From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756704AbZBTJoZ (ORCPT ); Fri, 20 Feb 2009 04:44:25 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756243AbZBTJoB (ORCPT ); Fri, 20 Feb 2009 04:44:01 -0500 Received: from silver.sucs.swan.ac.uk ([137.44.10.1]:52923 "EHLO silver.sucs.swan.ac.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756107AbZBTJn6 (ORCPT ); Fri, 20 Feb 2009 04:43:58 -0500 X-Greylist: delayed 744 seconds by postgrey-1.27 at vger.kernel.org; Fri, 20 Feb 2009 04:43:58 EST Date: Fri, 20 Feb 2009 09:43:56 +0000 From: Sitsofe Wheeler To: Justin Piszcz Cc: linux-kernel@vger.kernel.org, linux-ide@vger.kernel.org, linux-raid@vger.kernel.org Subject: Re: General question (scheduler) with SSDs? Message-ID: <20090220094356.GB26124@silver.sucs.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.2.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Whoops, I didn't mean to send that previous half formed mail :) Sorry. On Thu, Feb 19, 2009 at 08:38:38AM -0500, Justin Piszcz wrote: > > I was curious if anyone had done any benchmarks and/or has conclusive > information, what is the best Linux scheduler to use with SSDs? > > Noop? > CFQ? > AS? > Deadline? As mentioned in another mail there was a discussion on http://lkml.org/lkml/2009/1/31/28 and long thread talking about the introduction of the rotational flag here http://lkml.org/lkml/2009/1/5/340 . Cheapo SSDs or even USB keys are not auto detected as non-rotational devices by the kernel and after a bit of poking about I've come up with the following udev rules for my particular cases: SUBSYSTEM=="block", TEST=="/sys$devpath/queue/rotational", ATTRS{model}=="ASUS-PHISON *", RUN+="/bin/sh -c 'echo 0 > /sys$devpath/queue/rotational'" SUBSYSTEM=="block", TEST=="/sys$devpath/queue/rotational", ATTRS{idVendor}=="0951", ATTRS{idProduct}=="1606", RUN+="/bin/sh -c 'echo 0 > /sys$devpath/queue/rotational'" SUBSYSTEM=="block", TEST=="/sys$devpath/queue/rotational", ATTRS{manufacturer}=="SanDisk", ATTRS{product}=="Cruzer Micro", RUN+="/bin/sh -c 'echo 0 > /sys$devpath/queue/rotational'" Ever since the rotational option appeared I've been trying cfq but prior to that I was using noop or deadline. However it doesn't look like anyone has sat down and run the numbers to see what affect the ioscheulder/rotational flag is having on cheapo SSDs - all the suggestions are anecdotal. Could you run some benchmarks with these different options and report back the results? -- Sitsofe | http://sucs.org/~sits/