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>
diff --git a/mm/compaction.c b/mm/compaction.c
index a5849c4..de3e1e7 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -1202,7 +1202,7 @@
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 @@
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 @@
* 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 @@
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;
}