kernel26-lts-ck/mm-kswapd_inherit_prio-1.patch

   1 When kswapd is awoken due to reclaim by a running task, set the priority of
   2 kswapd to that of the calling task thus making memory reclaim cpu activity
   3 affected by nice level.
   4
   5 Signed-off-by: Con Kolivas <kernel@kolivas.org>
   6
   7  mm/vmscan.c |   33 ++++++++++++++++++++++++++++++++-
   8  1 file changed, 32 insertions(+), 1 deletion(-)
   9
  10 Index: linux-2.6.35.11-ck1/mm/vmscan.c
  11 ===================================================================
  12 --- linux-2.6.35.11-ck1.orig/mm/vmscan.c        2011-03-29 22:12:01.124555385 +1100
  13 +++ linux-2.6.35.11-ck1/mm/vmscan.c     2011-03-29 22:12:01.298555385 +1100
  14 @@ -1711,6 +1711,33 @@ static void shrink_zone(int priority, st
  15  }
  16
  17  /*
  18 + * Helper functions to adjust nice level of kswapd, based on the priority of
  19 + * the task (p) that called it. If it is already higher priority we do not
  20 + * demote its nice level since it is still working on behalf of a higher
  21 + * priority task. With kernel threads we leave it at nice 0.
  22 + *
  23 + * We don't ever run kswapd real time, so if a real time task calls kswapd we
  24 + * set it to highest SCHED_NORMAL priority.
  25 + */
  26 +static inline int effective_sc_prio(struct task_struct *p)
  27 +{
  28 +       if (likely(p->mm)) {
  29 +               if (rt_task(p))
  30 +                       return -20;
  31 +               return task_nice(p);
  32 +       }
  33 +       return 0;
  34 +}
  35 +
  36 +static void set_kswapd_nice(struct task_struct *kswapd, int active)
  37 +{
  38 +       long nice = effective_sc_prio(current);
  39 +
  40 +       if (task_nice(kswapd) > nice || !active)
  41 +               set_user_nice(kswapd, nice);
  42 +}
  43 +
  44 +/*
  45   * This is the direct reclaim path, for page-allocating processes.  We only
  46   * try to reclaim pages from zones which will satisfy the caller's allocation
  47   * request.
  48 @@ -2336,6 +2363,7 @@ static int kswapd(void *p)
  49                                 }
  50                         }
  51
  52 +                       set_user_nice(tsk, 0);
  53                         order = pgdat->kswapd_max_order;
  54                 }
  55                 finish_wait(&pgdat->kswapd_wait, &wait);
  56 @@ -2360,6 +2388,7 @@ static int kswapd(void *p)
  57  void wakeup_kswapd(struct zone *zone, int order)
  58  {
  59         pg_data_t *pgdat;
  60 +       int active;
  61
  62         if (!populated_zone(zone))
  63                 return;
  64 @@ -2407,7 +2407,9 @@ void wakeup_kswapd(struct zone *zone, in
  65         pgdat = zone->zone_pgdat;
  66         if (pgdat->kswapd_max_order < order)
  67                 pgdat->kswapd_max_order = order;
  68 -       if (!waitqueue_active(&pgdat->kswapd_wait))
  69 +       active = waitqueue_active(&pgdat->kswapd_wait);
  70 +       set_kswapd_nice(pgdat->kswapd, active);
  71 +       if (!active)
  72                 return;
  73         if (zone_watermark_ok_safe(zone, order, low_wmark_pages(zone), 0, 0))
  74                 return;