From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S264589AbTLTQCb (ORCPT ); Sat, 20 Dec 2003 11:02:31 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S264602AbTLTQCb (ORCPT ); Sat, 20 Dec 2003 11:02:31 -0500 Received: from fw.osdl.org ([65.172.181.6]:27069 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S264589AbTLTQCa (ORCPT ); Sat, 20 Dec 2003 11:02:30 -0500 Date: Sat, 20 Dec 2003 08:03:27 -0800 From: Andrew Morton To: jlnance@unity.ncsu.edu Cc: linux-kernel@vger.kernel.org Subject: Re: Test program with VM or FS problems Message-Id: <20031220080327.2aef4c11.akpm@osdl.org> In-Reply-To: <20031220154315.GA12763@ncsu.edu> References: <20031220154315.GA12763@ncsu.edu> X-Mailer: Sylpheed version 0.9.4 (GTK+ 1.2.10; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org jlnance@unity.ncsu.edu wrote: > > Hello Andrew, > About a year ago I told you I would get you some more information > about a problem I was seeing that might be in the Linux VM or ext{2,3} > code. I thought you'd forgotten! > For most of the run the temp file is smaller > than this. So for most of the run both files will fit into the > memory of the machine. Thus I would expect the program to run > quickly, because it will not need to touch the disk. Things are > in cache. This is not what I see. Instead the program seems to > be very much disk bound. I bet the use-once page replacement heuristic is doing the wrong thing. I noticed it playing up once - the machine had 30M on the inactive list and reading a 40M file repeatedly caused that file to never get cached. it just kept on reclaiming itself.