[libvirt-users] How to achieve higher priority of a process in a lxc on CentOS machine

Dear all, I use libvirt lxc to host a real-time application with priority of -50. The native OS is fedora21 and lxc is also fedora21. Everything works fine. Linux "top" command shows the priority is -50). Then I use Openstack to manage lxc. The native compute node OS is CentOS7.2. and the lxc is fedora. After the real-time application is started in the lxc. top command on the native machine sees the real-time application with priority of 20, which is not what I expect. If lxc is Ubuntu, the priority of real-time application is also 20. Can anybody help me on this? Cheng Wang