Re: Linux 2.6.29-rc6

[Jesper Krogh <jesper@krogh.cc>]

john stultz wrote:
> 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@quad12:~$ 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.

It's resetting.. without deep knowledge about ntp, doesnt that mean 
"start over again"? I believe it hits +/-500ppm

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

$ ntpdc -c version
ntpdc 4.2.4p4@1.1520-o Tue Jan  6 15:51:00 UTC 2009 (1)

> 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.

Will try those option while debugging.

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

http://krogh.cc/~jesper/ntp.conf

But this seems to be a "regression". Since 2.6.27.19 doesn't misbehave. 
Same NTP, same configuration, same hardware. only change is the kernel 
version. Or am I missing some parameter here?

Would it make sense to try to bisect it?

Jesper

-- 
Jesper