Question

An operating system uses the Banker's alogrithm, for deadlock avoidance when managing the allocation of three resource types X, Y, and Z to three processes P0, P1, and P2. The table given below presents the current system state. Here, the Allocation matrix shows the current number of resources of each type allocated to each process and the Max matrix shows the maximum number of resources of each type required by each process during its execution.

	Allocation	Max
	X Y Z	X Y Z
P0 P1 P2	0 0 1 3 2 0 2 1 1	8 4 3 6 2 0 3 3 3

There are 3 units of type X, 2 units of type Y and 2 uits of type Z still available. The system is currently in a safe state. Consider the following independent requests for additional resources in the current state :
REQ 1: P0 requests 0 units of X, 0 units of Y and 2 units of Z
REQ 2: P1 requests 2 units of X, 0 units of Y and 0 units of Z

Which one of the following is TRUE?

Answer 1

Allocation	Max	Need	Need with additional requests
X Y Z	X Y Z	X Y Z	X Y Z
P0|0 0 1	8 4 3	8 4 2	8 4 4 (REQ1)
P1|3 2 0	6 2 0	3 0 0	5 0 0(REQ2)
P2|2 1 1	3 3 3	1 2 2	1 2 2

Available $\underset{–}{XYZ}$
$322\to$P2 can satisfy it needs
$\underset{–}{211}\to$P2 releases its allocation
$533\to$P1 satisfies it needs
$\underset{–}{320}\to$ P1 releases its allocation
$853\to$ P0 can not satisfy with additional requests
$\therefore$ Only REQ2 can be permitted.