COSI 131a: Fall 2022

Operating Systems

Course Objectives and Outcomes

This course is an introduction to computer systems organization and operating systems. The objectives of the course are for you to learn three things:

• The first thing is how operating systems and, more generally, computers work. The goal is to demystify the interactions between the software you have written in other courses and hardware. A student graduating with a CS degree should be able to describe the chain of computer system events that occurs from when a user hits the reboot button to when user's program runs, reading input and displaying results, from the register level to operating system level to the application level. This is philosophically important, but it is also of practical interest to developers who need to figure out how to make a system do what they want it to do.
• The second thing is for you to learn the core ideas in operating systems: resource sharing, virtualization, memory protection, scheduling, concurrent programming, file systems, transactions, etc. Such ideas are often best explained as abstractions that some software layer (usually the operating system) provides above imperfect hardware to make that hardware usable by programmers and users. The intent is for you to understand such abstractions well enough to be able to synthesize new abstractions when faced with new problems.
• Many of the ideas and abstractions that we will cover are relevant not only to OS kernels but also to many large-scale systems. Thus, a third goal of this course is to enhance your ability to understand, design, and implement such systems.

Method:

• Lectures and reading assignments from the textbook will cover the concepts and techniques.
• Homework problem sets will test and improve your knowledge of the material. The intent is for you to use these as mini exams to self-assess your knowledge of the course material and evaluate your performance.
• Perhaps the most valuable part of this class will be the programming assignments. They will require you to apply in practice the concepts covered in the lectures and will require you to defend your design decisions. You will gain experience with implementing in Java advanced synchronization and file systems algorithms. The projects will be done individually or in two-person teams, providing collaborative project experience.
• There will be three in-class quizes testing the mastery of the material covered in the course. Unless stated otherwise, the quizes will be closed book and will cover material from lectures, readings, problem sets, and the projects.
• As with most technical courses, besides ability and motivation, it takes time to learn and master the subject. Expect to spend an additional 15 hours a week outside of class time on the average.

Topics Covered

Introduction: OS organization, Modularity, Protection. Machine organization: CPU, Memory, Devices, Interconnect. Hardware abstraction layer, Assembly Language. CPU abstractions: Processes, Address spaces, Threads. I/O Concurrency. Performance metrics. Scheduling Policies. Concurrency and Synchronization: Race conditions, Critical Section, Mutual Exclusion, Locks, Monitor synchronization. Multicore synchronization performance. Deadlock. Memory management: Logical and Physical addressing, Address translation, TLB, Virtual Memory, Demand paged virtual memory, Page Replacement Policies. Persistence: Anatomy of devices, Performance metrics. File Systems and Disk Management, Naming, Data vs Metadata, Crash Consistency and Recovery, Atomicity, Careful Ordering, COW, Journaling, Transactions.

Schedule, Lecture Notes and Assignments

Please see LATTE.

Logistics

Where

Lectures: Gerstenzang 121

When

Tuesday and Thursday 2:20-3:40pm

Where

Announced Recitations: Rosenstiel 118

When

Monday 10:00-11:30am

Professor

Prof. Liuba Shrira

Office

Volen 258

Email

liuba@cs.brandeis.edu

Office Hours

Thursday 4:00-5:00pm or by appointment

Course Requirements

Assignments

There will be four problem sets (i.e., written assignments) and three programming assignments. Both problem sets and programming assignments will be announced in class and posted on LATTE (Brandeis' online courseware). You will also use LATTE to submit your assignments.

You can find instructions on how to pack and submit your programming assignments on LATTE.

Readings

• Textbook: Operating System Concepts with Java (10th Ed) by Avi Silberschatz, Peter Galvin, and Greg Gagne.
• Texbook: Operating Systems: Principles and Practice (Second Edition) By Thomas Anderson and Michael Dahlin. ISBN 978-0-9856735-2-9.
• Additional Readings will be assigned periodically and either distributed in class or linked on this web page.
• It is also recommended that you buy or borrow a text on Java. For example, the classic reference is The Java Programming Language by Ken Arnold and James Gosling. There are also numerous online Java references, including:
  • The Java Tutorials
  • The Java Language API Reference

Prerequisites

COSI 12b and 21a. You should have familiarity with Linux and Java. All programming assignments will be written in Java and must run on a Linux box (do not rely on the portability of Java!).

Evaluation

Exams

There will be three (alternatively, two) in-class quizes. There is no final exam.

Grading

Grades will be apportioned roughly as follows:

Category	Weight (%)
Problem Sets	10
Programming Assignments	45
Quiz 1	15
Quiz 2	15
Quiz 3	15

Late Policy

Each student has 2 free late days which can be applied to any of the assignments except PA3 and PS4. The 2 days can be split between 2 assignments. You will need to tell us if you plan to use your late days.

After the 2 late days are exhausted, each additional day that an assignment is late will come with a significant grade penalty on that assignment.

Days Late	Penalty
1	5%
2	10%
3+	10% + 10% each additional day
7+	No credit

A "day" is defined as the 24-hour period following the time that an assignment is due. Weekends do not count towards the number of days late.

For example, once you have exausted your 2 free late days, and an assignment is due on a Tuesday at 11:55pm, and you turn it in the following Monday before 11:55pm, it will be 4 days late (Wednesday + Thursday + Friday + Monday = 4), so the late penalty will be to subtract 35% of the possible score from your score.

Students with Disabilities

If you are a student with a documented disability on record at Brandeis University and wish to have a reasonable accommodation made for you in this class, please see Prof. Shrira immediately.