Question :

a) Consider table 1.0 below, assume the processes arrived in the order P₁, P₂, P₃, P₄ at time shown and need the indicated burst time (both in milliseconds).

Create a Gantt chart for the preemptive Shortest Job First (SJF) scheduling algorithms below showing when each process will be scheduled, and also determine the average waiting time for each process.

b) Now consider table 2.0 and create the Gantt charts for each of the scheduling algorithms below showing when each process will be scheduled, and also determine the average waiting time for each of them, assuming they arrived in the following order P₁, P₂, P₃, P₄.

i. First-Come-First-Serve (FCFS)
ii. Round Robin with Quantum of 2 milliseconds
iii. Round Robin with time quantum of 6 milliseconds
iv. Round Robin with time quantum of 9 milliseconds

c) Based on the average waiting times you calculated in part (b) above, what can be deduced about the value of the time quantum for the round robin scheduling algorithms?

d) What is the main problem with the FCFS scheme?