E81 CSE 522S: Advances Operating Systems Fall 2019

1. E81 CSE 522S:Advances Operating SystemsFall 2019 Department of Computer Science & Engineering Washington University, St. Louis MO Brian Kocoloski brian.kocoloski@cse.wustl.edu *Thanks to Chris Gill and David Ferry who developed much of this material in previous iterations of the course

2. Three Goals for Students • Build deep understanding about OS operation and design principles • Additional mechanisms that we did not cover in 422: signals, pipes/fifos, sockets, etc. • Additional OS design models beyond Linux: virtual machines, unikernels, etc. • Enrich skills for monitoring the runtime operation of an OS • New features of monitoring tools, e.g., event queries for kernelshark • The scientific method (hypothesis, prediction, experiment, analysis, repeat) • Gain further experience enforcing/evaluating OS behavior • E.g., forensics for memory, file system, processes/threads, timing • As in CSE 422, the studios will help you gain experience and expertise to use in the lab assignments • Analyzing + developing code in experimental kernels CSE 522S – Advanced Operating Systems

3. Course Environment • As in CSE 422, our OS of choice is (mostly) the Linux kernel • Two reasons: general ubiquity and open source availability • This course is again designed around the Raspberry Pi 3 • Avoids modifying the kernel on machines others may need to use • Can quickly re-deploy a new version of the kernel if the one running locks up • “Personal computing” at its best  • The Raspberry Pi family is based on the ARM processor architecture • Will occasionally mention x86 differences, where relevant CSE 522S – Advanced Operating Systems

4. Grading CSE 522S – Advanced Operating Systems

5. Course Textbooks Linux Kernel Development, 3rd Ed., by Robert Love, 2010. • A great starting resource for kernel hackers • Focused on kernel design and implementation • Same books as in CSE 422S • Linux System Programming, by Robert Love, 2013. • - Focused on userspace programming instead of in-kernel issues • - Heavy IPC focus: pipes, sockets, signals, etc. CSE 522S – Advanced Operating Systems

6. Class Readings CSE 522S – Advanced Operating Systems

7. Other Resources • Many other textbooks listed online • lwn.net summarizes current debates in the kernel community regarding how features should be implemented • Google is your friend • Linux is widely documented (but documentation often is not current) • Lots of resources exist for individual directories, files, and even functions • We will provide links to some of those resources on the course web site CSE 522S – Advanced Operating Systems

8. Warnings from Previous Students • “You program in C to reconfigure a Linux Kernel on a Raspberry Pi. Prepare to optimize your workflow for testing, and brush up on C – you'll be using it a lot.” • “I had trouble doing studios because I never made it to class. So I was always playing catch–up and stressed out by the studios.” CSE 522S – Advanced Operating Systems

9. A Typical Class • About 20 minutes of lecture discussing that day’s readings and course topic • About 60 minutes of studio time • Studios • Offer direct experience working with (and within) the kernel • Familiarize students with key tools and techniques for using, profiling, analyzing, and extending kernel features. • Work in groups of up to 3 students CSE 522S – Advanced Operating Systems

10. Words of Advice (from me) • Kernel hacking requires a lot of patience (and thought) • Your systems will crash • It’s important to optimize your work environment to handle frequent crashes and reboots • Work efficiently but persistently • Start early, fail (or succeed) quickly, iterate rapidly, progress steadily over time • A few tips for this course (to avoid problems we’ve seen already) CSE 522S – Advanced Operating Systems

11. Optimize your Workflow • Your systems will hang a lot • Course reasons • We’re doing hands-on design and implementation of kernel code • Unlike userspace, when the kernel has a bug, the whole system usually crashes • Hardware reasons • WiFi is often spotty in this room • Many students really on VPN connection to transfer files between RPi3 and Linux development systems CSE 522S – Advanced Operating Systems

12. Optimize your Workflow • shell scripts • Automate tedious processes such as file transfers and kernel compilation commands • ssh keys • Can be used to authenticate between RPi and linuxlab without passwords • Develop code directly on the Raspberry Pi • In 422, you probably built on linuxlab and transferred to RPI3 • This was done to protect your work from corruption • If you use source control (e.g., git), you may find it easier to build directly on the RPi3 CSE 522S – Advanced Operating Systems

13. Today’s Studio • Downloading and Compiling the Linux kernel • Installing the Linux kernel on your RPi3 • If you took 422 here in the last 2 years, you’ve likely already done this CSE 522S – Advanced Operating Systems