Multilevel Queue Scheduling

Multilevel queue scheduling is a sophisticated CPU scheduling algorithm that partitions the ready queue into several separate queues, each with its own scheduling algorithm and priority level. Processes are permanently assigned to a queue based on some process characteristic such as process type, priority, memory size, or other criteria. Common queue classifications include system processes (highest priority), interactive processes (medium priority), batch processes (low priority), and student processes (lowest priority). Each queue can have its own scheduling algorithm - typically, higher priority queues use preemptive algorithms like Round Robin for good response time, while lower priority queues use non-preemptive algorithms like FCFS for throughput. Scheduling between queues is usually done with fixed priority preemptive scheduling (no process in a lower queue can run until all higher queues are empty) or with time slicing (each queue gets a certain percentage of CPU time). Multilevel feedback queues extend this concept by allowing processes to move between queues based on their behavior and CPU burst characteristics. This approach provides flexibility to handle different types of processes appropriately and is widely used in modern operating systems like UNIX and Windows where processes have different priorities and scheduling requirements.