ntpd struggling to keep up - how to fix?

[Xin LI]

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Hi,

On 2010/02/11 11:25, Jeremy Chadwick wrote:
> On Thu, Feb 11, 2010 at 07:06:52PM +0100, Torfinn Ingolfsen wrote:
>> Hi,
>>
>> One of my machines, the fileserver-with-zfs-to-be[1] has trouble
>> keeping correct time. Or rather, ntpd is struggling.
>> In /var/lkog/messages I see this:
>> Feb  7 12:05:54 kg-f2 ntpd[909]: ntpd 4.2.4p5-a (1)
>> Feb  7 12:11:16 kg-f2 ntpd[910]: time reset +1.020413 s
>> Feb  7 12:11:16 kg-f2 ntpd[910]: kernel time sync status change 2001
>> Feb  7 12:26:26 kg-f2 ntpd[910]: time reset +2.277793 s
>> Feb  7 12:41:29 kg-f2 ntpd[910]: time reset +2.260229 s
>> Feb  7 12:57:02 kg-f2 ntpd[910]: time reset +2.332972 s
>> Feb  7 13:21:24 kg-f2 ntpd[910]: time reset +3.659869 s
>> Feb  7 13:37:01 kg-f2 ntpd[910]: time reset +2.343230 s
>> Feb  7 13:52:24 kg-f2 ntpd[910]: time reset +2.310659 s
>> Feb  7 14:07:29 kg-f2 ntpd[910]: time reset +2.265705 s
>> Feb  7 14:23:03 kg-f2 ntpd[910]: time reset +2.335868 s
>> Feb  7 14:39:06 kg-f2 ntpd[910]: time reset +2.411116 s
>> Feb  7 14:54:32 kg-f2 ntpd[910]: time reset +2.318222 s
>> Feb  7 15:09:55 kg-f2 ntpd[910]: time reset +2.308120 s
>> Feb  7 15:25:49 kg-f2 ntpd[910]: time reset +2.388391 s
>> Feb  7 15:40:54 kg-f2 ntpd[910]: time reset +2.265464 s
>> Feb  7 15:55:57 kg-f2 ntpd[910]: time reset +2.257952 s
>> Feb  7 16:11:45 kg-f2 ntpd[910]: time reset +2.373325 s
>>
>> and this goes on an on, forever. At any give time, no matter how long the machine has been up, ntpq ca report this:
>> root at kg-f2# ntpq -p
>>      remote           refid      st t when poll reach   delay   offset  jitter
>> ==============================================================================
>>  kg-omni1.kg4.no 129.240.64.3     3 u   13   64   37    0.162  703.094 444.681
>>
>> Note: all machines on my LAN use my firewall as the ntp server. 
>> The ntp server runs FreeBSD, none of the other machines have any trouble keeping time.
>> My workstation for example:
>> tingo at kg-v2$ ntpq -p
>>      remote           refid      st t when poll reach   delay   offset  jitter
>> ==============================================================================
>> *kg-omni1.kg4.no 129.240.64.3     3 u   44   64  377    0.138    4.018   0.338
>> (my workstatuion also runs FreeBSD 8.0-stable / amd64)
>>
>> The machine runs FreeBSD 8.0-stable / amd64:
>> root at kg-f2# uname -a
>> FreeBSD kg-f2.kg4.no 8.0-STABLE FreeBSD 8.0-STABLE #2: Sun Jan 31 18:39:17 CET 2010     root at kg-f2.kg4.no:/usr/obj/usr/src/sys/GENERIC  amd64
>>
>> So, how can I get the machine to keep time / get ntpd synchronised?
>>
>> References:
>> 1) hw info: http://sites.google.com/site/tingox/ga-ma74gm-s2h
>> 2) FreeBSD info: http://sites.google.com/site/tingox/ga-ma74gm-s2h_freebsd
> 
> Your machine has a rapidly drifting clock, usually an indicator of a
> hardware problem (crystal gone bad is a common one -- seen this at work
> quite a few times), or possibly a bad time counter source chosen by the
> kernel.  Can you please provide the output of:
> 
> sysctl kern.timecounter
> 
> Finally, was this OS installation used on different hardware in the
> past?  Meaning: was the hard disk previously installed on another
> machine?  Why I'm asking: /var/db/ntpd.drift could be from an old
> computer (the previous hardware), and the clock drift rate would be
> different than that of your newer[1] hardware.  If that's the case,
> please stop ntpd, rm /var/db/ntpd.drift, and restart ntpd.  Be aware it
> will take up to 72 hours for the clock drift to be calculated correctly.

I think this looks like the same problem I had with another AMD system,
which may be related to some HPET stuff (I no longer have access to that
system, though :(

Cheers,
- -- 
Xin LI <delphij at delphij.net>	http://www.delphij.net/
FreeBSD - The Power to Serve!	       Live free or die
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