CS422/522: Operating Systems, Spring 2010 &mdash Overview

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  • Administrative
  • Overview
  • Reference Materials
  • Computers
  • Grading
  • Collaboration Policy
  • Attendance
  • Keeping In Touch

  • Administrative Information

    MW 1:00-2:15 PM, Room 500 AKW

    Bryan Ford, 211 Watson, 432-1055,
    Office hours: MW 4:00-5:00 PM, or by appointment.

    Teaching Assistant:
    Alex Vaynberg, 312 Watson, office: 432-2349, cell: (804)519-2540 alv@cs.yale.edu
    Office hours: TBA.

    URL: http://zoo.cs.yale.edu/classes/cs422


    This course covers the fundamentals of operating system design and implementation. The course takes a hands-on approach, emphasizing learning by studying the structure and implementation of existing operating systems and using this knowledge to build a new one.

    Lectures: Lectures in the first part of the course present basic operating system ideas and concepts, explaining how they manifest in the xv6 operating system, an instructional operating system that closely mirrors the structure of modern Unix systems while being much smaller and simpler. Some lectures will involve preparatory homework assignments requiring students to explore important aspects of xv6 by examining its source code and running it in a virtual machine. Later lectures will expose students to more recent operating system developments through research papers and other readings.

    Labs: Throughout the semester, students will work in teams to build their own version of PIOS, a small but real operating system, substantially different in design from xv6 though utilizing the same general principles, through a series of six programming labs. While the xv6-based homework assignments are to be completed individually, the programming labs emphasize teamwork and collaboration, and are structured to encourage collaborative learning and to help students develop the important skills of reading and building on code written by others.

    Prerequisites: CS 323 Introduction to Systems Programming and Computer Organization.

    Reference Materials

    All of the required reference materials for this course are available on-line on the reference page (also available in the quick links at the top).

    The primary reference for the lectures is xv6: a teaching operating system, an instructional operating system and draft commentary by Russ Cox, Frans Kaashoek, and Robert Morris. This operating system is an x86-based rewrite of an early version of Unix, which still reflects accurately the basic structure of modern operating systems while being small and simple enough to be understood at source code level in a one-semester course. The original xv6 home page is at MIT, but please use the local copies on the reference page for this class to ensure that everyone refers to the same version throughout the semester. We will arrange for printed copies to be available from Yale RIS for students who would like them.

    To provide a broader perspective on operating system design concepts than the primarily Unix-oriented xv6 commentary provides, students are encouraged to refer to the following optional, supplementary textbook, whose chapters will be referenced as appropriate in course lectures:

    A. Silberschatz, P. Galvin, and G. Gagne, Operating System Concepts (Eighth Edition) , John Wiley & Sons, Inc., 2008. ISBN 0-470-12872-0. Available from the Yale bookstore or on the web.

    This and several other other books that may be useful in this course have been placed on reserve at the Becton Library. See the reference page for a complete list, as well as links to many relevant resources available online.


    You will be using the Intel Linux PCs in the Zoo computing lab. You may access them either locally on the third floor of Watson Hall, or remotely via the following command, which will log you into a randomly-chosen Zoo machine in order to balance load on the cluster:
    	ssh netid@node.zoo.cs.yale.edu

    To access these PCs, you can either directly login from their consoles in the Zoo, or just remotely login from other machines across the campus.

    If you plan to take the course for credit, you should get an account on these machines in the first week. Please also visit the following web site to create a cs422 class directory (or just to sign up for a zoo account):


    Do not allow anyone else to use your accounts for any purpose. They are for your use alone, and you are responsible for any misuse. Your passwords control access to your accounts and should be kept secret.


    Your grade will be calculated as follows: These weights are subject to minor variation.

    Many lectures have associated preparatory homework assignments, labeled PREP: in the schedule. Homeworks will typically involve and answering a few questions about xv6 or other assigned material. Written homework assignments must be turned in at the beginning of the associated lecture; late homework will be accepted only during the first two-week "shopping period," until Monday January 25.

    The midterm exam is scheduled in class on Wednesday March 3, 2010. Unless prior arrangements are made, a grade of zero will be recorded for missed exam.

    Collaboration Policy

    Programming, like composition, is an individual creative process. Individuals must reach their own understanding of the problem and discover a path to its solution. During this time, discussions with friends are encouraged. However, when the time comes to write the code that solves the problem, such discussions are no longer appropriate: each team's code must be the work of the members of that team alone (although you may ask teaching assistants or lab assistants for help in debugging). In your coding you are encouraged to adopt ideas suggested by classmates or other reference sources, but must carefully acknowledge the sources of those ideas in your own code and/or documentation.

    Do not, under any circumstances, copy another team's code. Writing code for use by another or using another's code in any form violates the University's academic regulations and will be dealt with harshly.

    Time Logging

    As you work on each of the programming labs, keep a detailed record of how you spend your time working on the lab. Since the programming labs are team-oriented, you are expected to work closely with your teammates on each lab, but EACH team member must keep a separate log of time spent on the lab. To do this, place a log file with a name of the form 'labN-netid.txt' in the top-level lab source directory. The log file should have the following general form, adopted from Prof. Eisenstat's CPSC 323 course:
    ESTIMATE of time to complete lab: 15 hours
          Start  Time  Lab
    Date  Time   Spent Part Work completed
    ----  -----  ----  ---- ---------
    9/08  10:15  1:00  1    Read assignment, completed cprintf exercise
    9/09  20:15  2:00  1    Studied IA-32 programmer's guide, got backtrace working
    9/10  12:45  0:30  2    Reading IA-32 system guide on trap handling
    9/10  14:00  0:30  2    Discussing trap handling approach with teammates
    9/10  16:00  2:00  2    Helped debug Bob's implementation of _alltraps
    9/12  21:20  2:00  4    First cut on coding up physical page allocation
    9/13  09:00  3:00  3    Meet, help teammates debug protected control transfer
    9/13  20:00  5:00  4    Mysterious memory corruption bug in my page allocator
    9/14  10:00  1:00  4    Aha!  Was overwriting the last page of the kernel.
    	    17:00  TOTAL time spent
    a brief discussion of the major difficulties encountered
    The format above is only an example, but your log must contain:

    Lab Handin Procedures

    For each lab, the TA will create a directory named /c/cs422/SUBMIT/labN.ontime, in which you are to copy your lab solution into a subdirectory named according to one of the teammate's NetIDs. (We know who the other members of your team are from the log files you include in the solution, so be sure to include the log files!) At the lab deadline, the TA will freeze the labN.ontime directory and create a labN.late1 directory in which to submit labs that will be considered one day late. This process will continue as needed with directories named labN.lateD for labs D days late.

    You will be using the Git version control system to manage source code in your programming labs, as will be laid out in Lab 1. When you turn in a lab, you are to include your team's entire Git repository, including the .git directory and all its contents. The recommended approach to using Git is for one team member to maintain a "master" Git repository for each lab in a known location, and for all team members to 'git clone' that repository to create their own working repositories. Each team member can then work concurrently and 'git push' their code back to the master repostiory when ready. Team members may alternatively use completely separate Git repositories, but in that case you should combine all of your repositories into one before submitting: for example, other team members can incorporate their repositories into the submitting team member's repository as separate branches using the command 'git push myrepository submitters-repository labN:labN-mynetid'.


    Attendance at lectures is expected but will not be recorded. Students are, however, fully responsible for all material presented in lectures, even if some of it does not appear in the "official" lecture notes. Class attendance is recommended strongly.

    Lecture notes will be made available, though they are by no means guaranteed to be a complete record of the class and cannot substitute for class attendance.

    Keeping In Touch

    The best way to contact the instructor and the TA is by electronic mail. To get help quickly, your best bet is to send email to cs422ta@cs, where it will be seen only by the instructor and TA, or to cs422@cs, where your message will also be forwarded to every student in the class. Use of the whole-class mailing list is encouraged especially in the case of clarifications or debugging questions, since it is likely that other teams will be encountering the same or similar difficulties that you are and may offer the quickest answer. All the course-related information will be kept on the web (URL: http://zoo.cs.yale.edu/classes/cs422).


    This course is heavily based on Frans Kaashoek's course 6.828: Operating System Engineering at MIT. It also draws material from prior versions of CPSC 422 at Yale taught by Zhong Shao, and in turn from Kai Li's operating systems course at Princeton.

    Copyright (c) 2000-2010 Zhong Shao and Bryan Ford, Department of Computer Science, Yale University
    Many course materials derived from 6.828 by Frans Kaashoek and others at MIT.