From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751031AbWKAPWQ (ORCPT ); Wed, 1 Nov 2006 10:22:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752212AbWKAPWQ (ORCPT ); Wed, 1 Nov 2006 10:22:16 -0500 Received: from cavan.codon.org.uk ([217.147.92.49]:32646 "EHLO vavatch.codon.org.uk") by vger.kernel.org with ESMTP id S1750993AbWKAPWP (ORCPT ); Wed, 1 Nov 2006 10:22:15 -0500 Date: Wed, 1 Nov 2006 15:22:01 +0000 From: Matthew Garrett To: Arjan van de Ven Cc: Pavel Machek , kernel list , mingo@redhat.com, Andrew Morton Subject: Re: 2.6.19-rc4-mm1: noidlehz problems Message-ID: <20061101152201.GA13634@srcf.ucam.org> References: <20061101122319.GA13056@elf.ucw.cz> <1162386177.23744.17.camel@laptopd505.fenrus.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1162386177.23744.17.camel@laptopd505.fenrus.org> User-Agent: Mutt/1.5.9i X-SA-Exim-Connect-IP: X-SA-Exim-Mail-From: mjg59@codon.org.uk X-SA-Exim-Scanned: No (on vavatch.codon.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 01, 2006 at 02:02:57PM +0100, Arjan van de Ven wrote: > In some (hardware) C-states, the local apic timer stops (as does the > TSC), while in others it keeps running. If you change from AC to > battery, the bios can change the meaning of a software C-state from one > where local apic timer keeps going to one where it stops. This obviously > upsets the hrtimers/tickless code since that uses local apic timer for > event generation.... Is there any hope of working around this? I'd have expected that the most useful case for the tickless code was also the case where we want to be using C3/C4... -- Matthew Garrett | mjg59@srcf.ucam.org