I operate chrony 4.2 on Debian 11 in a KVM virtualized system with 4 dedicated CPU cores (KVM host is a AMD EPYC 7452).
Are there any recommended settings for the operating system and/or chrony in such an environment?
To name a few chrony settings, what about filter / minsamples / clockprecision?
The reason for my question is: I’ve noticed that the values in the columns NP and NR of chronys’ sourcestats command conspicuously often fall back to the minimum values (6|3), and they also rarely get high.
There is no special configuration.
Sync your hypervisor with a Reflcock or (Pool)server and on the client do the same. That’s it.
Or you can sync the hypervisor and use a client clock which sync with the hypervisor. IIRC Amazon EC2 is doing likely the same.
It’s my understanding that your NIC doesn’t have a clock, it just stamps network packages in order to minimise the offset.
Also, for it to work, all NIC’s need hardware timestamping else it’s ignored as far as I know.
In order to get accurate time from a refclock, you still need a GPS with PPS.
As for onboard clocks, forget about those, none of them is accurate and they wander all over the place.