Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753146Ab1C1Hnq (ORCPT ); Mon, 28 Mar 2011 03:43:46 -0400 Received: from cantor2.suse.de ([195.135.220.15]:42547 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752887Ab1C1Hnp (ORCPT ); Mon, 28 Mar 2011 03:43:45 -0400 Date: Mon, 28 Mar 2011 09:43:42 +0200 From: Michal Hocko To: Daisuke Nishimura Cc: KAMEZAWA Hiroyuki , Andrew Morton , linux-mm@kvack.org, LKML Subject: Re: [PATCH] memcg: update documentation to describe usage_in_bytes Message-ID: <20110328074341.GA5693@tiehlicka.suse.cz> References: <20110318152532.GB18450@tiehlicka.suse.cz> <20110321093419.GA26047@tiehlicka.suse.cz> <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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20110328132550.08be4389.nishimura@mxp.nes.nec.co.jp> User-Agent: Mutt/1.5.20 (2009-06-14) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2744 Lines: 66 On Mon 28-03-11 13:25:50, Daisuke Nishimura wrote: > From: Daisuke Nishimura > > Update the meaning of *.usage_in_bytes. They doesn't show the actual usage of > RSS+Cache(+Swap). They show the res_counter->usage for memory and memory+swap. Don't we want to add why this is not rss+cache? The reason is really non trivial for somebody who is not familiar with the code and with the fact that we are heavily caching charges. > > Signed-off-by: Daisuke Nishimura > --- > Documentation/cgroups/memory.txt | 16 ++++++++++++++-- > 1 files changed, 14 insertions(+), 2 deletions(-) > > diff --git a/Documentation/cgroups/memory.txt b/Documentation/cgroups/memory.txt > index 7781857..ab7d4c1 100644 > --- a/Documentation/cgroups/memory.txt > +++ b/Documentation/cgroups/memory.txt > @@ -52,8 +52,10 @@ Brief summary of control files. > tasks # attach a task(thread) and show list of threads > cgroup.procs # show list of processes > cgroup.event_control # an interface for event_fd() > - memory.usage_in_bytes # show current memory(RSS+Cache) usage. > - memory.memsw.usage_in_bytes # show current memory+Swap usage > + memory.usage_in_bytes # show current res_counter usage for memory > + (See 5.5 for details) > + memory.memsw.usage_in_bytes # show current res_counter usage for memory+Swap > + (See 5.5 for details) > memory.limit_in_bytes # set/show limit of memory usage > memory.memsw.limit_in_bytes # set/show limit of memory+Swap usage > memory.failcnt # show the number of memory usage hits limits > @@ -453,6 +455,16 @@ memory under it will be reclaimed. > You can reset failcnt by writing 0 to failcnt file. > # echo 0 > .../memory.failcnt > > +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? > If you want to know > +the actual usage, you can use memory.stat(see 5.2). > +It's the same for memory.memsw.usage_in_bytes, which shows the current > +res_counter usage for memory+swap. Should we clarify for who is this file intended? Thanks -- 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/