[libvirt-users] libvirt_lxc heavy cpu usage ?

I am running lxc via libvirt1.1.1, the cpu usage is heavy of process libvirt_lxc. PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 2384 root 20 0 10480 2048 1200 R 99.6 0.1 1291:39 libvirt_lxc 32157 root 20 0 10448 2032 1200 R 99.3 0.1 1316:02 libvirt_lxc 28228 root 20 0 10448 2064 1216 R 99.0 0.1 5663:43 libvirt_lxc 30461 root 20 0 10480 2048 1200 R 98.7 0.1 5663:15 libvirt_lxc btw: 0.9.3 is the same ,I googled it , only two reports . any suggestions ? thx