From mboxrd@z Thu Jan 1 00:00:00 1970 From: Gui Jianfeng Subject: Re: [PATCH] io-controller: implement per group request allocation limitation Date: Tue, 04 Aug 2009 14:38:35 +0800 Message-ID: <4A77D76B.3090502@cn.fujitsu.com> References: <1246564917-19603-1-git-send-email-vgoyal@redhat.com> <4A569FC5.7090801@cn.fujitsu.com> <20090713160352.GA3714@redhat.com> <4A5BA238.3030902@ds.jp.nec.com> <4A5C377F.4040105@cn.fujitsu.com> <4A77964A.7040602@ds.jp.nec.com> Reply-To: device-mapper development Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4A77964A.7040602@ds.jp.nec.com> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: dm-devel-bounces@redhat.com Errors-To: dm-devel-bounces@redhat.com To: Munehiro Ikeda Cc: dhaval@linux.vnet.ibm.com, snitzer@redhat.com, peterz@infradead.org, dm-devel@redhat.com, dpshah@google.com, jens.axboe@oracle.com, agk@redhat.com, balbir@linux.vnet.ibm.com, paolo.valente@unimore.it, fernando@oss.ntt.co.jp, mikew@google.com, jmoyer@redhat.com, nauman@google.com, Vivek Goyal , righi.andrea@gmail.com, lizf@cn.fujitsu.com, fchecconi@gmail.com, akpm@linux-foundation.org, jbaron@redhat.com, linux-kernel@vger.kernel.org, s-uchida@ap.jp.nec.com, containers@lists.linux-foundation.org List-Id: dm-devel.ids Munehiro Ikeda wrote: ... > > Consideration and Conclusion > ============================= > > From result(1), it is observed that it takes 1000~1200[ms] to rise P2 > bandwidth. In result(2), where both of g1 and g2 have > nr_group_requests=100, the delay gets longer as 1800~2000[ms]. In > addition to it, the average bandwidth becomes ~5% lower than result(1). > This is supposed that P2 couldn't allocate enough requests. > Then, result(3) shows that bandwidth of P2 can rise quickly (~300[ms]) > if nr_group_requests can be set per-cgroup. Result(4) shows that the > delay can be shortened by setting g2 as RT class, however, the delay is > still longer than result(3). > > I think it is confirmed that "per-cgroup nr_requests limitation is > useful in a certain situation". Beyond that, the discussion topic is > the benefit pointed out above is eligible for the complication of the > implementation. IMHO, I don't think the implementation of per-cgroup > request limitation is too complicated to accept. On the other hand I > guess it suddenly gets complicated if we try to implement further more, > especially hierarchical support. It is also true that I have a feeling > that implementation without per-device limitation and hierarchical > support is like "unfinished work". > > So, my opinion so far is that, per-cgroup nr_requests limitation should > be merged only if hierarchical support is concluded "unnecessary" for > it. If merging it tempts hierarchical support, it shouldn't be. > How about your opinion, all? Hi Munehiro-san, Thanks for the great job. It seems Per-cgroup requests allocation limits has its value in some cases. IMHO, for the time being, we can just drop the hierarchical support for "Per-cgroup requests allocation limits", and see whether it can work well. > > My considerations or verification method might be wrong. Please correct > them if any. And if you have any other idea of scenario to verify the > effect of per-cgroup nr_requests limitation, please let me know. I'll > try it. > > > > > ------------------------------------------------------------------------ > -- Regards Gui Jianfeng From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754871AbZHDGkW (ORCPT ); Tue, 4 Aug 2009 02:40:22 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754883AbZHDGkV (ORCPT ); Tue, 4 Aug 2009 02:40:21 -0400 Received: from cn.fujitsu.com ([222.73.24.84]:58914 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1755050AbZHDGkU (ORCPT ); Tue, 4 Aug 2009 02:40:20 -0400 Message-ID: <4A77D76B.3090502@cn.fujitsu.com> Date: Tue, 04 Aug 2009 14:38:35 +0800 From: Gui Jianfeng User-Agent: Thunderbird 2.0.0.5 (Windows/20070716) MIME-Version: 1.0 To: Munehiro Ikeda CC: Vivek Goyal , linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org, dm-devel@redhat.com, jens.axboe@oracle.com, nauman@google.com, dpshah@google.com, lizf@cn.fujitsu.com, mikew@google.com, fchecconi@gmail.com, paolo.valente@unimore.it, ryov@valinux.co.jp, fernando@oss.ntt.co.jp, s-uchida@ap.jp.nec.com, taka@valinux.co.jp, jmoyer@redhat.com, dhaval@linux.vnet.ibm.com, balbir@linux.vnet.ibm.com, righi.andrea@gmail.com, jbaron@redhat.com, agk@redhat.com, snitzer@redhat.com, akpm@linux-foundation.org, peterz@infradead.org Subject: Re: [PATCH] io-controller: implement per group request allocation limitation References: <1246564917-19603-1-git-send-email-vgoyal@redhat.com> <4A569FC5.7090801@cn.fujitsu.com> <20090713160352.GA3714@redhat.com> <4A5BA238.3030902@ds.jp.nec.com> <4A5C377F.4040105@cn.fujitsu.com> <4A77964A.7040602@ds.jp.nec.com> In-Reply-To: <4A77964A.7040602@ds.jp.nec.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Munehiro Ikeda wrote: ... > > Consideration and Conclusion > ============================= > > From result(1), it is observed that it takes 1000~1200[ms] to rise P2 > bandwidth. In result(2), where both of g1 and g2 have > nr_group_requests=100, the delay gets longer as 1800~2000[ms]. In > addition to it, the average bandwidth becomes ~5% lower than result(1). > This is supposed that P2 couldn't allocate enough requests. > Then, result(3) shows that bandwidth of P2 can rise quickly (~300[ms]) > if nr_group_requests can be set per-cgroup. Result(4) shows that the > delay can be shortened by setting g2 as RT class, however, the delay is > still longer than result(3). > > I think it is confirmed that "per-cgroup nr_requests limitation is > useful in a certain situation". Beyond that, the discussion topic is > the benefit pointed out above is eligible for the complication of the > implementation. IMHO, I don't think the implementation of per-cgroup > request limitation is too complicated to accept. On the other hand I > guess it suddenly gets complicated if we try to implement further more, > especially hierarchical support. It is also true that I have a feeling > that implementation without per-device limitation and hierarchical > support is like "unfinished work". > > So, my opinion so far is that, per-cgroup nr_requests limitation should > be merged only if hierarchical support is concluded "unnecessary" for > it. If merging it tempts hierarchical support, it shouldn't be. > How about your opinion, all? Hi Munehiro-san, Thanks for the great job. It seems Per-cgroup requests allocation limits has its value in some cases. IMHO, for the time being, we can just drop the hierarchical support for "Per-cgroup requests allocation limits", and see whether it can work well. > > My considerations or verification method might be wrong. Please correct > them if any. And if you have any other idea of scenario to verify the > effect of per-cgroup nr_requests limitation, please let me know. I'll > try it. > > > > > ------------------------------------------------------------------------ > -- Regards Gui Jianfeng