frequency tolerance: 500

[Achim Gratz]

Udo van den Heuvel via devel writes:
> On 31-03-19 12:34, Achim Gratz via devel wrote:
>>> This behaviour is not normal.
>> 
>> Uh, that is reporting from an ntpd that has just started and hasn't
>
> One that starts counting again after being up for a little while.
>
>> collected many statistics.  So the only way it can get a PLL frequency
>> of 186ppm will be if that value is stored in the drift file.  Do you
>> have one (usually found somewhere in /var/lib/ntp/), does it contain a
>> sensible value?
>
> 186 is not sensible.
> When I set it to 0.000 it still goes way up.

As long as the time is that much off, yes it'll do that.

>> If so, this doesn't seem to be a rasPi, what is it?
>
> No, x86_64 with AMD Ryzen.

Does anything in the boot log complain about unstable clock sources and
or switching between different ones?

>> Also, just mumbling about "different behaviour" without showing at
>> least one difference isn#t really going to get you much help.
>
> We either get a pps that is ~250ms off (4.19.30 etc) with ntpd going
> backa nd forth between the gps and remote clocks.

Well, then set the GPS to "noselect" sync the box to some NTP server
that has good time and fix up the time1 (without PPS) and time2 (with
PPS) values.  The time offset reported by ntpq in both cases (w/ and w/o PPS)
should be below the reported jitter and close to zero.

How is the GPS connected and how do you get the PPS in?

> Or we get this absurd PLL frequency. (4.19.23).

Same thing most likely.

> Of course this might just be timing, depending on how soon after bootup,
> at what spot in the PPS cycle ntpd came online.

No.  It's a problem with how you set up your GPS.  It's registers with a
too large offset.

> But I am not yet convinced of that.
> Restarting leads to same results.

Yes, as long as you don't correct the setup it's gonna do the same thing
over and over.  Care to show your ntp.conf next time?


Regards,
Achim.
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