ROUND ROBIN
R.R.
Basic Theory :
In Round-robin scheduling, each ready task runs turn
by turn only in a cyclic queue for a limited time slice. This
algorithm also offers starvation free execution of processes.
The name of this algorithm comes from the round-robin principle, where each person gets an equal share of something in turns. It is the oldest, simplest scheduling algorithm, which is mostly used for multitasking. One of the most commonly used technique in CPU scheduling as a core. It is preemptive as processes are assigned CPU only for a fixed slice of time at most.
The name of this algorithm comes from the round-robin principle, where each person gets an equal share of something in turns. It is the oldest, simplest scheduling algorithm, which is mostly used for multitasking. One of the most commonly used technique in CPU scheduling as a core. It is preemptive as processes are assigned CPU only for a fixed slice of time at most.
- Assume that initially there are no ready processes, when the first one, A, arrives. It has priority 0 to begin with. Since there are no other accepted processes, A is accepted immediately.
- After a while another process, B, arrives. As long as b / a < 1, B’s priority will eventually catch up to A’s, so it is accepted; now both A and B have the same priority.
- All accepted processes share a common priority (which rises at rate b ); that makes this policy easy to implement i.e any new process’s priority is bound to get accepted at some point. So no process has to experience starvation.
- Even if b / a > 1, A will eventually finish, and then B can be accepted.