Re: [chrony-users] Multi-PPS+RTC Setup Questions

[Miroslav Lichvar <mlichvar@xxxxxxxxxx>]

On Tue, Sep 29, 2020 at 10:27:51AM -0400, Matt Corallo wrote:
> Relevant selectdata on 4.0 (which seems to be working great) is:

Ok, if you are using the trust option, then there should be an
improvement in 4.0 over 3.5 in that it will allow non-trusted sources
to be selected in more cases.

> Indeed, RTC1 is an external daemon that reads in from an RTC, checks that
> chrony isn't using it as its timesource and then roughly disciplines it
> according to chrony's time, all before feeding samples back into chrony over
> sock. Indeed, the two GPS refclocks are of different model, and do adjust
> slightly differently as their internal RTCs drift, but all within noise, or
> only slightly outside of it (at least once I compensate for them being
> persistently off by 30us, which, uhhh...wtf u-blox?).

Try adding something like "mindelay 0.0001" to both sources.

> With 3.4, I had to add "combinelimit 100" to get chrony to look at both
> refclocks instead of picking one and deciding that the other one was
> persistently off (from the first?) by just enough that it wasn't worth
> looking at (which does seem like a bug?), and its still in my chrony.conf,
> though I haven't tested whether I can remove it with 4.0.

combinelimit should have no impact on the selection of the '*' source,
or which sources are considered to be selectable. It only decides
later after that point in the selection, whether each selectable
should be combined (+) with the '*' source, or not (-).

-- 
Miroslav Lichvar


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