Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759213AbZCZQeS (ORCPT ); Thu, 26 Mar 2009 12:34:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754977AbZCZQeD (ORCPT ); Thu, 26 Mar 2009 12:34:03 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:37553 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752359AbZCZQeB (ORCPT ); Thu, 26 Mar 2009 12:34:01 -0400 Date: Thu, 26 Mar 2009 09:24:54 -0700 From: Andrew Morton To: Linus Torvalds Cc: Frans Pop , mingo@elte.hu, tytso@mit.edu, jack@suse.cz, alan@lxorguk.ukuu.org.uk, arjan@infradead.org, a.p.zijlstra@chello.nl, npiggin@suse.de, jens.axboe@oracle.com, drees76@gmail.com, jesper@krogh.cc, linux-kernel@vger.kernel.org, oleg@redhat.com, roland@redhat.com Subject: Re: relatime: update once per day patches (was: ext3 IO latency measurements) Message-Id: <20090326092454.b74e3f96.akpm@linux-foundation.org> In-Reply-To: References: <20090325123744.GK23439@duck.suse.cz> <20090325150041.GM32307@mit.edu> <20090325185824.GO32307@mit.edu> <20090325215137.GQ32307@mit.edu> <20090325235041.GA11024@duck.suse.cz> <20090326090630.GA9369@elte.hu> <20090326113705.GV32307@mit.edu> <20090326140312.GB14822@elte.hu> <20090326140312.GB14822@elte.hu> <20090326073013.2fa83178.akpm@linux-foundation.org> <200903261632.42439.elendil@planet.nl> <20090326084733.156c4910.akpm@linux-foundation.org> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1377 Lines: 37 On Thu, 26 Mar 2009 09:14:28 -0700 (PDT) Linus Torvalds wrote: > > > On Thu, 26 Mar 2009, Andrew Morton wrote: > > > > Hard-wiring a 24-hour interval into the core VFS for all mounted > > filesystems is dumb. > > Umm. > > I generally agree witht he "leave policy to user space" people, but this > is an area where (a) user space has shown itself to not get it right (ie > people don't do even the existing relatime because distros don't) and (b) > what's the alternative? > > > I (and others) pointed out that it would be better to implement this as > > a mount option. That suggestion was met with varying sillinesses and > > that is where things stand. > > I'd suggest first just doing the 24 hour thing, and then, IF user space > actually ever gets its act together, and people care, and they _ask_ for a > mount option, that's when it's worth doing. > We wouldn't normally just enable the new feature by default because it changes kernel behaviour. Userspace needs to be changed in some manner to opt-in. One way it's `mount -o remount', the other way it's a poke in /proc. -- 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/