Last Updated :
06 Dec, 2018
Consider the following process and calculate the average waiting time when the longest remaining time first(preemptive)scheduling algorithm is applied:
Process ID |
Arrival Time |
Bust Time |
P0 |
2 |
1 |
P1 |
4 |
4 |
P2 |
5 |
4 |
P3 |
8 |
10 |
P4 |
10 |
11 |
All time is in milli seconds.
(A) 20 ms
(B) 18 ms
(C) 16 ms
(D) 14 ms
Answer: (D) Explanation: According to the longest remaining time first(preemptive) algorithm processes are scheduled:
Waiting time = Turn around time – burst time
Turn around time = Completion time – arrival time
Process ID |
Arrival Time |
Bust Time |
Turn around Time |
Waiting Time |
P0 |
2 |
1 |
1 |
0 |
P1 |
4 |
4 |
26 |
22 |
P2 |
5 |
4 |
26 |
22 |
P3 |
8 |
10 |
24 |
14 |
P4 |
10 |
11 |
23 |
12 |
Average waiting time = summation of all processes waiting time / number of processes
Average waiting time = 70 / 5 = 14 ms.
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