From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S261595AbTJRMw4 (ORCPT ); Sat, 18 Oct 2003 08:52:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S261601AbTJRMw4 (ORCPT ); Sat, 18 Oct 2003 08:52:56 -0400 Received: from ns.virtualhost.dk ([195.184.98.160]:23245 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S261595AbTJRMwx (ORCPT ); Sat, 18 Oct 2003 08:52:53 -0400 Date: Sat, 18 Oct 2003 14:52:52 +0200 From: Jens Axboe To: Jan Rychter Cc: linux-kernel@vger.kernel.org Subject: Re: [PATCH] laptop mode Message-ID: <20031018125252.GQ1128@suse.de> References: <3F856A7E.2010607@pobox.com> <20031009141143.GF1232@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Oct 17 2003, Jan Rychter wrote: > >>>>> "Jens" == Jens Axboe writes: > Jens> On Thu, Oct 09 2003, Marcelo Tosatti wrote: > >> On Thu, 9 Oct 2003, Jeff Garzik wrote: > > Linux Kernel Mailing List wrote: > > > ChangeSet 1.1150.1.52, 2003/10/08 10:49:45-03:00, axboe@suse.de > > > [PATCH] laptop mode > > > > > > Hi Marcelo, > > > > > > Lots of people have been using this patch with great success, > > > and it's been in the SuSE kernel for some months now too. It is > > > also in the -benh ppc tree > > > > > > Basically, it introduces a write back mode of dirty and journal > > > data that is more suitable for laptops. At the block layer end, > > > it schedules write out of dirty data after the disk has been > > > idle for 5 seconds. > > > > > > Laptop mode can be switched on and off with > > > /proc/sys/vm/laptop_mode. There is also a block_dump sysctl, > > > which if enabled will dump who dirties and writes out data. This > > > is very helpful in pinning down who is causing unnecessary > > > writes to the disk. > > > > Red Hat just dropped this patch since it was suspected of data > > corruption ;-( > >> > >> Uh, oh... Jens? > > Jens> See my previous mail. I don't see any problems with it, and I've > Jens> certainly not heard of (or experienced myself) problems with the > Jens> patch. I'm waiting for Jeff to expand on his mail, surely he/RH > Jens> must know more about this issue. > > FWIW, I've been using laptop-mode for a long time now, with no problems > whatsoever. It's a great addition and really helps laptop users. Glad to hear that. > On a related note, a very desirable feature would be to be able to trace > which processes do I/O. Unfortunately, Linux distributions aren't very > well adapted to laptops and many applications are way too > "trigger-happy" when it comes to hard drive accesses. I guess most > developers don't use laptops and just assume that they can write or > read data at will. It is very difficult to trace the culprits when your > HD light goes on every couple of seconds. You do know that the laptop-mode patch included a feature to help with just that very problem, block_dump? If you do echo "1" > /proc/sys/vm/block_dump (shut down klogd first), it will tell you which process caused the hd activity, either directly or by dirtying a page of data. -- Jens Axboe