Suppose a system has 12 magnetic tape drives and at time t₀, three processes are allotted tape drives out of their as given below:

Maximum Needs

Current Needs

p₀

10

5

p₁

4

2

p₂

9

2

At time t₀, the system is in safe state. Which of the following is safe sequence so that deadlock is avoided?

NOTE:

Current Need is currently allocated resource to a process

Question

Question

This question was previously asked in

UGC NET Computer Science (Paper 2) Dec 2019 Paper

Attempt Online

Answer 1

Data:

Remaining Need = Maximum need – Current need

Total resources = 12

Total resources allocated = 5 + 2 + 2 = 9

Available resources = 12 – 9 = 3

Calculation:

Available resource ≥ remaining need of p₁

Using 3 resources, p₁gets executed first. It frees 2 resources.

Available resources = 3 + 2 = 5

Available resource ≥ remaining need of p₀

Using 5 resources, p₀gets executed first. It frees 5 resources.

Available resources = 5 + 5 = 10

Available resource ≥ remaining need of p₂

Now, p₂can be executed easily. Hence, (p₁, p₀, p₂) is a safe sequence.