[ntp:questions] ntpdate works, but ntpd doesn't (reach = 0)

Martin Burnicki martin.burnicki at meinberg.de
Fri Feb 13 11:55:01 UTC 2009


Danny Mayer wrote:
> Martin Burnicki wrote:
>> Of course synchronization will be better if ntpd reaches an upstream
>> server continuously, but still this is better than no synchronization at
>> all ...
> No it wouldn't. That's a fallacy. ntpd already oversamples. This is all
> in the algorithms but sampling at the same rate provides no benefit and
> it is better off reducing the sampling frequency once it has a stable
> state.

What I meant is not to decrease the polling interval.

I meant to apply corrrections to the system time earlier. If you monitor the
offset in ntpq -p then you can see often it takes very long untio an
initial offset of a few milliseconds is started to be decreased.

>> And surely this results in the question which has been discussed here
>> several times: why does it takes so long for ntpd to adjust an initial
>> tiny offset of a few milliseconds?
> It's easy to overshoot when you have that small of a change.

The problem is not overshooting, it's just that ntpd applies initial
corrections very late.

Martin Burnicki

Meinberg Funkuhren
Bad Pyrmont

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