After recent updates to the kernel and reboot of a ClearOS machine, I noticed the following filling /var/log/messages like crazy:

Feb 17 04:34:07 mgtserver kernel: Clocksource tsc unstable (delta = 333297569 ns).  Enable clocksource failover by adding clocksource_failover kernel parameter

Feb 17 04:34:07 mgtserver kernel: Clocksource tsc unstable (delta = 333235032 ns).  Enable clocksource failover by adding clocksource_failover kernel parameter.

Feb 17 04:34:08 mgtserver kernel: Clocksource tsc unstable (delta = 333321526 ns).  Enable clocksource failover by adding clocksource_failover kernel parameter.

Feb 17 04:34:08 mgtserver kernel: Clocksource tsc unstable (delta = 334601362 ns).  Enable clocksource failover by adding clocksource_failover kernel parameter

Yes, twice per second!

echo kvm-clock > /sys/devices/system/clocksource/clocksource0/current_clocksource

should have solved that, but didn't. Maybe deactivating ntp could have been a solution, but since it was maintainance time anyway, I applied the kernel parameter to grub and rebooted. This solved the problem. The question is, will this remain effective after the enxt kernel update?

Just wanted to drop that here, since others might run into the same issue.

See this for more information: https://blog.johncheng.com/?p=2203