libvirt users - Sep 2014 - Re: win2k8 guest and (strange) number of cpus task manager sees

hi everybody

a qemu-kvm guest gets 16 cpus and Windows in "Device 
Manager" sees all sixteeen
but "Task Manager" shows only 4, the same "System" 
properties say "(4 processors)"

I'd like to learn a bit about this - is it some sort of 
"resources management" on the libvirt/qemu causing this? And 
what does it do to a guest performance-wise side?

it's on Scientific L 7,
qemu-kvm-1.5.3-60.el7_0.7.x86_64
libvirt-1.1.1-29.el7_0.1.x86_64

regards
P.

Windows has limits on the number of CPUs it can use based on the license 
level you have (Standard, Enterprise, etc).  You need to present the 
CPUs as two physical CPUs with multiple cores to get around this.

On 9/18/2014 5:14 AM, lejeczek wrote:
> hi everybody
>
> a qemu-kvm guest gets 16 cpus and Windows in "Device Manager"
sees all
> sixteeen
> but "Task Manager" shows only 4, the same "System"
properties say "(4
> processors)"
>
> I'd like to learn a bit about this - is it some sort of "resources
> management" on the libvirt/qemu causing this? And what does it do to a
> guest performance-wise side?
>
> it's on Scientific L 7,
> qemu-kvm-1.5.3-60.el7_0.7.x86_64
> libvirt-1.1.1-29.el7_0.1.x86_64
>
> regards
> P.
>
> _______________________________________________
> libvirt-users mailing list
> libvirt-users@redhat.com
> https://www.redhat.com/mailman/listinfo/libvirt-users

well, I've tried new to guest's config:
     <topology sockets='1' cores='16'
threads='1'/>
no change but I have also tried:
     <topology sockets='4' cores='4' threads='1'/>
which gets all sixteen cores to  "Task Manager" performance tab.
This win2008 is also an eval version so maybe why it did that.

I wonder if tampering with socket/cores/threads has any 
impact on guest performance?
thanks.


On 18/09/14 14:59, Brian Rak wrote:
> Windows has limits on the number of CPUs it can use based 
> on the license level you have (Standard, Enterprise, 
> etc).  You need to present the CPUs as two physical CPUs 
> with multiple cores to get around this.
>
> On 9/18/2014 5:14 AM, lejeczek wrote:
>> hi everybody
>>
>> a qemu-kvm guest gets 16 cpus and Windows in "Device 
>> Manager" sees all sixteeen
>> but "Task Manager" shows only 4, the same "System" 
>> properties say "(4 processors)"
>>
>> I'd like to learn a bit about this - is it some sort of 
>> "resources management" on the libvirt/qemu causing this? 
>> And what does it do to a guest performance-wise side?
>>
>> it's on Scientific L 7,
>> qemu-kvm-1.5.3-60.el7_0.7.x86_64
>> libvirt-1.1.1-29.el7_0.1.x86_64
>>
>> regards
>> P.
>>
>> _______________________________________________
>> libvirt-users mailing list
>> libvirt-users@redhat.com
>> https://www.redhat.com/mailman/listinfo/libvirt-users
>
>