From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757802AbYERUam (ORCPT ); Sun, 18 May 2008 16:30:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752952AbYERUaf (ORCPT ); Sun, 18 May 2008 16:30:35 -0400 Received: from one.firstfloor.org ([213.235.205.2]:56311 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752817AbYERUae (ORCPT ); Sun, 18 May 2008 16:30:34 -0400 Message-ID: <483091E6.9080703@firstfloor.org> Date: Sun, 18 May 2008 22:30:30 +0200 From: Andi Kleen User-Agent: Thunderbird 1.5.0.12 (X11/20060911) MIME-Version: 1.0 To: Thomas Gleixner CC: Vegard Nossum , "Rafael J. Wysocki" , Andreas Herrmann , Linux Kernel Mailing List , Arjan van de Ven , Ingo Molnar Subject: Re: [Bug #10710] [BISECTED] Lots of "rescheduling IPIs" in powertop References: <7wuznNhcUqC.A.xiH.EsBMIB@albercik> <19f34abd0805180523o12732812k87b8ddd832843af4@mail.gmail.com> <48306E8D.5050109@firstfloor.org> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Thomas Gleixner wrote: > stop these pointless ad hominem attacks! Just my experience from past incidents sorry. I'm sure it never happened to you. >> [In case someone is interested it's CPUID 5 ECX bit 0 which enumerates >> if the MWAIT enumeration is there. So the correct mwait_usable() that >> would have avoided your problem would be something like (untested): >> >> return c->cpuid_level >= 5 && >> ((cpuid_ecx(5) & 1) == 0 || (cpuid_edx(5) >> 4) & 0xf) > 0); >> ] > > I'm interested, but I'd be even more interested in some useful pointer > to the magic bitnumbers in that check, but don't exert yourself in > providing the information, It's documented in the IA32 SDM vol2 as part of the CPUID description. It's a reasonable expection that everyone hacking on cpuid code has that at hand. -Andi