From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751144AbWAPTia (ORCPT ); Mon, 16 Jan 2006 14:38:30 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751156AbWAPTia (ORCPT ); Mon, 16 Jan 2006 14:38:30 -0500 Received: from e35.co.us.ibm.com ([32.97.110.153]:23734 "EHLO e35.co.us.ibm.com") by vger.kernel.org with ESMTP id S1751144AbWAPTi3 (ORCPT ); Mon, 16 Jan 2006 14:38:29 -0500 Subject: Re: [Ext2-devel] Re: Fall back io scheduler for 2.6.15? From: Mingming Cao Reply-To: cmm@us.ibm.com To: Andrew Morton Cc: seelam@cs.utep.edu, linux-kernel@vger.kernel.org, ext2-devel@lists.sourceforge.net, Jens Axboe In-Reply-To: <20060113174914.7907bf2c.akpm@osdl.org> References: <1112673094.14322.10.camel@mindpipe> <1112971236.1975.104.camel@sisko.sctweedie.blueyonder.co.uk> <1112983801.10605.32.camel@dyn318043bld.beaverton.ibm.com> <1113220089.2164.52.camel@sisko.sctweedie.blueyonder.co.uk> <1113244710.4413.38.camel@localhost.localdomain> <1113249435.2164.198.camel@sisko.sctweedie.blueyonder.co.uk> <1113288087.4319.49.camel@localhost.localdomain> <1113304715.2404.39.camel@sisko.sctweedie.blueyonder.co.uk> <1113348434.4125.54.camel@dyn318043bld.beaverton.ibm.com> <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> Content-Type: text/plain Organization: IBM LTC Date: Mon, 16 Jan 2006 11:38:18 -0800 Message-Id: <1137440298.3724.12.camel@dyn9047017067.beaverton.ibm.com> Mime-Version: 1.0 X-Mailer: Evolution 2.0.4 (2.0.4-7) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2006-01-13 at 17:49 -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? > AS was compiled, and AS is set as the default scheduler. But since 2.6.15 doesn't recognize "elevator=as" (we need to say "elevator=anticipatory"), so in 2.6.15, elevator_setup_default() will explicitly fall back to "noop" scheduler. 2.6.14 doesn't recognize "elevator=as" either, but it fall back to the default scheduler instead. Which makes more sense, as Jen pointed out. > 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. > > > Is there any reason to fall back to noop instead of as? It seems > > anticipatory is much better than noop for ext3 with large sequential > > write tests (i.e, 1G dd test) ... > > I suspect that was an accident. Jens? > > > ------------------------------------------------------- > This SF.net email is sponsored by: Splunk Inc. Do you grep through log files > for problems? Stop! Download the new AJAX search engine that makes > searching your log files as easy as surfing the web. DOWNLOAD SPLUNK! > http://ads.osdn.com/?ad_id=7637&alloc_id=16865&op=click > _______________________________________________ > Ext2-devel mailing list > Ext2-devel@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/ext2-devel >