qemu-system-x86 eat 400% CPU

[Frantisek Hanzlik]

James Hogarth wrote:
> On 25 November 2013 04:20, Frantisek Hanzlik <franta at hanzlici.cz> wrote:
> 
>> On Fedora 19/x86_64, Xeon 4cores/8threads, 8GB RAM I have in a VM
>> installed windows 2000 (full qemu cmdline see below). What is weird,
>> 'top' on host show that all 4 threads load CPU at 100% each. On guest
>> are running only minimum processes and windows task manager show load
>> 0-2%; virtual machine is almost idle. VM itself seems react well, its
>> responses are fine.
>>
> 
> I've seen this behaviour before on Windows guests with incorrect HAL
> (non-ACPI) causing the guests to basically busy spin on the CPUs ...
> 
> I had to rebuild the box with an appropriate HAL to get it to behave
> sanely...
> 
> Incidentally your performance in that guest will always be fairly poor due
> to a lack of virtio drivers and windows 2000 has been out of support for a
> few years now ... you really should not be using it in general...

James, thank You for turning me to right direction - You was right,
there was ACPI/HAL problem. I solved it according to MS KB 919521 by
editing system registry (this will change w2k's HAL to use the PMTimer
instead of the ACPI timer). Host CPU load is then minimal.

It's a shame that KVM it lacks virtio drivers support for w2k. But for my
needs it isn't too big issue, I want it just for some termporary testing.

Thanks again, Franta Hanzlik