[libvirt] [Question] qemu cpu pinning

Hi, When I run a VM(qemu-0.13) on my host with the latest libvirt, I used following settings. == <domain type='kvm' id='1'> <name>RHEL6</name> <uuid>f7ad6bc3-e82a-1254-efb0-9e1a87d83d88</uuid> <memory>2048000</memory> <currentMemory>2048000</currentMemory> <vcpu cpuset='4-7'>2</vcpu> == I expected all works for this domain will be tied to cpu 4-7. After minites, I checked the VM behavior and it shows == [root@bluextal src]# cat /cgroup/cpuacct/libvirt/qemu/RHEL6/cpuacct.usage_percpu 0 511342 3027636 94237 657712515 257104928 513463748303 252386161 == Hmm, cpu 1,2,3 are used for some purpose. All threads for this qemu may be following. == [root@bluextal src]# cat /cgroup/cpuacct/libvirt/qemu/RHEL6/tasks 25707 25727 25728 25729 == And I found == [root@bluextal src]# grep Cpus /proc/25707/status Cpus_allowed: f0 Cpus_allowed_list: 4-7 [root@bluextal src]# grep Cpus /proc/25727/status Cpus_allowed: ff Cpus_allowed_list: 0-7 [root@bluextal src]# grep Cpus /proc/25728/status Cpus_allowed: f0 Cpus_allowed_list: 4-7 [root@bluextal src]# grep Cpus /proc/25729/status Cpus_allowed: f0 Cpus_allowed_list: 4-7 == Thread 25727 has no limitation. Is this an expected behavior and I need more setting in XML definition ? Thanks, -Kame