Scheduling Algorithms

6. Multilevel Feedback Queue Scheduling.
   • This is the same as Multilevel Queue Scheduling, except that a process can move from one queue to another.
   • A few reasons that we could decide to move a process to another queue are:
     1. During the process's execution, it might change its nature, such as being more CPU-bound or more I/O-bound, so moving it to another queue will make its execution (and this of other processes) more efficient.
     2. If priorities are used for scheduling, we might move a process to a queue whose priority is larger if the priority of the process increases due to aging.
   • Advantage: This algorithm is very flexible and lets us change process scheduling during the execution of the process and not only when it starts running (as we do in the Multilevel Queue Scheduling algorithm.)
   • Disadvantage: It is very difficult to implement this algorithm due to its complexity.