From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758108AbZB0Gry (ORCPT ); Fri, 27 Feb 2009 01:47:54 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756716AbZB0Grl (ORCPT ); Fri, 27 Feb 2009 01:47:41 -0500 Received: from 2605ds1-ynoe.1.fullrate.dk ([90.184.12.24]:50466 "EHLO shrek.krogh.cc" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756325AbZB0Grk (ORCPT ); Fri, 27 Feb 2009 01:47:40 -0500 Message-ID: <49A78C79.304@krogh.cc> Date: Fri, 27 Feb 2009 07:47:21 +0100 From: Jesper Krogh User-Agent: Thunderbird 2.0.0.19 (X11/20090105) MIME-Version: 1.0 To: john stultz CC: Thomas Gleixner , Linus Torvalds , Linux Kernel Mailing List , Len Brown Subject: Re: Linux 2.6.29-rc6 References: <49A6F39F.9040801@krogh.cc> <49A6FEE2.90700@krogh.cc> <1f1b08da0902261319k7a60d80xaafc1101facfd2d9@mail.gmail.com> <49A70B24.6090706@krogh.cc> <1235685269.6811.11.camel@localhost.localdomain> <1235687483.6811.26.camel@localhost.localdomain> In-Reply-To: <1235687483.6811.26.camel@localhost.localdomain> 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 john stultz wrote: > On Thu, 2009-02-26 at 23:06 +0100, Thomas Gleixner wrote: >> On Thu, 26 Feb 2009, john stultz wrote: >>> On Thu, 2009-02-26 at 22:35 +0100, Jesper Krogh wrote: >>>>> Also mind sending the full dmesg for both kernels? >>>> http://krogh.cc/~jesper/dmesg-2.6.29-rc6.txt >>>> http://krogh.cc/~jesper/dmesg-2.6.26.8.txt >>> So one interesting difference: >>> 2.6.26.8: TSC calibrated against PM_TIMER >>> 2.6.29-rc6: Fast TSC calibration using PIT >>> >>> Thomas, any thoughts as to why we might be calibrating off the PIT >>> instead of the PM_TIMER w/ 2.6.29? >> Yup, because we introduced the Fast PIT calibration in 2.6.28. > > Ah. Ok. > >> Is the delta anything NTP might get upset about: >> >> 2.6.26: time.c: Detected 2311.847 MHz processor. >> 2.6.29: Detected 2310.029 MHz processor. > > I wouldn't think so. > > Although, I'm recalling on some systems here right after we deploy them > we'll see something similar to the originally reported ntpd "time reset" > noise for a period of time while ntpd tries to find the right freq. For > some reason, I've noticed, having multiple servers in your ntp.conf > seems to increase NTP's difficulty at picking a time and converging. > > So this may be just the slight calibration change is confusing ntp or it > may be the NTP_INTERVAL_LENGTH change from awhile back which would cause > the drift value to change could be doing the same thing (although I > thought that landed in the 2.6.24 timeframe, but I may be forgetting). > > I'll kick up some of my own testing between these two releases to see if > I can't find something similar. > > Jesper: How long was the box up for when you noticed the ntpd noise? I was booted Feb 25 21:58 .. the first noice from ntp starts here: Feb 25 22:09:53 quad12 ntpd[4901]: synchronized to LOCAL(0), stratum 13 Feb 25 22:09:56 quad12 ntpd[4901]: synchronized to 10.194.133.13, stratum 4 Feb 25 22:14:08 quad12 ntpd[4901]: synchronized to LOCAL(0), stratum 13 Feb 25 22:16:20 quad12 ntpd[4901]: synchronized to 10.194.133.13, stratum 4 Feb 25 22:32:25 quad12 ntpd[4901]: time reset -1.601641 s Feb 25 22:36:18 quad12 ntpd[4901]: synchronized to LOCAL(0), stratum 13 Feb 25 22:36:45 quad12 ntpd[4901]: synchronized to 10.194.133.12, stratum 4 Feb 25 22:51:41 quad12 ntpd[4901]: time reset -0.922993 s Feb 25 22:55:05 quad12 ntpd[4901]: synchronized to LOCAL(0), stratum 13 > Also what's the output of the following under the different kernels: > ntpdc -c peers > ntpdc -c kerninfo Working (clocksource=acpi_pm) 2.6.29-rc6 jk@quad02:~$ ntpdc -c kerninfo pll offset: -0.001577 s pll frequency: -45.787 ppm maximum error: 0.066739 s estimated error: 0.000768 s status: 0001 pll pll time constant: 6 precision: 1e-06 s frequency tolerance: 500 ppm jk@quad02:~$ ntpdc -c peers remote local st poll reach delay offset disp ======================================================================= *hal.nzcorp.net 10.194.132.81 4 64 377 0.00008 0.003752 0.04816 =svn.nzcorp.net 10.194.132.81 4 64 377 0.00009 -0.008724 0.04979 =LOCAL(0) 127.0.0.1 13 64 377 0.00000 0.000000 0.03082 Working (clocksource=tsc) 2.6.26.8 jk@quad03:~$ ntpdc -c kerninfo pll offset: 0.003208 s pll frequency: -25.070 ppm maximum error: 0.833193 s estimated error: 0.002787 s status: 4001 pll pll time constant: 10 precision: 1e-06 s frequency tolerance: 500 ppm jk@quad03:~$ ntpdc -c peers remote local st poll reach delay offset disp ======================================================================= *hal.nzcorp.net 10.194.132.82 4 1024 377 0.00781 0.006788 0.13666 =sal.nzcorp.net 10.194.132.82 4 1024 377 0.00018 -0.000541 0.12175 =LOCAL(0) 127.0.0.1 13 64 377 0.00000 0.000000 0.03041 Non-working (clocksource=tsc) 2.6.29-rc6 jk@quad12:~$ ntpdc -c kerninfo pll offset: 0 s pll frequency: -34.754 ppm maximum error: 0.023514 s estimated error: 0 s status: 0001 pll pll time constant: 6 precision: 1e-06 s frequency tolerance: 500 ppm jk@quad12:~$ ntpdc -c peers remote local st poll reach delay offset disp ======================================================================= =hal.nzcorp.net 10.194.132.91 4 64 17 0.00011 -0.069377 0.96895 =trac.nzcorp.net 10.194.132.91 4 64 17 0.00011 -0.096107 0.96904 *LOCAL(0) 127.0.0.1 13 64 17 0.00000 0.000000 0.96857