[libvirt-users] Guest's CPU frequency cannot be similar to host system

[Daniel P. Berrangé]

On Fri, May 18, 2018 at 10:08:38AM +0800, Allence wrote:
> My resource:
>       kernel: 4.16.8
>       host system: Ubuntu 16.04
>       Llbvirt : 4.2
>       Qemu : 2.12
>       Cpu : intel at core i7 6700
>       guest system: windows7 professional 
> 
> 
> My problem:
>       In my host, Cpu frequency is 3800~3900 MHz(4 socket and 2 thread)
> because i turn on “Intel Turbo Boost”. And silent frequency is 3.40 GHz.
> Then i boot my guest, But in Guest my cpu frequency is 3408 MHz. why it's
> not 3800 MHz?

The host OS is in charge of CPU frequency scaling operation. The guest does
not see this ability, so has to be given a fixed CPU frequency. None the
less the guest CPUs will have their frequency changed dynamically by the
host OS as loading requires. The guest simply cannot see when these changes
happen.

Regards,
Daniel
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