From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757944Ab1BPBoz (ORCPT ); Tue, 15 Feb 2011 20:44:55 -0500 Received: from cn.fujitsu.com ([222.73.24.84]:50614 "EHLO song.cn.fujitsu.com" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1756854Ab1BPBot (ORCPT ); Tue, 15 Feb 2011 20:44:49 -0500 Message-ID: <4D5B2C07.9050909@cn.fujitsu.com> Date: Wed, 16 Feb 2011 09:44:39 +0800 From: Gui Jianfeng User-Agent: Thunderbird 2.0.0.24 (Windows/20100228) MIME-Version: 1.0 To: Vivek Goyal CC: Jens Axboe , Shaohua Li , lkml , Chad Talbott , Divyesh Shah Subject: Re: [PATCH 5/6 v4] cfq-iosched: CFQ group hierarchical scheduling and use_hierarchy interface References: <4D51ED26.8050809@cn.fujitsu.com> <4D539821.1090703@cn.fujitsu.com> <20110210205722.GB2600@redhat.com> <4D55EEBB.8060304@cn.fujitsu.com> <20110214180428.GF13097@redhat.com> <4D59E728.3030209@cn.fujitsu.com> <20110215142752.GC27296@redhat.com> In-Reply-To: <20110215142752.GC27296@redhat.com> X-MIMETrack: Itemize by SMTP Server on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-02-16 09:43:50, Serialize by Router on mailserver/fnst(Release 8.5.1FP4|July 25, 2010) at 2011-02-16 09:43:53, Serialize complete at 2011-02-16 09:43:53 Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Vivek Goyal wrote: > On Tue, Feb 15, 2011 at 10:38:32AM +0800, Gui Jianfeng wrote: >> Vivek Goyal wrote: >>> On Sat, Feb 12, 2011 at 10:21:47AM +0800, Gui Jianfeng wrote: >>> [..] >>>>>> +static struct cfq_group * >>>>>> +cfq_find_alloc_cfqg(struct cfq_data *cfqd, struct cgroup *cgroup, int create) >>>>>> +{ >>>>>> + struct blkio_cgroup *blkcg = cgroup_to_blkio_cgroup(cgroup); >>>>>> + struct cfq_group *cfqg = NULL; >>>>>> + void *key = cfqd; >>>>>> + struct backing_dev_info *bdi = &cfqd->queue->backing_dev_info; >>>>>> + unsigned int major, minor; >>>>>> + >>>>>> + cfqg = cfqg_of_blkg(blkiocg_lookup_group(blkcg, key)); >>>>>> + if (cfqg && !cfqg->blkg.dev && bdi->dev && dev_name(bdi->dev)) { >>>>>> + sscanf(dev_name(bdi->dev), "%u:%u", &major, &minor); >>>>>> + cfqg->blkg.dev = MKDEV(major, minor); >>>>>> + goto done; >>>>>> + } >>>>> Should we make this updation of this info hierarhical? >>>> IMHO, it's fine to defer the updation when we really get the cfqg. >>> But if cfqg is alrady present, we will never hit the allocation path >>> again. So if somebody creates 2-3 level deep hierarchy and does IO >>> only in the children cgroup, parent cgroups will potentially not get >>> device info updated hence no visible stats? >> Ahh, I see your concern. But do we really need to show the stats even if >> a cgroup doesn't issue any IO on a given device? > > I am assuming that once use_hierarchy=1, you are aggregating the stats > in parent cgroups? So if a child services 5 IOs, these are accounted > to parent group also when user_hier=1? > > What happens in case of memoy cgroup controller? Hmm, it seems memcg aggregating stats in parent group. But do we really need to do that in kernel? I think it's easier to do it in userland, and it makes kernel much simpler. Thanks, Gui > > Thanks > Vivek >