releases/2.6.32.3/vmscan-do-not-evict-inactive-pages-when-skipping-an-active-list-scan.patch

   1 From b39415b2731d7dec5e612d2d12595da82399eedf Mon Sep 17 00:00:00 2001
   2 From: Rik van Riel <riel@redhat.com>
   3 Date: Mon, 14 Dec 2009 17:59:48 -0800
   4 Subject: vmscan: do not evict inactive pages when skipping an active list scan
   5
   6 From: Rik van Riel <riel@redhat.com>
   7
   8 commit b39415b2731d7dec5e612d2d12595da82399eedf upstream.
   9
  10 In AIM7 runs, recent kernels start swapping out anonymous pages well
  11 before they should.  This is due to shrink_list falling through to
  12 shrink_inactive_list if !inactive_anon_is_low(zone, sc), when all we
  13 really wanted to do is pre-age some anonymous pages to give them extra
  14 time to be referenced while on the inactive list.
  15
  16 The obvious fix is to make sure that shrink_list does not fall through to
  17 scanning/reclaiming inactive pages when we called it to scan one of the
  18 active lists.
  19
  20 This change should be safe because the loop in shrink_zone ensures that we
  21 will still shrink the anon and file inactive lists whenever we should.
  22
  23 [kosaki.motohiro@jp.fujitsu.com: inactive_file_is_low() should be inactive_anon_is_low()]
  24 Reported-by: Larry Woodman <lwoodman@redhat.com>
  25 Signed-off-by: Rik van Riel <riel@redhat.com>
  26 Acked-by: Johannes Weiner <hannes@cmpxchg.org>
  27 Cc: Tomasz Chmielewski <mangoo@wpkg.org>
  28 Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
  29 Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
  30 Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
  31 Cc: Rik Theys <rik.theys@gmail.com>
  32 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  33
  34 ---
  35  mm/vmscan.c |   18 ++++++++++++------
  36  1 file changed, 12 insertions(+), 6 deletions(-)
  37
  38 --- a/mm/vmscan.c
  39 +++ b/mm/vmscan.c
  40 @@ -1464,20 +1464,26 @@ static int inactive_file_is_low(struct z
  41         return low;
  42  }
  43
  44 +static int inactive_list_is_low(struct zone *zone, struct scan_control *sc,
  45 +                               int file)
  46 +{
  47 +       if (file)
  48 +               return inactive_file_is_low(zone, sc);
  49 +       else
  50 +               return inactive_anon_is_low(zone, sc);
  51 +}
  52 +
  53  static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
  54         struct zone *zone, struct scan_control *sc, int priority)
  55  {
  56         int file = is_file_lru(lru);
  57
  58 -       if (lru == LRU_ACTIVE_FILE && inactive_file_is_low(zone, sc)) {
  59 -               shrink_active_list(nr_to_scan, zone, sc, priority, file);
  60 +       if (is_active_lru(lru)) {
  61 +               if (inactive_list_is_low(zone, sc, file))
  62 +                   shrink_active_list(nr_to_scan, zone, sc, priority, file);
  63                 return 0;
  64         }
  65
  66 -       if (lru == LRU_ACTIVE_ANON && inactive_anon_is_low(zone, sc)) {
  67 -               shrink_active_list(nr_to_scan, zone, sc, priority, file);
  68 -               return 0;
  69 -       }
  70         return shrink_inactive_list(nr_to_scan, zone, sc, priority, file);
  71  }
  72