From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758157Ab0KOSi1 (ORCPT ); Mon, 15 Nov 2010 13:38:27 -0500 Received: from mx2.fusionio.com ([64.244.102.31]:33665 "EHLO mx2.fusionio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757885Ab0KOSi0 (ORCPT ); Mon, 15 Nov 2010 13:38:26 -0500 X-ASG-Debug-ID: 1289846304-08b796290001-xx1T2L X-Barracuda-Envelope-From: JAxboe@fusionio.com Message-ID: <4CE17E1B.7000307@fusionio.com> Date: Mon, 15 Nov 2010 19:38:19 +0100 From: Jens Axboe MIME-Version: 1.0 To: Vivek Goyal CC: linux kernel mailing list , Gui Jianfeng , Balbir Singh , KAMEZAWA Hiroyuki , Li Zefan , Nauman Rafique , "Daniel P. Berrange" Subject: Re: [RFC] blk-cgroup: Allow creation of hierarchical cgroups References: <20101102222030.GI7198@redhat.com> <20101115152832.GH30792@redhat.com> X-ASG-Orig-Subj: Re: [RFC] blk-cgroup: Allow creation of hierarchical cgroups In-Reply-To: <20101115152832.GH30792@redhat.com> Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7bit X-Barracuda-Connect: mail1.int.fusionio.com[10.101.1.21] X-Barracuda-Start-Time: 1289846304 X-Barracuda-URL: http://10.101.1.181:8000/cgi-mod/mark.cgi X-Barracuda-Spam-Score: 0.00 X-Barracuda-Spam-Status: No, SCORE=0.00 using global scores of TAG_LEVEL=1000.0 QUARANTINE_LEVEL=1000.0 KILL_LEVEL=9.0 tests= X-Barracuda-Spam-Report: Code version 3.2, rules version 3.2.2.46721 Rule breakdown below pts rule name description ---- ---------------------- -------------------------------------------------- Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2010-11-15 16:28, Vivek Goyal wrote: > On Tue, Nov 02, 2010 at 06:20:30PM -0400, Vivek Goyal wrote: >> o Allow hierarchical cgroup creation for blkio controller >> >> o Currently we disallow it as both the io controller policies (throttling >> as well as proportion bandwidth) do not support hierarhical accounting >> and control. But the flip side is that blkio controller can not be used with >> libvirt as libvirt creates a cgroup hierarchy deeper than 1 level. >> >> //libvirt/qemu/ >> >> o So this patch will allow creation of cgroup hierarhcy but at the backend >> everything will be treated as flat. So if somebody created a an hierarchy >> like as follows. >> >> root >> / \ >> test1 test2 >> | >> test3 >> >> CFQ and throttling will practically treat all groups at same level. >> >> pivot >> / | \ \ >> root test1 test2 test3 >> >> o Once we have actual support for hierarchical accounting and control >> then we can introduce another cgroup tunable file "blkio.use_hierarchy" >> which will be 0 by default but if user wants to enforce hierarhical >> control then it can be set to 1. This way there should not be any >> ABI problems down the line. >> >> o The only not so pretty part is introduction of extra file "use_hierarchy" >> down the line. Kame-san had mentioned that hierarhical accounting is >> expensive in memory controller hence they keep it off by default. I >> suspect same will be the case for IO controller also as for each IO >> completion we shall have to account IO through hierarchy up to the root.. >> if yes, then it probably is not a very bad idea to introduce this extra >> file so that it will be used only when somebody needs it and some people >> might enable hierarchy only in part of the hierarchy. >> >> o This is how basically memory controller also uses "use_hierarhcy" and >> they also allowed creation of hierarchies when actual backend support >> was not available. >> >> Signed-off-by: Vivek Goyal >> --- > > Hi Jens, > > Do you have any concerns about this patch? If not, can you please apply > it. Applied to for-2.6.38/rc2-holder, it'll be merged into for-2.6.38/core once -rc2 has been tagged (and I can pull in the conflicting bits). -- Jens Axboe