libvirt users - Jul 2014 - changing the priority of a process in the container is not permitted

Dear all,

I want to run a process in a container with a real-time (RT) priority. When the
sched_setscheduler(0, SCHED_RR, &sparam) is called in the container, an
error is reported which is "operation not permitted"
I had added the following line in the file /etc/security/limits.conf for both
the host and the container, which means allowing all users to change the
priority of the process, but it still doesn't work.
*     -        rtprio 100
I wonder how to change the privilege of a container so that it has the similar
privilege of the root user of the host.

Thank you in advance
Cheng