I noticed today that /proc/sys/xen/independent_wallclock is set to 0 indicating that the domU uses the hypervisor's clock. As I understand it, this means that Xen will keep my domU within /proc/sys/xen/permitted_clock_jitter milliseconds of the hypervisor clock. I also noticed that permitted_clock_jitter is set to 10000000ms which is 2+ hours.

Is the value of permitted_clock_jitter controlled by the domU config? If so, is their a reason Linode has chosen to set this value so high? Is there any harm to setting this to something more reasonable like 1-5 minutes?

Also I assume that dom0 on each server is running ntp to keep the hypervisor clock in sync?

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Chet Burgess

Anyone know the answer to this one?

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Chet Burgess

I think your calculations are a bit off. A bit of googling reveals this number to be in nanoseconds (10 000 000 nanoseconds = 10 milliseconds).