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.

191. In which of the following scheduling criteria, context switching will never take place?
a. ROUND ROBIN
b. Preemptive SJF
c. Non-preemptive SJF
d. Preemptive priority
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Answer: (c).Non-preemptive SJF

192. In Distributed system, the capacity of a system to adapt the increased service load is called .................
a. Tolerance
b. Scalability
c. Capability
d. Loading
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Answer: (b).Scalability

193. In .................... disk scheduling algorithm, the disk head moves from one end to other end of the disk, serving the requests along the way. When the head reaches the other end, it immediately returns to the beginning of the disk without serving any requests on the return trip.
a. LOOK
b. SCAN
c. C - LOOK
d. C - SCAN
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Answer: (d).C - SCAN

194. Suppose there are six files F1, F2, F3, F4, F5, F6 with corresponding sizes 150 KB, 225KB, 75 KB, 60 KB, 275 KB and 65 KB respectively. The files are to be stored on a sequential device in such a way that optimizes access time. In what order should the files be stored?
a. F5, F2, F1, F3, F6, F4
b. F4, F6, F3, F1, F2, F5
c. F1, F2, F3, F4, F5, F6
d. F6, F5, F4, F3, F2, F1
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Answer: (b).F4, F6, F3, F1, F2, F5

195. Which module gives control of the CPU to the process selected by the short - term scheduler?
a. Dispatcher
b. Interrupt
c. Scheduler
d. Threading
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Answer: (a).Dispatcher

196. Two atomic operations permissible on Semaphores are .................. and ...............
a. wait, stop
b. wait, hold
c. hold, signal
d. wait, signal
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Answer: (d).wait, signal

197. Consider the following four schedules due to three transactions (indicated by the subscript) using read and write on a data item X, denoted by r(X) and w(X) respectively. Which one of them is conflict serializable?

S1 : r1(X); r2(X); w1(X); r3(X); w2(X)
S2 : r2(X); r1(X); w2(X); r3(X); w1(X)
S3 : r3(X); r2(X); r1(X); w2(X); w1(X)
S4 : r2(X); w2(X); r3(X); r1(X); w1(X)
a. S1
b. S2
c. S3
d. S4
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Answer: (d).S4

198. Suppose a database schedule S involves transactions T1, T2, .............,Tn. Consider the precedence graph of S with vertices representing the transactions and edges representing the conflicts. If S is serializable, which one of the following orderings of the vertices of the precedence graph is guaranteed to yield a serial schedule?
a. Topological order
b. Depth - first order
c. Breadth - first order
d. Ascending order of transaction indices
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Answer: (a).Topological order

199. Consider the following four processes with the arrival time and length of CPU burst given in milliseconds :

Process Arrival Time Burst Time
P1 0 8
P2 1 4
P3 2 9
P4 3 5

The average waiting time for preemptive SJF scheduling algorithm is .................
a. 6.5 ms
b. 7.5 ms
c. 6.75 ms
d. 7.75 ms
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Answer: (a).6.5 ms

200. Consider a virtual page reference string 7, 0, 1, 2, 0, 3, 0, 4, 2, 3, 0, 3, 2, 1, 2, 0, 1, 7, 0, 1. Suppose a demand paged virtual memory system running on a computer system such that the main memory has 3 page frames. Then ................. page replacement algorithm has minimum number of page faults.
a. FIFO
b. LIFO
c. LRU
d. Optimal
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Answer: (d).Optimal