Write the key criteria used to evaluate CPU scheduling performance. For the following set of processes, apply the Round Robin (RR) scheduling algorithm with a time quantum of 3 ms. Compute the average waiting time and average turnaround time for all processes.
| Process | Arrival Time | Burst Time |
|---|---|---|
| P1 | 0 ms | 7 ms |
| P2 | 1 ms | 4 ms |
| P3 | 2 ms | 5 ms |
| P4 | 3 ms | 6 ms |
Answer (2)
For the given set of processes using the Round Robin scheduling algorithm with a 3 ms time quantum, the average waiting time is 12.25 ms, and the average turnaround time is 17.75 ms. Key criteria for evaluating CPU scheduling performance include response time, turnaround time, waiting time, throughput, and utilization.
;
To evaluate CPU scheduling performance, we look at different criteria, including:
CPU Utilization : It measures how effectively the CPU is being used.
Throughput : This is the number of processes that complete their execution per time unit.
Turnaround Time : The total time taken from when a process is submitted until it is completed, including waiting time, execution time, and any other delays.
Waiting Time : The total time a process spends waiting in the ready queue before it gets executed.
Response Time : The time from the submission of a request until the first response is produced.
Now, we will apply the Round Robin (RR) scheduling algorithm with a time quantum of 3 ms to calculate the average waiting time and average turnaround time for the given processes.
Given Processes:
P1 : Arrival Time = 0 ms, Burst Time = 7 ms
P2 : Arrival Time = 1 ms, Burst Time = 4 ms
P3 : Arrival Time = 2 ms, Burst Time = 5 ms
P4 : Arrival Time = 3 ms, Burst Time = 6 ms
Round Robin Scheduling (Time Quantum = 3 ms):Time (ms)ProcessRemaining Burst Time0-3P143-6P216-9P329-12P4312-15P1115-16P20 (Complete)16-18P30 (Complete)18-21P40 (Complete)21-22P10 (Complete)
Calculating Completion, Turnaround, and Waiting Times:
P1 : Completion Time = 22 ms, Turnaround Time = 22 - 0 = 22 ms ⟹ Waiting Time = 22 - 7 = 15 ms
P2 : Completion Time = 16 ms, Turnaround Time = 16 - 1 = 15 ms ⟹ Waiting Time = 15 - 4 = 11 ms
P3 : Completion Time = 18 ms, Turnaround Time = 18 - 2 = 16 ms ⟹ Waiting Time = 16 - 5 = 11 ms
P4 : Completion Time = 21 ms, Turnaround Time = 21 - 3 = 18 ms ⟹ Waiting Time = 18 - 6 = 12 ms
Average Turnaround Time:
4 22 + 15 + 16 + 18 = 4 71 = 17.75 ms
Average Waiting Time:
4 15 + 11 + 11 + 12 = 4 49 = 12.25 ms
Hence, the average waiting time is 12.25 ms and the average turnaround time is 17.75 ms.
