Re: [KVM TSC trapping / migration 2/2] Add TSC KHZ MSR

Alexander Graf
2011-01-06T10:34:43Z

Am 06.01.2011 um 11:10 schrieb Zachary Amsden <zamsden@redhat.com>:

> Use an MSR to allow "soft" migration to hosts which do not support
> TSC trapping. Rather than make this a required element of any
> migration protocol, we allow the TSC rate to be exported as a data
> field (useful in its own right), but we also allow a one time write
> of the MSR during VM creation. The result is that for the common
> use case, no protocol change is required to communicate TSC rate
> to the receiving host.
>
> This allows administrative tools to configure migration policy
> as they see appropriate. Rather than dictate this policy with the
> KVM implementation, we properly allow migration to hosts which both
> do and do not support setting of the TSC rate on the receiving end.
> If it is wished to not support migration to a host which lacks
> support for the TSC rate feature, that can be coordinated externally.

Isn't there a real hw equivalent of such a register? It might make more sense to just implement that then.

Alex

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