From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Mon, 21 May 2001 18:22:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Mon, 21 May 2001 18:22:32 -0400 Received: from fe040.worldonline.dk ([212.54.64.205]:63760 "HELO fe040.worldonline.dk") by vger.kernel.org with SMTP id ; Mon, 21 May 2001 18:22:10 -0400 Date: Tue, 22 May 2001 00:22:27 +0200 From: Jens Axboe To: Andi Kleen Cc: "David S. Miller" , Andrea Arcangeli , Andrew Morton , Ivan Kokshaysky , Richard Henderson , linux-kernel@vger.kernel.org Subject: Re: alpha iommu fixes Message-ID: <20010522002227.D8020@suse.de> In-Reply-To: <15112.26868.5999.368209@pizda.ninka.net> <20010521034726.G30738@athlon.random> <15112.48708.639090.348990@pizda.ninka.net> <20010521105944.H30738@athlon.random> <15112.55709.565823.676709@pizda.ninka.net> <20010521112357.A1718@gruyere.muc.suse.de> <15112.57377.723591.710628@pizda.ninka.net> <20010521114216.A1968@gruyere.muc.suse.de> <15112.59192.613218.796909@pizda.ninka.net> <20010521122753.A2507@gruyere.muc.suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20010521122753.A2507@gruyere.muc.suse.de>; from ak@suse.de on Mon, May 21, 2001 at 12:27:53PM +0200 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, May 21 2001, Andi Kleen wrote: > On Mon, May 21, 2001 at 03:00:24AM -0700, David S. Miller wrote: > > > That's currently the case, but at least on IA32 the block layer > > > must be fixed soon because it's a serious performance problem in > > > some cases (and fixing it is not very hard). > > > > If such a far reaching change goes into 2.4.x, I would probably > > begin looking at enhancing the PCI dma interfaces as needed ;-) > > Hmm, I don't think it'll be a far reaching change. As far as I can see > all it needs is a new entry point for block device drivers that uses > bh->b_page. When that entry point exists skip the create_bounce call > in __make_request. After that it is purely problem for selected drivers. I've already done it, however not as a 2.4 solution. The partial and WIP patches is here: *.kernel.org/pub/linux/kernel/people/axboe/v2.5/bio-7 Block driver can indicate the need for bounce buffers above a certain page. Of course I can hack up something for 2.4 as well, but is this really a pressing need? -- Jens Axboe