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Question

Answer 1

Answer is option B.

This is because while Multi-level queues were implemented first without feedback, they did not take into consideration the dynamic nature of the task.

Suppose a job is first CPU bound and is place in interactive processes queue, it's very much OK. But it may happen that after sometime, the job becomes I/O bound. Now the problem arises with Multilevel queue without feedback. The job will still be placed in interactive processes' queue despite the fact that it has changed it's nature.

Here Multilevel feedback queues come to rescue. They will detect the change in nature of job from CPU bound to I/O bound and place it in appropriate queue second time and thereafter.

Answer 2

Feedback queue dispatch task according to execution characteristic.

 Feedback Queue Scheduling

Answer 3

ans is (b).

the explanation is,

Multilevel feedback queue scheduling is the most flexible, because it can be tuned for any situation. But it is also the most complex to implement because of all the adjustable parameters. Some of the parameters which define one of these systems include

The number of queues.

The scheduling algorithm for each queue.

The methods used to upgrade or demote processes from one queue to another. ( Which may be different. )

The method used to determine which queue a process enters initially.