Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750702AbWHIMXK (ORCPT ); Wed, 9 Aug 2006 08:23:10 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750704AbWHIMXJ (ORCPT ); Wed, 9 Aug 2006 08:23:09 -0400 Received: from wohnheim.fh-wedel.de ([213.39.233.138]:8104 "EHLO wohnheim.fh-wedel.de") by vger.kernel.org with ESMTP id S1750702AbWHIMXI (ORCPT ); Wed, 9 Aug 2006 08:23:08 -0400 Date: Wed, 9 Aug 2006 14:21:34 +0200 From: =?iso-8859-1?Q?J=F6rn?= Engel To: Valerie Henson Cc: Matthew Wilcox , dean gaudet , David Lang , Mark Fasheh , Chris Wedgwood , Arjan van de Ven , Dave Kleikamp , Christoph Hellwig , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Akkana Peck , Jesse Barnes , jsipek@cs.sunysb.edu, Al Viro Subject: Re: [RFC] [PATCH] Relative lazy atime Message-ID: <20060809122134.GF27863@wohnheim.fh-wedel.de> References: <20060803063622.GB8631@goober> <20060805122537.GA23239@lst.de> <1154797123.12108.6.camel@kleikamp.austin.ibm.com> <1154797475.3054.79.camel@laptopd505.fenrus.org> <20060805183609.GA7564@tuatara.stupidest.org> <20060805222247.GQ29686@ca-server1.us.oracle.com> <20060806030147.GG4379@parisc-linux.org> <20060809063947.GA13474@goober> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20060809063947.GA13474@goober> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1909 Lines: 50 On Tue, 8 August 2006 23:39:49 -0700, Valerie Henson wrote: > On Sat, Aug 05, 2006 at 09:01:47PM -0600, Matthew Wilcox wrote: > > On Sat, Aug 05, 2006 at 04:28:29PM -0700, dean gaudet wrote: > > > you can work around mutt's silly dependancy on atime by configuring it > > > with --enable-buffy-size. so far mutt is the only program i've discovered > > > which cares about atime. > > > > For the shell, atime is the difference between 'you have mail' and 'you > > have new mail'. > > > > I still don't understand though, how much does this really buy us over > > nodiratime? > > Lazy atime buys us a reduction in writes over nodiratime for any > workload which reads files, such as grep -r, a kernel compile, or > backup software. Do I misunderstand the question? At the risk of stating the obvious, let me try to explain what each method does: 1. standard Every read access to a file/directory causes an atime update. 2. nodiratime Every read access to a non-directory causes an atime update. 3. lazy atime The first read access to a file/directory causes an atime update. 4. noatime No read access to a file/directory causes an atime update. In comparison, lazy atime will cause more atime updates for directories and vastly fewer for non-directories. Effectively atime is turned into little more than a flag, stating whether the file was ever read since the last write to it. And it appears as if neither mutt nor the shell use atime for more than this flagging purpose, so I am rather fond of the idea. J?rn -- The cheapest, fastest and most reliable components of a computer system are those that aren't there. -- Gordon Bell, DEC labratories - 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/