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Chapter 15 – CPU Scheduling

Core idea

Scheduling decides which process or thread runs next.

Goals

• Fairness
• High throughput
• Low latency
• Predictability

Scheduling types

• Preemptive – OS can interrupt
• Non-preemptive – task yields voluntarily

Common algorithms

• FCFS – First Come, First Served
• SJF – Shortest Job First
• Round Robin – Time slices
• Priority scheduling

Key metric

• Time slice
  • Too small → overhead
  • Too large → poor responsiveness

Exam traps

• SJF is optimal but impractical
• Preemption improves responsiveness