CPU and I/O Scheduling: Multi-Level Feedback Queues

This lecture discusses the integration of I/O operations into CPU scheduling policies, focusing on the Multi-Level Feedback Queue (MLFQ) approach. It begins by outlining the simplifying assumptions of traditional scheduling methods, which often overlook I/O considerations. The instructor explains the importance of I/O awareness, as most programs perform I/O operations that can significantly delay CPU processing. Through examples, the lecture illustrates how traditional scheduling can lead to inefficient CPU utilization when I/O requests are involved. The MLFQ is introduced as a solution that accommodates both long-running background tasks and low-latency interactive processes. The lecture details the rules governing MLFQ, including dynamic priority adjustments and periodic boosting to prevent starvation. The instructor emphasizes the significance of using past behavior to predict future job performance, allowing for better resource allocation. The session concludes with practical insights on monitoring system performance through utilities like 'uptime', summarizing the key concepts of context switching, preemption, and the various scheduling policies discussed.