From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932374Ab0LHBrA (ORCPT ); Tue, 7 Dec 2010 20:47:00 -0500 Received: from mail-gx0-f180.google.com ([209.85.161.180]:42780 "EHLO mail-gx0-f180.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932327Ab0LHBq5 (ORCPT ); Tue, 7 Dec 2010 20:46:57 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:content-type:content-transfer-encoding; b=eOu9LOm9j4eaxfj3BB0iC6kdb9v9IYknpAa1Qaj7I8oQ0oL9+abgm7SmLA9ketWQ28 knYvMnoaQpQW3x+8BvJusijoP19g5AmOdrXKrbGk2uY0XbYr2HLP1eltfYtTdbBSwzc7 hNt9P5GIZ6n+xiDhd0I5RZ2cyhHtb57Jn9p94= Message-ID: <4CFEE38E.3020500@gmail.com> Date: Tue, 07 Dec 2010 19:46:54 -0600 From: Robert Hancock User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.2.12) Gecko/20101103 Fedora/1.0-0.33.b2pre.fc14 Thunderbird/3.1.6 MIME-Version: 1.0 To: Sanka Piyaratna CC: linux-kernel@vger.kernel.org Subject: Re: Posted Write onto a PCI end point device using Linux References: <712019.56679.qm@web31702.mail.mud.yahoo.com> In-Reply-To: <712019.56679.qm@web31702.mail.mud.yahoo.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/07/2010 05:29 AM, Sanka Piyaratna wrote: > Hi, > > > I am wondering whether it is possible to issue a posted write using the host > computer's root complex towards an PCI express end point. I have done this using > > DMA in the past. However, if posted writes are possible that would save a lot of > > time and effort and would be quicker too. Writes from the CPU to PCI memory are always posted. However, the posted write buffer size is usually quite limited and so this probably will still cause CPU overhead when writing any significant amount of data this way.