From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752095AbWKANDA (ORCPT ); Wed, 1 Nov 2006 08:03:00 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752098AbWKANDA (ORCPT ); Wed, 1 Nov 2006 08:03:00 -0500 Received: from pentafluge.infradead.org ([213.146.154.40]:13961 "EHLO pentafluge.infradead.org") by vger.kernel.org with ESMTP id S1752095AbWKANC7 (ORCPT ); Wed, 1 Nov 2006 08:02:59 -0500 Subject: Re: 2.6.19-rc4-mm1: noidlehz problems From: Arjan van de Ven To: Pavel Machek Cc: kernel list , mingo@redhat.com, Andrew Morton In-Reply-To: <20061101122319.GA13056@elf.ucw.cz> References: <20061101122319.GA13056@elf.ucw.cz> Content-Type: text/plain Organization: Intel International BV Date: Wed, 01 Nov 2006 14:02:57 +0100 Message-Id: <1162386177.23744.17.camel@laptopd505.fenrus.org> Mime-Version: 1.0 X-Mailer: Evolution 2.8.0 (2.8.0-7.fc6) Content-Transfer-Encoding: 7bit X-SRS-Rewrite: SMTP reverse-path rewritten from by pentafluge.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2006-11-01 at 13:23 +0100, Pavel Machek wrote: > Hi! > > First, it would be nice if we had someone listed as a maintainer of > noidlehz stuff... > > Then... I'm getting strange messages from noidlehz each time I > unplug/replug AC power (perhaps due to interrupt latency?). there probably is a different story going on. When you unplug/replug AC power, several bioses change the meaning of the software C-states in your system. (there is a mapping between software visible C states and the hardware C-states) 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.... -- if you want to mail me at work (you don't), use arjan (at) linux.intel.com Test the interaction between Linux and your BIOS via http://www.linuxfirmwarekit.org