memcg: optimize per-cpu statistics
KAMEZAWA Hiroyuki [Sun, 19 Oct 2008 03:28:10 +0000 (20:28 -0700)]
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>

mm/memcontrol.c

index 6f8b5b3..10846b9 100644 (file)
@@ -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;