From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758772Ab0LNRXQ (ORCPT ); Tue, 14 Dec 2010 12:23:16 -0500 Received: from terminus.zytor.com ([198.137.202.10]:56730 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755285Ab0LNRXP (ORCPT ); Tue, 14 Dec 2010 12:23:15 -0500 Message-ID: <4D07A7CB.7010205@zytor.com> Date: Tue, 14 Dec 2010 09:22:19 -0800 From: "H. Peter Anvin" 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: Christoph Lameter CC: Eric Dumazet , Tejun Heo , akpm@linux-foundation.org, Pekka Enberg , linux-kernel@vger.kernel.org, Mathieu Desnoyers Subject: Re: [cpuops cmpxchg V2 5/5] cpuops: Use cmpxchg for xchg to avoid lock semantics References: <20101214162842.542421046@linux.com> <20101214162855.392020353@linux.com> <1292345072.5934.32.camel@edumazet-laptop> <4D07A2B7.8080405@zytor.com> In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/14/2010 09:19 AM, Christoph Lameter wrote: >> >> Is it genuinely faster to do the pre-load mov, or can we drop that too? >> My guess would be that yes it is, but if it happens not to be it would >> be nice to reduce the code size. > > Dropping the load increases the cycle count from 11 to 16. > Great, that answers that! I'll pick up the patch hopefully today (I'm finally ramping back up on arch/x86 again after having been diverted to an internal project for a while...) -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.