From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932489AbVLJBVk (ORCPT ); Fri, 9 Dec 2005 20:21:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932507AbVLJBVk (ORCPT ); Fri, 9 Dec 2005 20:21:40 -0500 Received: from smtp3.Stanford.EDU ([171.67.16.138]:48353 "EHLO smtp3.Stanford.EDU") by vger.kernel.org with ESMTP id S932489AbVLJBVj (ORCPT ); Fri, 9 Dec 2005 20:21:39 -0500 Subject: Re: 2.6.14-rt22 (acpi_pm vs tsc vs BIOS) From: Fernando Lopez-Lezcano To: linux-kernel@vger.kernel.org Cc: cc@ccrma.Stanford.EDU, nando@ccrma.Stanford.EDU, Thomas Gleixner , Steven Rostedt , Ingo Molnar , john stultz In-Reply-To: <1134172105.12624.27.camel@cmn3.stanford.edu> References: <1134172105.12624.27.camel@cmn3.stanford.edu> Content-Type: text/plain Date: Fri, 09 Dec 2005 17:21:11 -0800 Message-Id: <1134177671.4811.4.camel@cmn3.stanford.edu> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 (2.2.3-2.fc4) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 2005-12-09 at 15:48 -0800, Fernando Lopez-Lezcano wrote: > Hi all, I'm running 2.6.14-rt22 and just noticed something strange. I > have not installed it in all machines yet, but in some of them (same > hardware as others that seems to work fine) the TSC was selected as the > main clock for the kernel. Remember this is one of the Athlon X2 > machines in which the TCS's drift... > > dmesg shows this: > PM-Timer running at invalid rate: 2172% of normal - aborting. > > and after that the tsc is selected as the timing source. > Time: tsc clocksource has been installed. > > The strange thing is that this is the same hardware as on other > machines. Aha! Yes but no. The BIOS makes a difference. The first BIOS that has support for the X2 processors on this particular motherboard works fine with regards to the acpi_pm clock source, subsequent ones make linux say things like: PM-Timer running at invalid rate: 2159% of normal - aborting. and then tsc is selected as the clock source... > I have to install this kernel on more machines, will report > then... > > This is what's available after the boot: > # cat /sys/devices/system/clocksource/clocksource0/available_clocksource > jiffies tsc pit > > So I selected by hand: > # cat /sys/devices/system/clocksource/clocksource0/current_clocksource > pit > > On the machine that's not selecting tsc the options are: > # cat /sys/devices/system/clocksource/clocksource0/available_clocksource > acpi_pm jiffies tsc pi > (and acpi_pm is selected, of course). > > I think TSC's should never be selected on this hardware and it is known > not to work. -- Fernando