CSE 120: Principles of Computer Operating Systems

Spring 2023

Amy Ousterhout (aousterhout@ucsd.edu)
Office Hour: Fri 2–3pm (CSE 3130)
Tu/Th 3:30–4:50pm in Franklin Antonio Hall 1450
TAs and Tutors
Charlotte Tang Yunxiang Chi
Kaiyuan Wang Yuke Liu
Fengyuan Wu Xiyan Shao
Steven Wu  
Discussion Section
Fri 4–4:50pm in Center Hall 214
TA/Tutor Lab Hours
Calendar (CSE Basement)
Discussion Board
Announcements and Grading
Remzi H. Arpaci-Dusseau and Andrea C. Arpaci-Dusseau
Operating Systems: Three Easy Pieces
Version 1.00   (Available free online!)

Course Objectives

This course covers the principles of operating systems. It emphasizes the basic concepts of OS kernel organization and structure, processes and threads, concurrency and synchronization, memory management, file systems, and communication. It is also a project course, providing essential experience in programming with concurrency, implementing and unmasking abstractions, working within an existing complex system, and collaborating with other students in a group effort.

Course Schedule

The following table outlines the schedule for the course. We will update it as the quarter progresses.

The optional readings include primary sources and in-depth supplements for concepts in the class. Supplemental reading is for your own interest — the readings are not required, nor will you be tested on the material. Note that some of the links to the documents point to the ACM Digital Library. UCSD has a subscription to the ACM Digital Library, so you can access these links from a web browser on campus.

Date Lecture Readings Optional Readings Homework Project
Tu 4/4 Course Intro CH. 1, CH. 2 The UNIX Time-Sharing System HW 1: Out PR 0: Out
Th 4/6 Interactions with Apps and Hardware CH. 6 Linux context switch
A Case Against (Most) Context Switches
Tu 4/11 Processes CH. 3, CH. 4, CH. 5 A fork() in the road   PR 0: Due
PR 1: Out
Th 4/13 Threads CH. 26, CH. 27 Illustrated Tales of Go Runtime Scheduler
C++ Coroutine Tutorial
Tu 4/18 Synchronization CH. 28, CH. 29 RCU Usage In the Linux Kernel: One Decade Later HW 1: Due
HW 2: Out
Th 4/20 Semaphores CH. 31 The Structure of the 'THE'-Multiprogramming System    
Tu 4/25 Condition Variables and Deadlock CH. 30, CH. 32 Understanding Real-World Concurrency Bugs in Go    
Th 4/27 CPU Scheduling CH. 7, CH. 8 Lottery Scheduling: Flexible Proportional-Share Resource Management
Shenango: Achieving High CPU Efficiency for Latency-sensitive Datacenter Workloads
  PR 2: Out
Tu 5/2 Midterm Review     HW 2: Due
HW 3: Out
PR 1: Due
Th 5/4 Midterm Exam        
Tu 5/9 Memory Management Overview CH. 15, CH. 16 A Study of Virtual Memory Usage and Implications for Large Memory    
Th 5/11 Paging CH. 18, CH. 19, CH. 20 Mitosis: Transparently Self-Replicating Page-Tables for Large-Memory Machines    
Tu 5/16 TLBs, Swapping CH. 21 Coordinated and Efficient Huge Page Management with Ingens   PR 3: Out
Th 5/18 Page Replacement and Memory Allocation CH. 17, CH. 22 Learning-based Memory Allocation for C++ Server Workloads    
Fri 5/19 n/a       PR 2: Due
Tu 5/23 Storage Devices and File System API CH. 37, CH. 39 A case for redundant arrays of inexpensive disks (RAID) HW 3: Due
HW 4: Out
Th 5/25 File System Disk Layout CH. 40 The Google File System    
Tu 5/30 File Caching and Reliability CH. 41, CH. 42 IRON File Systems    
Th 6/1 Virtual Machines Appendix B Virtual Machine Monitors: Current Technology and Future Trends    
Tu 6/6 Protection CH. 53, CH. 55 RedLeaf: Isolation and Communication in a Safe Operating System HW 4: Due  
Th 6/8 Final Review        
Sat 6/10 n/a       PR 3: Due
M 6/12 Final Exam, 3-6 pm        
Thanks to Geoff Voelker, Yiying Zhang, John Ousterhout, and the faculty who teach COS 318 at Princeton whose slides and notes heavily inspired the slides above.

Course Organization

The course is organized as a series of lectures by the instructor, discussion sections by the TAs, reading, homework, and project assignments, and exams:


The course will have four homeworks, and I will post them as the quarter progresses. You will submit all your homework electronically via Canvas. We will reduce homework grades by 20% for each day that they are late.

Due to extensive copying on homeworks in the past, we have changed how homeworks are graded. As long as you submit a technical answer related to the question, you will get full credit for the question. The goal of the homeworks is to give you practice learning the material. The homework questions both supplement and complement the material from lecture and in the project, and you will also find the homework questions to be useful for practicing for the exams. We will post solutions to all homeworks after they are submitted, and you can use them for studying as well. But, even with the solutions, the amount you learn from the homeworks will be directly correlated with your effort working on them.

I encourage you to collaborate on the homeworks: you can learn a lot from your fellow students. Collaboration consists of discussing problems with other students and independently writing your own answers to the problems based upon those discussions. As a rule of thumb, you should be able to discuss a homework problem in the hall with others, go home, and then write up your answer to the problem on your own.

  • Homework 1
  • Homework 1 Solution
  • Homework 2
  • Homework 2 Solution
  • Homework 3
  • Homework 3 Solution
  • Homework 4
  • Homework 4 Solution
  • Projects

    The course has one tutorial project and three programming projects using the Nachos instructional operating system.


    The course has two exams: a midterm and a final. The midterm will cover the first half of the class, and the final will focus on the second half of the class.

    Discussion Sections

    Discussion sections answer questions about the lectures, homeworks, projects, and programming environment. They may also supplement the lectures with additional material.


    Your grade for the course will be based on your performance on the homeworks, midterm exam, final exam, and projects, as follows:

    The academic honesty guidelines outlined by Charles Elkan apply to this course. I urge you to resist any temptation to cheat, no matter how desperate the situation may seem. If you are in circumstances that you feel compel you to cheat, come to me first before you do so.