E81 CSE 422S: Operating Systems Organization

Fall 2020

1. Course Description
2. Prerequisites
3. Discussions/Studios
4. Lab Projects
5. FAQ/Tips
6. Computers, Textbooks, and Other Resources
7. Grading
8. Academic Support
9. Title IX, Diversity, and Inclusion
10. Academic Integrity

Course Description

The objectives of this course are for each student to:

• develop a solid base of knowledge about the Linux kernel and its user space libraries;
• employ existing kernel and user space mechanisms to implement different capabilities in C programs;
• review principles underpinning how different kernel and user space mechanisms behave; and
• design and apply mechanisms based on those principles to gauge and demonstrate understanding of them.

This is a hands-on 400-level course dealing with complex system behaviors, using off-the-shelf platforms and software. Hiccups are to be expected, and finding previously unknown flaws in (or improvements to) the course exercises is encouraged, as the instructors pursue ongoing refinement of the content and scope of this course.

Prerequisites

• CSE 361S is a prerequisite for undergraduate students
• Proficiency in C (and/or C++) is essential: please take a look at the C Practice Exercises we have provided and make sure that you're readily able to complete them (if not, we recommend taking CSE 332S/504N prior to taking this course).

The following are recommended but not required:

• CSE 332S/504N
• Basic proficiency using Linux and/or a background in Linux software development. Tutorials on the Linux Journey web site (especially those in the "Grasshopper" section but also possibly some in the "Journeyman" section) may be helpful to brush up on using the Linux command-line environment.

Discussions and Studios

Most class periods are accompanied by additional assigned readings (and possibly additional suggested readings that may be useful). The Linux kernel is notable in that many of the discussions (and disagreements) among the original developers have been saved verbatim in repositories such as the the Linux Kernel Mailing List (LKML) or documented by firsthand witnesses at sites such as lwn.net. The course textbooks can be used as technical references for kernel mechanisms, and the suggested supplemental readings can be used to understand particular design choices affecting the Linux kernel.

The course schedule is as follows. If any changes are made to this schedule, students will be notified both in class and through e-mail, and will be given enough advance notice so that rescheduling readings and other preparation can be accommodated readily.

Lab Projects

There will be three lab assignments for this course. The purpose of these labs is to apply course concepts and to evaluate kernel mechanisms and behaviors. As such, each lab will require a written report detailing your findings in addition to the code you wrote.

Each lab will be completed in a team of up to three students, and teams may be different for each lab or may remain the same. Students from different teams may discuss the lab assignments only during scheduled zoom sessions that the instructors are attending, when anyone is able to join in those discussions. Students on the same team are of course encouraged to discuss and work on lab assignments at any time.

Labs submitted on time (as determined by timestamps on Box) will be given full credit. Labs submitted up to 24 hours late will be given a ten percent penalty. Labs submitted between 24 and 48 hours late will be given a twenty percent penalty. Labs submitted after 48 hours late will not be given credit, except in the case of extenuating circumstances approved by the instructor. If you anticipate that your team may need an extension on a lab assignment, please make sure to ask prior to the deadline.

FAQ/Tips

Current and past instructors, TAs, and students of the CSE 422/522 courses have contributed various tips, tricks, and solutions to problems that they have encountered. Please let your instructor know if you have something you'd like to add here!

Class FAQ

Computers, Textbooks, and Other Resources

To be able to complete the studios and lab assignments this semester, you will need to purchase a CanaKit Raspberry Pi 3 B+ Starter Kit (32 GB EVO+ Edition), which is the platform on which we have tested out our solutions to those assignments.

The in-class studios and assigned readings offer a reasonable coverage of Linux. However, the studios and assigned readings will not yet make you an expert on the Linux kernel. When it comes to learning the details of a code base as deep and complex as Linux, there is no substitute for reading source code. Some of the lectures and studios will give pointers to relevant source code files, and for overall understanding it is expected that students will spend some time absorbing the content there as well.

To be clear, you are not expected to understand or memorize every line of the Linux source. The exams will not have questions derived directly from the Linux source (though basic kernel concepts and pseudo-code are fair game). However, the kernel is a huge set of deeply interdependent source code files. A useful way to understand it more and more thoroughly is by looking through it many times.

There are two required textbooks for this course:

Linux Kernel Development by Robert Love, 2010 (noted as LKD in the assigned readings). This is an excellent, compact, and inexpensive text that gives the reader a basic but also reasonably detailed understanding of kernel design, written in depth by a Linux kernel expert.

The Linux Programming Interface by Michael Kerrisk, 2010 (noted as LPI in the assigned readings). This an excellent, somewhat more extensive reference manual, also written in depth by a Linux kernel expert.

Please note that the Linux kernel source code is frequently (and sometimes rapidly) updated, so that while the general information in these textbooks is correct, many details of the source code itself, the names of source code files, and where those files exist, are somewhat likely to change (and have done so since the required text books above and the additional references below were written).

There are a number of other references that you may find useful for this course and more broadly for your study and use of the Linux kernel.

• The C Programming Language (2nd Edition) by Brian W. Kernighan by Dennis M. Ritchie gives a terse but reasonably complete coverage of the C language and its libraries.

• The C Pocket Reference (1st Edition) by Peter Prinz and Ulla Kirch-Prinz is a good but somewhat more concise reference for basic C topics.

• The Bootlin Elixir Cross Referencer allows you to search different releases of the Linux kernel source code to find files, symbols, etc. For the 5.4.42 version of the Linux kernel that we'll be using this semester, the direct link is https://elixir.bootlin.com/linux/v5.4.42/source.

• An additional resource for up-to-date kernel documentation is the kernel.org documentation website. It contains documentation from the Linux source code's Documentation directory in a nicely formatted, searchable medium.

• The manual pages that are installed with Linux are a great source of information about different functions and variables you'll be using in studio and lab assignments. In a terminal window on your Raspberry Pi or on shell.cec.wustl.edu or on one of the Linux lab machines, you can issue the command man man to see more about those manual pages, or issue the appropriate man command that's listed in the assigned readings in the course syllabus, to see a specific manual page.

• Once you have installed linux on your Raspberry Pi, the user space library header files in the /usr/include/ directory on it are worth looking through in an editor of your choice, to see the declarations of various functions and variables that also are shown in the relevant man pages we've assigned in the readings. Emacs (you may need to run sudo apt-get install emacs to obtain and install it on your Raspberry Pi) is one good general purpose editor that also can be used to run gdb and other useful tools from within it.

• Linux System Programming by Robert Love, 2013, gives a somewhat more compact coverage of a number of basic topics that the LPI text addresses, and offers a number of more advanced discussions of topics that are pertinent to CSE 422S Operating Systems Organization and CSE 522S Advanced Operating Systems.

• Operating Systems: Three Easy Pieces by Arpaci-Dusseau and Arpaci-Dusseau is a good introduction to operating systems, without all the complexities of Linux.

• Understanding the Linux Kernel by Bovet and Cesati, 2006, offers a more exhaustive reference than the course textbook, covering many data structures and code snippets in detail. It is also available online for free through the university's subscription to the O'Riley Safari service.

• Linux Device Drivers by Corbet, Rubini, and Kroah-Hartman, 2005. This book covers a topic that we will not go into in detail, but contains some useful reference material over kernel modules, kernel development, kernel locking, timing, and other topics. Available online for free through lwn.net.

• LWN.net is a news and information outlet for the open source community. They often run very high quality articles about kernel development, kernel architecture, and kernel mechanisms. When I have trouble finding a good online resource, a search for "lwn.net (my_topic)" often yields good results. However, beware of out-of-date material.

• Linux Journal is a magazine covering the Linux community. They often run very high quality articles about kernel development, kernel architecture, and kernel mechanisms. Similar to above, searching for "Linux Journal (my_topic)" often yields good results. As above, beware of out-of-date material.

Students will need to acquire a Raspberry Pi 3 B+ in order to complete daily studios and lab assignments. To increase flexibility during the Covid-19 pandemic, so that students can work from remote locations as well as on campus, the studio and lab instructions in this course have been redesigned to support a variety of different settings in which the Raspberry Pi 3 B+. If you run into any problems using your Raspberry Pi 3 B+ in this course this semester please let us know right away so we can help.

Grading

There are three activities for which you will receive credit in this course: studios, exams, and labs. Studios are daily guided assignments primarily designed to familiarize you with course concepts, development tools, and the kernel source code (i.e. knowledge and comprehension tasks). Exams will evaluate your technical understanding of course concepts, including nuances of the material covered in the lectures and in the assigned readings. The lab assignments will ask you to apply course concepts and analyze and implement design alternatives.

We will make every effort to grade your work, and to post a grade in Canvas and provide comments to you regarding it, within one week (7 days) of when it is submitted.

Especially for the early studios, even though they are not due until just before the first exam, please do work to submit them as early as you can so that you'll have grades and feedback on at least a few of them prior to the end of the semester's drop/add period.

Your semester grade will be determined as follows, with an overall weighted average of 90% corresponding to at least an A-, of 80% corresponding to at least a B-, and of 70% to at least a C-  and to a passing grade if the course is being taken P/F rather than for a letter grade:

Academic Support, Health and Wellness, and Disabilities

Especially with the challenges many students may face in an on-line learning environment, we encourage everyone to take a look at, and potentially make use of, the many academic support resources available at Washington University in St. Louis, including: The Learning Center, and The Writing Center, and Student Technology Services.

Washington University recognizes that students serving in the U.S. Armed Forces and their family members may encounter situations where military service forces them to withdraw from a course of study, sometimes with little notice. Students may contact the Office of Military and Veteran Services at (314) 935-2609 or veterans@wustl.edu and their academic dean for guidance and assistance.

The Habif Health and Wellness Center, WashU Cares, Mental Health Services, and RSVP are important university resources for issues pertaining to physical and mental health.

Students with disabilities or suspected disabilities are strongly encouraged both to bring any additional considerations to the attention of the instructor and to make full use of Washington University's Disability Resources, potentially including accommodations for studios, labs, and/or exams.

Title IX, Diversity, and Inclusion

Washington University is firmly committed to addressing and preventing sexual misconduct on our campuses: please see the Washington University statement on new Title IX rules. If a student discusses or discloses an instance of sexual assault, sex discrimination, sexual harassment, dating violence, domestic violence or stalking, or if a faculty member otherwise observes or becomes aware of such an allegation, the faculty member will keep the information as private as possible, but as a faculty member of Washington University, they are required to report it immediately to their Department Chair or Dean or directly to Ms. Jessica Kennedy, the University's Title IX Director, at (314) 935-3118 or jwkennedy@wustl.edu. Additionally, incidents or complaints can be reported to the Office of Student Conduct and Community Standards or by contacting WUPD at (314) 935-5555 or contacting your local law enforcement agency. To explore options for medical care, protections, or reporting, free and confidential support resources and professional counseling services are available through the Relationship and Sexual Violence Prevention (RSVP) Center in Seigle Hall, Suite 435, which can be reached at rsvpcenter@wustl.edu or at (314) 935-3445. For after-hours emergency response services, call 314-935-6666 or 314-935-5555 and ask to speak with an RSVP Counselor on call.

Washington University's Center for Diversity and Inclusion supports and advocates for undergraduate, graduate, and professional school students from underrepresented and/or marginalized populations, collaborates with campus and community partners, and promotes dialogue and social change to cultivate and foster a supportive campus climate for students of all backgrounds, cultures, and identities. The University has a process through which students, faculty, staff, and community members who have experienced or witnessed incidents of bias, prejudice, or discrimination against a student can report their experiences to the University's Bias Report and Support System team. For procedures and information on reporting an instance of bias, please visit the Bias Report and Support System page on the Center for Diversity and Inclusion web site. In order to affirm each person's gender identity and lived experiences, it is important that we each ask and check in with others about pronouns. This simple effort can make a profound difference in a person's experience of safety, respect, and support. Please see the University's Gender Pronouns Information page and the Office of the Registrar's Preferred Name page for additional information and resources.

Academic Integrity

Each studio and lab assigned in this course is expected to be completed collaboratively in teams of up to three people (and not more than that), though you are permitted to work individually on any assignment instead, if you prefer. During the scheduled zoom sessions that the instructors are attending, students may be allowed to share their screens to show code for purposes of getting help with debugging, illustrating solution approaches that are being discussed, etc., and communication about a particular studio or lab assignment within your team of (3 or fewer) people who are working together on it is allowed at any time. Communication between different teams is not allowed outside of the scheduled zoom sessions that the instructors are attending. Student teams may change from assignment to assignment, but the sharing of code between teams without prior permission of the instructor is strictly prohibited, and you must acknowledge and document in detail all contributions that anyone has made to the work.

Exams must be completed individually without assistance from any other person, and without reference to external materials except as is specifically allowed by the instructor (documentation of what is allowed will be described in the review lecture, provided in the corresponding review slides, and written on the font page of the exam).

Cheating costs everyone something. Someone who cheats misses out on the intended opportunity to improve through the assigned work, and like anyone helping them cheat is at risk of diminished reputation as well as specific sanctions (see below). Cheating also degrades the value of the degree earned by those who complete their work with integrity.

Academic integrity is a serious matter in this course, and the instructor will decide whether any situation of concern in this course warrants referral to the appropriate formal academic integrity adjudication process at the school or university level. If in any doubt, please ask your instructor first.

Anyone found to have cheated or to have helped someone else cheat will face penalties that may include receiving a negative score equal in magnitude to the value of the assignment in question (e.g., cheating on an assignment worth 10% of the course grade would result in -10% being assigned for a total loss of 20% from the course grade, which is twice as large a loss as simply not turning in the assignment).

Academic integrity is itself worth studying and thinking about as a key component of your education. Please read, familiarize yourself with, and reflect on the Engineering School's and Washington University's undergraduate and graduate policies on academic integrity.