Linux : Clocksource tsc unstable

By | April 26, 2014

Getting this output on your RHEL/CentOS virtual machine?

Clocksource tsc unstable (delta = 000000000 ns). Enable clocksource failover by
adding clocksource_failover kernel parameter.

First find out the available clock sources :

cat /sys/devices/system/clocksource/clocksource0/available_clocksource

You will likely get the following results :

kvm-clock tsc acpi_pm

You are currently using “tsc” as per the initial output error, try using “acpi_pm” first, if you are under a KVM environment, you can try out “kvm-clock”.

Edit Grub configuration :

/boot/grub/grub.conf

And append this to the kernel parameters :

clocksource_failover=acpi_pm