Hello, On 03.09.22 13:51, Matthias Petermann wrote:
it took a while - in the meantime I could test the 1000HZ kernel on my system. Unfortunately I had an effect right at the first test, which forced me to roll back the change first. I hope I'll get around to recreating this on a less critical system early in the new week. What happened: the 1000HZ kernel could not activate the ZFS pool for some reason.The zfs module was loaded though, I also built the kernel with exactly the same sources as the "original" one, so I assume for now that the modules are compatible.In the meantime I was able to take the original problem under control with chrony (see post from another user), but the time jumps are enormous so I would like to try the solution with the 1000HZ kernel.
here is a small update to my mail from yesterday.Short review: I had noticed after booting the new kernel with HZ=1000 that my ZPOOL is not available. Consequently I could not test the effect on the VMs. I had managed a medium-term compensation of the deviations with net/chrony, but the corrections are very erratic - the deviations are simply too large with HZ=100.
Today I made another attempt. The workaround for the ZPOOL problem at the moment is not to start ZFS at boot time (zfs=NO in rc.conf) but only after the system is completely booted (doas service zfs onestart; doas zfs mount -a). It almost seems to me that there is a race condition at HZ=1000 that causes ZFS to try to initialize the ZPOOL even though the wedge of the VDEV is not ready. Unfortunately I could not analyze this in detail yet. But I can live with the workaround for the moment, and the good news is that the clocks in the VMs now run exactly to the second. Btw, on my low end NUC I cannot measure a significant increase in power consumption :-)
At this point once again a big thank you to everyone who answered me. Many greetings & have a nice sunday Matthias
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