Question

What is the minimum number of resources required to ensure that deadlock will never occur, if there are currently three processes P₁, P₂, and P₃ running in a system whose maximum demand for the resources of the same type are 3, 4, and 5 respectively?
1. 3
2. 7
3. 9
4. 10

Answer 1

Correct Answer - Option 4 : 10

The correct answer is option 4:

Data:

Maximum resource requirement of Process P1 = 3

Maximum resource requirement of Process P2 = 4

Maximum resource requirement of Process P3 = 5

Concept:

Deadlock can occur If any process gets available resource < demanded resource

Max resource for process P1 to be in deadlock = needed - 1 = 3 - 1 = 2

Max resource for process P2 to be in deadlock = needed - 1 = 4 - 1 = 3

Max resource for process P3 to be in deadlock = needed - 1 = 5 - 1 = 4

If one resource is added, any of the n processes can take it a finish its execution leaving behind the allocated resource, and hence the system will be deadlock-free.

Calculation:

The minimum value of m that ensures that deadlock will never occur = (2 + 3 + 4) + 1 = 10