- P = 4, Q = 10, R = 6, S = 2
- P = 2, Q = 9, R = 5, S = 1
- P = 4, Q = 12, R = 5, S = 4
- P = 3, Q = 7, R = 7, S = 3
Option 4 : P = 3, Q = 7, R = 7, S = 3
The correct answer is option 4.
Concept:
The round-robin algorithm is a preventative algorithm. After a defined interval of time, the CPU is transferred to the next process, which is known as time quantum/time slice. The preempted process gets moved to the end of the queue. The round-robin model is a clock-driven hybrid model.
Explanation:
The given data, Given four processes P, Q, R, and S.
Scheduling algorithm: Round Robin
Time quantum = 4-time units.
All the processes arrive at time t = 0.
Analysis:
Different Gantt charts of different processes,
Option 1: P = 4, Q = 10, R = 6, S = 2
Time quantum = 4-time units.
True, It is a possibility as the CPU bursts time of these processes and accepts all context switches.
P | Q | R | S | Q | R | Q |
0-4 | 4-8 | 8-12 | 12-6 | 16-20 | 20-21 | 21-25 |
Option 2: P = 2, Q = 9, R = 5, S = 1
Time quantum = 4-time units.
True, It is a possibility as the CPU bursts time of these processes and accepts all context switches.
P | Q | R | S | Q | R | Q |
0-2 | 2-6 | 6-10 | 10-11 | 11-15 | 15-16 | 16-17 |
Option 3:P = 3, Q = 7, R = 7, S = 3
Time quantum = 4-time units.
True, It is a possibility as the CPU bursts time of these processes and accepts all context switches.
P | Q | R | S | Q | R | Q |
0-4 | 4-8 | 8-12 | 12-14 | 14-18 | 18-20 | 20-22 |
Option 4:P = 3, Q = 7, R = 7, S = 3
Time quantum = 4-time units.
False, there is no context switching exist from R to Q. Hence it is not a possibility as CPU burst time of these processes.
P | Q | R | S | Q | R |
0-3 | 3-7 | 7-11 | 11-14 | 14-17 | 17-20 |
Hence the correct answer is P = 3, Q = 7, R = 7, S = 3.