[libvirt-users] How do you set real time bandwidth for a container?

When I create a VM using libvirt, the VM comes up the path /sys/fs/cgroup/cpu/cpu.rt_runtime_us set to something like 1000000. When I create a container however, the path /sys/fs/cgroup/cpu/cpu.rt_runtime_us is 0. This prevents my containers from being able to run any real time applications. I have to explicitly echo a value into this field in order to give the container some real time bandwidth and allow it to run real time processes. Is it possible to define this in a container's XML config? Or is there another method I should be using to enable real time capability in a container? Peter