Return-Path: <linux-kernel-owner+w=401wt.eu-S1761444AbZDCBWb@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1761444AbZDCBWb (ORCPT <rfc822;w@1wt.eu>);
	Thu, 2 Apr 2009 21:22:31 -0400
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751019AbZDCBWW
	(ORCPT <rfc822;linux-kernel-outgoing>);
	Thu, 2 Apr 2009 21:22:22 -0400
Received: from cavan.codon.org.uk ([93.93.128.6]:51429 "EHLO
	vavatch.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1750825AbZDCBWW (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Thu, 2 Apr 2009 21:22:22 -0400
Date: Fri, 3 Apr 2009 02:22:09 +0100
From: Matthew Garrett <mjg59@srcf.ucam.org>
To: david@lang.hm
Cc: Nick Piggin <nickpiggin@yahoo.com.au>, Theodore Tso <tytso@mit.edu>,
       Sitsofe Wheeler <sitsofe@yahoo.com>,
       "Andreas T.Auer" <andreas.t.auer_lkml_73537@ursus.ath.cx>,
       Alberto Gonzalez <info@gnebu.es>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Ext4 and the "30 second window of death"
Message-ID: <20090403012209.GB10777@srcf.ucam.org>
References: <200903291224.21380.info@gnebu.es> <200904030535.00335.nickpiggin@yahoo.com.au> <20090402183834.GB4773@srcf.ucam.org> <200904030556.41270.nickpiggin@yahoo.com.au> <20090402234751.GC9538@srcf.ucam.org> <alpine.DEB.1.10.0904021755250.28893@asgard.lang.hm> <20090403010901.GB10545@srcf.ucam.org> <alpine.DEB.1.10.0904021816420.28893@asgard.lang.hm>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <alpine.DEB.1.10.0904021816420.28893@asgard.lang.hm>
User-Agent: Mutt/1.5.12-2006-07-14
X-SA-Exim-Connect-IP: <locally generated>
X-SA-Exim-Mail-From: mjg59@codon.org.uk
X-SA-Exim-Scanned: No (on vavatch.codon.org.uk); SAEximRunCond expanded to false
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1192
Lines: 33

On Thu, Apr 02, 2009 at 06:17:12PM -0700, david@lang.hm wrote:
> On Fri, 3 Apr 2009, Matthew Garrett wrote:
> 
> >On Thu, Apr 02, 2009 at 05:59:53PM -0700, david@lang.hm wrote:
> >
> >>is laptop mode
> >>
> >>A. "write everything now, don't delay writes" in the hope that the drive
> >>will be idle enough later to spin down
> >
> >laptop-mode doesn't delay writes. Ever.
> >
> >>or
> >>
> >>B. "delay all writes until later, then when the drive wakes up do all
> >>pending writes at that time" so that the drive can go to sleep in the
> >>meantime?
> >
> >Yes.
> 
> you just contridicted yourself in these two statements.

That's because I'm horribly drunk and managed to confuse the order of 
your statements. My substantive point stands - the laptop-mode code 
doesn't delay writes, and it's pretty easy for anyone to prove this to 
themselves. Neither of your options actually describe its behaviour.
-- 
Matthew Garrett | mjg59@srcf.ucam.org
--
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/