[PATCH] [mmotm] don't attempt to reclaim anon page in lumpy reclaim when no swap space is avilable

[PATCH] [mmotm] don't attempt to reclaim anon page in lumpy reclaim when no swap space is avilable

[Minchan Kim]

This patch is based on mmotm 2009-07-15-20-57

This version is better than old one.
That's because enough swap space check is done in case of only lumpy reclaim.
so it can't degrade performance in normal case.

== CUT HERE ==

VM already avoids attempting to reclaim anon pages in various places, But
it doesn't avoid it for lumpy reclaim.

It shuffles lru list unnecessary so that it is pointless.

Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: Rik van Riel <riel@redhat.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
---
 mm/vmscan.c |    9 +++++++++
 1 files changed, 9 insertions(+), 0 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 543596e..8b1132f 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -930,6 +930,15 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
 			/* Check that we have not crossed a zone boundary. */
 			if (unlikely(page_zone_id(cursor_page) != zone_id))
 				continue;
+
+			/*
+			 * If we don't have enough swap space, reclaiming of anon page
+			 * which don't already have a swap slot is pointless.
+			 */
+			if (nr_swap_pages <= 0 && (PageAnon(cursor_page) &&
+									!PageSwapCache(cursor_page)))
+				continue;
+
 			if (__isolate_lru_page(cursor_page, mode, file) == 0) {
 				list_move(&cursor_page->lru, dst);
 				mem_cgroup_del_lru(cursor_page);
-- 
1.5.4.3


-- 
Kind regards,
Minchan Kim

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