From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757125AbYJQWtw (ORCPT ); Fri, 17 Oct 2008 18:49:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754647AbYJQWtp (ORCPT ); Fri, 17 Oct 2008 18:49:45 -0400 Received: from terminus.zytor.com ([198.137.202.10]:53501 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753677AbYJQWtp (ORCPT ); Fri, 17 Oct 2008 18:49:45 -0400 Message-ID: <48F91673.6090901@zytor.com> Date: Fri, 17 Oct 2008 15:49:23 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: "Pallipadi, Venkatesh" CC: Ingo Molnar , Thomas Gleixner , linux-kernel Subject: Re: [PATCH] x86: Add clflush before monitor for Intel 7400 series References: <20081007210056.GA5802@linux-os.sc.intel.com> <48EBCFF8.6050500@zytor.com> <20081007214920.GA17439@linux-os.sc.intel.com> <48EBEA97.9020404@zytor.com> <7E82351C108FA840AB1866AC776AEC4637B798D6@orsmsx505.amr.corp.intel.com> <48F8F1DB.9030202@zytor.com> <7E82351C108FA840AB1866AC776AEC4637B799FB@orsmsx505.amr.corp.intel.com> In-Reply-To: <7E82351C108FA840AB1866AC776AEC4637B799FB@orsmsx505.amr.corp.intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Pallipadi, Venkatesh wrote: >>> >> I guess I'm a bit confused about the tradeoff of CLFLUSH versus simply >> disabling MWAIT. This is a relatively recent processor and so >> optimizing matters (if this was a P4 I would be more worried about what >> has least impact on the kernel as a whole.) > > As of now this is only for a limited models of CPUs (MP CPUs) > and not a norm. It is a errata on this CPU and not > something that is going to become architectural. > Yes, I understand. However, there is still the option to disable MWAIT, and the question is still open if it makes sense. -hpa