1
GATE CSE 2018
MCQ (Single Correct Answer)
+2
-0.6
In a system, there are three types of resources: $$E, F$$ and $$G.$$ Four processes $${P_0},$$ $${P_1},$$ $${P_2}$$ and $${P_3}$$ execute concurrently. At the outset, the processes have declared their maximum resource requirements using a matrix named Max as given below. For example, Max$$\left[ {{P_{2,}}F} \right]$$ is the maximum number of instances of $$F$$ that $${{P_{2,}}}$$ would require. The number of instances of the resources allocated to the various processes at any given state is given by a matrix named Allocation.

Consider a state of the system with the Allocation matrix as shown below, and in which $$3$$ instances of $$E$$ and $$3$$ instances of $$F$$ are the only resources available.

Allocation
E F G
P0 1 0 1
P1 1 1 2
P2 1 0 3
P3 2 0 0

Max
E F G
P0 4 3 1
P1 2 1 4
P2 1 3 3
P3 5 4 1

From the perspective of deadlock avoidance, which one of the following is true?

A
The system is in $$safe$$ state.
B
The system is not in $$safe$$ state, but would be $$safe$$ if one more instance of $$E$$ were available
C
The system is not in $$safe$$ state, but would be $$safe$$ if one more instance of $$F$$ were available
D
The system is not in $$safe$$ state, but would be $$safe$$ if one more instance of $$G$$ were available
2
GATE CSE 2016 Set 2
Numerical
+2
-0
Consider a non-negative counting semaphore $$S.$$ The operation $$P(S)$$ decrements $$S,$$ and $$V(S)$$ increments $$S.$$ During an execution, $$20$$ $$P(S)$$ operations and $$12$$ $$V(S)$$ operations are issued in some order. The largest initial value of $$S$$ for which at least one $$P(S)$$ operation will remain blocked is _____________ .
3
GATE CSE 2015 Set 3
MCQ (Single Correct Answer)
+2
-0.6
Consider the following policies for preventing deadlock in a system with mutually exclusive resources.

$$\,\,\,\,\,\,\,{\rm I}.$$ $$\,\,\,\,\,\,$$ Processes should acquire all their resources at the beginning of execution. If
$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ any resource is not available, all resources acquired so far are released
$$\,\,\,\,\,{\rm II}.$$ $$\,\,\,\,\,\,$$ The resources are numbered uniquely, and processes are allowed to request
$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ for resources only in increasing resource numbers
$$\,\,\,{\rm III}.$$ $$\,\,\,\,\,\,$$ The resources are numbered uniquely, and processes are allowed to request
$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ for resources only in decreasing resource numbers
$$\,\,\,{\rm IV}.$$ $$\,\,\,\,\,\,$$ The resources are numbered uniquely. A process is allowed to request only
$$\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,$$ for a resource with resource number larger than its currently held resources

Which of the above policies can be used for preventing deadlock?

A
Any one of $${\rm I}$$ and $${\rm III}$$ but not $${\rm II}$$ or $${\rm IV}$$
B
Any one of $${\rm I},$$ $${\rm III},$$ and $${\rm IV}$$ but not $${\rm II}$$
C
Any one of $${\rm II}$$ and $${\rm III}$$ but not $${\rm I}$$ or $${\rm IV}$$
D
Any one of $${\rm I},$$ $${\rm II},$$ $${\rm III},$$ and $${\rm IV}$$
4
GATE CSE 2014 Set 2
MCQ (Single Correct Answer)
+2
-0.6
Consider the procedure below for the Producer-Consumer problem which uses semaphores:
semaphore n = 0;
semaphore s = 1;
void producer()
{
while(true)
{
produce();
semWait(s);
semSignal(s);
semSignal(n);
}
}
void consumer()
{
while(true)
{
semWait(s);
semWait(n);
removeFromBuffer();
semSignal(s);
consume();
}
}
Which one of the following is TRUE?
A
The producer will be able to add an item to the buffer, but the consumer can never consume it.
B
The consumer will remove no more than one item from the buffer.
C
Deadlock occurs if the consumer succeeds in acquiring semaphore s when the buffer is empty.
D
The starting value for the semaphore n must be 1 and not 0 for deadlock-free operation.
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