title: Cgroups /sys/fs/cgroup is empty on ubuntu
body: <p>I am new to <code>cgroup</code>. I want to use <code>cgroup</code> to bind <code>Qemu</code> to some CPUs. I am working on Ubuntu 12.04.3 with my own compiled kernel <code>3.11.0+</code>.<br/>
  Below is some output of my commands.</p>
  
  <pre><code>root@xiao-laptop:~/tamlok# service cgconfig start
  start: Job failed to start
  root@xiao-laptop:~/tamlok# ls /sys/fs/cgroup/
  root@xiao-laptop:~/tamlok# cat /proc/mounts | grep cgroup
  root@xiao-laptop:~/tamlok# lssubsys --al
  cpuset
  cpu
  cpuacct
  devices
  freezer
  blkio
  perf_event
  </code></pre>
  
  <p><code>/sys/fs/cgroup/</code> being empty really confused me. I don't know what should I do next to achieve my target. It seems that the <code>cgroup</code> is not mounted? So what's wrong with this? If you need any info about my platform to solve it, please let me know.<br/> </p>
  
  <p>Actually I didn't know the whole process to config and use the <code>cgroup</code>. Or you could help me out with this step by step. I am afraid that lacking some necessary configuration before resulted in this problem.
  Thanks very much!</p>