The default Linux scheduling configuration divides CPU time on a per process basis. If a system accepts multiple interactive users, that is not the desired situation since a user that is running many processes will have a larger CPU share than the others. […] Once up on a time there was a kernel option called FAIR_USER_SCHED that divided the CPU time slices on a per user basis. […] Eventually it got removed because its existence meant a lot of code to maintain. As a result, each google search about “fair share user scheduling” brings now up old discussion threads and college homework assignments. But as this option was removed a hot replacement called cgroups was ready to rock… well, sort of….