Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752911AbZCOPow (ORCPT ); Sun, 15 Mar 2009 11:44:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751553AbZCOPom (ORCPT ); Sun, 15 Mar 2009 11:44:42 -0400 Received: from 2605ds1-ynoe.1.fullrate.dk ([90.184.12.24]:43833 "EHLO shrek.krogh.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751238AbZCOPom (ORCPT ); Sun, 15 Mar 2009 11:44:42 -0400 Message-ID: <49BD225C.4070305@krogh.cc> Date: Sun, 15 Mar 2009 16:44:28 +0100 From: Jesper Krogh User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: Linus Torvalds CC: john stultz , Thomas Gleixner , Linux Kernel Mailing List , Len Brown Subject: Re: Linux 2.6.29-rc6 References: <49A6FEE2.90700@krogh.cc> <1f1b08da0902261319k7a60d80xaafc1101facfd2d9@mail.gmail.com> <49A70B24.6090706@krogh.cc> <1235685269.6811.11.camel@localhost.localdomain> <1235687483.6811.26.camel@localhost.localdomain> <49A78C79.304@krogh.cc> <1235766936.7402.5.camel@localhost.localdomain> <49ABACA0.3090300@krogh.cc> <1236029277.7756.0.camel@localhost.localdomain> <49ACC853.8070205@krogh.cc> <1236110026.6068.18.camel@localhost> <49AD90E2.7050209@krogh.cc> <1236118969.6068.87.camel@localhost> <49AE9EA4.2080500@krogh.cc> <49AECA3B.5030503@krogh.cc> <1236193075.3793.63.camel@jstultz-laptop> <1236220759.6863.7.camel@localhost.localdomain> <1236221530.6863.9.camel@localhost.localdomain> <49B57F3D.5030008@krogh.cc> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1923 Lines: 53 Linus Torvalds wrote: > > Jesper, here's a patch that actually tries to take teh TSC error really > into account, and which I suspect will result (on your machine) in failing > the fast PIT calibration. > > It also has a few extra printk's for debugging, and to see just what the > values are on your machine. > > The idea behind the patch is to just keep track of how big the difference > was in TSC values between two successive reads of the PIT timer. We only > really care about the difference when the MSB turns around, and we only > really care about the two end points. The maximum error in TSC estimation > will simply be the sum of the differences at those points (d1 and d2). > > We can then compare the maximum error with the actual TSC differences > between those points, and see if the max error is within 500 ppm. That > _should_ mean that it all works - assuming that the PIT itself is running > at the correct frequency, of course! > > Regardless of whether is succeeds or not, it will print out some debug > messages, which will be interesting to see. [ 0.000000] Fast TSC delta=34227730, error=6223+6219=12442 [ 0.000000] Fast TSC calibration using PIT [ 0.000000] Detected 2312.045 MHz processor. Using "ntpq -c peers" .. the offset steadily grows as time goes. Full dmesg: http://krogh.cc/~jesper/dmesg-linux-2.6.29-rc8-linus1.txt jk@quad11:~$ ntpdc -c kerninfo pll offset: 0.085167 s pll frequency: -18.722 ppm maximum error: 0.137231 s estimated error: 0.008823 s status: 0001 pll pll time constant: 6 precision: 1e-06 s frequency tolerance: 500 ppm -- Jesper -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/