Question

Consider a system having m resources of the same type. These resources are shared by 3 processes A, B, C, which have peak time demands of 3, 4, 6 respectively. The minimum value of m that ensures that deadlock will never occur is
1. 11
2. 12
3. 13
4. 14

Answer 1

Correct Answer - Option 1 : 11

Data:

Maximum resource requirement of Process A = 3

Maximum resource requirement of Process B = 4

Maximum resource requirement of Process C = 6

Concepts:

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

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

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

Max resource for process C to be in deadlock = needed - 1 = 6 - 1 = 5

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 + 5) + 1 = 11

∴ m = 11