From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S937225AbYEBXEV (ORCPT ); Fri, 2 May 2008 19:04:21 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S935309AbYEBXEE (ORCPT ); Fri, 2 May 2008 19:04:04 -0400 Received: from sj-iport-3.cisco.com ([171.71.176.72]:40577 "EHLO sj-iport-3.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1765907AbYEBXED (ORCPT ); Fri, 2 May 2008 19:04:03 -0400 From: Roland Dreier To: "Moore\, Eric" Cc: Subject: Re: HELP: Is writeq an atomic operation?? References: <0631C836DBF79F42B5A60C8C8D4E822901047B2F@NAMAIL2.ad.lsil.com> X-Message-Flag: Warning: May contain useful information Date: Fri, 02 May 2008 16:04:00 -0700 In-Reply-To: <0631C836DBF79F42B5A60C8C8D4E822901047B2F@NAMAIL2.ad.lsil.com> (Eric Moore's message of "Fri, 2 May 2008 16:40:40 -0600") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.0.60 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-OriginalArrivalTime: 02 May 2008 23:04:01.0184 (UTC) FILETIME=[CF435A00:01C8ACA8] Authentication-Results: sj-dkim-2; header.From=rdreier@cisco.com; dkim=pass ( sig from cisco.com/sjdkim2002 verified; ); Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org > Here is a trace from pci express analyzer. I'm sending > 0x0800010000000000 to the adress DD1400C0 using writeq. Notice that in > the TLP header it sent a 32bit Memory write with data length of two. By the way, are you worried that there is something wrong with this trace? Your write went out in a single PCIe packet, so it looks perfect to me. Does the "Mem MWr(32)" worry you? I can't see why it would be a problem -- the PCIe TLP only has one type of memory write transaction (well, except for 32-bit or 64-bit addressing, but you don't care about that), and memory write transactions are sent as a string of 32-bit chunks, so there's no other way a 64-bit write could be sent. > Trace follows: > > Link Tra(597) Downstream 2.5(x1) TLP(1992) Mem MWr(32)(10:00000) TC(0) > TD(0) > _______| EP(0) Attributes(01) Length(2) RequesterID(000:02:0) Tag(8) > _______| Address(DD1400C0) 1st BE(1111) Last BE(1111) Data(08000100 > 00000000) > _______| VC ID(0) Explicit ACK(Packet #1195) Metrics # Packets(2) > _______| Time Stamp(0003 . 120 181 840 s)