From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx2.fusionio.com ([64.244.102.31]:38629 "EHLO mx2.fusionio.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755603Ab0KJUE3 (ORCPT ); Wed, 10 Nov 2010 15:04:29 -0500 Message-ID: <4CDAFAC5.9070608@fusionio.com> Date: Wed, 10 Nov 2010 21:04:21 +0100 From: Jens Axboe MIME-Version: 1.0 Subject: Re: IOPS higher than expected on randwrite, direct=1 tests References: <20101109182801.GP15588@sebastiankayser.de> <20101110082223.GB14261@sebastiankayser.de> <4CDAA783.9050902@fusionio.com> <20101110171856.GI28050@sebastiankayser.de> <20101110185826.GJ28050@sebastiankayser.de> <20101110195214.GK28050@sebastiankayser.de> In-Reply-To: <20101110195214.GK28050@sebastiankayser.de> Content-Type: text/plain; charset="ISO-8859-15" Content-Transfer-Encoding: 7bit Sender: fio-owner@vger.kernel.org List-Id: fio@vger.kernel.org To: Sebastian Kayser Cc: fio@vger.kernel.org On 2010-11-10 20:52, Sebastian Kayser wrote: > * John Cagle wrote: >> If the disk is 2TB, then your 100GB test is only using 5% of it-- thus >> your observed IOPS will be a lot better than expected due to >> short-stroking. Right? > > I don't know. The inital 80 IOPS (observed over about 2 full minutes) > made me believe that 100GB would have covered a high enough percentage > to at least eliminate track-to-track seeks. Are short-stroked seeks also > that much faster compared to average seek times? And where would the > steady increase in IOPS during the test come from? > > But you are definitly right when it comes to the test setup. I just > started a test with size=1800g. Looking foward to what that will show. If you have the full device, you could just test on that instead of using a filesystem and file. Just to get more 'raw' performance. -- Jens Axboe