For the following processes Show the scheduling sequence and

For the following processes: Show the scheduling sequence and average waiting time with a preemptive Shortest-Job-First scheduling algorithm. Show the scheduling sequence and average waiting time with a non-preemptive Shortest-Job-First scheduling algorithm.

Solution

1. Pre-emptive Shortest Job First

0.0-----------------2.0------------------6.0-----------------8.0-----------------------12.0---------------17.0

Average waiting time = ((12-0)+(4-2)+(6-4)+(8-5))/4 = (12+2+2+3)/4 = 4.75

2. Non Preemptive scheduling

0----------------------7.0-------------------------9.0-----------------------13.0----------------------17.0

Average waiting time = ((0-0)+(7-2)+(8-4)+(12-5))/4 = (0+5+4+7)/4 = 16/4 = 4

P1

P2

P3

P4

P5