From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail203.messagelabs.com (mail203.messagelabs.com [216.82.254.243]) by kanga.kvack.org (Postfix) with ESMTP id AD52F8D0040 for ; Mon, 28 Mar 2011 06:37:38 -0400 (EDT) Received: from m2.gw.fujitsu.co.jp (unknown [10.0.50.72]) by fgwmail6.fujitsu.co.jp (Postfix) with ESMTP id 0111A3EE0B6 for ; Mon, 28 Mar 2011 19:37:35 +0900 (JST) Received: from smail (m2 [127.0.0.1]) by outgoing.m2.gw.fujitsu.co.jp (Postfix) with ESMTP id D455745DE6E for ; Mon, 28 Mar 2011 19:37:34 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (s2.gw.fujitsu.co.jp [10.0.50.92]) by m2.gw.fujitsu.co.jp (Postfix) with ESMTP id B59CE45DE55 for ; Mon, 28 Mar 2011 19:37:34 +0900 (JST) Received: from s2.gw.fujitsu.co.jp (localhost.localdomain [127.0.0.1]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id A47441DB8041 for ; Mon, 28 Mar 2011 19:37:34 +0900 (JST) Received: from m105.s.css.fujitsu.com (m105.s.css.fujitsu.com [10.240.81.145]) by s2.gw.fujitsu.co.jp (Postfix) with ESMTP id 6C5D81DB8038 for ; Mon, 28 Mar 2011 19:37:34 +0900 (JST) Date: Mon, 28 Mar 2011 19:31:08 +0900 From: KAMEZAWA Hiroyuki Subject: Re: [PATCH] memcg: update documentation to describe usage_in_bytes Message-Id: <20110328193108.07965b4a.kamezawa.hiroyu@jp.fujitsu.com> In-Reply-To: <20110328094820.GC5693@tiehlicka.suse.cz> References: <20110321102420.GB26047@tiehlicka.suse.cz> <20110322091014.27677ab3.kamezawa.hiroyu@jp.fujitsu.com> <20110322104723.fd81dddc.nishimura@mxp.nes.nec.co.jp> <20110322073150.GA12940@tiehlicka.suse.cz> <20110323092708.021d555d.nishimura@mxp.nes.nec.co.jp> <20110323133517.de33d624.kamezawa.hiroyu@jp.fujitsu.com> <20110328085508.c236e929.nishimura@mxp.nes.nec.co.jp> <20110328132550.08be4389.nishimura@mxp.nes.nec.co.jp> <20110328074341.GA5693@tiehlicka.suse.cz> <20110328181127.b8a2a1c5.kamezawa.hiroyu@jp.fujitsu.com> <20110328094820.GC5693@tiehlicka.suse.cz> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: Michal Hocko Cc: Daisuke Nishimura , Andrew Morton , linux-mm@kvack.org, LKML On Mon, 28 Mar 2011 11:48:20 +0200 Michal Hocko wrote: > On Mon 28-03-11 18:11:27, KAMEZAWA Hiroyuki wrote: > > On Mon, 28 Mar 2011 09:43:42 +0200 > > Michal Hocko wrote: > > > > > On Mon 28-03-11 13:25:50, Daisuke Nishimura wrote: > > > > From: Daisuke Nishimura > [...] > > > > +5.5 usage_in_bytes > > > > + > > > > +As described in 2.1, memory cgroup uses res_counter for tracking and limiting > > > > +the memory usage. memory.usage_in_bytes shows the current res_counter usage for > > > > +memory, and DOESN'T show a actual usage of RSS and Cache. It is usually bigger > > > > +than the actual usage for a performance improvement reason. > > > > > > Isn't an explicit mention about caching charges better? > > > > > > > It's difficult to distinguish which is spec. and which is implemnation details... > > Sure. At least commit log should contain the implementation details IMO, > though. > > > > > My one here ;) > > == > > 5.5 usage_in_bytes > > > > For efficiency, as other kernel components, memory cgroup uses some optimization to > > avoid unnecessary cacheline false sharing. usage_in_bytes is affected by the > > method and doesn't show 'exact' value of usage, it's an fuzz value for efficient > > access. (Of course, when necessary, it's synchronized.) > > In usual, the value (RSS+CACHE) in memory.stat shows more exact value. IOW, > > - In usual, the value (RSS+CACHE) in memory.stat shows more exact value. IOW, > + (RSS+CACHE) value from memory.stat shows more exact value and should be used > + by userspace. IOW, > > ? > seems good. Nishimura-san, could you update ? Thanks, -Kame -- 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