A total of 9 units of a resource type available, and given the safe state…
2011
A total of 9 units of a resource type available, and given the safe state shown below, which of the following sequence will be a safe state?
Process Used Max
P1 2 7
P2 1 6
P3 2 5
P4 1 4- A.
(P4, P1, P3, P2)
- B.
(P4, P2, P1, P3)
- C.
(P4, P2, P3, P1)
- D.
(P3, P1, P2, P4)
Attempted by 101 students.
Show answer & explanation
Correct answer: D
First, calculate the available resources: Total (9) - Sum of Used (2+1+2+1=6) = 3 units.
Next, determine the Need for each process (Max - Used): P1=5, P2=5, P3=3, P4=3.
With 3 units available, P3 or P4 can execute. If P3 runs first, it releases 2 units, making Available = 5.
With 5 units available, P1 or P2 can execute. If P1 runs next, it releases 2 units, making Available = 7.
With 7 units available, P2 can execute (Need 5), releasing 1 unit. Finally, P4 executes.
Thus, the sequence P3 → P1 → P2 → P4 is a valid safe sequence.
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