Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S269639AbUJLLcj (ORCPT ); Tue, 12 Oct 2004 07:32:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S269627AbUJLLci (ORCPT ); Tue, 12 Oct 2004 07:32:38 -0400 Received: from smtp204.mail.sc5.yahoo.com ([216.136.130.127]:948 "HELO smtp204.mail.sc5.yahoo.com") by vger.kernel.org with SMTP id S269639AbUJLLcX (ORCPT ); Tue, 12 Oct 2004 07:32:23 -0400 Message-ID: <416BBF48.4070102@yahoo.com.au> Date: Tue, 12 Oct 2004 21:26:00 +1000 From: Nick Piggin User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.2) Gecko/20040820 Debian/1.7.2-4 X-Accept-Language: en MIME-Version: 1.0 To: "Ronny V. Vindenes" CC: Jens Axboe , ck@vds.kolivas.org, linux-kernel@vger.kernel.org, Andrew Morton Subject: Re: CFQ v2 high cpu load fix(?) References: <1097579760.4086.27.camel@tentacle125.gozu.lan> In-Reply-To: <1097579760.4086.27.camel@tentacle125.gozu.lan> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1519 Lines: 38 Ronny V. Vindenes wrote: > CFQ v2 is much better in a lot of cases, but certain situations trigger > a cpu load so high it starves the rest of the system thus completely > ruining the interactive experience. While casually looking at the > problem, I stumbled upon a patch by Arjan van de Ven sent to lkml on > sept. 1 (Subject: block fixes). Part of it is already included in the > CFQ v2 patches and after applying the rest[1] I'm no longer able to > trigger the problem. > > [1] Patch attached against 2.6.9-rc4-ck1 but applies to rc4-mm1 with > some minor fuzz. > > > > ------------------------------------------------------------------------ > > --- patches/linux-2.6.9-rc4-ck1/drivers/block/ll_rw_blk.c 2004-10-12 12:25:09.798003278 +0200 > +++ linux-2.6.9-rc4-ck1/drivers/block/ll_rw_blk.c 2004-10-12 12:25:42.959479479 +0200 > @@ -100,7 +100,7 @@ > nr = q->nr_requests; > q->nr_congestion_on = nr; > > - nr = q->nr_requests - (q->nr_requests / 8) - 1; > + nr = q->nr_requests - (q->nr_requests / 8) - (q->nr_requests/16)- 1; > if (nr < 1) > nr = 1; > q->nr_congestion_off = nr; I thought this first hunk looked like a good idea when Arjan sent the patch. Can you check if it alone helps your problem? The second hunk should be basically a noop. - 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/