FCFS Job Scheduling Algorithm in OS (Operating System)

A process scheduler schedules different process to be assigned to the CPU based on particular scheduling algorithms. In this section we will discuss about FCFS (First come First Server) Scheduling algorithm.

First Come First Serve (FCFS)
In this algorithm jobs are executed on first come, first serve basis. It is a non preemptive, preemptive scheduling algorithm. This algorithm is easy to understand and implement. Its implementation is based on FIFO queue. It is poor in performance as average wait time is high.

Example :
Consider following process and calculate average turnover FCFS algorithm.

= Solution
Gaint Chart

Average Waiting Time = Finished time - Arrival time - Brush time
                                     = (0+25+32)/3
                                     = 19
Average Turnaround Time = Finished time - Arrival time
                                           = (27+34+34)/3
                                           = 31.67