From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754351AbaJGPeF (ORCPT ); Tue, 7 Oct 2014 11:34:05 -0400 Received: from cantor2.suse.de ([195.135.220.15]:53000 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752956AbaJGPeB (ORCPT ); Tue, 7 Oct 2014 11:34:01 -0400 From: Vlastimil Babka To: Andrew Morton Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Vlastimil Babka , Minchan Kim , Mel Gorman , Joonsoo Kim , Michal Nazarewicz , Naoya Horiguchi , Christoph Lameter , Rik van Riel , David Rientjes Subject: [PATCH 3/5] mm, compaction: defer only on COMPACT_COMPLETE Date: Tue, 7 Oct 2014 17:33:37 +0200 Message-Id: <1412696019-21761-4-git-send-email-vbabka@suse.cz> X-Mailer: git-send-email 1.8.4.5 In-Reply-To: <1412696019-21761-1-git-send-email-vbabka@suse.cz> References: <1412696019-21761-1-git-send-email-vbabka@suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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 Cc: Rik van Riel Cc: David Rientjes --- mm/compaction.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/mm/compaction.c b/mm/compaction.c index 4b3e0bd..9107588 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1340,7 +1340,7 @@ unsigned long try_to_compact_pages(struct zonelist *zonelist, goto break_loop; } - if (mode != MIGRATE_ASYNC) { + if (mode != MIGRATE_ASYNC && status == COMPACT_COMPLETE) { /* * We think that allocation won't succeed in this zone * so we defer compaction there. If it ends up -- 1.8.4.5