[PATCH] mm: batch-free pcp list if possible

[Namhyung Kim <namhyung@gmail.com>]

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.

Signed-off-by: Namhyung Kim <namhyung@gmail.com>
---
 mm/page_alloc.c |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)

diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index a873e61e312e..470fb42e303c 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -614,6 +614,10 @@ static void free_pcppages_bulk(struct zone *zone, int count,
 			list = &pcp->lists[migratetype];
 		} while (list_empty(list));
 
+		/* This is an 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 */
-- 
1.7.3.4.600.g982838b0

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