Limitations of FCFS Scheduling Algorithm

Q3. What are the limitations of FCFS scheduling algorithm? Explain with the help of above question.

Ans. If we just change the order to P2, then P3, then P1, then

Waiting Time for P1=6

P2=0

P3=3

Average Waiting Time     

=(6+0+3)/3

=9/3

=3 milliseconds

Clearly, the average waiting time under a purely first-in first-out system is going to often be poor if one task is significantly longer than the others.

Gantt Chart:

0                       3                         6                                                                                     30