Kent Tong wrote:
Hi,
I was wondering the kvm live migration function is reliable? I read that if
the TSC is not monotonically increasing, then the guest will hang. How to
prevent this?
KVM transfers the tsc as part of the CPU state so it will continue to
increase monotonically.
However, if you're migrating between two CPUs of different frequency,
the result will be that the TSC frequency will change. This could have
negative effects depends on how much the guest relies on the TSC. The
worst case would be if your guest was Linux and was using TSC as a time
source. You would likely see severe time drift.
A PV clock source (like KVM_CLOCK) helps this quite a bit.
Regards,
Anthony Liguori
Thanks!
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