROT_READ | PROT_WRITE, PG_MMAP_FLAGS, -1, 0); ptr = mmap(NULL, allocsize, PROT_READ | PROT_WRITE, PG_MMAP_FLAGS, -1, 0);
} }
if (ptr == MAP_FAILED) if (ptr == MAP_FAILED)