Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751667AbXB0QXM (ORCPT ); Tue, 27 Feb 2007 11:23:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751847AbXB0QXL (ORCPT ); Tue, 27 Feb 2007 11:23:11 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:33259 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751667AbXB0QXK (ORCPT ); Tue, 27 Feb 2007 11:23:10 -0500 Date: Tue, 27 Feb 2007 17:16:17 +0100 From: Ingo Molnar To: Avi Kivity Cc: suparna@in.ibm.com, Jens Axboe , linux-kernel@vger.kernel.org, Linus Torvalds , Arjan van de Ven , Christoph Hellwig , Andrew Morton , Alan Cox , Ulrich Drepper , Zach Brown , Evgeniy Polyakov , "David S. Miller" , Davide Libenzi , Thomas Gleixner Subject: Re: A quick fio test (was Re: [patch 00/13] Syslets, "Threadlets", generic AIO support, v3) Message-ID: <20070227161617.GA16774@elte.hu> References: <20070223151515.GA12960@in.ibm.com> <20070223162508.GA16782@kernel.dk> <20070223171348.GA27838@in.ibm.com> <20070226135736.GF3822@kernel.dk> <20070226141315.GA15631@in.ibm.com> <20070226144548.GH3822@kernel.dk> <20070227043331.GA29942@in.ibm.com> <45E43827.4000102@argo.co.il> <20070227152507.GA8294@elte.hu> <45E45915.20204@argo.co.il> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <45E45915.20204@argo.co.il> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 975 Lines: 26 * Avi Kivity wrote: > > yeah - that's what testing on ramdisk (Jens') or on a loopback block > > device (mine) approximates to a certain degree. > > Ramdisks or fully cached loopback return immediately, so cache > thrashing effects don't show up. even fully cached loopback schedules the loopback kernel thread - but i agree that it's inaccurate: hence the 'approximates to a certain degree'. > Maybe a device mapper delay target or nbd + O_DIRECT can insert delays > to make the workload more disk-like. yeah. I'll hack a small timeout into loopback requests i think. But then real disk-platter effects are left out ... so it all comes down to eventually having to try it on real disks too :) Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/