RE: [chrony-dev] [GIT] chrony/chrony.git branch, master, updated. 2.1.1-89-g3cd32ed

[Adri Koppes <adrik@xxxxxxxxxxxxxxx>]

> > If the clock is too far behind or ahead, doesn't chrony already step the
> clock?
> 
> Not by default. You need to specify the threshold and the number of
> updates in which are allowed steps with the makestep directive in
> chrony.conf. Or you can do that manually with the makestep command from
> chronyc.

I use initstepslew instead of makestep, but I guess the result would be the same.

> > I remember having chronyd running, using adjtime() to try to slew the clock
> or adjust the frequency, but failing to do so.
> > I discovered when a previous instance of ntpd has set the kernel frequency
> and phase offset, it did get reset when ntpd was terminated.
> > The kernel discipline then seemed to be trying to adjust the clock, while
> chronyd was trying to do the same using adjtime().
> > After resetting the kernel discipline manually, chronyd finally seemed to be
> able to adjust the clock properly.
> > This was a long time ago and currently I always reset the kernel discipline in
> the startup script, before starting chronyd.
> 
> Hm, interesting. How long did you wait? A fixed frequency offset shouldn't
> be a problem for adjtime(). Maybe the PLL was still adjusting a larger offset
> with longer time constant and it would need couple hours to settle down. Or
> the frequency offset was set in the opposite direction and adjtime() had to
> overcome a larger drift.

I think ntpd leaves both frequency offset AND the PPL/FLL running.
So you might be right about the PLL trying to adjust the offset and frequency, competing with chrony's adjtime().

> > I am currently running the latest release version 2.1.1 on real HW in
> production.
> > If the latest code from git is fairly stable, I can install it and try for a while.
> > Currently I am running FreeBSD 10.2p3 amd64.
> 
> I try to keep the code in git always compilable and working, so bisecting
> works, etc. If the new drivers work well, I think the current code is almost
> ready for a new prerelease.

I just switched to the latest release and keep an eye on how it's performing.

Adri.


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