Allence
2018-May-18 02:08 UTC
[libvirt-users] Guest's CPU frequency cannot be similar to host system
My resource:
kernel: 4.16.8
host system: Ubuntu 16.04
Llbvirt : 4.2
Qemu : 2.12
Cpu : intel@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?
And here is my guest xml:
<cpu mode='host-passthrough' check='none'>
<topology sockets='1' cores='8' threads='1'/>
</cpu>
Daniel P. Berrangé
2018-May-18 07:52 UTC
Re: [libvirt-users] Guest's CPU frequency cannot be similar to host system
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@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 -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|
Allence
2018-May-18 08:21 UTC
Re: [libvirt-users] Guest's CPU frequency cannot be similar to host system
Well, Thanks. This does not seem to effect my performance on the Guest, Maybe future version will be support Turbo Boost. At 2018-05-18 15:52:01, "Daniel P. Berrangé" <berrange@redhat.com> wrote:>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@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 >-- >|: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| >|: https://libvirt.org -o- https://fstop138.berrange.com :| >|: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|