From: Matthew Garrett Subject: Re: [PATCH, resend] relatime: Let relatime update atime at least once per day Date: Sun, 28 Dec 2008 19:59:21 +0000 Message-ID: <20081228195921.GB19176@srcf.ucam.org> References: <20081228152901.GB13565@srcf.ucam.org> <4957CDD2.9040903@tudelft.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org To: =?iso-8859-1?Q?=C9ric?= Piel Return-path: Received: from cavan.codon.org.uk ([93.93.128.6]:56729 "EHLO vavatch.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752432AbYL1T7Z (ORCPT ); Sun, 28 Dec 2008 14:59:25 -0500 Content-Disposition: inline In-Reply-To: <4957CDD2.9040903@tudelft.nl> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Sun, Dec 28, 2008 at 08:04:50PM +0100, =C9ric Piel wrote: > Matthew Garrett schreef: > > Ensure relatime updates atime at least once per day > > =20 > > Allow atime to be updated once per day even with relatime. This let= s > > utilities like tmpreaper (which delete files based on last access t= ime) > > continue working. > : > Sorry, but I doubt it's a good idea. First, it breaks the simple > semantic of relatime (mtime > atime?), mixing it with a rather arbitr= ary > constant. Second, and most important, there are lots of workloads whi= ch > will be strongly affected by this modification. For instance, running > md5sum daily on the filesystem will cause a write for every file. Yes. And? I can't think of a single case where something could=20 absolutely depend on the current relatime semantics, so altering them t= o=20 more usefully match the atime semantics doesn't seem likely to cause an= y=20 trouble. > I think that to solve the problem for your use case, it's better to u= se > a different approach such as mounting separately /tmp (with the atime > option). The use case in this case is the significant body of currently installe= d=20 machines that don't have /tmp on a separate filesystem. In the very=20 common setup of tmpreaper being used, the current relatime semantics=20 will result in undesired data loss. I think the proposed alteration=20 makes the behaviour of relatime massively more useful without any=20 obvious drawbacks. --=20 Matthew Garrett | mjg59@srcf.ucam.org -- To unsubscribe from this list: send the line "unsubscribe linux-fsdevel= " in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html