Guest Dynamic frequency scaling

[dan57]

Hi all - does VirtualBox support Dynamic frequency scaling in a guest computer?

My host does and is currently using it, I am new to all this and unsure of the details as to how VirtualBox does it all. The logic behind my question is that since it creates a 'mirror' of the hardware and gets resources allocated to it by the host can it not apply Dynamic frequency scaling to the resources it is allocated?

I have a feeling this is going to be a big NO but had to ask.

Much obliged for any help!

[mpack]

The VM is not a mirror of the host hardware. It's an entirely separate (though simulated) PC. The hardware being simulated bears no relationship to the host hardware.

I can't think of a reason why VirtualBox should need to know anything about frequency scaling. If the VM application is idle then the host will throttle back, just like it does for every other application you run on that host.

[dan57]

thanks. It is for a Uni project I am working on and I was wondering if I could simulate an environment with frequency scaling.

[BillG]

Incidentally, frequency scaling on the host has caused problems for virtual machines in the past. Early versions of SpeedStep caused unexpected slowdowns in virtual machines because the activity in the vm was not being detected. Because the host was fairly inactive Speedstep would reduce the CPU frequency slowing the vm. The workaround was to run an application on the host to keep it busy and the CPU running full speed.

[mpack]

because the activity in the vm was not being detected.

I'm not sure how that can be true. VirtualBox is just another application running on the host, nothing special really. The host can't be ignorant of how much CPU any app is using, otherwise it couldn't schedule tasks. Old versions of SpeedStep may be badly written and make unwarranted assumptions... but the rest sounds like a PR BS excuse to me!

[BillG]

This was the actual problem.
http://support.microsoft.com/kb/899525