mm: batch-free pcp list if possible

free_pcppages_bulk() frees pages from pcp lists in a round-robin fashion by keeping batch_free counter. But it doesn't need to spin if there is only one non-empty list. This can be checked by batch_free == MIGRATE_PCPTYPES. [akpm@linux-foundation.org: fix comment] Signed-off-by: Namhyung Kim <namhyung@gmail.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: batch-free pcp list if possible
free_pcppages_bulk() frees pages from pcp lists in a round-robin fashion by keeping batch_free counter. But it doesn't need to spin if there is only one non-empty list. This can be checked by batch_free == MIGRATE_PCPTYPES. [akpm@linux-foundation.org: fix comment] Signed-off-by: Namhyung Kim <namhyung@gmail.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mel@csn.ul.ie> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Namhyung Kim · Linus Torvalds
1 parent e64a782fec
Showing 1 changed file with 4 additions and 0 deletions Side-by-side Diff
mm/page_alloc.c
@@ -614,6 +614,10 @@
 			list = &pcp->lists[migratetype];
 		} while (list_empty(list));
  
+		/* This is the only non-empty list. Free them all. */
+		if (batch_free == MIGRATE_PCPTYPES)
+			batch_free = to_free;
+
 		do {
 			page = list_entry(list->prev, struct page, lru);
 			/* must delete as __free_one_page list manipulates */
...	...	@@ -614,6 +614,10 @@
614	614	list = &pcp->lists[migratetype];
615	615	} while (list_empty(list));
616	616
	617	+ /* This is the only non-empty list. Free them all. */
	618	+ if (batch_free == MIGRATE_PCPTYPES)
	619	+ batch_free = to_free;
	620	+
617	621	do {
618	622	page = list_entry(list->prev, struct page, lru);
619	623	/* must delete as __free_one_page list manipulates */