Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758101AbZDCBRi (ORCPT ); Thu, 2 Apr 2009 21:17:38 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755581AbZDCBR3 (ORCPT ); Thu, 2 Apr 2009 21:17:29 -0400 Received: from mail.lang.hm ([64.81.33.126]:33577 "EHLO bifrost.lang.hm" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752148AbZDCBR3 (ORCPT ); Thu, 2 Apr 2009 21:17:29 -0400 Date: Thu, 2 Apr 2009 18:17:12 -0700 (PDT) From: david@lang.hm X-X-Sender: dlang@asgard.lang.hm To: Matthew Garrett cc: Nick Piggin , Theodore Tso , Sitsofe Wheeler , "Andreas T.Auer" , Alberto Gonzalez , Linux Kernel Mailing List Subject: Re: Ext4 and the "30 second window of death" In-Reply-To: <20090403010901.GB10545@srcf.ucam.org> Message-ID: 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> <20090403010901.GB10545@srcf.ucam.org> User-Agent: Alpine 1.10 (DEB 962 2008-03-14) MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1246 Lines: 38 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. David Lang >> I've heard things in these threads that would indicate both behaviors. > > The code's pretty trivial. The only real functional differences > laptop-mode brings are to write out all dirty pages (rather than just > writing down to the watermark) and to call sys_sync() a few seconds > after the last thing that hit disk rather than being satisfied from > cache. It's entirely a mechanism to opportunistically take advantage of > the disk being spun up. > > -- 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/