From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965143AbVHPIft (ORCPT ); Tue, 16 Aug 2005 04:35:49 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965144AbVHPIft (ORCPT ); Tue, 16 Aug 2005 04:35:49 -0400 Received: from ZIVLNX17.UNI-MUENSTER.DE ([128.176.188.79]:32465 "EHLO ZIVLNX17.uni-muenster.de") by vger.kernel.org with ESMTP id S965143AbVHPIfs (ORCPT ); Tue, 16 Aug 2005 04:35:48 -0400 From: Borislav Petkov To: john stultz Subject: Re: [PATCH] pmtmr and PRINTK_TIME timings display Date: Tue, 16 Aug 2005 10:35:30 +0200 User-Agent: KMail/1.7.2 Cc: Steven Rostedt , lkml References: <200508041459.43500.petkov@uni-muenster.de> <200508041723.25848.petkov@uni-muenster.de> <1124144326.8630.9.camel@cog.beaverton.ibm.com> In-Reply-To: <1124144326.8630.9.camel@cog.beaverton.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200508161035.31085.petkov@uni-muenster.de> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 16 August 2005 00:18, john stultz wrote: > On Thu, 2005-08-04 at 17:23 +0200, Borislav Petkov wrote: > > I get it. Actually, I wasn't very sure whether this is the right solution > > since my desktop machine uses tsc timer as default while the laptop the > > pmtmr. I also remember that there was a patch a while ago on lkml which > > enabled a modifiable behavior for PRINTK_TIME through a /proc interface > > and kernel boot option but it somehow didn't get accepted. Ok, then, > > since we keep the jiffies solution across arch's, how can I force the > > kernel to use tsc for printk timings so that i can see the deltas between > > the different printk's instead of the jiffies_64 ns value? The Pentium-M > > Centrino on the laptop evidently supports rdtsc as a msr instruction. > > The issue is that there are a number of laptops that do not properly > support cpufreq and additionally newer laptop chips halt their TSC's > when they go into C3 mode. This keeps the TSC from working as a proper > timesource on these systems, and causes the need for alternative > timesources like the ACPI PM timer. This _is_ actually my laptop I'm testing it on and sofar no problem. But as Steven pointed out earlier, one probably needs a different kind of timing information besides delta timings. Besides, can do all the formatting and delta computation already. Thanks & regards, Borislav Petkov.