[ntp:questions] Re: ntpd going wild

Johan Swenker no_spam_please at swenker.xs4all.nl
Tue Feb 14 22:35:10 UTC 2006

On Tue, 14 Feb 2006 16:13:12 +0100, Hermann Hastig wrote:

> Hi,
> could anybody explain what caused the following messages from my ntpd
> around February 1?
[lots of random time reset removed]
> Feb  1 12:46:24 [ntpd] time reset -1.731346 s
> Feb  1 12:46:24 [ntpd] frequency error 512 PPM exceeds tolerance 500 PPM

Last summer something similar happened to me. but it strongly depended on
my configuration. So please tell us about your configuration (like
operating system etc.)

My situation was:
- linux 2.4 kernel with PPS and NANO patches
- debian distribution with adjtimex in init.d

adjtimex uses a system call which has been redefined. The current
definition sets some bits in the kernel. These bits tell the ntp-daemon
that it should not discipline kernel time (with the assumption that
another proces desciplines the kernel).

Symptom: when the GPS-clock lost signal, the kernel time was not
disciplined anymore and ntpd had a hard time adjusting the clock with

Solution: get rid of adjtimex

Thus: my symptom is similar to your symptom. As I don't have enough
information on your configuration, I cannot tell whether my solution would
help you as well.

> Even though I have set maxpoll to 16 in order to cause as few traffic as
> possible to the pool.ntp.org servers I'm a bit surprised that ntpd had
> _that_ much problems to keep the clock stable late January 31.
> So, what might have caused this, and is it my fault or the three
> upstream servers'?
> I don't see why ntpd completely lost control with a setting that worked
> flawlessly 24/7 for a year, on the other hand I can't believe that all
> of the three configured servers had different times the same day. I
> mean, one, ok, but all three?
> Thanks, Hermann

Regards, Johan Swenker

More information about the questions mailing list