Consider a pre-emptive priority processor scheduler. There are three processes P1, P2, and P3 in the job mix that have the following characteristics:

Process	Arrival Time	Priority	Activity
P1	0 sec	1	8 sec CPU burst followed by 4 sec I/O burst followed by 6 sec CPU burst and quit
P2	2 sec	3	64 sec CPU burst and quit
P3	4 sec	2	2 sec CPU burst followed by 2 sec I/O burst followed by 2 sec CPU burst followed by 2 sec I/O burst followed by 2 sec CPU burst followed by 2 sec I/O burst followed by 2 sec CPU burst and quit

Diagram showing process execution:

1) What is the turnaround time for each of P1, P2, and P3?

Solution:

2) What is the average waiting time for this job mix?

Solution:

CPU P1 I/O Time 64 P3 Pl P3 P1 P3 P1 P3 Pl 2 2 2 2 2 2 2 6 P3 P3 P3 P1 2 2 2 2 2