mm/compaction: do not call suitable_migration_target() on every page
suitable_migration_target() checks that pageblock is suitable for
migration target. In isolate_freepages_block(), it is called on every
page and this is inefficient. So make it called once per pageblock.
suitable_migration_target() also checks if page is highorder or not, but
it's criteria for highorder is pageblock order. So calling it once
within pageblock range has no problem.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Rik van Riel <riel@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 9a03fdb..3a18285 100644
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -244,6 +244,7 @@
struct page *cursor, *valid_page = NULL;
unsigned long flags;
bool locked = false;
+ bool checked_pageblock = false;
cursor = pfn_to_page(blockpfn);
@@ -275,8 +276,16 @@
break;
/* Recheck this is a suitable migration target under lock */
- if (!strict && !suitable_migration_target(page))
- break;
+ if (!strict && !checked_pageblock) {
+ /*
+ * We need to check suitability of pageblock only once
+ * and this isolate_freepages_block() is called with
+ * pageblock range, so just check once is sufficient.
+ */
+ checked_pageblock = true;
+ if (!suitable_migration_target(page))
+ break;
+ }
/* Recheck this is a buddy page under lock */
if (!PageBuddy(page))