From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756726AbXLLOth (ORCPT ); Wed, 12 Dec 2007 09:49:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756393AbXLLOt3 (ORCPT ); Wed, 12 Dec 2007 09:49:29 -0500 Received: from smtpq1.groni1.gr.home.nl ([213.51.130.200]:59013 "EHLO smtpq1.groni1.gr.home.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756103AbXLLOt2 (ORCPT ); Wed, 12 Dec 2007 09:49:28 -0500 Message-ID: <475FF4A1.4020401@keyaccess.nl> Date: Wed, 12 Dec 2007 15:48:01 +0100 From: Rene Herman User-Agent: Thunderbird 2.0.0.9 (X11/20071031) MIME-Version: 1.0 To: linux@horizon.com CC: Linux Kernel Subject: Re: [RFT] Port 0x80 I/O speed References: <20071212112049.17891.qmail@science.horizon.com> In-Reply-To: <20071212112049.17891.qmail@science.horizon.com> Content-Type: text/plain; charset=ISO-8859-15; format=flowed Content-Transfer-Encoding: 7bit X-Spam-Score: -1.0 (-) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12-12-07 12:20, linux@horizon.com wrote: > Here are a variety of machines: Thanks much for all! Collecting all data now... > With -O2, the cycle counts come out (before division) as > out: 0xFFFFFFFFFFEA6F4F > in: 0xFFFFFFFFFCE68BB6 > I think the "A" constraint doesn't work quite the same in > 64-bit code. The compiler seems to be using %rdx rather than > %edx:%eax. Yes indeed, that tripped me up. Have been using the "=A" locally for a while for similar timing tests. Will use a manual "=a" (lo), "=d" (hi) I guess for amd64 compatibility from now on. If I'd care deeply I'd probably categorize this as a backwards compatibility bug in GCC though. Things were probably never guaranteed but they certainly worked that way... Rene.