Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932474AbZDAPMk (ORCPT ); Wed, 1 Apr 2009 11:12:40 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1762473AbZDAPMa (ORCPT ); Wed, 1 Apr 2009 11:12:30 -0400 Received: from cavan.codon.org.uk ([93.93.128.6]:41333 "EHLO vavatch.codon.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1760752AbZDAPMa (ORCPT ); Wed, 1 Apr 2009 11:12:30 -0400 Date: Wed, 1 Apr 2009 16:12:21 +0100 From: Matthew Garrett To: Sitsofe Wheeler Cc: Theodore Tso , "Andreas T.Auer" , Alberto Gonzalez , Linux Kernel Mailing List Subject: Re: Ext4 and the "30 second window of death" Message-ID: <20090401151219.GA12285@srcf.ucam.org> References: <200903291224.21380.info@gnebu.es> <200903311452.05210.info@gnebu.es> <20090331134547.GJ13356@mit.edu> <200904010002.47077.info@gnebu.es> <49D2A5AB.1090704@ursus.ath.cx> <20090401015010.GB4529@mit.edu> <20090401052050.GA20456@sucs.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20090401052050.GA20456@sucs.org> User-Agent: Mutt/1.5.12-2006-07-14 X-SA-Exim-Connect-IP: 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: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 956 Lines: 21 On Wed, Apr 01, 2009 at 06:20:50AM +0100, Sitsofe Wheeler wrote: > Just out of curiosity, when laptop mode is happening is there a > guarantee that writes to other files won't be reordered to before the > fsync? laptop-mode does two things - tweak the dirty page semantics slightly (not in an interestingly relevant way) and call sys_sync() a few seconds after something hits disk rather than cache. In contrast to Ted's suggestion that laptop-mode reduces data integrity, it actually enhances it by opportunistically ensuring that data hits disk. It's the lengthening of the commit intervals that usually accompanies it that increases the risk of data loss. -- 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/