[Qemu-devel] [Bug 654913] Re: Windows XP uses 200% CPU when given 2 VCPUs

[.:. brainsik]

It turns out, that if you use the ACPI Multiprocessor, this problem goes
away. If you use MPS Multiprocessor, then this problem occurs. The worst
part is if you originally built the VM without ACPI, then there is *no
way* to use on the ACPI HALs in Windows XP without reinstalling. There's
a ton of MS knowledge base articles about this.

-- 
Windows XP uses 200% CPU when given 2 VCPUs
https://bugs.launchpad.net/bugs/654913
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Status in QEMU: New

Bug description:
When using libvirt to give a domain 2 CPUs (<domain 
type='kvm'><vcpu>2</vcpu></domain>), the Windows XP kvm process will use 200% 
CPU when Windows is idle. Switching the number of CPUs back to 1, the kvm 
process gives normal idle percentages.

Using libvirt 0.8.3-1ubuntu9, tried with the following qemu-kvm packages:

qemu-kvm_0.12.4+noroms-0ubuntu7_amd64.deb
qemu-kvm_0.12.5+noroms-0ubuntu4_amd64.deb

The smp flag being set by libvirt is:

-smp 2,sockets=2,cores=1,threads=1