65.

66.

67.

68.

69.

70.

Consider the following two resource allocation policies (to processes) :
21: Make a process to release all resources before requesting a new resource.
P2: Make a process to request and get allocated all the required resources before execution.
Which of the policies will lead to deadlock prevention?
(^) Both Pl and P2 ൯) Plonly
(0 P2only (D) Neither P1 nor P2

In a uniprocessor system, three processes P1, P2, and P3 having overall execution time of 10,
20 and 30 units respectively, arrive at the zeroth instant. Each process spends the first 20%
of the overall execution time doing I/O operations, the next 70% of time doing computation,
and the last 10% of time doing I/O operations again. The operating system employs Shortest
Remaining Time First scheduling algorithm and schedules a new process either when the
running process gets blocked due to its I/O operations or when the running process finishes
its computing. Assume that all I/O operations of the processes can be overlapped. For what
percentage of the total time (from the zeroth instant till all processes finish) does the CPU
remain idle?

(A) 0% (B) 4.26%
(C) 10.64% (D) 30.03%

Which of the following scheduling algorithms is most suitable for a time-sharing operating
system?

(^) First Come First Serve (B) Shortest Job First

(C) Shortest Remaining Time First (D) Round Robin

A process executes the equivalent executable code of the following code:

for(i = 0; 1< n; i++) forkQ;

The number of child processes created which do not further create any child processes is :
(^) 25-1 @)
‏هم‎ 20-1 ©) 2

The arrival time and processing time of four processes, in the pattern (Process name, Arrival
time, Processing time) are as follows: (P1, 0, 6), (P2, 2, 12), (P3, 8, 8), (P4, 12, 4). Which of the
following process scheduling algorithms will give the lowest average turnaround time?

(^) First Come First Serve

(B)_ Shortest Job First (Without Preemption)

(C) Shortest Remaining Time First

(D) Round Robin with slot size of four time units

Belady's anomaly may occur if —————— page replacement policy is employed.
(A) FIFO (B) LRU
(C) MRU (D) Optimal

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