F 7 qemu-kvm (virtual machine manager) windows XP cpu utilization

[russellr]

Hi,

I have Windows XP installed using Fedora 7's Virtual Machine Manager with qemu-kvm.

It works great, except that the CPU us fully utilized even when Windows is idle.

Various searches have come up with these solutions....

I've set the video hardware acceleration to none.

I've ensured that -no-acpi is specified at startup and that the Computer is set to "Standard PC" in Windows.

I've even ensured that "-usb" is *not* specified on startup.

Nothing seems to make any difference to the cpu utilization.

BTW, if I start qemu-kvm on the command line, CPU goes right down. But, I have no idea how to get to the Windows system to see what's actually happening. But it makes me think the problem is with virt-manager.

Any advice appreciated.

regards,
RR

[Crito]

Only times I've had this problem solution was to disable the kernel/hardware acceleration. It's that first checkbox in virt-manager wizard right below where you pick the architecture (i686, PowerPC, etc..). Sometimes you can re-enable it after setup is complete (like when installing OpenSuSE), other times not -- for some reason the web edition of Windows Server 2003 won't run with acceleration enabled but the standard edition works just fine... I have no clue why.

[russellr]

Hi,

Thanks for your reply.

Indeed, if I change the Virtual Machine to use "qemu" instead of "qemu-kvm", it stops using lots of CPU.

But it also runs slower.

There's not much point to hardware acceleration (what KVM provides) if it unnecessarily overloads the host hardware.

I consider this a bug, and I've reported it in bugzilla.redhat.com.

regards,
RR

[Crito]

oops... editing the XML file didn't work like I previously said. Deleted post so as not to mislead anyone.

[Crito]

Also FWIW, I usually have gkrellm running and noticed that when the bug occurs it always shows up as system time (orange). Whereas if I do something in the VM that pegs the CPU it always shows up as user time (light blue). Maybe a clue someone can use.

EDIT: I'm using the default gkrellm theme... I'm sure others probably use different colors.