From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754978AbYIZKGb (ORCPT ); Fri, 26 Sep 2008 06:06:31 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752822AbYIZKGX (ORCPT ); Fri, 26 Sep 2008 06:06:23 -0400 Received: from earthlight.etchedpixels.co.uk ([81.2.110.250]:60590 "EHLO lxorguk.ukuu.org.uk" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1752316AbYIZKGW (ORCPT ); Fri, 26 Sep 2008 06:06:22 -0400 Date: Fri, 26 Sep 2008 11:06:10 +0100 From: Alan Cox To: Jens Axboe Cc: marty , linux-kernel@vger.kernel.org, martin.leisner@xerox.com Subject: Re: disk IO directly from PCI memory to block device sectors Message-ID: <20080926110610.17603d30@lxorguk.ukuu.org.uk> In-Reply-To: <20080926091135.GV2677@kernel.dk> References: <247018.46515.qm@web50603.mail.re2.yahoo.com> <20080926094653.1e0a9260@lxorguk.ukuu.org.uk> <20080926091135.GV2677@kernel.dk> X-Mailer: Claws Mail 3.5.0 (GTK+ 2.12.11; x86_64-redhat-linux-gnu) Organization: Red Hat UK Cyf., Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SL4 1TE, Y Deyrnas Gyfunol. Cofrestrwyd yng Nghymru a Lloegr o'r rhif cofrestru 3798903 Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 26 Sep 2008 11:11:35 +0200 Jens Axboe wrote: > On Fri, Sep 26 2008, Alan Cox wrote: > > > What I'm looking is for a more generic/driver independent way of sticking > > > contents of PCI ram onto a disk. > > > > Ermm seriously why not have a userspace task with the PCI RAM mmapped > > and just use write() like normal sane people do ? > > To avoid the fault and copy, I would assume. It's a write to a raw partition so with O_DIRECT you won't have to copy and MAP_POPULATE will premap the object if even the first write wants to occur without faulting overhead. Alan