memcg: optimize per-cpu statistics

Some obvious optimization to memcg.

I found mem_cgroup_charge_statistics() is a little big (in object) and
does unnecessary address calclation.  This patch is for optimization to
reduce the size of this function.

And res_counter_charge() is 'likely' to succeed.

Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 10 insertions, 8 deletions

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 6f8b5b3b38b2..10846b9656aa 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -66,11 +66,10 @@ struct mem_cgroup_stat {
 /*
  * For accounting under irq disable, no need for increment preempt count.
  */
-static void __mem_cgroup_stat_add_safe(struct mem_cgroup_stat *stat,
+static inline void __mem_cgroup_stat_add_safe(struct mem_cgroup_stat_cpu *stat,
                 enum mem_cgroup_stat_index idx, int val)
 {
-        int cpu = smp_processor_id();
-        stat->cpustat[cpu].count[idx] += val;
+        stat->count[idx] += val;
 }
 
 static s64 mem_cgroup_read_stat(struct mem_cgroup_stat *stat,
@@ -190,18 +189,21 @@ static void mem_cgroup_charge_statistics(struct mem_cgroup *mem, int flags,
 {
         int val = (charge)? 1 : -1;
         struct mem_cgroup_stat *stat = &mem->stat;
+        struct mem_cgroup_stat_cpu *cpustat;
 
         VM_BUG_ON(!irqs_disabled());
+
+        cpustat = &stat->cpustat[smp_processor_id()];
         if (flags & PAGE_CGROUP_FLAG_CACHE)
-                __mem_cgroup_stat_add_safe(stat, MEM_CGROUP_STAT_CACHE, val);
+                __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_CACHE, val);
         else
-                __mem_cgroup_stat_add_safe(stat, MEM_CGROUP_STAT_RSS, val);
+                __mem_cgroup_stat_add_safe(cpustat, MEM_CGROUP_STAT_RSS, val);
 
         if (charge)
-                __mem_cgroup_stat_add_safe(stat,
+                __mem_cgroup_stat_add_safe(cpustat,
                                 MEM_CGROUP_STAT_PGPGIN_COUNT, 1);
         else
-                __mem_cgroup_stat_add_safe(stat,
+                __mem_cgroup_stat_add_safe(cpustat,
                                 MEM_CGROUP_STAT_PGPGOUT_COUNT, 1);
 }
 
@@ -558,7 +560,7 @@ static int mem_cgroup_charge_common(struct page *page, struct mm_struct *mm,
                 css_get(&memcg->css);
         }
 
-        while (res_counter_charge(&mem->res, PAGE_SIZE)) {
+        while (unlikely(res_counter_charge(&mem->res, PAGE_SIZE))) {
                 if (!(gfp_mask & __GFP_WAIT))
                         goto out;