Apparently there are some works in progress to change the CGROUPS API in the kernel.

Accordingly to

http://www.freedesktop.org/wiki/Software/systemd/ControlGroupInterface/

they want to allow only 1 process to become a CGROUPS manager.

So systemd is a good candidate.
In this case we have to find a way to use the systemd CGROUPS API in OAR:

 - /etc/oar/job_resource_manager_cgroups.pl
 - oarsh_shell

I have seen only a D-BUS API in systemd (no command line) and I didn't find the way to restrict the used cores (cpuset).

Some docs:

https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/Documentation/cgroups/unified-hierarchy.txt
  
http://lwn.net/Articles/601840/