Study · Course Companion

OS Course Notes — Weeks 3 & 5.md

High confidencesourceedited by Cairni · 방금 · AIv1

Source Overview

Lecture notes for an Operating Systems course, spanning Week 3 (Processes & Threads) and Week 5 (CPU Scheduling). OS Course Notes — Weeks 3 & 5.md

Sections at a Glance

Section	Key Topics
Week 3 — Processes	Process vs. program, address space, PCB, process states, context switch
Week 3 — Threads	Thread definition, shared vs. private resources, multithreading trade-offs
Week 5 — CPU Scheduling	Scheduling goals, FCFS, SJF, Round Robin, Priority Scheduling
Week 5 — Preemption	Preemptive vs. non-preemptive scheduling
Exam Note	Midterm: Wed 22 April 2026 at 14:00, covering Weeks 3–5

Key Facts

A process is an active entity with its own address space; the OS tracks it via a PCB (Process Control Block).
Process lifecycle: new → ready → running → waiting → terminated.
A context switch saves/restores PCB state and is pure overhead.
Threads within a process share code, data, and heap but each has its own stack and registers.
Scheduling goals: maximize utilization & throughput; minimize waiting, response, and turnaround time — goals can conflict.
Four main scheduling algorithms discussed: FCFS, SJF, Round Robin, Priority Scheduling.
Starvation risk in SJF and Priority Scheduling; mitigated by aging in the latter.

Exam Note

Midterm on Wednesday, 22 April 2026 at 14:00 — covers Weeks 3–5 (processes, threads, IPC, scheduling). Average-waiting-time calculations and Gantt charts are highlighted as frequent question types. OS Course Notes — Weeks 3 & 5.md