Commit b39415b2 authored Dec 14, 2009 by Rik van Riel Committed by Linus Torvalds Dec 15, 2009

vmscan: do not evict inactive pages when skipping an active list scan



In AIM7 runs, recent kernels start swapping out anonymous pages well
before they should.  This is due to shrink_list falling through to
shrink_inactive_list if !inactive_anon_is_low(zone, sc), when all we
really wanted to do is pre-age some anonymous pages to give them extra
time to be referenced while on the inactive list.

The obvious fix is to make sure that shrink_list does not fall through to
scanning/reclaiming inactive pages when we called it to scan one of the
active lists.

This change should be safe because the loop in shrink_zone ensures that we
will still shrink the anon and file inactive lists whenever we should.

[kosaki.motohiro@jp.fujitsu.com: inactive_file_is_low() should be inactive_anon_is_low()]
Reported-by: Larry Woodman <lwoodman@redhat.com>
Signed-off-by: Rik van Riel <riel@redhat.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Cc: Tomasz Chmielewski <mangoo@wpkg.org>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent 8aa043d7

mm/vmscan.c

+12 −6

Original line number	Diff line number	Diff line
		@@ -1463,20 +1463,26 @@ static int inactive_file_is_low(struct zone zone, struct scan_control sc)
		return low;
		}

		static int inactive_list_is_low(struct zone zone, struct scan_control sc,
		int file)
		{
		if (file)
		return inactive_file_is_low(zone, sc);
		else
		return inactive_anon_is_low(zone, sc);
		}

		static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
		struct zone zone, struct scan_control sc, int priority)
		{
		int file = is_file_lru(lru);

		if (lru == LRU_ACTIVE_FILE && inactive_file_is_low(zone, sc)) {
		if (is_active_lru(lru)) {
		if (inactive_list_is_low(zone, sc, file))
		shrink_active_list(nr_to_scan, zone, sc, priority, file);
		return 0;
		}

		if (lru == LRU_ACTIVE_ANON && inactive_anon_is_low(zone, sc)) {
		shrink_active_list(nr_to_scan, zone, sc, priority, file);
		return 0;
		}
		return shrink_inactive_list(nr_to_scan, zone, sc, priority, file);
		}