提交 a8e025e5 编写于 作者: V Vlastimil Babka 提交者: Linus Torvalds

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@suse.cz
[vbabka@suse.cz: use the MIN_COMPACT_PRIORITY alias]
  Link: http://lkml.kernel.org/r/d443b884-87e7-1c93-8684-3a3a35759fb1@suse.czSigned-off-by: NVlastimil Babka <vbabka@suse.cz>
Tested-by: NLorenzo Stoakes <lstoakes@gmail.com>
Acked-by: NMichal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@techsingularity.net>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: David Rientjes <rientjes@google.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>
上级 7ceb009a
...@@ -6,8 +6,9 @@ ...@@ -6,8 +6,9 @@
* Lower value means higher priority, analogically to reclaim priority. * Lower value means higher priority, analogically to reclaim priority.
*/ */
enum compact_priority { enum compact_priority {
COMPACT_PRIO_SYNC_FULL,
MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_FULL,
COMPACT_PRIO_SYNC_LIGHT, COMPACT_PRIO_SYNC_LIGHT,
MIN_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
DEF_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT, DEF_COMPACT_PRIORITY = COMPACT_PRIO_SYNC_LIGHT,
COMPACT_PRIO_ASYNC, COMPACT_PRIO_ASYNC,
INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC INIT_COMPACT_PRIORITY = COMPACT_PRIO_ASYNC
......
...@@ -1644,6 +1644,8 @@ static enum compact_result compact_zone_order(struct zone *zone, int order, ...@@ -1644,6 +1644,8 @@ static enum compact_result compact_zone_order(struct zone *zone, int order,
.alloc_flags = alloc_flags, .alloc_flags = alloc_flags,
.classzone_idx = classzone_idx, .classzone_idx = classzone_idx,
.direct_compaction = true, .direct_compaction = true,
.whole_zone = (prio == MIN_COMPACT_PRIORITY),
.ignore_skip_hint = (prio == MIN_COMPACT_PRIORITY)
}; };
INIT_LIST_HEAD(&cc.freepages); INIT_LIST_HEAD(&cc.freepages);
INIT_LIST_HEAD(&cc.migratepages); INIT_LIST_HEAD(&cc.migratepages);
...@@ -1689,7 +1691,8 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order, ...@@ -1689,7 +1691,8 @@ enum compact_result try_to_compact_pages(gfp_t gfp_mask, unsigned int order,
ac->nodemask) { ac->nodemask) {
enum compact_result status; enum compact_result status;
if (compaction_deferred(zone, order)) { if (prio > MIN_COMPACT_PRIORITY
&& compaction_deferred(zone, order)) {
rc = max_t(enum compact_result, COMPACT_DEFERRED, rc); rc = max_t(enum compact_result, COMPACT_DEFERRED, rc);
continue; continue;
} }
......
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