Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753531Ab1BPRWx (ORCPT ); Wed, 16 Feb 2011 12:22:53 -0500 Received: from smtp-out.google.com ([74.125.121.67]:54383 "EHLO smtp-out.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752239Ab1BPRWv (ORCPT ); Wed, 16 Feb 2011 12:22:51 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=google.com; s=beta; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type; b=DP5Xvq0ZIgr7tKrZAiMhgK/D/03mUP7Pr7K1ym30oJzZYNvnGAn6I26wWeW0PuCUYL 3FFD0Apkp7BU9myxKZSA== MIME-Version: 1.0 In-Reply-To: <4D5B2C07.9050909@cn.fujitsu.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> <20110215142752.GC27296@redhat.com> <4D5B2C07.9050909@cn.fujitsu.com> From: Divyesh Shah Date: Wed, 16 Feb 2011 09:22:28 -0800 Message-ID: Subject: Re: [PATCH 5/6 v4] cfq-iosched: CFQ group hierarchical scheduling and use_hierarchy interface To: Gui Jianfeng Cc: Vivek Goyal , Jens Axboe , Shaohua Li , lkml , Chad Talbott Content-Type: text/plain; charset=ISO-8859-1 X-System-Of-Record: true Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1061 Lines: 24 On Tue, Feb 15, 2011 at 5:44 PM, Gui Jianfeng wrote: > 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. > I would prefer having stats aggregated up the hierarchy. One trick we used at Google earlier was to do lazy updates for most stats. So we would accumulate stats for a given timeslice and at the end of that timeslice propagate those counts all the way up to the parent. For device info like this, the update can be instantaneous since its not a very frequent event. It would also be very useful to distinguish between stats for the cgroup itself vs total values accumulated from the subtree rooted at that cgroup like memcg does. -- Thanks, Divyesh -- 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/