From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161580AbWANFXD (ORCPT ); Sat, 14 Jan 2006 00:23:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161594AbWANFXD (ORCPT ); Sat, 14 Jan 2006 00:23:03 -0500 Received: from mx1.redhat.com ([66.187.233.31]:47747 "EHLO mx1.redhat.com") by vger.kernel.org with ESMTP id S1161580AbWANFXC (ORCPT ); Sat, 14 Jan 2006 00:23:02 -0500 Date: Sat, 14 Jan 2006 00:22:22 -0500 From: Dave Jones To: Andrew Morton Cc: cmm@us.ibm.com, seelam@cs.utep.edu, linux-kernel@vger.kernel.org, ext2-devel@lists.sourceforge.net, Jens Axboe Subject: Re: Fall back io scheduler for 2.6.15? Message-ID: <20060114052222.GA6212@redhat.com> Mail-Followup-To: Dave Jones , Andrew Morton , cmm@us.ibm.com, seelam@cs.utep.edu, linux-kernel@vger.kernel.org, ext2-devel@lists.sourceforge.net, Jens Axboe References: <1113388142.3019.12.camel@sisko.sctweedie.blueyonder.co.uk> <1114207837.7339.50.camel@localhost.localdomain> <1114659912.16933.5.camel@mindpipe> <1114715665.18996.29.camel@localhost.localdomain> <1136935562.4901.41.camel@dyn9047017067.beaverton.ibm.com> <20060110212551.411a766d.akpm@osdl.org> <1137007032.4395.24.camel@localhost.localdomain> <20060111114303.45540193.akpm@osdl.org> <1137201135.4353.81.camel@localhost.localdomain> <20060113174914.7907bf2c.akpm@osdl.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20060113174914.7907bf2c.akpm@osdl.org> User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Jan 13, 2006 at 05:49:14PM -0800, Andrew Morton wrote: > Mingming Cao wrote: > > > > On 2.6.14, the > > fall back io scheduler (if the chosen io scheduler is not found) is set > > to the default io scheduler (anticipatory, in this case), but since > > 2.6.15-rc1, this semanistic is changed to fall back to noop. > > OK. And I assume that AS wasn't compiled, so that's why it fell back? > > I actually thought that elevator= got removed, now we have > /sys/block/sda/queue/scheduler. But I guess that's not very useful with > CONFIG_SYSFS=n. It's also a lifesaver if the default scheduler happens to trigger some breakage preventing boot, and you can tell users to workaround it with a bootparam until the real problem is fixed (which has bitten us twice now, as Fedora like several other distros chooses CFQ by default). Dave