What Is Banker's Algorithm in Operating System ?
The Banker's Algorithm is a resource allocation and deadlock avoidance algorithm that tests whether the system can allocate resources to each process in a safe sequence. It works by simulating the allocation of predetermined maximum resources to each process and checking the system's state to prevent deadlock.
What are the Method to Solve Banker's Algorithm ?
- Step 1: Identify the available resources and maximum demand of each process.
- Step 2: Calculate the "Need" matrix by subtracting the allocated resources from the maximum demand for each process.
- Step 3: Check if the system has a safe state by allocating resources based on the "Need" matrix while ensuring the system remains in a safe state.
- Step 4: Allocate resources to processes only if they satisfy the "Need" matrix and resources are available.
- Step 5: If a safe sequence is found, allocate resources; if not, resources remain unallocated to prevent deadlock.
What are the Advantages and Disadvantages of Banker's Algorithm
| Advantages | Disadvantages |
|---|---|
| Effective in preventing deadlocks | Works only with known resources and maximum demand |
| Ensures the system remains in a safe state | Complex and time-consuming calculations |
| Prevents the starvation of processes | Not suitable for systems with unpredictable resources |
| Maintains system stability and availability | Requires significant memory and CPU time |
| Identifies safe and unsafe states | Inapplicable to real-time systems |
| Applicable in systems with fixed resources | Does not allow resource sharing flexibility |
Why Banker's Algorithm is Better than Other Algorithms?
Banker's Algorithm is better than other deadlock prevention algorithms as it dynamically checks for safe and unsafe states based on each process's resource needs, ensuring efficient resource utilization. Unlike static resource allocation methods, it provides a safe sequence, preventing deadlock while allowing processes to request resources flexibly. This adaptability makes it effective in multi-process systems with stable resources.
question 1 : Answer the question using banker's algorithms.
consider the following snapshot(Available in table form) of a
system:
| Available | |||
|---|---|---|---|
| R1 | R2 | R3 | R4 |
| 0 | 2 | 1 | 1 |
| Process | Current Allocation | Maximum Demand | ||||||
|---|---|---|---|---|---|---|---|---|
| R1 | R2 | R3 | R4 | R1 | R2 | R3 | R4 | |
| P1 | 2 | 0 | 1 | 2 | 2 | 1 | 1 | 3 |
| P2 | 2 | 1 | 2 | 0 | 2 | 4 | 3 | 2 |
| P3 | 1 | 0 | 3 | 3 | 4 | 2 | 4 | 3 |
| P4 | 2 | 3 | 4 | 3 | 4 | 3 | 5 | 4 |
| P5 | 1 | 3 | 3 | 2 | 2 | 5 | 4 | 2 |
| P6 | 0 | 1 | 1 | 0 | 1 | 2 | 1 | 1 |
Is the system is in Safe state? If yes, then find out the safe sequences.
solution :
All Formulas
Resources = Available + Σ (allocation)
Available = Resources - Σ (allocation)
Need = maximum - Allocation
No , it is not in safe state
the all safe sequences are :
(1): P1 > P6 > P4 > P5 > P2 > P3
| Maximum Demand | ||||
|---|---|---|---|---|
| Process | R1 | R2 | R3 | R4 |
| P1 | 2 | 1 | 1 | 3 |
| P2 | 2 | 4 | 3 | 2 |
| P3 | 4 | 2 | 4 | 3 |
| P4 | 4 | 3 | 5 | 4 |
| P5 | 2 | 5 | 4 | 2 |
| P6 | 1 | 2 | 1 | 1 |
question 2 : consider the following snapshot(Available in table form) of a system:
| Available | |||
|---|---|---|---|
| R1 | R2 | R3 | R4 |
| 3 | 1 | 1 | 1 |
| Process | Current Allocation | Maximum Demand | ||||||
|---|---|---|---|---|---|---|---|---|
| R1 | R2 | R3 | R4 | R1 | R2 | R3 | R4 | |
| P1 | 1 | 0 | 1 | 2 | 1 | 3 | 3 | 3 |
| P2 | 1 | 3 | 0 | 0 | 2 | 4 | 3 | 0 |
| P3 | 2 | 0 | 3 | 4 | 4 | 3 | 5 | 6 |
| P4 | 2 | 1 | 2 | 2 | 4 | 1 | 2 | 3 |
| P5 | 0 | 3 | 3 | 2 | 0 | 6 | 5 | 2 |
| P6 | 1 | 2 | 4 | 4 | 4 | 3 | 5 | 4 |
Answer the following question using the Banker's algorithm :
(a) Is the system in a safe state ?
(b) If a request from process p3 arrives for (0, 1, 1, 0), can the request be granted immediately?