MLQ with Feedback Scheduling

In MLQ with feedback, rather than having fixed classes of processes allocated to specific queues, the idea is to make traversal of a process through the system dependent on its run time behavior.

An Example of Multilevel Queue with Feedback Scheduling

In many multilevel feedback schemes, the quantum given to the process as it moves to each lower-level queue becomes larger. Thus the longer a process has been in the queuing network, the larger quantum it is assigned each time it gets the CPU. But it may not get the CPU very often because processes in the higher queues are given higher priority. A process in a given queue cannot run unless all higher-level queues are empty. A running process is preempted by a process arriving in a higher queue.

MLQ with feedback scheduler is defined by the following parameters:

The scheduling algorithm for each queue, the number of queues, the method used to determine when to upgrade a process to a higher priority queue, the method used to determine which queue a process will enter when that process needs service, and the method used to determine when to demote a process to a lower priority queue.

      

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