Re: [chrony-users] Comparing timekeeping performance with chronyd to ntpd

[Bill Unruh <unruh@xxxxxxxxxxxxxx>]

Ah, I had thought it was a comparison also of ntp/chrony. You have done those
comparisons as well I believe.

The question is how much smaller. And do you have any idea how much of the
jitter comes from the software reading the system clock, and how much is
external jitter?


William G. Unruh __| Canadian Institute for|____ Tel: +1(604)822-3273
Physics&Astronomy _|___ Advanced Research _|____ Fax: +1(604)822-5324
UBC, Vancouver,BC _|_ Program in Cosmology |____ unruh@xxxxxxxxxxxxxx
Canada V6T 1Z1 ____|____ and Gravity ______|_ www.theory.physics.ubc.ca/

On Fri, 3 May 2019, Miroslav Lichvar wrote:

> On Thu, May 02, 2019 at 11:01:28AM -0700, Bill Unruh wrote:
> > > > Here are some measurements I did with a RPI and other hardware:
> > > >
> > > > https://fedorapeople.org/~mlichvar/ntpserver/
> >
> > There does not seem to be any indication on this page of which of the
> > situation were chrony and which an ntp implimentation.
>
> There were no tests with ntpd. It was more about testing the
> hardware, drivers and timestamping. With the PPS refclock and
> server using user/kernel timestamps in the basic mode, I'd expect the
> difference in clock control between chronyd and ntpd to be smaller
> than the timestamping jitter.
>
> --
> Miroslav Lichvar
>
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