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mm, compaction: distinguish contended status in tracepoints 

Compaction returns prematurely with COMPACT_PARTIAL when contended or has
fatal signal pending.  This is ok for the callers, but might be misleading
in the traces, as the usual reason to return COMPACT_PARTIAL is that we
think the allocation should succeed.  After this patch we distinguish the
premature ending condition in the mm_compaction_finished and
mm_compaction_end tracepoints.

The contended status covers the following reasons:
- lock contention or need_resched() detected in async compaction
- fatal signal pending
- too many pages isolated in the zone (only for async compaction)
Further distinguishing the exact reason seems unnecessary for now.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: David Rientjes <rientjes@google.com>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: Ingo Molnar <mingo@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
hifive-unleashed-5.1
Vlastimil Babka 2015-11-05 18:48:02 -08:00 committed by Linus Torvalds
parent 1743d05060
commit 2d1e10412c
3 changed files with 9 additions and 4 deletions
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1
include/linux/compaction.h
View File

@ -15,6 +15,7 @@
/* For more detailed tracepoint output */
#define COMPACT_NO_SUITABLE_PAGE 5
#define COMPACT_NOT_SUITABLE_ZONE 6
#define COMPACT_CONTENDED 7
/* When adding new states, please adjust include/trace/events/compaction.h */
/* Used to signal whether compaction detected need_sched() or lock contention */

3
include/trace/events/compaction.h
View File

@ -16,7 +16,8 @@
EM( COMPACT_PARTIAL, "partial") \
EM( COMPACT_COMPLETE, "complete") \
EM( COMPACT_NO_SUITABLE_PAGE, "no_suitable_page") \
EMe(COMPACT_NOT_SUITABLE_ZONE, "not_suitable_zone")
EM( COMPACT_NOT_SUITABLE_ZONE, "not_suitable_zone") \
EMe(COMPACT_CONTENDED, "contended")
#ifdef CONFIG_ZONE_DMA
#define IFDEF_ZONE_DMA(X) X

9
mm/compaction.c
View File

@ -1202,7 +1202,7 @@ static int __compact_finished(struct zone *zone, struct compact_control *cc,
unsigned long watermark;
if (cc->contended || fatal_signal_pending(current))
return COMPACT_PARTIAL;
return COMPACT_CONTENDED;
/* Compaction run completes if the migrate and free scanner meet */
if (compact_scanners_met(cc)) {
@ -1393,7 +1393,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
switch (isolate_migratepages(zone, cc)) {
case ISOLATE_ABORT:
ret = COMPACT_PARTIAL;
ret = COMPACT_CONTENDED;
putback_movable_pages(&cc->migratepages);
cc->nr_migratepages = 0;
goto out;
@ -1424,7 +1424,7 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
* and we want compact_finished() to detect it
*/
if (err == -ENOMEM && !compact_scanners_met(cc)) {
ret = COMPACT_PARTIAL;
ret = COMPACT_CONTENDED;
goto out;
}
}
@ -1477,6 +1477,9 @@ out:
trace_mm_compaction_end(start_pfn, cc->migrate_pfn,
cc->free_pfn, end_pfn, sync, ret);
if (ret == COMPACT_CONTENDED)
ret = COMPACT_PARTIAL;
return ret;
}