GATE 2020 : Operating System Quiz 5

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Question 1

When several processes access the same data concurrently and the outcome of the execution depends on the particular order in which the access takes place is called ________

• AMutual exclusion
• BDeadlock
• CRace condition
• DStarvation

Question 2

Consider the following three concurrent processes.

Initially A = 3 , B = 0
What is the minimum number of 1’s printed by the execution of the above processes?

• A0
• B1
• C2
• D3

Question 3

Two processes, P1 and P2, need to access a critical section of code. Consider the following synchronization construct used by the processes:

Here, wants1 and wants2 are shared variables, which are initialized to false.
Which one of the following statements is TRUE about the above construct?

• AIt does not ensure mutual exclusion.
• BIt does not ensure bounded waiting.
• CIt requires that processes enter the critical section in strict alternation.
• DIt does not prevent deadlocks, but ensures mutual exclusion.

Question 4

Consider the following code for two processes .

Assume A and B are binary semaphore variable initialized with values 1 and 0 respectively. X and y are shared variable initialized with 5 and 0 respectively. There is no deadlock occurs while executing then what are the values of x and y respectively after the execution of given code?

• A2 and 6
• B8 and 6
• C2 and 3
• DNone of these

Question 5

Assume threads P1 and P2 executes the codes with the following shared data: Share data and Semaphore variables

Which of the following satisfies for the above two concurrent threads

• ANo race condition
• BNo deadlock
• CRace condition and deadlock
• DBoth (a) and (b)

Question 6

Consider a process ‘P’ tries to acquire a lock using the test-and-set instruction as following.
while (Test-and-Set (lock));
If the lock is busy (some other process acquired the lock) and all interrupts are disabled then which of the following is correct?

• AProcess ‘P’ blocks, waiting for the lock to be available
• BProcess ‘P’ wastes processor and memory cycles
• CBoth A and B
• DNeither A nor B

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