GATE CSE 2022 | Deadlocks Question 1 | Operating Systems

GATE CSE 2022

MCQ (Single Correct Answer)

-0.33

Consider the following threads, T₁, T₂ and T₃ executing on a single processor, synchronized using three binary semaphore variables, S₁, S₂ and S₃, operated upon using standard wait( ) and signal( ). The threads can be context switched in any order and at any time.

$${T_1}$$	$${T_2}$$	$${T_3}$$
while (true) { wait ($${S_3}$$); print ("C"); signal ($${S_2}$$); }	while (true) { wait ($${S_1}$$); print ("B"); signal ($${S_3}$$); }	while (true) { wait ($${S_2}$$); print ("A") signal ($${S_1}$$); }

Which initialization of the semaphores would print the sequence BCABCABCA....... ?

S₁ = 1; S₂ = 1; S₃ = 1

S₁ = 1; S₂ = 1; S₃ = 0

S₁ = 1; S₂ = 0; S₃ = 0

S₀ = 1; S₂ = 1; S₃ = 1

GATE CSE 2022

MCQ (More than One Correct Answer)

-0.33

Which of the following statements is/are TRUE with respect to deadlocks?

Circular wait is a necessary condition for the formation of deadlock.

In a system where each resource has more than one instance, a cycle in its wait for graph indicates the presence of a deadlock.

If the current allocation of resources to processes leads the system to unsafe state, then deadlock will necessarily occur.

In the resource-allocation graph of a system, if every edge is an assignment edge, then the system is not in deadlock state.

GATE CSE 2018

Numerical

-0

Consider a system with $$3$$ processes that share $$4$$ instances of the same resource type. Each process can request a maximum of $$K$$ instances. Resource instances can be requested and released only one at a time. The largest value of $$K$$ that will always avoid deadlock is ____.

Your input ____

GATE CSE 2015 Set 2

MCQ (Single Correct Answer)

-0.3

A system has 6 identical resources and N processes competing for them. Each process can request atmost 2 resources. Which one of the following values of N could lead to a deadlock?