8. Multi-Level Feedback Queue

Question 1

What does MLFQ stand for?

Answer 1

Multi-level Feedback Queue

Question 2

What problems do MLFQ solve?

Answer 2

1. Minimise turnaround time
2. Minimise response time

Question 3

What is starvation?

Answer 3

A situation when a process is never given a chance because it is always preempted by higher-priority processes

Question 4

What are the five rules of MLFQ?

Answer 4

1. When Priority(A) is more than Priority(B), A runs
2. When Priority(A) is equal to Priority(B), A and B runs in round robin fashion
3. When a job enters the queue, it is placed at the highest priority
4. Once a job uses up all its time allotment at a given priority level (regardless of the number of times it has given up CPU), the priority reduces by one.
5. After some time period S, move all jobs to the top priority.

Question 5

What is the challenge in MLFQ?

Answer 5

Determining the best parameters for time period to reprioritise all jobs, time quantum and number of priority levels.