From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753900AbZHLD4O (ORCPT ); Tue, 11 Aug 2009 23:56:14 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752394AbZHLD4O (ORCPT ); Tue, 11 Aug 2009 23:56:14 -0400 Received: from e23smtp01.au.ibm.com ([202.81.31.143]:52653 "EHLO e23smtp01.au.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751928AbZHLD4N (ORCPT ); Tue, 11 Aug 2009 23:56:13 -0400 Date: Wed, 12 Aug 2009 09:26:05 +0530 From: Balbir Singh To: Andrew Morton Cc: kamezawa.hiroyu@jp.fujitsu.com, nishimura@mxp.nes.nec.co.jp, kosaki.motohiro@jp.fujitsu.com, menage@google.com, prarit@redhat.com, andi.kleen@intel.com, xemul@openvz.org, lizf@cn.fujitsu.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: Help Resource Counters Scale better (v4) Message-ID: <20090812035605.GF7176@balbir.in.ibm.com> Reply-To: balbir@linux.vnet.ibm.com References: <20090811144405.GW7176@balbir.in.ibm.com> <20090811163159.ddc5f5fd.akpm@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20090811163159.ddc5f5fd.akpm@linux-foundation.org> User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Andrew Morton [2009-08-11 16:31:59]: > On Tue, 11 Aug 2009 20:14:05 +0530 > Balbir Singh wrote: > > > Enhancement: Remove the overhead of root based resource counter accounting > > > > From: Balbir Singh > > > > This patch reduces the resource counter overhead (mostly spinlock) > > associated with the root cgroup. This is a part of the several > > patches to reduce mem cgroup overhead. I had posted other > > approaches earlier (including using percpu counters). Those > > patches will be a natural addition and will be added iteratively > > on top of these. > > > > The patch stops resource counter accounting for the root cgroup. > > The data for display is derived from the statisitcs we maintain > > via mem_cgroup_charge_statistics (which is more scalable). > > > > The tests results I see on a 24 way show that > > > > 1. The lock contention disappears from /proc/lock_stats > > 2. The results of the test are comparable to running with > > cgroup_disable=memory. > > > > Please test/review. > > I don't get it. > > The patch apepars to skip accounting altogether for the root memcgroup > and then adds some accounting back in for swap. Or something like > that. How come? Do we actually not need the root memcgroup > accounting? > The changelog mentions that the statistics are derived. For memsw as Daisuke-San mentioned, the SWAP accounting is for memsw. We can derive memory.usage_in_bytes from RSS+Cache fields in the memory.stat accounting. For memsw, we needed SWAP accounting. > IOW, the changelog sucks ;) > > Is this an alternative approach to using percpu_counters, or do we do > both or do we choose one or the other? res_counter_charge() really is > quite sucky. > > The patch didn't have a signoff. > > It would be nice to finalise those performance testing results and > include them in the new, improved patch description. > I'll submit a new patch with better changelog, checkpatch.pl fixes and test results. -- Balbir