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: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Acked-by: Hillf 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/compaction.h b/include/linux/compaction.h
index 9b37f9d..ff39fa0 100644
--- a/include/linux/compaction.h
+++ b/include/linux/compaction.h
@@ -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 @@
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
- */
- COMPACT_PARTIAL,
- /*
- * direct compaction has scanned part of the zone but wasn't successfull
- * to compact suitable pages.
- */
- COMPACT_PARTIAL_SKIPPED,
+
/*
* The full zone was compacted scanned but wasn't successfull to compact
* suitable pages.
*/
COMPACT_COMPLETE,
- /* For more detailed tracepoint output */
- COMPACT_NO_SUITABLE_PAGE,
- COMPACT_NOT_SUITABLE_ZONE,
+ /*
+ * 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,
+
+ /*
+ * direct compaction partially compacted a zone and there might be
+ * suitable pages
+ */
+ COMPACT_PARTIAL,
};
/* Used to signal whether compaction detected need_sched() or lock contention */