Here are 9 questions on RR(Round Robin) process scheduling algorithms . 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 12: find the average Turn Around Time and Waiting Time of following processes using RR(Round Robin) process scheduling algorithm? Consider the following processes with their Arrival Time, Burst Time (take Quantum Time = 1.0)
| Process | Arrival Time | Burst Time |
|---|---|---|
| P1 | 0 | 4.5 |
| P2 | 2 | 0.5 |
| P3 | 3 | 6 |
| P4 | 4 | 2 |
| P5 | 4 | 1 |
| P6 | 6 | 3.5 |
| P7 | 10 | 1 |
| P8 | 11 | 3 |
Solution:
Given Time Quantum: 1.0
Formulas:
- Turnaround Time (TAT) = Completion Time - Arrival Time
- Waiting Time (WT) = Turnaround Time - Burst Time
Gantt Chart
Calculation:
| Process | Completion Time | Turnaround Time | Waiting Time |
|---|---|---|---|
| P1 | 9 | 9 - 0 = 9 | 9 - 4.5 = 5.5 |
| P2 | 2.5 | 2.5 - 2 = 0.5 | 0.5 - 0.5 = 0 |
| P3 | 21.5 | 21.5 - 3 = 18.5 | 18.5 - 6 = 12.5 |
| P4 | 11 | 11 - 4 = 7 | 7 - 2 = 5 |
| P5 | 7.5 | 7.5 - 4 = 3.5 | 3.5 - 1 = 2.5 |
| P6 | 19.5 | 19.5 - 6 = 13.5 | 13.5 - 3.5 = 10 |
| P7 | 13 | 13 - 10 = 3 | 3 - 1 = 2 |
| P8 | 20.5 | 20.5 - 11 = 9.5 | 9.5 - 3 = 6.5 |
Average Turnaround Time = (9 + 0.5 + 18.5 + 7 + 3.5 + 13.5 + 3 + 9.5) / 8 = 8.0625
Average Waiting Time = (5.5 + 0 + 12.5 + 5 + 2.5 + 10 + 2 + 6.5) / 8 = 5.5
Question 13: consider the following set of processes, with the length of the cpu burst time given in millisecond. Draw Gantt charts illustrating the execution of these processes using Round Robin (quantum = 1) scheduling. what is turn around time and waiting time of each of the processes.
| Process | Arrival Time | Burst Time |
|---|---|---|
| P1 | 0 | 8 |
| P2 | 2 | 4 |
| P3 | 4 | 2 |
| P4 | 5 | 3 |
| P5 | 6 | 5 |
| P6 | 8 | 1 |
| P7 | 10 | 2 |
Solution:
Given Time Quantum: 1.0
Formulas:
- Turnaround Time (TAT) = Completion Time - Arrival Time
- Waiting Time (WT) = Turnaround Time - Burst Time
Gantt Chart
Calculation:
| Process | Completion Time | Turnaround Time | Waiting Time |
|---|---|---|---|
| P1 | 24 | 24 - 0 = 24 | 24 - 8 = 16 |
| P2 | 15 | 15 - 2 = 13 | 13 - 4 = 9 |
| P3 | 11 | 11 - 4 = 7 | 7 - 2 = 5 |
| P4 | 19 | 19 - 5 = 14 | 14 - 3 = 11 |
| P5 | 25 | 25 - 6 = 19 | 19 - 5 = 14 |
| P6 | 13 | 13 - 8 = 5 | 5 - 1 = 4 |
| P7 | 20 | 20 - 10 = 10 | 10 - 2 = 8 |
Average Turnaround Time = (24 + 13 + 7 + 14 + 19 + 5 + 10 ) / 7 = 13.14
Average Waiting Time = (16 + 9 + 5 + 11 + 14 + 4 + 8 ) / 7 = 8.42