From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751573AbcFXJzQ (ORCPT ); Fri, 24 Jun 2016 05:55:16 -0400 Received: from mx2.suse.de ([195.135.220.15]:35091 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751424AbcFXJzJ (ORCPT ); Fri, 24 Jun 2016 05:55:09 -0400 From: Vlastimil Babka To: Andrew Morton Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Mel Gorman , Joonsoo Kim , David Rientjes , Rik van Riel , Vlastimil Babka Subject: [PATCH v3 11/17] mm, compaction: add the ultimate direct compaction priority Date: Fri, 24 Jun 2016 11:54:31 +0200 Message-Id: <20160624095437.16385-12-vbabka@suse.cz> X-Mailer: git-send-email 2.8.4 In-Reply-To: <20160624095437.16385-1-vbabka@suse.cz> References: <20160624095437.16385-1-vbabka@suse.cz> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org During reclaim/compaction loop, it's desirable to get a final answer from unsuccessful compaction so we can either fail the allocation or invoke the OOM killer. However, heuristics such as deferred compaction or pageblock skip bits can cause compaction to skip parts or whole zones and lead to premature OOM's, failures or excessive reclaim/compaction retries. To remedy this, we introduce a new direct compaction priority called COMPACT_PRIO_SYNC_FULL, which instructs direct compaction to: - ignore deferred compaction status for a zone - ignore pageblock skip hints - ignore cached scanner positions and scan the whole zone The new priority should get eventually picked up by should_compact_retry() and this should improve success rates for costly allocations using __GFP_REPEAT, such as hugetlbfs allocations, and reduce some corner-case OOM's for non-costly allocations. Signed-off-by: Vlastimil Babka Acked-by: Michal Hocko --- include/linux/compaction.h | 3 ++- mm/compaction.c | 5 ++++- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/include/linux/compaction.h b/include/linux/compaction.h index 0cc702ec80a2..869b594cf4ff 100644 --- a/include/linux/compaction.h +++ b/include/linux/compaction.h @@ -6,8 +6,9 @@ * Lower value means higher priority, analogically to reclaim priority. */ enum compact_priority { + COMPACT_PRIO_SYNC_FULL, + MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_FULL, COMPACT_PRIO_SYNC_LIGHT, - MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT, DEF_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT, COMPACT_PRIO_ASYNC, INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC diff --git a/mm/compaction.c b/mm/compaction.c index 5c15db0001a5..76897850c3c2 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1644,6 +1644,8 @@ static enum compact_result compact_zone_order(struct zone *zone, int order, .alloc_flags = alloc_flags, .classzone_idx = classzone_idx, .direct_compaction = true, + .whole_zone = (prio == COMPACT_PRIO_SYNC_FULL), + .ignore_skip_hint = (prio == COMPACT_PRIO_SYNC_FULL) }; INIT_LIST_HEAD(&cc.freepages); INIT_LIST_HEAD(&cc.migratepages); @@ -1689,7 +1691,8 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order, ac->nodemask) { enum compact_result status; - if (compaction_deferred(zone, order)) { + if (prio > COMPACT_PRIO_SYNC_FULL + && compaction_deferred(zone, order)) { rc = max_t(enum compact_result, COMPACT_DEFERRED, rc); continue; } -- 2.8.4