From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932939AbWFWIbL (ORCPT ); Fri, 23 Jun 2006 04:31:11 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932941AbWFWIbL (ORCPT ); Fri, 23 Jun 2006 04:31:11 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:30647 "EHLO mx2.mail.elte.hu") by vger.kernel.org with ESMTP id S932939AbWFWIbJ (ORCPT ); Fri, 23 Jun 2006 04:31:09 -0400 Date: Fri, 23 Jun 2006 10:26:09 +0200 From: Ingo Molnar To: Thomas Gleixner Cc: Robert Hancock , LKML , Andrew Morton , Con Kolivas , Michal Piotrowski Subject: Re: [PATCHSET] Announce: High-res timers, tickless/dyntick and dynamic HZ -V4 Message-ID: <20060623082609.GB1040@elte.hu> References: <449B60A9.2000809@shaw.ca> <1151051238.25491.223.camel@localhost.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1151051238.25491.223.camel@localhost.localdomain> User-Agent: Mutt/1.4.2.1i X-ELTE-SpamScore: -3.1 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-3.1 required=5.9 tests=ALL_TRUSTED,AWL,BAYES_50 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts 0.0 BAYES_50 BODY: Bayesian spam probability is 40 to 60% [score: 0.5000] 0.2 AWL AWL: From: address is in the auto white-list X-ELTE-VirusStatus: clean Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * Thomas Gleixner wrote: > > Disabling NO_HZ and high resolution timers due to timer broadcasting > > > > Not sure exactly what this is indicating or what's triggered this, but > > I'm assuming the patch isn't doing much on this machine? > > The system is configured for SMP, but this is an UP machine and the > APIC is disabled in the BIOS. Linux uses then the PIT and an IPI > mechanism to broadcast timer events. We need to do the event > reprogramming per CPU, so we switch off in that situation. hm, we should update the message to be less cryptic. Something like: 'Disabling NO_HZ and high resolution timers due to no APIC' and in this particular case we should also finetune the condition a bit and make it conditional on the number of CPUs. I.e. if someone boots an SMP kernel on a UP box we should still allow the PIT. (there wont be any broadcasting done) [the only exception would be if CONFIG_HOTPLUG_CPU is specified - in that case we cannot be sure whether a new CPU will be plugged in or not] Ingo