From: Michal Hocko <mhocko@xxxxxxxx>
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@xxxxxxxx>
---
include/linux/compaction.h | 26 ++++++++++++++++----------
1 file changed, 16 insertions(+), 10 deletions(-)
diff --git a/include/linux/compaction.h b/include/linux/compaction.h
index 7c4de92d12cc..a7b9091ff349 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 @@ 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 */
--
2.8.0.rc3
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