memcg: fix calculation of active_ratio

Currently, inactive_ratio of memcg is calculated at setting limit.
because page_alloc.c does so and current implementation is straightforward
porting.

However, memcg introduced hierarchy feature recently.  In hierarchy
restriction, memory limit is not only decided memory.limit_in_bytes of
current cgroup, but also parent limit and sibling memory usage.

Then, The optimal inactive_ratio is changed frequently.  So, everytime
calculation is better.

Tested-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Balbir Singh <balbir@linux.vnet.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 31 insertions, 33 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index ab2ecbb95b8d..c7d78eca8363 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -166,9 +166,6 @@ struct mem_cgroup {
 
         unsigned int    swappiness;
 
-
-        unsigned int inactive_ratio;
-
         /*
          * statistics. This must be placed at the end of memcg.
          */
@@ -432,15 +429,43 @@ void mem_cgroup_record_reclaim_priority(struct mem_cgroup *mem, int priority)
         spin_unlock(&mem->reclaim_param_lock);
 }
 
-int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg, struct zone *zone)
+static int calc_inactive_ratio(struct mem_cgroup *memcg, unsigned long *present_pages)
 {
         unsigned long active;
         unsigned long inactive;
+        unsigned long gb;
+        unsigned long inactive_ratio;
 
         inactive = mem_cgroup_get_all_zonestat(memcg, LRU_INACTIVE_ANON);
         active = mem_cgroup_get_all_zonestat(memcg, LRU_ACTIVE_ANON);
 
-        if (inactive * memcg->inactive_ratio < active)
+        gb = (inactive + active) >> (30 - PAGE_SHIFT);
+        if (gb)
+                inactive_ratio = int_sqrt(10 * gb);
+        else
+                inactive_ratio = 1;
+
+        if (present_pages) {
+                present_pages[0] = inactive;
+                present_pages[1] = active;
+        }
+
+        return inactive_ratio;
+}
+
+int mem_cgroup_inactive_anon_is_low(struct mem_cgroup *memcg)
+{
+        unsigned long active;
+        unsigned long inactive;
+        unsigned long present_pages[2];
+        unsigned long inactive_ratio;
+
+        inactive_ratio = calc_inactive_ratio(memcg, present_pages);
+
+        inactive = present_pages[0];
+        active = present_pages[1];
+
+        if (inactive * inactive_ratio < active)
                 return 1;
 
         return 0;
@@ -1432,29 +1457,6 @@ int mem_cgroup_shrink_usage(struct mm_struct *mm, gfp_t gfp_mask)
         return 0;
 }
 
-/*
- * The inactive anon list should be small enough that the VM never has to
- * do too much work, but large enough that each inactive page has a chance
- * to be referenced again before it is swapped out.
- *
- * this calculation is straightforward porting from
- * page_alloc.c::setup_per_zone_inactive_ratio().
- * it describe more detail.
- */
-static void mem_cgroup_set_inactive_ratio(struct mem_cgroup *memcg)
-{
-        unsigned int gb, ratio;
-
-        gb = res_counter_read_u64(&memcg->res, RES_LIMIT) >> 30;
-        if (gb)
-                ratio = int_sqrt(10 * gb);
-        else
-                ratio = 1;
-
-        memcg->inactive_ratio = ratio;
-
-}
-
 static DEFINE_MUTEX(set_limit_mutex);
 
 static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
@@ -1496,9 +1498,6 @@ static int mem_cgroup_resize_limit(struct mem_cgroup *memcg,
                 if (!progress)                  retry_count--;
         }
 
-        if (!ret)
-                mem_cgroup_set_inactive_ratio(memcg);
-
         return ret;
 }
 
@@ -1858,7 +1857,7 @@ static int mem_control_stat_show(struct cgroup *cont, struct cftype *cft,
         }
 
 #ifdef CONFIG_DEBUG_VM
-        cb->fill(cb, "inactive_ratio", mem_cont->inactive_ratio);
+        cb->fill(cb, "inactive_ratio", calc_inactive_ratio(mem_cont, NULL));
 
         {
                 int nid, zid;
@@ -2150,7 +2149,6 @@ mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont)
                 res_counter_init(&mem->res, NULL);
                 res_counter_init(&mem->memsw, NULL);
         }
-        mem_cgroup_set_inactive_ratio(mem);
         mem->last_scanned_child = NULL;
         spin_lock_init(&mem->reclaim_param_lock);