Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit e66f0972 authored by Joonsoo Kim's avatar Joonsoo Kim Committed by Linus Torvalds
Browse files

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: default avatarJoonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: default avatarJohannes 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1da6f0e1

mm/page_alloc.c

+1 −1
Original line number Diff line number Diff line
@@ -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