From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932145Ab0F3RNh (ORCPT ); Wed, 30 Jun 2010 13:13:37 -0400 Received: from terminus.zytor.com ([198.137.202.10]:42786 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756921Ab0F3RNg (ORCPT ); Wed, 30 Jun 2010 13:13:36 -0400 Message-ID: <4C2B7B28.1000506@zytor.com> Date: Wed, 30 Jun 2010 10:13:12 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.10) Gecko/20100621 Fedora/3.0.5-1.fc13 Thunderbird/3.0.5 MIME-Version: 1.0 To: Jan Beulich CC: jeremy.fitzhardinge@citrix.com, mingo@elte.hu, tglx@linutronix.de, Ky Srinivasan , linux-kernel@vger.kernel.org Subject: Re: [PATCH 3/4, v2] x86: enlightenment for ticket spin locks - eliminate NOPs introduced by first patch References: <4C2A205902000078000089E7@vpn.id2.novell.com> <4C2A9A1E.6010005@zytor.com> <4C2B09450200007800008B95@vpn.id2.novell.com> In-Reply-To: <4C2B09450200007800008B95@vpn.id2.novell.com> 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 06/30/2010 12:07 AM, Jan Beulich wrote: >> >> If you're stretching (bloating) them anyway, perhaps we should be using >> "add" instructions instead, with their better EFLAGS behavior? > > Hmm, yes, that possibility I didn't even consider. Would have > the potential to get away without that admittedly ugly "unary" > assembler macro altogether, though at the price of growing all > instructions rather than just those that have a non-symbolic > and small displacement. Since unlock generally gets inlined, I'm > not certain this additional growth in code size would be > acceptable... > > Please let me know, though before submitting an eventual third > version I'd appreciate knowing especially the first two patches > need further changes in order to get accepted. > Will look at it today, hopefully. The Syslinux 4.00 release has unfortunately occupied me over the last week-plus. As far as the "unary" macro is concerned... I have to admit I couldn't even figure out what it was supposed to do. It could definitely use a better comment. -hpa -- H. Peter Anvin, Intel Open Source Technology Center I work for Intel. I don't speak on their behalf.