From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755252AbYF0Kxm (ORCPT ); Fri, 27 Jun 2008 06:53:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752781AbYF0Kxe (ORCPT ); Fri, 27 Jun 2008 06:53:34 -0400 Received: from yw-out-2324.google.com ([74.125.46.30]:41976 "EHLO yw-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752657AbYF0Kxd (ORCPT ); Fri, 27 Jun 2008 06:53:33 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:reply-to:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=XiUXiP+7ucENybxUMk39ze0j0RCxpVOpM1895MuNH/UY6yJDJepStFTttXXC8tT06C w/Arga/y+lb/Nztx1aZES3uFCas7GwKQHvREnuJDKrx0htltBs5KmOCsm0P6Jsg99PD8 Xs3UzzAlfFanbSS8mHGWFDr2IcYTXs3GLliDw= Message-ID: <4864C6A8.6050605@gmail.com> Date: Fri, 27 Jun 2008 12:53:28 +0200 From: Andrea Righi Reply-To: righi.andrea@gmail.com User-Agent: Swiftdove 2.0.0.14 (X11/20080505) MIME-Version: 1.0 To: Andrew Morton CC: balbir@linux.vnet.ibm.com, menage@google.com, chlunde@ping.uio.no, axboe@kernel.dk, matt@bluehost.com, roberto@unbit.it, randy.dunlap@oracle.com, dpshah@google.com, containers@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 2/3] i/o bandwidth controller infrastructure References: <1213956335-29866-3-git-send-email-righi.andrea@gmail.com> <20080625172900.6cfe79cf.akpm@linux-foundation.org> <486419FE.6070600@gmail.com> <20080626155948.34f30751.akpm@linux-foundation.org> In-Reply-To: <20080626155948.34f30751.akpm@linux-foundation.org> Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: > On Fri, 27 Jun 2008 00:36:46 +0200 > Andrea Righi wrote: > >>> Does all this code treat /dev/sda1 as a separate device from /dev/sda2? >>> If so, that would be broken. >> Yes, all the partitions are treated as separate devices with >> (potentially) different limiting rules, but I don't understand why it >> would be broken... dev_t has both minor and major numbers, so it would >> be possible to select single partitions as well. > > Well it's functionally broken, isn't it? A physical disk has a fixed > IO bandwidth and when the administrator wants to partition that > bandwidth amongst control groups he will need to consider the entire > device when doing so? > > I mean, the whole point of this feature and of control groups as a > whole is isolation. But /dev/sda1 and /dev/sda2 are very much _not_ > isolated. Whereas /dev/sda and /dev/sdb are (to a large degree) > isolated. well... yes, sounds reasonable. In this case we could just ignore the minor number and consider only major number as the key to identify a specific block device (both for userspace<->kernel interface and when accounting/throttling i/o requests). -Andrea