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Re: [libvirt] Is it possible to use more then 2 CPUs in the guest?



On Thu, Aug 06, 2009 at 12:59:19PM +0100, Tom Hughes wrote:
> On 06/08/09 12:36, Daniel P. Berrange wrote:
> >On Wed, Aug 05, 2009 at 10:11:07AM +0200, Mirko Raasch wrote:
> >
> >>in my server i use an Intel Quad Core CPU and i want to use in one
> >>WindowsXP guest all 4 cores.
> >>The device manager shows four CPU (Qemu Virtual CPU version 0.10.5).
> >>When i start prime95 or superpi, only 2 of them are in use. CPU-Z shows
> >>also 2 Cores, instead of 4 like the device manager.
> >
> >I don't know what those apps are, but they sound broken to me. If the
> >guest has been launched with 4 virtual CPus, the guest OS should be
> >able to use them, regardless of what your host core/socket/thread cpu
> >topology is. KVM/QEMU allow upto 16  virtual CPUs IIRC, and this is
> >totally independant of how many physical CPUs you have.
> 
> As other people have already said, it's a Windows licensing thing where 
> some versions of Windows are designed to only work on a limited number 
> of physical CPU packages. So they will run 4-way on a quad core but not 
> on four single core CPUs.

Oh I see what you mean, that really sucks horribly. There's no real 
workaround for that kind of problem at this time I'm afraid, other
than to not use that version of Windows ;-)

Daniel
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