[ntp:questions] ntpd on embedded risc

Unruh unruh-spam at physics.ubc.ca
Sun Feb 22 04:18:34 UTC 2009

cnm3332 at gmail.com writes:

>On Feb 20, 10:27=A0pm, Unruh <unruh-s... at physics.ubc.ca> wrote:
>> David Woolley <da... at ex.djwhome.demon.co.uk.invalid> writes:
>> >Unruh wrote:
>> >> Then do not use ntp. Its behaviour is converging to the correct time i=
>> >> very very slow. It is a completely inappropriate tool for the requirem=
>> >> that you have. chrony is much better.
>> >chrony is excluded because it doesn't support locally attached reference
>> >clocks.
>> Agreed. I was so concentrated on the rate question I negected the fact th=
>> he is running a PPS clock.
>> So at present he is stuck. Make sure you have no /etc/ntp/drift file. Use
>> -g, and use the iburst, etc to try to reduce the startup transientx.

>So, I will need to let NTP run for long time, to build correct drift
>file, which might
>help with accuracy and sync time?   So should this be my ntp conf file

It might. If linux configures itself properly. Recent kernels have trouble
with the tsc time interpolation, and get the wrong rate. This causes ntp to
take many hours on each bootup. That may not be a problem for you depending
on your system. Of course your system may have no interpolation at all in
which case you will have very bad time keeping.

>doing this

>server minpoll 4 maxpoll 4
>fudge burst iburst refid NMEA
>server minpoll 4 maxpoll 4 prefer
>fudge burst iburst refid PPS

>Not sure I understand need for -g option though.
>I'm was looking at other computers to try, something
>small and low power, and found this neat little thing:

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