Calculate the Need of each resource by using the need formula and draw the Need Matrix.

Suppose a system has resource type A with 18 instances and 5 processes and
the current system state is shown in the following table.
 

Process	Max Need	Allocated
P0	12	5
P1	6	4
P2	14	4
P3	16	3
P4	8	2

 
Calculate the Need of each resource by using the need
formula and draw the Need Matrix.

Solution:

The need of each resource for a process can be calculated by using the following formula: 

Needi = Maxi – Allocatedi

Where: i = process number Maxi = maximum need of a resource for process i Allocatedi = allocated resource for process i

Based on the given information, we can calculate the need of each resource for each process as follows:

Process Max Need Allocated Need 

P0 = 12 - 5 = 7 

P1 = 6 - 4 = 2

P2 = 14 - 4 = 10 

P3 = 16 - 3 = 13 

P4 = 8 - 2 = 6

The Need Matrix can be represented as follows:

	P0	P1	P2	P3	P4
A	7	2	10	13	6

It's worth mentioning that, the Need Matrix represents the remaining need of each resource for each process.