from the RedHat /fedora Cgroups manual:
section 3.2 CPU/cpu.shares I understand the following:

If 2 different cgroups under same sybsystem, BUT only at the same level (tree depth), have the same cpu.shares value then they will receive equal CPU time .
That is: if the 2 cgroups are not under same ancestor then this is not necessarily corrcet

In other words: the CPU resources are divided at each cgroup tree level by relative cpu.shares and the CPU resources are further divided recursivly as one goes down the tree of cgroups

AM I correct ?