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Commit 2d1e1041 authored by Vlastimil Babka's avatar Vlastimil Babka Committed by Linus Torvalds
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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: default avatarVlastimil 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: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 1743d050

include/linux/compaction.h

+1 −0
Original line number Diff line number Diff line
@@ -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 */

include/trace/events/compaction.h

+2 −1
Original line number Diff line number Diff line
@@ -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

mm/compaction.c

+6 −3
Original line number Diff line number Diff line
@@ -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 @@ static int compact_zone(struct zone *zone, struct compact_control *cc) 
	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;

}