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Message-Id: <20100204143645.87b5fc28.kamezawa.hiroyu@jp.fujitsu.com>
Date: Thu, 4 Feb 2010 14:36:45 +0900
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To: "linux-mm@...ck.org" <linux-mm@...ck.org>
Cc: "nishimura@....nes.nec.co.jp" <nishimura@....nes.nec.co.jp>,
"balbir@...ux.vnet.ibm.com" <balbir@...ux.vnet.ibm.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"akpm@...ux-foundation.org" <akpm@...ux-foundation.org>
Subject: [PATCH] memcg: use for each online for making sum of percpu counter
Tested on mmotm-2010-02-03.
Balbir-san, how about this patch ? It seems not so difficult as expected.
==
From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
memcg-use-for-each-online-cpus-for-making-sum-of-percpu-counter
Now, memcg's percpu coutner uses for_each_possible_cpus() for
handling cpu hotplug. But it adds some overhead on a server
which has an additonal cpu hotplug slot which is not used.
This patch adds cpu hotplug callback for memcg's percpu counter
and make use of for_each_online_cpu().
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
---
mm/memcontrol.c | 35 ++++++++++++++++++++++++++++++++---
1 file changed, 32 insertions(+), 3 deletions(-)
Index: mmotm-2.6.33-Feb3/mm/memcontrol.c
===================================================================
--- mmotm-2.6.33-Feb3.orig/mm/memcontrol.c
+++ mmotm-2.6.33-Feb3/mm/memcontrol.c
@@ -223,6 +223,8 @@ struct mem_cgroup {
*/
unsigned long move_charge_at_immigrate;
+ /* list of all memcgs. currently used for cpu hotplug+percpu counter */
+ struct list_head list;
/*
* percpu counter.
*/
@@ -504,7 +506,7 @@ static s64 mem_cgroup_read_stat(struct m
int cpu;
s64 val = 0;
- for_each_possible_cpu(cpu)
+ for_each_online_cpu(cpu)
val += per_cpu(mem->stat->count[idx], cpu);
return val;
}
@@ -1405,17 +1407,37 @@ static void drain_all_stock_sync(void)
atomic_dec(&memcg_drain_count);
}
-static int __cpuinit memcg_stock_cpu_callback(struct notifier_block *nb,
+DEFINE_MUTEX(memcg_hotcpu_lock);
+LIST_HEAD(memcg_hotcpu_list);
+
+static int __cpuinit memcg_cpu_unplug_callback(struct notifier_block *nb,
unsigned long action,
void *hcpu)
{
int cpu = (unsigned long)hcpu;
+ struct mem_cgroup *memcg;
struct memcg_stock_pcp *stock;
+ int idx;
+ s64 val;
if (action != CPU_DEAD)
return NOTIFY_OK;
stock = &per_cpu(memcg_stock, cpu);
drain_stock(stock);
+
+ /* Move dead percpu counter's value to online cpu */
+ mutex_lock(&memcg_hotcpu_lock);
+ list_for_each_entry(memcg, &memcg_hotcpu_list, list) {
+ for (idx = MEM_CGROUP_STAT_CACHE;
+ idx <= MEM_CGROUP_STAT_SWAPOUT;
+ idx++) {
+ val = per_cpu(memcg->stat->count[idx], cpu);
+ per_cpu(memcg->stat->count[idx], cpu) = 0;
+ this_cpu_add(memcg->stat->count[idx], val);
+ }
+ }
+ mutex_unlock(&memcg_hotcpu_lock);
+
return NOTIFY_OK;
}
@@ -3626,6 +3648,10 @@ static struct mem_cgroup *mem_cgroup_all
else
vfree(mem);
mem = NULL;
+ } else {
+ mutex_lock(&memcg_hotcpu_lock);
+ list_add(&mem->list, &memcg_hotcpu_list);
+ mutex_unlock(&memcg_hotcpu_lock);
}
return mem;
}
@@ -3651,6 +3677,9 @@ static void __mem_cgroup_free(struct mem
for_each_node_state(node, N_POSSIBLE)
free_mem_cgroup_per_zone_info(mem, node);
+ mutex_lock(&memcg_hotcpu_lock);
+ list_del(&mem->list);
+ mutex_unlock(&memcg_hotcpu_lock);
free_percpu(mem->stat);
if (sizeof(struct mem_cgroup) < PAGE_SIZE)
kfree(mem);
@@ -3753,7 +3782,7 @@ mem_cgroup_create(struct cgroup_subsys *
&per_cpu(memcg_stock, cpu);
INIT_WORK(&stock->work, drain_local_stock);
}
- hotcpu_notifier(memcg_stock_cpu_callback, 0);
+ hotcpu_notifier(memcg_cpu_unplug_callback, 0);
} else {
parent = mem_cgroup_from_cont(cont->parent);
mem->use_hierarchy = parent->use_hierarchy;
--
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