Windows Guest ignores CPU topology settings on Lucid host

**karaluh** · January 22nd, 2015

I try to assign 8 host cores to Windows 2003 Server Standard guest. Because this OS version has a limit of 4 sockets, I have to change the CPU topology. My guest definition:

Code:

  <vcpu>8</vcpu>
  <cpu match='minimum'>
    <model>core2duo</model>
    <topology sockets='4' cores='1' threads='2'/>
  </cpu>

doesn't work as expected. I should have 4 CPUs in the Device Manager and 8 CPU charts in Task Manager, but I have the opposite. And no matter what numbers I set in the topology, the guest always detects 8 sockets. What am I doing wrong?

**Doug S** · January 23rd, 2015

If I do the same as you did, I get the same result as you. Note that my host is an Ubuntu 14.04 server.
However, if I do this (and "virsh edit" forces some of this upon exit, so it cann't look exactly like what you did):

Code:

  <vcpu placement='static'>8</vcpu>
  <os>
    <type arch='x86_64' machine='pc-i440fx-1.7'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <pae/>
  </features>
  <cpu mode='custom' match='minimum'>
    <model fallback='allow'>core2duo</model>
    <topology sockets='4' cores='2' threads='2'/>
  </cpu>

Then I get what I think you wanted:

Code:

doug@desk-dev:~$ cat /proc/cpuinfo | grep "core id"
core id         : 0
core id         : 1
core id         : 0
core id         : 1
core id         : 0
core id         : 1
core id         : 0
core id         : 1
doug@desk-dev:~$ cat /proc/cpuinfo | grep "cpu cores"
cpu cores       : 2
cpu cores       : 2
cpu cores       : 2
cpu cores       : 2
cpu cores       : 2
cpu cores       : 2
cpu cores       : 2
cpu cores       : 2
doug@desk-dev:~$ cat /proc/cpuinfo | grep "physical id"
physical id     : 0
physical id     : 0
physical id     : 1
physical id     : 1
physical id     : 2
physical id     : 2
physical id     : 3
physical id     : 3

My guest VM is an Ubuntu 15.04 desktop