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Commit 4f9a358c authored by Michal Hocko's avatar Michal Hocko Committed by Linus Torvalds
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mm, compaction: update compaction_result ordering 



compaction_result will be used as the primary feedback channel for
compaction users.  At the same time try_to_compact_pages (and
potentially others) assume a certain ordering where a more specific
feedback takes precendence.

This gets a bit awkward when we have conflicting feedback from different
zones.  E.g one returing COMPACT_COMPLETE meaning the full zone has been
scanned without any outcome while other returns with COMPACT_PARTIAL aka
made some progress.  The caller should get COMPACT_PARTIAL because that
means that the compaction still can make some progress.  The same
applies for COMPACT_PARTIAL vs COMPACT_PARTIAL_SKIPPED.

Reorder PARTIAL to be the largest one so the larger the value is the
more progress we have done.

Signed-off-by: default avatarMichal Hocko <mhocko@suse.com>
Acked-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarHillf Danton <hillf.zj@alibaba-inc.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Joonsoo Kim <js1304@gmail.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Vladimir Davydov <vdavydov@virtuozzo.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c8f7de0b

include/linux/compaction.h

+16 −10
Original line number Diff line number Diff line
@@ -4,6 +4,8 @@ 
/* Return values for compact_zone() and try_to_compact_pages() */

/* When adding new states, please adjust include/trace/events/compaction.h */

enum compact_result {

	/* For more detailed tracepoint output - internal to compaction */

	COMPACT_NOT_SUITABLE_ZONE,

	/*

	 * compaction didn't start as it was not possible or direct reclaim

	 * was more suitable
@@ -11,30 +13,34 @@ enum compact_result { 
	COMPACT_SKIPPED,

	/* compaction didn't start as it was deferred due to past failures */

	COMPACT_DEFERRED,



	/* compaction not active last round */

	COMPACT_INACTIVE = COMPACT_DEFERRED,



	/* For more detailed tracepoint output - internal to compaction */

	COMPACT_NO_SUITABLE_PAGE,

	/* compaction should continue to another pageblock */

	COMPACT_CONTINUE,



	/*

	 * direct compaction partially compacted a zone and there are suitable

	 * pages

	 * The full zone was compacted scanned but wasn't successfull to compact

	 * suitable pages.

	 */

	COMPACT_PARTIAL,

	COMPACT_COMPLETE,

	/*

	 * direct compaction has scanned part of the zone but wasn't successfull

	 * to compact suitable pages.

	 */

	COMPACT_PARTIAL_SKIPPED,



	/* compaction terminated prematurely due to lock contentions */

	COMPACT_CONTENDED,



	/*

	 * The full zone was compacted scanned but wasn't successfull to compact

	 * suitable pages.

	 * direct compaction partially compacted a zone and there might be

	 * suitable pages

	 */

	COMPACT_COMPLETE,

	/* For more detailed tracepoint output */

	COMPACT_NO_SUITABLE_PAGE,

	COMPACT_NOT_SUITABLE_ZONE,

	COMPACT_CONTENDED,

	COMPACT_PARTIAL,

};



/* Used to signal whether compaction detected need_sched() or lock contention */