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authorMichal Hocko <mhocko@suse.com>2016-05-20 16:56:44 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-05-20 17:58:30 -0700
commit1d4746d395975e0ff5103e20ab169d1a95b4ef9e (patch)
treea5890a92a5059dde4f5746c544f3defcb2a80c88 /mm/compaction.c
parentc46649deae3f00aa8ba8716f0ddb8eef2dc9532f (diff)
downloadop-kernel-dev-1d4746d395975e0ff5103e20ab169d1a95b4ef9e.zip
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mm, compaction: distinguish COMPACT_DEFERRED from COMPACT_SKIPPED
try_to_compact_pages() can currently return COMPACT_SKIPPED even when the compaction is defered for some zone just because zone DMA is skipped in 99% of cases due to watermark checks. This makes COMPACT_DEFERRED basically unusable for the page allocator as a feedback mechanism. Make sure we distinguish those two states properly and switch their ordering in the enum. This would mean that the COMPACT_SKIPPED will be returned only when all eligible zones are skipped. As a result COMPACT_DEFERRED handling for THP in __alloc_pages_slowpath will be more precise and we would bail out rather than reclaim. 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>
Diffstat (limited to 'mm/compaction.c')
-rw-r--r--mm/compaction.c8
1 files changed, 5 insertions, 3 deletions
diff --git a/mm/compaction.c b/mm/compaction.c
index 455ecd8..b2b9447 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1578,7 +1578,7 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
int may_perform_io = gfp_mask & __GFP_IO;
struct zoneref *z;
struct zone *zone;
- enum compact_result rc = COMPACT_DEFERRED;
+ enum compact_result rc = COMPACT_SKIPPED;
int all_zones_contended = COMPACT_CONTENDED_LOCK; /* init for &= op */
*contended = COMPACT_CONTENDED_NONE;
@@ -1595,8 +1595,10 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
enum compact_result status;
int zone_contended;
- if (compaction_deferred(zone, order))
+ if (compaction_deferred(zone, order)) {
+ rc = max_t(enum compact_result, COMPACT_DEFERRED, rc);
continue;
+ }
status = compact_zone_order(zone, order, gfp_mask, mode,
&zone_contended, alloc_flags,
@@ -1667,7 +1669,7 @@ break_loop:
* If at least one zone wasn't deferred or skipped, we report if all
* zones that were tried were lock contended.
*/
- if (rc > COMPACT_SKIPPED && all_zones_contended)
+ if (rc > COMPACT_INACTIVE && all_zones_contended)
*contended = COMPACT_CONTENDED_LOCK;
return rc;
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