[ntp:questions] Slow convergence of NTP with GPS/PPS
terje.mathisen at hda.hydro.com
Wed Oct 1 12:09:57 UTC 2008
> David Woolley <david at ex.djwhome.demon.co.uk.invalid> writes:
>> My understanding was that -g turns off the 1000 second check for the
>> first step, but still leaves the time within +/- 128ms, which will still
>> take an unacceptable time to converge to +/- 5ms. Certainly the 4.2.4p4
>> documentation makes no claims for it beyond once only disabling the 1000
>> second check.
> 128ms at 500PPM is 250sec or 4 min. It will take longer than that since the
> rate will not peg out, but it should not be hours.
> Maybe it is best to set the clock initiallly so that it is out by by more
> than 128ms (Eg advance it by 10 sec) and then use -g.
Afair the 128 ms is also a 'tinker' configuration parameter, i.e. it
should be possible to reduce it to 10 or 15 ms, at the cost of getting a
few more steps during runtime.
- <Terje.Mathisen at hda.hydro.com>
"almost all programming can be viewed as an exercise in caching"
More information about the questions