From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161134AbWF0QGR (ORCPT ); Tue, 27 Jun 2006 12:06:17 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161135AbWF0QGR (ORCPT ); Tue, 27 Jun 2006 12:06:17 -0400 Received: from smtp.ustc.edu.cn ([202.38.64.16]:62696 "HELO ustc.edu.cn") by vger.kernel.org with SMTP id S1161134AbWF0QGQ (ORCPT ); Tue, 27 Jun 2006 12:06:16 -0400 Message-ID: <351424373.01759@ustc.edu.cn> X-EYOUMAIL-SMTPAUTH: wfg@mail.ustc.edu.cn Date: Wed, 28 Jun 2006 00:06:24 +0800 From: Fengguang Wu To: Helge Hafting Cc: Linux Kernel Mailing List Subject: Re: New readahead - ups and downs Message-ID: <20060627160624.GB6014@mail.ustc.edu.cn> Mail-Followup-To: Fengguang Wu , Helge Hafting , Linux Kernel Mailing List References: <44A12D84.5010400@aitel.hist.no> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <44A12D84.5010400@aitel.hist.no> User-Agent: Mutt/1.5.11+cvs20060403 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi Helge, Thanks for testing it out. I'll check it when I have time(I'll be out for a week...). Wu On Tue, Jun 27, 2006 at 03:07:16PM +0200, Helge Hafting wrote: > Many have noticed positive sides of the new readahead system. > I too see that, bootup is quicker and starting a big app like firefox is > also noticeable faster. > > I made my own little io-intensive test, that shows a case where > performance drops. > > I boot the machine, and starts "debsums", a debian utility that > checksums every file managed by debian package management. > As soon as the machine starts swapping, I also start > start a process that applies an mm-patch to the kernel tree, and > times this. > > This patching took 1m28s with cold cache, without debsums running. > With the 2.6.15 kernel (old readahead), and debsums running, this > took 2m20s to complete, and 360kB in swap at the worst. > > With the new readahead in 2.6.17-mm3 I get 6m22s for patching, > and 22MB in swap at the most. Runs with mm1 and mm2 were > similiar, 5-6 minutes patching and 22MB swap. > > My patching clearly takes more times this way. I don't know > if debsums improved though, it could be as simple as a fairness > issue. Memory pressure definitely went up. > > > Helge Hafting > - > 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/