1.
Consider the following set of processes, with the arrival times and the length of the CPUburst times given in milliseconds,
Process
Arrival Time Burst Time
P1
0.0
7
P2
2.0
4
P3
4.0
1
P4
5.0
4
Draw a Gantt chart illustrating the execution of these processes and Calculate the
average waiting time using the following scheduling algorithms
a. SJF non-preemptive
b. SJF preemptive
Soluction
a) SJF (non-preemptive)
P1
0
P2
3
7
8
P4
12
16
Average waiting time = (0 + 6 + 3 + 7)/4 = 4
b) SFJ preemptive
P1
0
P2
2
P3
4
P2
5
P4
7
P1
11
 Average waiting time = (9 + 1 + 0 +2)/4 = 3
2) Consider the following set of processes, with the length of the CPU-burst times
given in milliseconds
Process
Burst Time
P1
53
P2
17
P3
68
P4
24
16
P3
Draw a Gantt chart illustrating the execution of these processes using the round
robbing algorithm with a time quantum = 20
P1
0
P2
2
0
P3
3
7
P4
5
7
P1
7
7
P3
9
7
P4
11
7
P1
12
1
P3
13
4
P3
15
4
16
2
1. 3) Consider the following set of processes, with the arrival times and the length of
the CPU-burst times given in milliseconds, and the priorities given so that smaller
priority number means a higher priority.
Process
------P1
P2
P3
P4
P5
Arrival time
-----------0
2
3
4
6
Burst time
---------10
1
2
1
5
Priority
-------3
1
3
4
2
Draw a Gantt chart illustrating the execution of these processes using a
preemptive priority scheduling. (Use FCFS for equal priority processes)
Calculate a waiting time and a turnaround time for each process, and an average
waiting time and an average turnaround time for the scheduling
Solution will be discussed in the class