Deck 12: Semaphores, Spinlocks, and Monitors: Understanding Synchronization in Operating Systems

Question 1

Semaphore is a/an___________to solve the critical section problem.

A)hardware for a system
B)special program for a system
C)integer variable
D)none of the mentioned

Answer 1

integer variable

Question 2

What are the two atomic operations permissible on semaphores?

A)wait
B)stop
C)hold
D)none of the mentioned

Answer 2

wait

Question 3

What are Spinlocks?

A)cpu cycles wasting locks over critical sections of programs
B)locks that avoid time wastage in context switches
C)locks that work better on multiprocessor systems
D)all of the mentioned

Answer 3

all of the mentioned

Question 4

What is the main disadvantage of spinlocks?

A)they are not sufficient for many process
B)they require busy waiting
C)they are unreliable sometimes
D)they are too complex for programmers

Question 5

The wait operation of the semaphore basically works on the basic___________system call.

A)stop()
B)block()
C)hold()
D)wait()

Question 6

The signal operation of the semaphore basically works on the basic___________system call.

A)continue()
B)wakeup()
C)getup()
D)start()

Question 7

If the semaphore value is negative

A)its magnitude is the number of processes waiting on that semaphore
B)it is invalid
C)no operation can be further performed on it until the signal operation is performed on it
D)none of the mentioned

Question 8

The code that changes the value of the semaphore is___________

A)remainder section code
B)non - critical section code
C)critical section code
D)none of the mentioned

Question 9

What will happen if a non-recursive mutex is locked more than once?

A)starvation
B)deadlock
C)aging
D)signaling

Question 10

What is a semaphore?

A)is a binary mutex
B)must be accessed from only one process
C)can be accessed from multiple processes
D)none of the mentioned

Question 11

What are the two kinds of semaphores?

A)mutex & counting
B)binary & counting
C)counting & decimal
D)decimal & binary

Question 12

What is a mutex?

A)is a binary mutex
B)must be accessed from only one process
C)can be accessed from multiple processes
D)none of the mentioned

Question 13

A binary semaphore is a semaphore with integer values

A)1
B)-1
C)0.8
D)0.5

Question 14

Semaphores are mostly used to implement

A)system calls
B)ipc mechanisms
C)system protection
D)none of the mentioned

Question 15

The bounded buffer problem is also known as___________

A)readers - writers problem
B)dining - philosophers problem
C)producer - consumer problem
D)none of the mentioned

Question 16

In the bounded buffer problem, there are the empty and full semaphores that

A)count the number of empty and full buffers
B)count the number of empty and full memory spaces
C)count the number of empty and full queues
D)none of the mentioned

Question 17

To ensure difficulties do not arise in the readers - writers problem___________are given exclusive access to the shared object.

A)readers
B)writers
C)readers and writers
D)none of the mentioned

Question 18

The dining - philosophers problem will occur in case of___________

A)5 philosophers and 5 chopsticks
B)4 philosophers and 5 chopsticks
C)3 philosophers and 5 chopsticks
D)6 philosophers and 5 chopsticks

Question 19

A deadlock free solution to the dining philosophers problem___________

A)necessarily eliminates the possibility of starvation
B)does not necessarily eliminate the possibility of starvation
C)eliminates any possibility of any kind of problem further
D)none of the mentioned

Question 20

A monitor is a type of___________

A)semaphore
B)low level synchronization construct
C)high level synchronization construct
D)none of the mentioned

Question 21

A monitor is characterized by

A)a set of programmer defined operators
B)an identifier
C)the number of variables in it
D)all of the mentioned

Question 22

A procedure defined within a___________   can access only those variables declared locally within the___________and its formal parameters.

A)process, semaphore
B)process, monitor
C)semaphore, semaphore
D)monitor, monitor

Question 23

If no process is suspended, the signal operation___________

A)puts the system into a deadlock state
B)suspends some default process execution
C)nothing happens
D)the output is unpredictable

Question 24

A collection of instructions that performs a single logical function is called

A)only one process can be active at a time within the monitor
B)n number of processes can be active at a time within the monitor (n being greater than 1)
C)the queue has only one process in it at a time
D)all of the mentioned

Question 25

What are the operations that can be invoked on a condition variable?

A)wait & signal
B)hold & wait
C)signal & hold
D)continue & signal