The patch titled
Subject: mm, compaction: add the ultimate direct compaction priority
has been added to the -mm tree. Its filename is
mm-compaction-add-the-ultimate-direct-compaction-priority.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-add-the-ultimate-direct-compaction-priority.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-add-the-ultimate-direct-compaction-priority.patch
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------------------------------------------------------
From: Vlastimil Babka <vbabka@xxxxxxx>
Subject: mm, compaction: add the ultimate direct compaction priority
During reclaim/compaction loop, it's desirable to get a final answer from
unsuccessful compaction so we can either fail the allocation or invoke the
OOM killer. However, heuristics such as deferred compaction or pageblock
skip bits can cause compaction to skip parts or whole zones and lead to
premature OOM's, failures or excessive reclaim/compaction retries.
To remedy this, we introduce a new direct compaction priority called
COMPACT_PRIO_SYNC_FULL, which instructs direct compaction to:
- ignore deferred compaction status for a zone
- ignore pageblock skip hints
- ignore cached scanner positions and scan the whole zone
The new priority should get eventually picked up by should_compact_retry()
and this should improve success rates for costly allocations using
__GFP_REPEAT, such as hugetlbfs allocations, and reduce some corner-case
OOM's for non-costly allocations.
Link: http://lkml.kernel.org/r/20160810091226.6709-6-vbabka@xxxxxxx
Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Cc: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
Cc: David Rientjes <rientjes@xxxxxxxxxx>
Cc: Rik van Riel <riel@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/compaction.h | 3 ++-
mm/compaction.c | 5 ++++-
2 files changed, 6 insertions(+), 2 deletions(-)
diff -puN include/linux/compaction.h~mm-compaction-add-the-ultimate-direct-compaction-priority include/linux/compaction.h
--- a/include/linux/compaction.h~mm-compaction-add-the-ultimate-direct-compaction-priority
+++ a/include/linux/compaction.h
@@ -6,8 +6,9 @@
* Lower value means higher priority, analogically to reclaim priority.
*/
enum compact_priority {
+ COMPACT_PRIO_SYNC_FULL,
+ MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_FULL,
COMPACT_PRIO_SYNC_LIGHT,
- MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
DEF_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
COMPACT_PRIO_ASYNC,
INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC
diff -puN mm/compaction.c~mm-compaction-add-the-ultimate-direct-compaction-priority mm/compaction.c
--- a/mm/compaction.c~mm-compaction-add-the-ultimate-direct-compaction-priority
+++ a/mm/compaction.c
@@ -1644,6 +1644,8 @@ static enum compact_result compact_zone_
.alloc_flags = alloc_flags,
.classzone_idx = classzone_idx,
.direct_compaction = true,
+ .whole_zone = (prio == COMPACT_PRIO_SYNC_FULL),
+ .ignore_skip_hint = (prio == COMPACT_PRIO_SYNC_FULL)
};
INIT_LIST_HEAD(&cc.freepages);
INIT_LIST_HEAD(&cc.migratepages);
@@ -1689,7 +1691,8 @@ enum compact_result try_to_compact_pages
ac->nodemask) {
enum compact_result status;
- if (compaction_deferred(zone, order)) {
+ if (prio > COMPACT_PRIO_SYNC_FULL
+ && compaction_deferred(zone, order)) {
rc = max_t(enum compact_result, COMPACT_DEFERRED, rc);
continue;
}
_
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-more-reliably-increase-direct-compaction-priority.patch
mm-compaction-use-correct-watermark-when-checking-compaction-success.patch
mm-compaction-create-compact_gap-wrapper.patch
mm-compaction-use-proper-alloc_flags-in-__compaction_suitable.patch
mm-compaction-require-only-min-watermarks-for-non-costly-orders.patch
mm-vmscan-make-compaction_ready-more-accurate-and-readable.patch
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