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mm, page_alloc: pull out side effects from free_pages_check

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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@suse.cz>
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mel Gorman 2016-05-19 17:14:21 -07:00 committed by Linus Torvalds
parent bb552ac6c6
commit da838d4fcb
1 changed files with 8 additions and 5 deletions
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13
mm/page_alloc.c
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@ -833,11 +833,8 @@ static void free_pages_check_bad(struct page *page)
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 page *page, unsigned int order)
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 page *page, unsigned int order)
if (bad)
return false;
page_cpupid_reset_last(page);
page->flags &= ~PAGE_FLAGS_CHECK_AT_PREP;
reset_page_owner(page, order);
if (!PageHighMem(page)) {