linux-kernel - Re: Linux 2.6.29-rc6

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Date:	Tue, 03 Mar 2009 11:53:46 -0800
From:	john stultz <johnstul@...ibm.com>
To:	Jesper Krogh <jesper@...gh.cc>
Cc:	Thomas Gleixner <tglx@...utronix.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Len Brown <len.brown@...el.com>
Subject: Re: Linux 2.6.29-rc6

On Tue, 2009-03-03 at 07:04 +0100, Jesper Krogh wrote:
> john stultz wrote:
> > On Mon, 2009-03-02 at 10:53 +0100, Jesper Krogh wrote:
> >> john stultz wrote:
> >>> Ok, so it seems ntp hasn't really had a chance to settle down, its only
> >>> made a 10ppm adjustment so far. NTPd will stop corrections at ~
> >>> +/-500ppm, so you're not at that bound yet, where things would be really
> >>> broken.
> >>>
> >>> If the affected kernel isn't resetting in the logs anymore, I'd be
> >>> interested in what the new ppm value is.
> >> After 20 hours.. its still resetting.
> >> Mar  2 10:43:24 quad12 ntpd[4416]: synchronized to 10.194.133.12, stratum 4
> >> Mar  2 10:50:37 quad12 ntpd[4416]: time reset -1.103654 s
> > 
> > So what's the "ntpdc -c kerninfo" output now?
> 
> Mar  3 06:41:10 quad12 ntpd[4416]: time reset -0.813957 s
> Mar  3 06:45:20 quad12 ntpd[4416]: synchronized to LOCAL(0), stratum 13
> Mar  3 06:45:36 quad12 ntpd[4416]: synchronized to 10.194.133.12, stratum 4
> Mar  3 06:51:57 quad12 ntpd[4416]: synchronized to 10.194.133.13, stratum 4
> Mar  3 07:00:29 quad12 ntpd[4416]: time reset -0.783390 s
> jk@...d12:~$ ntpdc -c kerninfo
> pll offset:           0 s
> pll frequency:        -28.691 ppm


This is baffling. You've only gone from -34.754ppm to -28.691ppm in over
a day? And you're still not syncing? If the calibration was so bad that
NTP couldn't sync, I'd expect the freq value to hit +/-500ppm before it
gave up. This just doesn't follow my expectations.

Could you provide:
/usr/sbin/ntpdc -c version

Do you see the same behavior if you drop all but one server (including
the local clock: 127.127.1.0)? 

You might also add "minpoll 4 maxpoll 4" to the server line to speed up
testing.

Actually, if you could, I'd be interested if you could send your
ntp.conf 

thanks
-john


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