From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760780AbZEGATQ (ORCPT ); Wed, 6 May 2009 20:19:16 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758953AbZEGAS6 (ORCPT ); Wed, 6 May 2009 20:18:58 -0400 Received: from fms-01.valinux.co.jp ([210.128.90.1]:59065 "EHLO mail.valinux.co.jp" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1756075AbZEGAS6 (ORCPT ); Wed, 6 May 2009 20:18:58 -0400 Date: Thu, 07 May 2009 09:18:58 +0900 (JST) Message-Id: <20090507.091858.226775723.ryov@valinux.co.jp> To: vgoyal@redhat.com Cc: akpm@linux-foundation.org, nauman@google.com, dpshah@google.com, lizf@cn.fujitsu.com, mikew@google.com, fchecconi@gmail.com, paolo.valente@unimore.it, jens.axboe@oracle.com, fernando@oss.ntt.co.jp, s-uchida@ap.jp.nec.com, taka@valinux.co.jp, guijianfeng@cn.fujitsu.com, jmoyer@redhat.com, dhaval@linux.vnet.ibm.com, balbir@linux.vnet.ibm.com, linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org, righi.andrea@gmail.com, agk@redhat.com, dm-devel@redhat.com, snitzer@redhat.com, m-ikeda@ds.jp.nec.com, peterz@infradead.org Subject: Re: IO scheduler based IO Controller V2 From: Ryo Tsuruta In-Reply-To: <20090506023332.GA1212@redhat.com> References: <1241553525-28095-1-git-send-email-vgoyal@redhat.com> <20090505132441.1705bfad.akpm@linux-foundation.org> <20090506023332.GA1212@redhat.com> X-Mailer: Mew version 5.2.52 on Emacs 22.1 / Mule 5.0 (SAKAKI) Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Vivek, > Ryo, dm-ioband breaks the notion of classes and priority of CFQ because > of FIFO dispatch of buffered bios. Apart from that it tries to provide > fairness in terms of actual IO done and that would mean a seeky workload > will can use disk for much longer to get equivalent IO done and slow down > other applications. Implementing IO controller at IO scheduler level gives > us tigher control. Will it not meet your requirements? If you got specific > concerns with IO scheduler based contol patches, please highlight these and > we will see how these can be addressed. I'd like to avoid making complicated existing IO schedulers and other kernel codes and to give a choice to users whether or not to use it. I know that you chose an approach that using compile time options to get the same behavior as old system, but device-mapper drivers can be added, removed and replaced while system is running. Thanks, Ryo Tsuruta