Operating systems exams - multiple choice questions (MCQ) and answers
Operating
Systems MCQ Questions and Answers – Set 11
1. The primary difference between
user-level threads and kernel threads is ______
(a)
User level threads do not use OS services via system calls, whereas kernel
threads require system calls.
(b) User level threads are
independent of each other, whereas kernel threads can write into each other’s
memory space.
(c) User level threads
require memory management where kernel threads do not.
(d) None of above.
View Answer
Answer: (a)
User
level threads do not use OS services via system calls, whereas kernel threads
require system calls. Kernel-level threads require a system call for the
switch to occur; user-level threads do not.
Other
differences are;
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2. CPU burst distribution is generally
characterized as
(a) Constant
(b) Linear
(c) Polynomial
(d)
Exponential or hyper-exponential
View Answer
Answer: (d) Exponential
or hyper-exponential
CPU burst distribution is mostly exponential. The length of CPU bursts measured across all processes is distributed approximately exponentially, with short bursts much more likely than long bursts.
This
pattern is somewhat true even for single processes (think of a program that
has to do several I/O operations in a row after a long computation), but the
distribution may be shifted depending on whether the process is CPU bound
(mostly wanting to use the CPU for long computations) or I/O bound (mostly
waiting for I/O).
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3. Which of the following is not a CPU
scheduling criterion?
(a) CPU utilization
(b)
Burst time
(c) Throughput
(d) Response time
View Answer
Answer: (b) Burst time
Burst time
is the amount of time required
by a process for executing on CPU.
CPU scheduling criterions
CPU utilization
(use of CPU), Throughput (number of processes completed per unit time), and Response time
(time taken in an interactive program from the issuance of a command to the
commencement of a response to that command) are the CPU scheduling criterions.
Other
such criterions are Turnaround time and waiting time.
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4. Which among the following is a
preemptive only scheduling algorithm?
(a)
RR
(b) FCFS
(c) SJF
(d) None of the above
View Answer
Answer: (a) Round Robin
(RR)
Round
robin algorithm is the preemptive scheduling algorithm.
FCFS
is preemptive and SJF is both preemptive and non-preemptive scheduling
algorithm.
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5. If the time quantum is very large, a
RR (Round-Robin) scheduling is the same as:
(a)
FCFS
(b) SJF
(c) SRTF
(d) Multi-level queue
View Answer
Answer: (a) FCFS
The
performance of round robin scheduling algorithm depends on the time quantum
selected. If the time quantum is very large, then RR is same as FCFS. Because
with large time quantum it is likely to finish each process as they arrive.
Such way it is showing the behavior of FCFS algorithm.
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