From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933576AbXCOTvh (ORCPT ); Thu, 15 Mar 2007 15:51:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S933588AbXCOTvh (ORCPT ); Thu, 15 Mar 2007 15:51:37 -0400 Received: from heisenberg.zen.co.uk ([212.23.3.141]:59498 "EHLO heisenberg.zen.co.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933576AbXCOTvg (ORCPT ); Thu, 15 Mar 2007 15:51:36 -0400 X-Greylist: delayed 126986 seconds by postgrey-1.27 at vger.kernel.org; Thu, 15 Mar 2007 15:51:35 EDT Message-ID: <45F9A3C1.3000700@gmail.com> Date: Thu, 15 Mar 2007 19:51:29 +0000 From: Matt Keenan User-Agent: Icedove 1.5.0.10 (X11/20070307) MIME-Version: 1.0 To: Andrew Morton CC: linux-kernel@vger.kernel.org, Christoph Hellwig , bgoglin@free.fr, addy@quadrics.com Subject: Re: copy_one_pte() References: <45F6F84D.20302@free.fr> <20070313191844.GA4206@infradead.org> <45F7B3BB.1030404@gmail.com> <20070315110634.a2d08dce.akpm@linux-foundation.org> In-Reply-To: <20070315110634.a2d08dce.akpm@linux-foundation.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Originating-Heisenberg-IP: [82.69.27.224] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Andrew Morton wrote: > (cc restored. Please always do reply-to-all). > > >> On Wed, 14 Mar 2007 08:35:07 +0000 Matt Keenan wrote: >> Christoph Hellwig wrote: >> >>> On Tue, Mar 13, 2007 at 08:15:25PM +0100, Zoltan Menyhart wrote: >>> >>> >>>> I had a look at copy_one_pte(). >>>> I cannot see any ioproc_update_page() call, not even for the COW pages. >>>> Is it intentional? >>>> >>>> >>> There is no such thing as ioproc_update_page in any mainline tree. >>> You must be looking at some vendor tree with braindead patches applied. >>> >>> >>> >> It looks like this function exists as a part of patches to support >> Quadrics NICs / RDMA (HPC platforms). The patches are there so the >> driver doesn't need to pin pages, it can be informed of page updates >> directly. A patch was submitted to l-k sometime in 2005. >> > > Oh Dear. > > Which vendor's kernel are we talking about here? > I don't know of any vendor's kernels that support this (but then I run vanilla kernels on Debian). I just grep'ed for the patch because it sounded interesting. There was a posting for it to l-k on 26th April 2005 from David Addison of Quadrics Ltd xref http://lkml.org/lkml/2005/4/26/198 According to David, you (Andrew) and Andrea Arcangeli asked for it to be posted for some feedback, the main feedback was on whitespace issues and COWs w.r.t. fork(). Brice Goglin made an interesting comment about using a similar method but tracking VMAs rather than address spaces. By the looks of things it never went into the mainline kernel. I lurk a bit (I sometimes miss things) on l-k but I hadn't noticed any other methods for dynamic DMA direct to user space (other than pinning pages), is there anything planned? Matt p.s. I Cc'ed Brice Goglin and David Addison