Summary
Explore the Multi-Level Feedback Queue scheduling method, understanding how it uses job execution history to dynamically adjust priorities. Learn how this approach balances efficient processing of short interactive jobs with fairness for long-running CPU tasks, and why major operating systems use it as their scheduler.
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We have described a scheduling approach known as the Multi-Level Feedback Queue (MLFQ). Hopefully, you can now see why it is called that: it has multiple levels of queues, and uses feedback to determine the priority of a given job. History is its guide: pay attention to how jobs behave over time and treat them accordingly.
The refined set of MLFQ rules, spread throughout the chapter, are reproduced here for your viewing pleasure:
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Rule 1: If ...