Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932776Ab0BGSa4 (ORCPT ); Sun, 7 Feb 2010 13:30:56 -0500 Received: from casper.infradead.org ([85.118.1.10]:37374 "EHLO casper.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932346Ab0BGSaz (ORCPT ); Sun, 7 Feb 2010 13:30:55 -0500 Date: Sun, 7 Feb 2010 10:32:08 -0800 From: Arjan van de Ven To: Michael Breuer Cc: Linux Kernel Mailing List Subject: Re: x86 - cpu_relax - why nop vs. pause? Message-ID: <20100207103208.4e2ecfb4@infradead.org> In-Reply-To: <4B6EF853.9090704@majjas.com> References: <4B6EF853.9090704@majjas.com> Organization: Intel X-Mailer: Claws Mail 3.7.3 (GTK+ 2.16.6; i586-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 831 Lines: 25 On Sun, 07 Feb 2010 12:28:51 -0500 Michael Breuer wrote: > I did search and noticed some old discussions. Looking at both Intel > and AMD documentation, it would seem that PAUSE is the preferred > instruction within a spin lock. Further, both Intel and AMD > specifications state that the instruction is backward compatible with > older x86 processors. > that's odd.... rep nop and pause ought to be the same... -- Arjan van de Ven Intel Open Source Technology Centre For development, discussion and tips for power savings, visit http://www.lesswatts.org -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/