CSEN5322 – Operating Systems
Homework-5
Student Name | Student ID | Section | Date | | | | |

Bankers Algorithm

The Banker's algorithm is a resource allocation and deadlock avoidance algorithm. Using C++ programming language, implement the Banker's algorithm for deadlock avoidance.
5 <= # of process, P0~P4
4 <= # of resource, A~D

0 0 1 2 <= Allocation
1 0 0 0
1 3 5 4
0 6 3 2
0 0 1 4

0 0 1 2 <= Max
1 7 5 0
2 3 5 6
0 6 5 2
0 6 5 6

1 5 2 0 <= Available

5 <= # of process, P0~P4
4 <= # of resource, A~D

0 0 1 2 <= Allocation
1 0 0 0
1 3 5 4
0 6 3 2
0 0 1 4

0 0 1 2 <= Max
1 7 5 0
2 3 5 6
0 6 5 2
0 6 5 6

1 5 2 0 <= Available

Input a text file that includes the number of processes, resources, and the matrixes for allocations, max, and available.
Output System Safe or Unsafe 1) Read the # of processes and the # of resources 2) Read allocation, max and available for each process and each resource 3) Print whether this system is safe or not.

Data Structures for the Banker’s Algorithm
Let n = number of processes, and m = number of resources types.
Available: Vector of length m. If available [j] = k, there are k instances of resource type Rj available
Input.txt
Input.txt
Max: n x m matrix. If Max [i,j] = k, then process Pi may request at most k instances of resource type Rj
Allocation: n x m matrix. If Allocation[i,j] = k then Pi is currently allocated k instances of Rj
Need: n x m matrix. If Need[i,j] = k, then Pi may need k more instances of Rj to complete its task
Need [i,j] = Max[i,j] – Allocation [i,j]

Safety Algorithm
1. Let Work and Finish be vectors of length m and n, respectively.
Initialize:
Work = Available
Finish [i] = false for i = 0, 1, …, n- 1
2. Find an i such that both:
(a) Finish [i] = false
(b) Needi ≤ Work
If no such i exists, go to step 4
3. Work = Work + Allocationi
Finish[i] = true go to step 2
4. If Finish [i] == true for all i, then the system is in a safe state