Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1762282AbZDCBYz (ORCPT ); Thu, 2 Apr 2009 21:24:55 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754146AbZDCBYr (ORCPT ); Thu, 2 Apr 2009 21:24:47 -0400 Received: from mail.lang.hm ([64.81.33.126]:53930 "EHLO bifrost.lang.hm" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751019AbZDCBYq (ORCPT ); Thu, 2 Apr 2009 21:24:46 -0400 Date: Thu, 2 Apr 2009 18:24:28 -0700 (PDT) From: david@lang.hm X-X-Sender: dlang@asgard.lang.hm To: Matthew Garrett cc: 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: <20090403011953.GA10777@srcf.ucam.org> Message-ID: References: <20090401151219.GA12285@srcf.ucam.org> <20090401173521.GA15423@mit.edu> <20090401174336.GA14726@srcf.ucam.org> <20090402182925.GA4502@srcf.ucam.org> <20090402234617.GB9538@srcf.ucam.org> <20090403010600.GA10545@srcf.ucam.org> <20090403011953.GA10777@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: 2630 Lines: 57 On Fri, 3 Apr 2009, Matthew Garrett wrote: > On Thu, Apr 02, 2009 at 06:16:20PM -0700, david@lang.hm wrote: >> On Fri, 3 Apr 2009, Matthew Garrett wrote: >> >>> On Thu, Apr 02, 2009 at 05:55:11PM -0700, david@lang.hm wrote: >>>> On Fri, 3 Apr 2009, Matthew Garrett wrote: >>>>> Then they shouldn't use a mail client that fsync()s. >>>> >>>> so they need to use one mail client when they want to have good battery >>>> life and a different one when they are plugged in to power? >>> >>> They need to make a decision about whether they care about their mailbox >>> being precisely in sync with their server or not, and either use a >>> client that adapts appropriately or choose a client that behaves >>> appropriately. It's certainly not the kernel's business. >> >> the kernel is not deciding this, the kernel would be implementing the >> user's choice > > No it wouldn't. The kernel would be implementing an adminstrator's > choice about whether fsync() is important or not. That's something that > would affect the mail client, but it's hardly a decision based on the > mail client. Sucks to be that user if they do anything involving mysql. in the case of laptops, in 99+% of the cases the user and the administrator are the same person. in the other cases that's something the user should take up with the administrator, because the administrator can do a lot of things to the system that will affect the safety of their data (including loading a kernel that turns fsync into a noop, but more likely involving enabling or disabling write caches on disks) >>> If you can demonstrate a real world use case where the hard drive >>> (typically well under a watt of power consumption on modern systems) >>> spindown policy will be affected sufficiently pathologically by a mail >>> client that you lose an hour of battery life, then I'd rethink this. But >>> mostly I'd conclude that this was an example of an inappropriate >>> spindown policy. >> >> remember that the mail client was an example. >> >> you want another example, think of anything that uses sqlite (like the >> firefox history stuff, although that was weakened drasticly due to the >> ext3 problems). > > Benchmarks please. if spinning down a drive saves so little power that it wouldn't make a significant difference to battery lift to leave it on, why does anyone bother to spin the drive down? David Lang -- 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/