RR (Round Robin) scheduling algorithm

In terms of the overall effect of the RR scheduling algorithm, it can be considered as a fair algorithm because all processes are allowed to run for a predefined and equal amount of time, which is repeated until they are completed with the shorter process completing faster than a longer one. When fairness is viewed in terms of jobs that arrive first should be completed first, RR scheduling algorithm tries to be fair by giving that process a share of the time first before proceeding to the next process.

The following are identified as differences between RR and FCFS (First Come First Served)
 In FCFS, tasks are performed and completed in accordance with how the process arrives the CPU while RR takes into account the order in which the processes arrives while at the same time giving each process a time slice so that the current process do not have to be completed before the next one can run.
 When FCFS is undergoing an IO operation, it becomes very inefficient as it does not release the CPU to another process (non-preemptive) while RR is a preemptive scheduling algorithm that frees the CPU to the next process when in the BLOCKED state.
 The average wait time of RR is higher than that of FCFS because RR tends to make all processes to spend an equal amount of time in the system at the expense of an increased average wait time.
 When undergoing only CPU intensive processes, FCFS becomes faster than RR because the context switch time introduced in RR increases the elapsed time.

The following are identified as differences between RR and SJF
 In SJF, tasks are performed and completed in accordance with the shortest time it takes to complete a particular process while RR takes into account the order in which the processes arrives while at the same time giving each process a time slice so that the current process do not have to be completed before the next one can run.
 In SJF, there is a fore knowledge of the runtime of each of the processes which it uses to determine the next process to execute; there is no previous knowledge of the runtime in RR.
 When SJF is undergoing an IO operation, it becomes very inefficient as it does not release the CPU to another process (non-preemptive) while RR is a preemptive scheduling algorithm that frees the CPU to the next process when in the BLOCKED state.
 The average wait time of RR is higher than that of SJF because RR tends to make all processes to spend an equal amount of time in the system at the expense of an increased average wait time.
 When undergoing only CPU intensive processes, SJF becomes faster than RR because the context switch time introduced in RR increases the elapsed time.
 SJF has the potential of starving longer tasks so that they do not get the chance to run if a job with a considerable shorter time is continuously added.