[RFC v4 PATCH 5/5] mm/can_skip_merge(): make it more aggressive to attempt cluster alloc/free

[Aaron Lu]

After system runs a long time, it's easy for a zone to have no
suitable high order page available and that will stop cluster alloc
and free in current implementation due to compact_considered > 0.

To make it favour order0 alloc/free, relax the condition to only
disallow cluster alloc/free when problem would occur, e.g. when
compaction is in progress.

Signed-off-by: Aaron Lu <aaron.lu@xxxxxxxxx>
---
 mm/internal.h | 4 ----
 1 file changed, 4 deletions(-)

diff --git a/mm/internal.h b/mm/internal.h
index fb4e8f7976e5..309a3f43e613 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -538,10 +538,6 @@ void try_to_merge_page(struct page *page);
 #ifdef CONFIG_COMPACTION
 static inline bool can_skip_merge(struct zone *zone, int order)
 {
-	/* Compaction has failed in this zone, we shouldn't skip merging */
-	if (zone->compact_considered)
-		return false;
-
 	/* Only consider no_merge for order 0 pages */
 	if (order)
 		return false;
-- 
2.17.2