Multilevel Feedback Queues
- Different processes have different needs
- Short I/O-bound interactive processes should generally run before processor-bound batch processes
- Behavior patterns not immediately obvious to the scheduler
- Multilevel feedback queues
- Arriving processes enter the highest-level queue and execute with higher priority than processes in lower queues
- Long processes repeatedly descend into lower levels
- Gives short processes and I/O-bound processes higher priority
- Long processes will run when short and I/O-bound processes terminate
- Processes in each queue are serviced using round-robin
- Process entering a higher-level queue preempt running processes