From a582a738c763e106f47eab24b8146c698a9c700b Mon Sep 17 00:00:00 2001 From: Shaohua Li Date: Wed, 15 Jun 2011 15:08:49 -0700 Subject: [PATCH] compaction: checks correct fragmentation index fragmentation_index() returns -1000 when the allocation might succeed This doesn't match the comment and code in compaction_suitable(). I thought compaction_suitable should return COMPACT_PARTIAL in -1000 case, because in this case allocation could succeed depending on watermarks. The impact of this is that compaction starts and compact_finished() is called which rechecks the watermarks and the free lists. It should have the same result in that compaction should not start but is more expensive. Acked-by: Mel Gorman Signed-off-by: Shaohua Li Cc: Minchan Kim Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/compaction.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/mm/compaction.c b/mm/compaction.c index 94bdbe1f7caf..cf7086c6dc07 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -480,7 +480,8 @@ unsigned long compaction_suitable(struct zone *zone, int order) * fragmentation index determines if allocation failures are due to * low memory or external fragmentation * - * index of -1 implies allocations might succeed dependingon watermarks + * index of -1000 implies allocations might succeed depending on + * watermarks * index towards 0 implies failure is due to lack of memory * index towards 1000 implies failure is due to fragmentation * @@ -490,7 +491,8 @@ unsigned long compaction_suitable(struct zone *zone, int order) if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold) return COMPACT_SKIPPED; - if (fragindex == -1 && zone_watermark_ok(zone, order, watermark, 0, 0)) + if (fragindex == -1000 && zone_watermark_ok(zone, order, watermark, + 0, 0)) return COMPACT_PARTIAL; return COMPACT_CONTINUE;