Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755439Ab2FYJqw (ORCPT ); Mon, 25 Jun 2012 05:46:52 -0400 Received: from cantor2.suse.de ([195.135.220.15]:48011 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753251Ab2FYJqv (ORCPT ); Mon, 25 Jun 2012 05:46:51 -0400 Date: Mon, 25 Jun 2012 11:46:50 +0200 From: Michal Hocko To: Wanpeng Li Cc: Johannes Weiner , KAMEZAWA Hiroyuki , Balbir Singh , Andrew Morton , Eric Dumazet , Mike Frysinger , Arun Sharma , linux-kernel@vger.kernel.org, cgroups@vger.kernel.org Subject: Re: [PATCH v3 3/4] memcg: optimize memcg_get_hierarchical_limit Message-ID: <20120625094649.GF19805@tiehlicka.suse.cz> References: <1340613872-9581-1-git-send-email-liwp.linux@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1340613872-9581-1-git-send-email-liwp.linux@gmail.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1301 Lines: 44 On Mon 25-06-12 16:44:32, Wanpeng Li wrote: > From: Wanpeng Li > > Optimize memcg_get_hierarchical_limit to save cpu cycle. How did you check that this actually saves some cycles? There are no (compiler) barriers here so it should reordered. > Signed-off-by: Wanpeng Li > --- > mm/memcontrol.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/memcontrol.c b/mm/memcontrol.c > index 2e81328..4520b57 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; > -- > 1.7.9.5 > -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/