From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262064AbULHHjD (ORCPT ); Wed, 8 Dec 2004 02:39:03 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262065AbULHHhv (ORCPT ); Wed, 8 Dec 2004 02:37:51 -0500 Received: from fw.osdl.org ([65.172.181.6]:6017 "EHLO mail.osdl.org") by vger.kernel.org with ESMTP id S262060AbULHHap (ORCPT ); Wed, 8 Dec 2004 02:30:45 -0500 Date: Tue, 7 Dec 2004 23:30:27 -0800 From: Andrew Morton To: Jens Axboe Cc: nickpiggin@yahoo.com.au, andrea@suse.de, linux-kernel@vger.kernel.org Subject: Re: Time sliced CFQ io scheduler Message-Id: <20041207233027.20f29a16.akpm@osdl.org> In-Reply-To: <20041208072052.GC19522@suse.de> References: <20041202195232.GA26695@suse.de> <20041208003736.GD16322@dualathlon.random> <1102467253.8095.10.camel@npiggin-nld.site> <20041208013732.GF16322@dualathlon.random> <20041207180033.6699425b.akpm@osdl.org> <20041208022020.GH16322@dualathlon.random> <20041207182557.23eed970.akpm@osdl.org> <1102473213.8095.34.camel@npiggin-nld.site> <20041208065858.GH3035@suse.de> <1102490086.8095.63.camel@npiggin-nld.site> <20041208072052.GC19522@suse.de> X-Mailer: Sylpheed version 0.9.7 (GTK+ 1.2.10; i386-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Jens Axboe wrote: > > I think we need to end up with something that sets the machine profile > for the interesting disks. Some things you can check for at runtime > (like the writes being extremely fast is a good indicator of write > caching), but it is just not possible to cover it all. Plus, you end up > with 30-40% of the code being convoluted stuff added to detect it. We can detect these things from userspace. Parse the hdparm/scsiinfo output, then poke numbers into /sys tunables.