Learn Multilevel Feedback Queue Scheduling (MLFQ) Algorithm - with solved Questions + PYQs

Operating systems' multilevel Feedback Queue Scheduling (MLFQ) algorithm is a sophisticated CPU scheduling technique that enhances multilevel queue scheduling by permitting process switching between queues. This approach helps to maximize CPU utilization and responsiveness by handling a variety of process kinds and dynamically allocating them according to their behavior and CPU burst time.

1. Step 1: Set up several queues with varying priorities. The time quantum of higher-priority queues is shorter.
2. Step 2: Assign every new process to the queue with the greatest priority.
3. Step 3: Apply Round Robin scheduling to every queue.
4. Step 4: A process is relegated to a lower-priority queue if it consumes its whole time quantum without finishing.
5. Step 5: A process in a lower-priority queue descends once more if it doesn't complete within its allotted time.
6. Step 6: Upon restarting, a process in any queue that has reached an I/O limit may move back up to a higher-priority queue.
7. Step 7: Keep doing this reallocation until every process is finished or shut down.

Multilevel Feedback Queue Scheduling offers several advantages over simpler algorithms such as First-Come-First-Serve (FCFS), Round Robin (RR), and Shortest Job Next (SJN) due to its ability to adapt dynamically to the changing needs of processes. By enabling processes to shift between various priority queues, MLFQS helps to prevent process starvation, optimizes CPU time utilization, and minimizes turnaround time for interactive and I/O-bound processes. This flexibility ensures balanced performance in systems that manage a variety of workloads, making it a highly efficient option for many contemporary operating systems.

Multilevel Feedback Queue (MLFQ) scheduling is used in systems where different tasks need to be handled based on their priority. It’s helpful in the following areas:

• 1. Operating Systems : MLFQ is utilized in operating systems to handle tasks such as applications and background processes. It ensures that critical tasks are completed promptly while still allowing time for less urgent ones.
• 2. Real-Time Systems: In systems that require immediate processing, such as real-time applications, MLFQ prioritizes critical tasks to ensure they are addressed first.
• 3. Shared Systems: On servers or computers used by multiple people, MLFQ makes sure every user’s tasks are given fair attention based on their importance.