SJF(SHORTEST JOB FIRST) premptive and non-premptive question

Here are 30 questions on SJF(SHORTEST JOB FIRST) process scheduling algorithms (premptive AND non-premptive). Each question is presented in a table format, followed by the solution with Gantt charts, average turnaround time (TAT), and average waiting time (WT).

Question 1:

find the average Turn Around Time and Waiting Time of following processes using Non-Preemptive SJF(SHORTEST JOB FIRST) process scheduling algorithm?

Process Arrival Time Burst Time
P1 0 8
P2 1 4
P3 2 9
P4 3 5
P5 4 2

Solution :

Formulas:

Gantt Chart

Process Burst Time Completion Time Turn Around Time (TAT) Waiting Time (WT)
P1 8 8 8 - 0 = 8 8 - 8 = 0
P5 2 10 10 - 4 = 6 6 - 2 = 4
P2 4 14 14 - 1 = 13 13 - 4 = 9
P4 5 19 19 - 3 = 16 16 - 5 = 11
P3 9 28 28 - 2 = 26 26 - 9 = 17

Formula for average TAT and WT:

Average TAT = (8 + 6 + 13 + 16 + 26) / 5 = 13.8
Average WT = (0 + 4 + 9 + 11 + 17) / 5 = 8.2

Question 2:

find the average Turn Around Time and Waiting Time of following processes using Preemptive SJF(SHORTEST JOB FIRST) process scheduling algorithm?

Process Arrival Time Burst Time
P1 0 7
P2 2 4
P3 4 1
P4 5 4
P5 7 3
P6 8 2

Solution :

Formulas:

Gantt Chart

Process Burst Time Completion Time Turn Around Time (TAT) Waiting Time (WT)
P1 7 21 21 - 0 = 21 21 - 7 = 14
P2 4 7 7 - 2 = 5 5 - 4 = 1
P3 1 5 5 - 4 = 1 1 - 1 = 0
P4 4 16 16 - 5 = 11 11 - 4 = 7
P5 3 10 10 - 7 = 3 3 - 3 = 0
P6 2 12 12 - 8 = 4 4 - 2 = 2

Formula for average TAT and WT:

Average TAT = (21 + 5 + 1 + 11 + 3 + 14) / 6 = 9.16
Average WT = (14 + 1 + 0 + 7 + 0 + 2) / 6 = 4

Question 3:

find the average Turn Around Time and Waiting Time of following processes using Non-Preemptive SJF(SHORTEST JOB FIRST) process scheduling algorithm?

Process Arrival Time Burst Time
P1 0 5
P2 1 3
P3 2 8
P4 3 6
P5 4 2

Solution :

Formulas:

Gantt Chart

Process Burst Time Completion Time Turn Around Time (TAT) Waiting Time (WT)
P1 5 5 5 - 0 = 5 5 - 5 = 0
P5 2 7 7 - 4 = 3 3 - 2 = 1
P2 3 10 10 - 1 = 9 9 - 3 = 6
P4 6 16 16 - 3 = 13 13 - 6 = 7
P3 8 24 24 - 2 = 22 22 - 8 = 14

Formula for average TAT and WT:

Average TAT = (5 + 3 + 9 + 13 + 22) / 5 = 10.4
Average WT = (0 + 1 + 6 + 7 + 14) / 5 = 5.6

Question 4:

find the average Turn Around Time and Waiting Time of following processes using Preemptive SJF(SHORTEST JOB FIRST) process scheduling algorithm?

Process Arrival Time Burst Time
P1 0 6
P2 1 4
P3 2 9
P4 3 5
P5 4 2

Solution :

Formulas:

Gantt Chart

Process Burst Time Completion Time Turn Around Time (TAT) Waiting Time (WT)
P1 6 12 12 - 0 = 12 12 - 6 = 6
P2 4 6 6 - 1 = 5 5 - 4 = 1
P3 9 26 26 - 2 = 24 24 - 9 = 15
P4 5 17 17 - 3 = 14 14 - 5 = 9
P5 2 7 7 - 4 = 3 3 - 2 = 1

Formula for average TAT and WT:

Average TAT = (12 + 5 + 24 + 14 + 3) / 5 = 11.6
Average WT = (6 + 1 + 15 + 9 + 1) / 5 = 6.4

Question 5:

find the average Turn Around Time and Waiting Time of following processes using Non-Preemptive SJF(SHORTEST JOB FIRST) process scheduling algorithm?

Process Arrival Time Burst Time
P1 0 3
P2 1 6
P3 3 8
P4 5 5
P5 6 4
P6 7 2

Solution :

Formulas:

Gantt Chart

Process Burst Time Completion Time Turn Around Time (TAT) Waiting Time (WT)
P1 3 3 3 - 0 = 3 3 - 3 = 0
P2 6 9 9 - 1 = 8 8 - 6 = 2
P3 8 28 28 - 3 = 25 25 - 8 = 17
P4 5 20 20 - 5 = 15 15 - 5 = 10
P5 4 15 15 - 6 = 9 9 - 4 = 5
P6 2 11 11 - 7 = 4 4 - 2 = 2

Formula for average TAT and WT:

Average TAT = (3 + 8 + 25 + 15 + 9 + 4) / 6 = 10.6
Average WT = (0 + 2 + 17 + 10 + 5 + 2) / 6 = 6

Question 6:

find the average Turn Around Time and Waiting Time of following processes using Preemptive SJF(SHORTEST JOB FIRST) process scheduling algorithm?

Process Arrival Time Burst Time
P1 0 8
P2 1 4
P3 2 9
P4 3 5
P5 5 2

Solution :

Formulas:

Gantt Chart

Process Burst Time Completion Time Turn Around Time (TAT) Waiting Time (WT)
P1 8 19 19 - 0 = 19 19 - 8 = 11
P2 4 5 5 - 1 = 4 4 - 4 = 0
P3 9 28 28 - 2 = 26 26 - 9 = 17
P4 5 12 12 - 3 = 9 9 - 5 = 4
P5 2 7 7 - 5 = 2 2 - 2 = 0

Formula for average TAT and WT:

Average TAT = (19+4+26+9+2) / 5 = 12
Average WT = (11+0+17+4+0) / 5 = 6.4

Question 7:

find the average Turn Around Time and Waiting Time of following processes using Non-Preemptive SJF(SHORTEST JOB FIRST) process scheduling algorithm?

Process Arrival Time Burst Time
P1 0 2
P2 1 3
P3 2 4
P4 3 6
P5 4 1
P6 5 5

Solution :

Formulas:

Gantt Chart

Process Burst Time Completion Time Turn Around Time (TAT) Waiting Time (WT)
P1 2 2 2 - 0 = 2 2 - 2 = 0
P2 3 5 5 - 1 = 4 4 - 3 = 1
P3 4 10 10 - 2 = 8 8 - 4 = 4
P4 6 21 21 - 3 = 18 18 - 6 = 12
P5 1 6 6 - 4 = 2 2 - 1 = 1
P6 5 15 15 - 5 = 10 10 - 5 = 5

Formula for average TAT and WT:

Average TAT = (2+4+8+18+2+10) / 6 = 7.33
Average WT = (0 + 1 + 4 +12 + 1+5) / 6 = 3.83

Question 8:

find the average Turn Around Time and Waiting Time of following processes using Preemptive SJF(SHORTEST JOB FIRST) process scheduling algorithm?

Process Arrival Time Burst Time
P1 0 5
P2 1 2
P3 3 6
P4 4 3
P5 5 4

Solution :

Formulas:

Gantt Chart

Process Burst Time Completion Time Turn Around Time (TAT) Waiting Time (WT)
P1 5 7 7 - 0 = 7 7 - 5 = 2
P2 2 3 3 - 1 = 2 2 - 2 = 0
P3 6 20 20 - 3 = 17 17 - 6 = 11
P4 3 10 10 - 4 = 6 6 - 3 = 3
P5 4 14 14 - 5 = 9 9 - 4 = 5

Formula for average TAT and WT:

Average TAT = (7 + 2 + 17 +6 + 9) / 5 = 8.2
Average WT = (2 + 0 + 11 + 3 + 5) / 5 = 4.2

Question 9:

find the average Turn Around Time and Waiting Time of following processes using Non-Preemptive SJF(SHORTEST JOB FIRST) process scheduling algorithm?

Process Arrival Time Burst Time
P1 0 8
P2 1 3
P3 2 7
P4 3 4
P5 4 2

Solution :

Formulas:

Gantt Chart

Process Burst Time Completion Time Turn Around Time (TAT) Waiting Time (WT)
P1 8 8 8 - 0 = 8 8 - 8 = 0
P2 3 13 13 - 1 = 12 12 - 3 = 9
P3 7 24 24 - 2 = 22 22 - 7 = 15
P4 4 17 17 - 3 = 14 14 - 4 = 10
P5 2 10 10 - 4 = 6 6 - 2 = 4

Formula for average TAT and WT:

Average TAT = (8 + 6 + 12 + 14 + 22) / 5 = 12.4
Average WT = (0 + 4 + 9 + 10 + 15) / 5 = 7.6

Question 10:

find the average Turn Around Time and Waiting Time of following processes using Preemptive SJF(SHORTEST JOB FIRST) process scheduling algorithm?

Process Arrival Time Burst Time
P1 0 5
P2 1 7
P3 2 4
P4 3 1
P5 4 3

Solution :

Formulas:

Gantt Chart

Process Burst Time Completion Time Turn Around Time (TAT) Waiting Time (WT)
P1 5 6 6 - 0 = 6 6 - 5 = 1
P2 7 20 20 - 1 = 19 19 - 7 = 12
P3 4 13 13 - 2 = 11 11 - 4 = 7
P4 1 4 4 - 3 = 1 1 - 1 = 0
P5 3 9 9 - 4 = 5 5 - 3 = 2

Formula for average TAT and WT:

Average TAT = (6 + 19 + 11 + 1 + 5) / 5 = 8.4
Average WT = (1 + 12 + 7 + 0 + 2) / 5 = 4.4