From: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Subject: mm, page_alloc: pull out side effects from free_pages_check
Check without side-effects should be easier to maintain. It also removes
the duplicated cpupid and flags reset done in !DEBUG_VM variant of both
free_pcp_prepare() and then bulkfree_pcp_prepare(). Finally, it enables
the next patch.
It shouldn't result in new branches, thanks to inlining of the check.
!DEBUG_VM bloat-o-meter:
add/remove: 0/0 grow/shrink: 0/2 up/down: 0/-27 (-27)
function old new delta
__free_pages_ok 748 739 -9
free_pcppages_bulk 1403 1385 -18
DEBUG_VM:
add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-28 (-28)
function old new delta
free_pages_prepare 806 778 -28
This is also slightly faster because cpupid information is not set on tail
pages so we can avoid resets there.
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Signed-off-by: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff -puN mm/page_alloc.c~mm-page_alloc-pull-out-side-effects-from-free_pages_check mm/page_alloc.c
--- a/mm/page_alloc.c~mm-page_alloc-pull-out-side-effects-from-free_pages_check
+++ a/mm/page_alloc.c
@@ -833,11 +833,8 @@ static void free_pages_check_bad(struct
static inline int free_pages_check(struct page *page)
{
- if (likely(page_expected_state(page, PAGE_FLAGS_CHECK_AT_FREE))) {
- page_cpupid_reset_last(page);
- page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
+ if (likely(page_expected_state(page, PAGE_FLAGS_CHECK_AT_FREE)))
return 0;
- }
/* Something has gone sideways, find it */
free_pages_check_bad(page);
@@ -1078,7 +1075,11 @@ static bool free_pages_prepare(struct pa
for (i = 1; i < (1 << order); i++) {
if (compound)
bad += free_tail_pages_check(page, page + i);
- bad += free_pages_check(page + i);
+ if (unlikely(free_pages_check(page + i))) {
+ bad++;
+ continue;
+ }
+ (page + i)->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
}
}
if (PageAnonHead(page))
@@ -1087,6 +1088,8 @@ static bool free_pages_prepare(struct pa
if (bad)
return false;
+ page_cpupid_reset_last(page);
+ page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
reset_page_owner(page, order);
if (!PageHighMem(page)) {
_
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