Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755321Ab1BOOf3 (ORCPT ); Tue, 15 Feb 2011 09:35:29 -0500 Received: from mx1.redhat.com ([209.132.183.28]:49821 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755211Ab1BOOf0 (ORCPT ); Tue, 15 Feb 2011 09:35:26 -0500 Date: Tue, 15 Feb 2011 09:27:52 -0500 From: Vivek Goyal To: Gui Jianfeng 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 Message-ID: <20110215142752.GC27296@redhat.com> 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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4D59E728.3030209@cn.fujitsu.com> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1847 Lines: 43 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? Thanks Vivek -- 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/