A directory of Objective Type Questions covering all the Computer Science subjects. Here you can access and discuss Multiple choice questions and answers for various compitative exams and interviews.

91. Suppose S and Q are two semaphores initialized to 1. P1 and P2 are two processes which are sharing resources.

P1 has statements                 P2 has statements
wait(S) ;                                     wait(Q) ;
wait(Q) ;                                     wait(S) ;
critical section1;                       critical section 2;
signal(S) ;                                 signal(Q) ;
signal(Q) ;                                 signal(S) ;

Their execution may sometimes lead to an undesirable situation called
a. Starvation
b. Race condition
c. Multithreading
d. Deadlock
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Answer: (d).Deadlock

92. An operating system using banker’s algorithm for deadlock avoidance has ten dedicated devices (of same type) and has three processes P1, P2 and P3 with maximum resource requirements of 4, 5 and 8 respectively. There are two states of allocation of devices as follows:

State 1   Processes                 P1       P2       P3
Devices allocated    2          3          4

State 2   Processes                 P1       P2       P3
Devices allocated    0          2          4

Which of the following is correct?
a. State 1 is unsafe and state 2 is safe.
b. State 1 is safe and state 2 is unsafe.
c. Both, state 1 and state 2 are safe.
d. Both, state 1 and state 2 are unsafe.
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Answer: (a).State 1 is unsafe and state 2 is safe.

93. Let the time taken to switch between user mode and kernel mode of execution be T1 while time taken to switch between two user processes be T2. Which of the following is correct?
a. T1 < T2
b. T1 > T2
c. T1 = T2
d. Nothing can be said about the relation between T1 and T2.
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Answer: (a).T1 < T2

94. Working set model is used in memory management to implement the concept of
a. Swapping
b. Principal of Locality
c. Segmentation
d. Thrashing
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Answer: (b).Principal of Locality

95. A thread is usually defined as a light weight process because an Operating System (OS) maintains smaller data structure for a thread than for a process. In relation to this, which of the following statement is correct?
a. OS maintains only scheduling and accounting information for each thread.
b. OS maintains only CPU registers for each thread.
c. OS does not maintain a separate stack for each thread.
d. OS does not maintain virtual memory state for each thread.
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Answer: (b).OS maintains only CPU registers for each thread.

96. The versions of windows operating system like windows XP and window Vista uses following file system:
a. FAT-16
b. FAT-32
c. NTFS (NT File System)
d. All of the above
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Answer: (d).All of the above

97. Pre-emptive scheduling is the strategy of temporarily suspending a gunning process
a. before the CPU time slice expires
b. to allow starving processes to run
c. when it requests I/O
d. to avoid collision
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Answer: (a).before the CPU time slice expires

98. In round robin CPU scheduling as time quantum is increased the average turn around time
a. increases
b. decreases
c. remains constant
d. varies irregularly
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Answer: (d).varies irregularly

99. Consider the following page trace : 4,3, 2, 1, 4, 3, 5, 4, 3, 2, 1, 5. Percentage of page fault that would occur if FIFO page replacement algorithm is used with number of frames for the JOB m=4 will be
a. 8
b. 9
c. 10
d. 12
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Answer: (c).10

100. Which of the following is scheme to deal with deadlock ?
a. Time out
b. Time in
c. Both (A) & (B)
d. None of the above
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Answer: (a).Time out

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