The Banker's Algorithm is a critical deadlock avoidance method in operating…
2024
The Banker's Algorithm is a critical deadlock avoidance method in operating systems, designed to facilitate resource allocation without causing deadlock. It operates by maintaining information about the maximum resources Each process may require, the current allocated resources and the available resources in the system. The algorithm checks each resource request to determine, if granting it would leave the system in a safe state, meaning that there is always a sequence in which all processes can complete their execution without getting stuck due to resource unavailability. Each process must specify its maximum demand for each resource type before it starts execution. When a process requests additional resources, the algorithm checks if granting the request will keep the system in a safe state. If so, the resources are allocated otherwise the process must wait until its request can be safely fulfilled.
What is the primary goal of the Banker's Algorithm?
- A.
To allocate resources optimally
- B.
To prevent processes from requesting resources
- C.
To detect and recover from deadlocks
- D.
To maximise CPU utilization.
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Correct answer: A
Primary goal: ensure the system never enters a deadlock by only granting resource requests that keep the system in a safe state.
Key ideas:
Maintain information for each process: maximum demand, current allocation, and remaining need.
When a request arrives, simulate granting it and run a safety check to decide whether the system can still reach a state where all processes can finish.
If the simulation shows a safe state, permanently grant the request; otherwise, deny or delay the request to avoid possible deadlock.
Standard safety-check procedure (summary):
Verify the request does not exceed the process's declared maximum need. If it does, the request is invalid.
Check if the requested resources are currently available. If not available, the process must wait.
Temporarily allocate the requested resources and update Available, Allocation, and Need.
Attempt to find a sequence of all processes where each process's remaining need can be satisfied from the currently available resources (after repeatedly adding the allocated resources of completed processes). If such a sequence exists, the state is safe.
If the state is safe, keep the allocation; if not, roll back the temporary allocation and make the process wait.
Note: This is a deadlock avoidance technique — it prevents deadlocks by enforcing safety checks. It is distinct from deadlock detection and recovery methods, and it is not primarily an algorithm for optimizing resource usage or CPU utilization.
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