compaction: checks correct fragmentation index
fragmentation_index() returns -1000 when the allocation might succeed
This doesn't match the comment and code in compaction_suitable(). I
thought compaction_suitable should return COMPACT_PARTIAL in -1000
case, because in this case allocation could succeed depending on
watermarks.
The impact of this is that compaction starts and compact_finished() is
called which rechecks the watermarks and the free lists. It should have
the same result in that compaction should not start but is more expensive.
Acked-by: Mel Gorman <mel@csn.ul.ie>
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Cc: Minchan Kim <minchan.kim@gmail.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 94bdbe1..cf7086c 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -480,7 +480,8 @@
* fragmentation index determines if allocation failures are due to
* low memory or external fragmentation
*
- * index of -1 implies allocations might succeed dependingon watermarks
+ * index of -1000 implies allocations might succeed depending on
+ * watermarks
* index towards 0 implies failure is due to lack of memory
* index towards 1000 implies failure is due to fragmentation
*
@@ -490,7 +491,8 @@
if (fragindex >= 0 && fragindex <= sysctl_extfrag_threshold)
return COMPACT_SKIPPED;
- if (fragindex == -1 && zone_watermark_ok(zone, order, watermark, 0, 0))
+ if (fragindex == -1000 && zone_watermark_ok(zone, order, watermark,
+ 0, 0))
return COMPACT_PARTIAL;
return COMPACT_CONTINUE;