1 files changed, 41 insertions, 45 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 006fe142d4ba..f9ae4b4c36eb 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -63,8 +63,15 @@ static int really_do_swap_account __initdata = 1; /* for remember boot option*/
 #define do_swap_account         (0)
 #endif
 
-#define SOFTLIMIT_EVENTS_THRESH (1000)
-#define THRESHOLDS_EVENTS_THRESH (100)
+/*
+ * Per memcg event counter is incremented at every pagein/pageout. This counter
+ * is used for trigger some periodic events. This is straightforward and better
+ * than using jiffies etc. to handle periodic memcg event.
+ *
+ * These values will be used as !((event) & ((1 <<(thresh)) - 1))
+ */
+#define THRESHOLDS_EVENTS_THRESH (7) /* once in 128 */
+#define SOFTLIMIT_EVENTS_THRESH (10) /* once in 1024 */
 
 /*
  * Statistics for memory cgroup.
@@ -79,10 +86,7 @@ enum mem_cgroup_stat_index {
         MEM_CGROUP_STAT_PGPGIN_COUNT,   /* # of pages paged in */
         MEM_CGROUP_STAT_PGPGOUT_COUNT,  /* # of pages paged out */
         MEM_CGROUP_STAT_SWAPOUT, /* # of pages, swapped out */
-        MEM_CGROUP_STAT_SOFTLIMIT, /* decrements on each page in/out.
-                                        used by soft limit implementation */
-        MEM_CGROUP_STAT_THRESHOLDS, /* decrements on each page in/out.
-                                        used by threshold implementation */
+        MEM_CGROUP_EVENTS,      /* incremented at every  pagein/pageout */
 
         MEM_CGROUP_STAT_NSTATS,
 };
@@ -154,7 +158,6 @@ struct mem_cgroup_threshold_ary {
         struct mem_cgroup_threshold entries[0];
 };
 
-static bool mem_cgroup_threshold_check(struct mem_cgroup *mem);
 static void mem_cgroup_threshold(struct mem_cgroup *mem);
 
 /*
@@ -392,19 +395,6 @@ mem_cgroup_remove_exceeded(struct mem_cgroup *mem,
         spin_unlock(&mctz->lock);
 }
 
-static bool mem_cgroup_soft_limit_check(struct mem_cgroup *mem)
-{
-        bool ret = false;
-        s64 val;
-
-        val = this_cpu_read(mem->stat->count[MEM_CGROUP_STAT_SOFTLIMIT]);
-        if (unlikely(val < 0)) {
-                this_cpu_write(mem->stat->count[MEM_CGROUP_STAT_SOFTLIMIT],
-                                SOFTLIMIT_EVENTS_THRESH);
-                ret = true;
-        }
-        return ret;
-}
 
 static void mem_cgroup_update_tree(struct mem_cgroup *mem, struct page *page)
 {
@@ -542,8 +532,7 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *mem,
                 __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGIN_COUNT]);
         else
                 __this_cpu_inc(mem->stat->count[MEM_CGROUP_STAT_PGPGOUT_COUNT]);
-        __this_cpu_dec(mem->stat->count[MEM_CGROUP_STAT_SOFTLIMIT]);
-        __this_cpu_dec(mem->stat->count[MEM_CGROUP_STAT_THRESHOLDS]);
+        __this_cpu_inc(mem->stat->count[MEM_CGROUP_EVENTS]);
 
         preempt_enable();
 }
@@ -563,6 +552,29 @@ static unsigned long mem_cgroup_get_local_zonestat(struct mem_cgroup *mem,
         return total;
 }
 
+static bool __memcg_event_check(struct mem_cgroup *mem, int event_mask_shift)
+{
+        s64 val;
+
+        val = this_cpu_read(mem->stat->count[MEM_CGROUP_EVENTS]);
+
+        return !(val & ((1 << event_mask_shift) - 1));
+}
+
+/*
+ * Check events in order.
+ *
+ */
+static void memcg_check_events(struct mem_cgroup *mem, struct page *page)
+{
+        /* threshold event is triggered in finer grain than soft limit */
+        if (unlikely(__memcg_event_check(mem, THRESHOLDS_EVENTS_THRESH))) {
+                mem_cgroup_threshold(mem);
+                if (unlikely(__memcg_event_check(mem, SOFTLIMIT_EVENTS_THRESH)))
+                        mem_cgroup_update_tree(mem, page);
+        }
+}
+
 static struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont)
 {
         return container_of(cgroup_subsys_state(cont,
@@ -1686,11 +1698,7 @@ static void __mem_cgroup_commit_charge(struct mem_cgroup *mem,
          * Insert ancestor (and ancestor's ancestors), to softlimit RB-tree.
          * if they exceeds softlimit.
          */
-        if (mem_cgroup_soft_limit_check(mem))
-                mem_cgroup_update_tree(mem, pc->page);
-        if (mem_cgroup_threshold_check(mem))
-                mem_cgroup_threshold(mem);
-
+        memcg_check_events(mem, pc->page);
 }
 
 /**
@@ -1760,6 +1768,11 @@ static int mem_cgroup_move_account(struct page_cgroup *pc,
                 ret = 0;
         }
         unlock_page_cgroup(pc);
+        /*
+         * check events
+         */
+        memcg_check_events(to, pc->page);
+        memcg_check_events(from, pc->page);
         return ret;
 }
 
@@ -2128,10 +2141,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)
         mz = page_cgroup_zoneinfo(pc);
         unlock_page_cgroup(pc);
 
-        if (mem_cgroup_soft_limit_check(mem))
-                mem_cgroup_update_tree(mem, page);
-        if (mem_cgroup_threshold_check(mem))
-                mem_cgroup_threshold(mem);
+        memcg_check_events(mem, page);
         /* at swapout, this memcg will be accessed to record to swap */
         if (ctype != MEM_CGROUP_CHARGE_TYPE_SWAPOUT)
                 css_put(&mem->css);
@@ -3215,20 +3225,6 @@ static int mem_cgroup_swappiness_write(struct cgroup *cgrp, struct cftype *cft,
         return 0;
 }
 
-static bool mem_cgroup_threshold_check(struct mem_cgroup *mem)
-{
-        bool ret = false;
-        s64 val;
-
-        val = this_cpu_read(mem->stat->count[MEM_CGROUP_STAT_THRESHOLDS]);
-        if (unlikely(val < 0)) {
-                this_cpu_write(mem->stat->count[MEM_CGROUP_STAT_THRESHOLDS],
-                                THRESHOLDS_EVENTS_THRESH);
-                ret = true;
-        }
-        return ret;
-}
-
 static void __mem_cgroup_threshold(struct mem_cgroup *memcg, bool swap)
 {
         struct mem_cgroup_threshold_ary *t;