From f86697953976b465a55e175ac999d43495a1dacc Mon Sep 17 00:00:00 2001 From: Vlastimil Babka Date: Wed, 10 Dec 2014 15:43:28 -0800 Subject: [PATCH] mm, compaction: defer only on COMPACT_COMPLETE Deferred compaction is employed to avoid compacting zone where sync direct compaction has recently failed. As such, it makes sense to only defer when a full zone was scanned, which is when compact_zone returns with COMPACT_COMPLETE. It's less useful to defer when compact_zone returns with apparent success (COMPACT_PARTIAL), followed by a watermark check failure, which can happen due to parallel allocation activity. It also does not make much sense to defer compaction which was completely skipped (COMPACT_SKIP) for being unsuitable in the first place. This patch therefore makes deferred compaction trigger only when COMPACT_COMPLETE is returned from compact_zone(). Results of stress-highalloc becnmark show the difference is within measurement error, so the issue is rather cosmetic. Signed-off-by: Vlastimil Babka Cc: Minchan Kim Cc: Mel Gorman Cc: Joonsoo Kim Cc: Michal Nazarewicz Cc: Naoya Horiguchi Cc: Christoph Lameter Acked-by: Rik van Riel Cc: David Rientjes Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Reading git-format-patch failed