CSE 120: Principles of Computer Operating Systems

Fall 2021

Tu/Th 2–3:20pm (Zoom)
Discussion Session
Fri 4–4:50pm (Zoom)
Yiying Zhang (yiying@ucsd.edu)
Office Hours: Wed 1:30pm - 3:30pm (Zoom)
TAs and Tutors
Jefferson Chien (TA) jkchien@ucsd.edu
Max Gao (TA) magao@ucsd.edu
Ruohan Hu(TA) r8hu@ucsd.edu
Yizhou Shan (TA) ys@ucsd.edu
Muyuan Chi (TA) muchi@ucsd.edu
Grant Jiang (Tutor) gjiang@ucsd.edu
Patrick Lin (Tutor) p9lin@ucsd.edu
Joshua Narezo (Tutor) jnarezo@ucsd.edu
Kyle Wang (Tutor) k5wang@ucsd.edu
Fengyuan Wu (Tutor) fwu@ucsd.edu
TA/Tutor Lab Hours
Calendar (Zoom and in-person)
Discussion Board
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 tentative 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 will need to use a web browser on campus to access them.

Date Lecture Readings Optional Homework Project
9/23 Course Intro CH. 1, CH. 2 The Structure of the 'THE'-Multiprogramming System
The UNIX Time-Sharing System
HW 1: Out   PR 0: Out  
9/28 Interaction between hardware, OS, and applications CH. 6 Linux context switch
A Case Against (Most) Context Switches (HotOS'21)
9/30 Processes CH. 4, CH. 5 A fork() in the road (HotOS'19)    
10/5 Threads CH. 26, CH. 27 POSIX Threads Programming
Illustrated Tales of Go Runtime Scheduler
C++ Coroutine Tutorial
  PR 1: Out
10/7 Synchronization CH. 28, CH. 29 RCU Usage In the Linux Kernel: One Decade Later (Linux RCU lock) HW 1: Due
HW 2: Out
PR 0: Due
10/12 Semaphores CH. 31      
10/14 Conditional Variables, Concurrency Bugs CH. 30, CH. 32 Monitors: An Operating System Structuring Concept
Understanding Real-World Concurrency Bugs in Go (ASPLOS'19)
10/19 CPU Scheduling CH. 7, CH. 8 Lottery Scheduling (OSDI'94)
Shenango: Achieving High CPU Efficiency for Latency-sensitive Datacenter Workloads (NSDI'19) 
10/21 Midterm Review       PR 2: Out
10/22         PR 1: Due
10/26 Midterm Exam      
10/28 Memory Management Overview CH. 15, CH. 16,   HW 2: Due
HW 3: Out
11/2 Paging (Annotated Slides) CH. 18, CH. 19, CH. 20    
11/4 TLB, Swapping (Annotated Slides) CH. 21,      
11/9 Swapping ctd, Memory Allocation (Annotated Slides) CH. 21,      
11/11 Veteran's Day. No Class.       PR 3: Out
11/16 Page Replacement (Annotated Slides) CH. 22,    
11/18 Storage Devices, File System Interface (Annotated Slides) CH. 37, CH. 39, A File is Not A File (SOSP'11) HW 4: Out  
11/19         PR 2: Due
11/23 Disk Layout (Annotated Slides) CH. 40   HW 3: Due  
12/2 File System Implementation and Reliability (Annotated Slides) CH. 41 CH. 42 IRON File System (SOSP'05)    
12/3 Summary & Final Review (Annotated Slides)        
12/7 Data Centers and Clouds (not in exam!) (Annotated Slides) CH. 48 Berkeley View of Cloud Computing   HW 4: Due
PR 3: Due
12/9 Final Exam 3pm - 6pm      

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. 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, I 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.


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 cover 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 with one of the following two calculations. You can decide which of them to choose towards the end of the quarter.

If you choose to do only the first two projects:

If you choose to do all the three projects:

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.