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| author | Joonsoo Kim <iamjoonsoo.kim@lge.com> | 2013-09-11 14:21:26 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-11 15:57:29 -0700 |
| commit | e66f09725771ac5b1b868d6b19eba84e30ffad88 (patch) | |
| tree | 82cd7bb01c1253efa6c13986882fab63a50201e6 /mm/page_alloc.c | |
| parent | 1da6f0e1b316d0215989fe4d7c657edead1fdea7 (diff) | |
| download | lwn-e66f09725771ac5b1b868d6b19eba84e30ffad88.tar.gz lwn-e66f09725771ac5b1b868d6b19eba84e30ffad88.zip | |
mm, page_alloc: add unlikely macro to help compiler optimization
We rarely allocate a page with ALLOC_NO_WATERMARKS and it is used in slow
path. For helping compiler optimization, add unlikely macro to
ALLOC_NO_WATERMARKS checking.
This patch doesn't have any effect now, because gcc already optimize this
properly. But we cannot assume that gcc always does right and nobody
re-evaluate if gcc do proper optimization with their change, for example,
it is not optimized properly on v3.10. So adding compiler hint here is
reasonable.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/page_alloc.c')
| -rw-r--r-- | mm/page_alloc.c | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/mm/page_alloc.c b/mm/page_alloc.c index 544d19d681a2..42c59300bacd 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -1909,7 +1909,7 @@ zonelist_scan: !cpuset_zone_allowed_softwall(zone, gfp_mask)) continue; BUILD_BUG_ON(ALLOC_NO_WATERMARKS < NR_WMARK); - if (alloc_flags & ALLOC_NO_WATERMARKS) + if (unlikely(alloc_flags & ALLOC_NO_WATERMARKS)) goto try_this_zone; /* * Distribute pages in proportion to the individual |