| Re: [chrony-users] refclock local |
[ Thread Index |
Date Index
| More chrony.tuxfamily.org/chrony-users Archives
]
On Tue, Aug 08, 2023 at 14:33:10 +0200, Miroslav Lichvar wrote:
> On Tue, Aug 08, 2023 at 08:15:35AM -0400, Josef 'Jeff' Sipek wrote:
> > I understood this to mean:
> >
> > 1. some of the sanity check are skipped (e.g., checking phase alignment
> > with other sources)
> > 2. the source will be used for *frequency* calculations
> > 3. the source will not be used for *phase* calculations
> >
> > So, based on these, I expected chrony to report some random but very stable
> > offset but still make (partial) use of the clock.
> >
> > Is my understanding wrong?
>
> I think it's good.
Ok, good :)
> The chronyc reports in your original post are as expected.
>
> The reported phase offset is expected to drift slowly between -1 and 1
> seconds with occasional jumps when the maximum is reached.
Out of curiosity, why is the range (-1,+1) instead of [-0.5,+0.5]? I caught
me off guard when I restarted chrony and the PPS "jumped" from +400 to
-600ms.
> The most useful report would be sourcestats.
sourcestats from same time I captured the sources output yesterday evening:
Name/IP Address NP NR Span Frequency Freq Skew Offset Std Dev
==============================================================================
PPS0 64 54 1010 +0.491 0.305 -590ms 201us
kerberos.mit.edu 29 17 98m +0.035 0.083 +20us 200us
time.cloudflare.com 8 7 51m +0.016 0.238 +14us 115us
....
> If the stabilization
> works well, the skew of other sources should become smaller and they
> should use more samples (NP).
Noted. I restarted chrony this morning with the PPS configured but no
signal going in, then after ~4 hours (which I assume is enough for the
system to stabilize), I turned on the PPS signal. I'm going to give it a
few more hours and then look at the logs to see how the frequency skew of
the sources changed throughout the day - and especially after I enabled the
PPS signal.
> With a refclock on USB (which adds a lot
> of jitter) I'd not expect it to perform very well. You can try longer
> polling intervals and more filtering.
My desktop doesn't have a real serial port and that's why I used a USB
adapter. This is purely an experiment to make sure I understand how things
work before I make a simple circuit around an OCXO and connect it to a real
serial port on my server.
Thanks,
Jeff.
--
To unsubscribe email chrony-users-request@xxxxxxxxxxxxxxxxxxxx
with "unsubscribe" in the subject.
For help email chrony-users-request@xxxxxxxxxxxxxxxxxxxx
with "help" in the subject.
Trouble? Email listmaster@xxxxxxxxxxxxxxxxxxxx.