Message-ID: <4FE81DEB.5090407@parallels.com>
Date: Mon, 25 Jun 2012 12:14:35 +0400
From: Glauber Costa <glommer@parallels.com>
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To: Wanpeng Li <liwp.linux@gmail.com>
CC: <linux-mm@kvack.org>, Michal Hocko <mhocko@suse.cz>,
        Johannes Weiner <hannes@cmpxchg.org>,
        Balbir Singh <bsingharora@gmail.com>,
        KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Andrew Morton <akpm@linux-foundation.org>, Mel Gorman <mel@csn.ul.ie>,
        Minchan Kim <minchan@kernel.org>, <linux-kernel@vger.kernel.org>,
        <cgroups@vger.kernel.org>, Gavin Shan <shangw@linux.vnet.ibm.com>
Subject: Re: [PATCH 5/6] memcg: optimize memcg_get_hierarchical_limit
References: <1340432297-5362-1-git-send-email-liwp.linux@gmail.com>
In-Reply-To: <1340432297-5362-1-git-send-email-liwp.linux@gmail.com>
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On 06/23/2012 10:18 AM, Wanpeng Li wrote:
> From: Wanpeng Li <liwp@linux.vnet.ibm.com>
>
> Optimize memcg_get_hierarchical_limit to save cpu cycle.
>
> Signed-off-by: Wanpeng Li <liwp.linux@gmail.com>
> ---
>   mm/memcontrol.c |    2 +-
>   1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index c821e36..1ca79e2 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3917,9 +3917,9 @@ static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
>
>   	min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
>   	min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
> -	cgroup = memcg->css.cgroup;
>   	if (!memcg->use_hierarchy)
>   		goto out;
> +	cgroup = memcg->css.cgroup;
>
>   	while (cgroup->parent) {
>   		cgroup = cgroup->parent;
>
Seriously, this saves nothing.


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