tree 3af739a4e8ff892de86c8d55a42c86468f7608be
parent 53853e2d2bfb748a8b5aa2fd1de15699266865e0
author Vlastimil Babka <vbabka@suse.cz> 1412893624 -0700
committer Linus Torvalds <torvalds@linux-foundation.org> 1412907953 -0400

mm, compaction: do not count compact_stall if all zones skipped compaction

The compact_stall vmstat counter counts the number of allocations stalled
by direct compaction.  It does not count when all attempted zones had
deferred compaction, but it does count when all zones skipped compaction.
The skipping is decided based on very early check of
compaction_suitable(), based on watermarks and memory fragmentation.
Therefore it makes sense not to count skipped compactions as stalls.
Moreover, compact_success or compact_fail is also already not being
counted when compaction was skipped, so this patch changes the
compact_stall counting to match the other two.

Additionally, restructure __alloc_pages_direct_compact() code for better
readability.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Minchan Kim <minchan@kernel.org>
Acked-by: Mel Gorman <mgorman@suse.de>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Rik van Riel <riel@redhat.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>