Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757075Ab1ETWD0 (ORCPT ); Fri, 20 May 2011 18:03:26 -0400 Received: from mailout-de.gmx.net ([213.165.64.23]:56185 "HELO mailout-de.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1753621Ab1ETWDR (ORCPT ); Fri, 20 May 2011 18:03:17 -0400 X-Authenticated: #911537 X-Provags-ID: V01U2FsdGVkX1/Ofo5CU5rOYnlW906VCCDH5uZ7clxDOBDLbiGumm BpLgsOYvFUV58h Date: Sat, 21 May 2011 00:03:14 +0200 From: torbenh To: "D. Jansen" Cc: Valdis.Kletnieks@vt.edu, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, tytso@mit.edu Subject: Re: [rfc] Ignore Fsync Calls in Laptop_Mode Message-ID: <20110520220314.GA8271@siel.b> Mail-Followup-To: "D. Jansen" , Valdis.Kletnieks@vt.edu, linux-kernel@vger.kernel.org, akpm@linux-foundation.org, tytso@mit.edu References: <9534.1305905293@localhost> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/1.5.20 (2009-06-14) X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1575 Lines: 35 On Fri, May 20, 2011 at 06:40:49PM +0200, D. Jansen wrote: > On Fri, May 20, 2011 at 5:28 PM, wrote: > > On Thu, 19 May 2011 15:34:46 +0200, Dennis Jansen said: > > > >> Testing: > >> I've been using this workaround on my netbook for over six months now. > >> It works as expected for me with all software in a Ubuntu 9.10 > >> environment and saves me at least 0.5 Watt or roughly 10 % battery > >> time - without destroying my hard disk. I have seen no negative side > >> effects. > > > > How much destructive testing did you do? ?In the 6 months, how many times did > > the system crash (or had the battery pulled out, or whatever) while large > > amounts of data were still pending after apps thought they were fsync'ed? How > > much crash testing was done against apps that use fsync for ordering or > > correctness reasons? > > I don't see the point in verifying the obvious. Of course applications > that rely on fsync will lose data. > The real problem comes with ordering correctness, which could actually > _destroy previous data_ as well. > In my scenario (office applications, browsing) I have not hit such a problem. how about making fsync block until the harddisk spins up ? this would also enable you to detect these apps you wouldnt be using in laptop mode anyways ? -- torben Hohn -- 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/