The patch titled
Subject: mm, compaction: more reliably increase direct compaction priority
has been added to the -mm tree. Its filename is
mm-compaction-more-reliably-increase-direct-compaction-priority.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-more-reliably-increase-direct-compaction-priority.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-more-reliably-increase-direct-compaction-priority.patch
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From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm, compaction: more reliably increase direct compaction priority
During reclaim/compaction loop, compaction priority can be increased by
the should_compact_retry() function, but the current code is not optimal.
Priority is only increased when compaction_failed() is true, which means
that compaction has scanned the whole zone. This may not happen even
after multiple attempts with a lower priority due to parallel activity, so
we might needlessly struggle on the lower priorities and possibly run out
of compaction retry attempts in the process.
After this patch we are guaranteed at least one attempt at the highest
compaction priority even if we exhaust all retries at the lower
priorities.
Link: http://lkml.kernel.org/r/20160906135258.18335-3-vbabka@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Cc: Michal Hocko <mhocko@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Cc: Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/page_alloc.c | 18 +++++++++++-------
1 file changed, 11 insertions(+), 7 deletions(-)
diff -puN mm/page_alloc.c~mm-compaction-more-reliably-increase-direct-compaction-priority mm/page_alloc.c
--- a/mm/page_alloc.c~mm-compaction-more-reliably-increase-direct-compaction-priority
+++ a/mm/page_alloc.c
@@ -3172,13 +3172,8 @@ should_compact_retry(struct alloc_contex
* so it doesn't really make much sense to retry except when the
* failure could be caused by insufficient priority
*/
- if (compaction_failed(compact_result)) {
- if (*compact_priority > MIN_COMPACT_PRIORITY) {
- (*compact_priority)--;
- return true;
- }
- return false;
- }
+ if (compaction_failed(compact_result))
+ goto check_priority;
/*
* make sure the compaction wasn't deferred or didn't bail out early
@@ -3202,6 +3197,15 @@ should_compact_retry(struct alloc_contex
if (compaction_retries <= max_retries)
return true;
+ /*
+ * Make sure there is at least one attempt at the highest priority
+ * if we exhausted all retries at the lower priorities
+ */
+check_priority:
+ if (*compact_priority > MIN_COMPACT_PRIORITY) {
+ (*compact_priority)--;
+ return true;
+ }
return false;
}
#else
_
Patches currently in -mm which might be from vbabka@xxxxxxx are
mm-compaction-make-whole_zone-flag-ignore-cached-scanner-positions.patch
mm-compaction-cleanup-unused-functions.patch
mm-compaction-rename-compact_partial-to-compact_success.patch
mm-compaction-dont-recheck-watermarks-after-compact_success.patch
mm-compaction-add-the-ultimate-direct-compaction-priority.patch
mm-compaction-add-the-ultimate-direct-compaction-priority-fix.patch
mm-compaction-use-correct-watermark-when-checking-compaction-success.patch
mm-compaction-create-compact_gap-wrapper.patch
mm-compaction-create-compact_gap-wrapper-fix.patch
mm-compaction-use-proper-alloc_flags-in-__compaction_suitable.patch
mm-compaction-require-only-min-watermarks-for-non-costly-orders.patch
mm-compaction-require-only-min-watermarks-for-non-costly-orders-fix.patch
mm-vmscan-make-compaction_ready-more-accurate-and-readable.patch
revert-mm-oom-prevent-premature-oom-killer-invocation-for-high-order-request.patch
mm-compaction-more-reliably-increase-direct-compaction-priority.patch
mm-compaction-restrict-full-priority-to-non-costly-orders.patch
mm-compaction-make-full-priority-ignore-pageblock-suitability.patch
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