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8/13/2019 CSC520 Chapter 4 Exercise Solutions
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8/13/2019 CSC520 Chapter 4 Exercise Solutions
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Exercise
Suppose a system uses priority schedulingwhere a small integer means higher priority
Create a Gantt chart to illustrate the execution of
these processes What is the turnaround time for process P2 under
priority scheduling? What is the average waiting time for the
processes?
8/13/2019 CSC520 Chapter 4 Exercise Solutions
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Turnaround time for P2 160 Waiting time
P0 70 P1 0 P2 150 P3 160 P4 20
Average waiting time 400/5 = 80
P1 P4 P2P0 P30 20 70 150 160 180
8/13/2019 CSC520 Chapter 4 Exercise Solutions
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8/13/2019 CSC520 Chapter 4 Exercise Solutions
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8/13/2019 CSC520 Chapter 4 Exercise Solutions
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Exercise
Suppose a system uses SJN scheduling wherea small integer means higher priority
Create a Gantt chart to illustrate the execution of
these processes What is the turnaround time for process P3 under
SJN scheduling? What is the average waiting time for the
processes?
8/13/2019 CSC520 Chapter 4 Exercise Solutions
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P3 Turnaround time 95 55 = 40
Waiting Time P0 0 P1 150 P2 85 P3 20 P4 65
Average waiting time 320/5 = 64
P0 P30 75 95
P2120
P1160
P4205
8/13/2019 CSC520 Chapter 4 Exercise Solutions
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Exercise
Based on the information given below, draw aGantt chart illustrating the execution of eachprocess using the following algorithms
FCFS SJF Priority Scheduling
Calculate the waiting time for Process B and Dfor each of the scheduling algorithm
8/13/2019 CSC520 Chapter 4 Exercise Solutions
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FCFS/SJF PB 9 FCFS/SJF PD 12
Priority PB 14 Priority PD 7
A
0 10
B
12
C
15
D
20
A
0 10
B
12
C
15
D
20
A
0 10
D
15
B
17
C
20
8/13/2019 CSC520 Chapter 4 Exercise Solutions
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Exercise
Based on the information given below, draw aGantt chart illustrating the execution of eachprocess using the priority scheduling
algorithm Calculate the average turnaround time for all
processes
Calculate the average waiting time for allprocesses
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P0 20 P1 45 P2 45 P3 50 P4 60 Average turnaround time 320/5 = 64 P0 0
P1 10 P2 25 P3 35 P4 35 Average waiting time 105/5 = 21
P0
0 20
P1
55
P2
75
P3
90
P4
115
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Exercise
Suppose a system uses RR (q =15) schedulingwhere a small integer means higher priority
Create a Gantt chart to illustrate the execution of these processes
What is the turnaround time for process P2 underRR scheduling?
What is the average waiting time for theprocesses?
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P2 turnaround time = 25 Waiting time
P0 25 + 35 + 20 + 15 + 5 = 100 P1 25 P2 15 P3 30 P4 10 + 20 + 15 + 15 = 60
Average waiting time 230/5 = 46
P0
0 15
P1
30
P2
40
P0
55
P1
60
P3
75
P4
90
P0
105
P3
110
P4
125
P0
140
P4
140 155
P0 P4
170 175 180
P0