Round Robin (RR)

• Each process gets a small unit of CPU time (time quantum), usually 10-100 milliseconds.  After this time has elapsed, the process is preempted and added to the end of the ready queue.
• If there are n processes in the ready queue and the time quantum is q, then each process gets 1/n of the CPU time in chunks of at most q time units at once.  No process waits more than (n-1)q time units.
• Performance

1. q large Þ FIFO
2. q small Þ q must be large with respect to context switch, otherwise overhead is too high.