What is the Round Robin Scheduling algorithm in operating systems? Explain with an example.
Explain the Round Robin Scheduling algorithm with an example in OS.
Ask by Revati S Misra
Updated 31 Mar 2023
The Round Robin (RR) scheduling algorithm is a preemptive scheduling algorithm used by the operating system to allocate CPU time to processes. In this algorithm, each process is assigned a time slice or quantum, and the CPU is allocated to each process for a fixed time slice, regardless of whether the process has completed its execution or not.
Let's take an example to understand this algorithm:
Suppose there are three processes, P1, P2, and P3, that require CPU time to execute. The time quantum is 4 units. The arrival time and burst time for each process are as follows:
The RR algorithm assigns the CPU time to the processes in a cyclic order, giving each process a time slice of 4 units of time. Therefore, the CPU time is first assigned to P1, then P2, and P3, and the cycle repeats until all processes are completed. If a process has completed its execution within the time slice, the CPU is allocated to the next process in the queue.
The Gantt chart for the execution of the processes using the RR algorithm is as follows:
As you can see from the Gantt chart, each process is assigned a time slice of 4 units of time. P1 is assigned the CPU time first and executes for 4 units of time. Then, the CPU time is allocated to P2, which executes for 2 units of time and finishes its execution. P3 is allocated the CPU time next and executes for 4 units of time. The cycle then repeats until all the processes are completed.
The RR algorithm provides fairness among processes and ensures that no process is starved for CPU time for a long time. However, it may cause overhead due to frequent context switching, which can affect the system's performance.