From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750736AbWFWORe (ORCPT ); Fri, 23 Jun 2006 10:17:34 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750743AbWFWORe (ORCPT ); Fri, 23 Jun 2006 10:17:34 -0400 Received: from shawidc-mo1.cg.shawcable.net ([24.71.223.10]:55610 "EHLO pd2mo3so.prod.shaw.ca") by vger.kernel.org with ESMTP id S1750736AbWFWORd (ORCPT ); Fri, 23 Jun 2006 10:17:33 -0400 Date: Fri, 23 Jun 2006 08:17:24 -0600 From: Robert Hancock Subject: Re: [PATCHSET] Announce: High-res timers, tickless/dyntick and dynamic HZ -V4 In-reply-to: <20060623082609.GB1040@elte.hu> To: Ingo Molnar Cc: Thomas Gleixner , LKML , Andrew Morton , Con Kolivas , Michal Piotrowski Message-id: <449BF7F4.9080408@shaw.ca> MIME-version: 1.0 Content-type: text/plain; charset=ISO-8859-1; format=flowed Content-transfer-encoding: 7bit References: <449B60A9.2000809@shaw.ca> <1151051238.25491.223.camel@localhost.localdomain> <20060623082609.GB1040@elte.hu> User-Agent: Thunderbird 1.5.0.4 (Windows/20060516) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Ingo Molnar wrote: > * 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] Yes, I would say that this case should be handled better, considering this configuration is the default one for Fedora kernels, for one.. -- Robert Hancock Saskatoon, SK, Canada To email, remove "nospam" from hancockr@nospamshaw.ca Home Page: http://www.roberthancock.com/