From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx157.postini.com [74.125.245.157]) by kanga.kvack.org (Postfix) with SMTP id C9DB26B004F for ; Thu, 26 Jan 2012 04:16:05 -0500 (EST) Date: Thu, 26 Jan 2012 10:16:03 +0100 From: Michal Hocko Subject: Re: [RFC] [PATCH 3/7 v2] memcg: remove PCG_MOVE_LOCK flag from pc->flags Message-ID: <20120126091602.GC13421@tiehlicka.suse.cz> References: <20120113173001.ee5260ca.kamezawa.hiroyu@jp.fujitsu.com> <20120113174019.8dff3fc1.kamezawa.hiroyu@jp.fujitsu.com> <20120117164605.GB22142@tiehlicka.suse.cz> <20120118091226.b46e0f6e.kamezawa.hiroyu@jp.fujitsu.com> <20120118104703.GA31112@tiehlicka.suse.cz> <20120119085309.616cadb4.kamezawa.hiroyu@jp.fujitsu.com> <20120124084335.GE26289@tiehlicka.suse.cz> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: owner-linux-mm@kvack.org List-ID: To: Ying Han Cc: KAMEZAWA Hiroyuki , "linux-mm@kvack.org" , "hugh.dickins@tiscali.co.uk" , "hannes@cmpxchg.org" , cgroups@vger.kernel.org, "bsingharora@gmail.com" On Wed 25-01-12 15:07:47, Ying Han wrote: > On Tue, Jan 24, 2012 at 12:43 AM, Michal Hocko wrote: > > On Mon 23-01-12 14:05:33, Ying Han wrote: [...] > >> Just want to make sure I understand it, even we make the lock > >> per-memcg, there is still a false sharing of pc within one memcg. > > > > Yes that is true. I have missed that we might fault in several pages at > > once but this would happen only during task move, right? And that is not > > a hot path anyway. Or? > > I was thinking of page-statistics update which is hot path. If the > moving task and non-moving task share the same per-memcg lock, any > page-statistic update from the non-moving task will be blocked? Sorry > If i missed something here :) OK, I got your point, finally. I guess there is a plan to reduce the effect by array of locks. -- Michal Hocko SUSE Labs SUSE LINUX s.r.o. Lihovarska 1060/12 190 00 Praha 9 Czech Republic -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: email@kvack.org