Measuring clock drift results

Hi all,

Thank you for suggesting we use /sys/class/pps/pps1/assert to measure the
clock. Attached are graphs from running both chronyd and ntpd overnight.
The images are also online:

https://ibb.co/album/5YxH2m

Chrony clearly improves the offsets to sub-20 microseconds much of the
time. We're seeing some spikes in the timing, though, that exceed ntpd.*
The chrony configuration file is the same as in the other thread (
https://www.mail-archive.com/[email protected]/msg03281.html).
We can't use the GPIO polling driver until I have a clear yes/no answer on
the licensing issue.

Other processes may be affected by changing the CPU, so we haven't switched
to a constant frequency nor disabled the power saving states (e.g.
idle=poll).

Are there any other ways we could help chronyd stay below 20 microseconds
(e.g., optimized build)?

Many thanks!

*ntpd had a single 1500+ us outlier, which we removed.