Question

The following processes are being scheduled using a preemptive,
priority-based, round-robin scheduling algorithm.
Process
Priority
Burst
Arrival
P
1
8 15 0
P
2
3 20 0
P
3
4 20 20
P
4
4 20 25
P
5
5 545
P
6
5 15 55
Each process is assigned a numerical priority, with a higher number indicating a higher relative priority. The scheduler will execute the highestpriority process. For processes with the same priority, a round-robin
scheduler will be used with a time quantum of 10 units. If a process is
preempted by a higher-priority process, the preempted process is placed
at the end of the queue.
a. Show the scheduling order of the processes using a Gantt chart.
b. What is the turnaround time for each process?
c. What is the waiting time for each process?

Answer 1

Process	Burst Time	Arrival Time	Priority
1	15	0	8
2	20	0	3
3	20	20	4
4	20	25	4
5	54	5	5
6	15	55	5

GANTT CHART :

P1

P1

P5

P5

P5

P5

P5

P5

P6

P6

P3

P3

P4

P4

P2

P2

0 10 15 25 35 45 55 65 69 79 84 94 104 114 124 134 144

NOTE : WATITING TIME (WT), TURN AROUND TIME(TAT)

WT(P1) = 0

WT(P2) = 124

WT(P3) = 84 - 20 = 64

WT(P4) = 104 - 25 = 79

WT(P5) = 15 - 5 = 10

WT(P6) = 69 - 55 = 14

TAT(P1) = 0 + 15 =15

TAT(P2) = 124 + 20 = 144

TAT(P3) = 64 + 20 = 84

TAT(P4) = 79 + 20 = 99

TAT(P5) = 10 + 54 = 67

TAT(P6) = 14 + 15 = 29