CMPT 886: Special Topics in Operating Systems and Computer Architecture

1. CMPT 886: Special Topics in Operating Systems and Computer Architecture Dr. Alexandra Fedorova School of Computing Science SFU

2. Meet the Instructor • Ph.D. in Computer Science from Harvard, 2006 • Dissertation on operating system design for multicore processors • Concurrently with Ph.D., an intern at Sun Labs (3 years) • Third year at SFU • Over 20 publications on research topics related to multicore processors • Industrial collaborations with Sun Microsystems, Intel, Google, and Electronic Arts

3. Course Topic • Multicore processors • New type of computer architecture • Dominates new processor market • Desktops, servers, mobile devices, etc. • Almost all new processors are multicore • Many research problems to solve • How to design software for these chips? • How to design the chips themselves? • How to structure hardware/software interaction?

4. Today • Introduction to multicore processors • Examples of research problems • Overview of the course

5. Conventional vs. Multicore Core 0 Core 0 Core 1 Core 2 Core 3 • Conventional processor • Single core • One thread at a time • Multicore processors • Several cores • Many threads simultaneously

6. The Multicore Revolution • Most new processors are multicore • intel.com: Most processors shipped are multicore: • 2006: 75% for desktops, 85% for servers • 2007: 90% for desktop and mobile, 100% for servers • Everyone’s doing it • Sun Microsystems Rock, Niagara 1, Niagara 2 • IBM Power4, Power5, Power6, Cell • AMD Quad Core (Barcelona) • Embedded: ARM

7. Why Multicore? • Building conventional chips no longer profitable • How do you speed up a conventional chip? • Increase its clock frequency • No longer feasible: • Increasing clock speed increases power consumption out of proportion • Chips are too expensive to build (errors) • Too expensive to operate (energy consumption)

8. Multicore is the Answer! • Instead of using one large fast core… • Use many smaller, simpler cores • Collectively, they use less power • Collectively, they give more computing power

9. Superior Performance/Watt • Example: • Reduce CPU clock frequency by 20% • Power consumption reduces by 50%! • Put two 0.8 frequency cores on the same chip • Get 1.6 times the computation at the same power consumption 0.5x power 0.5x power Core 0 Core 1 0.8x frequency 0.8x frequency

10. Multicore vs. Unicore • Multicore: • 1.6x throughput increase • No power consumption increase • Single-core: • Given the same power envelope • Potentially 60% less throughput

11. Transistor density still rising Clock speed isn’t Transistors are used for parallelism: multicore processors Source: Sutter, The Free Lunch is over

12. Multicore: State of Affairs • Multicore processors are here • Operating systems and applications run on them unmodified • Why do we need to do research on them?

13. The Multicore Challenge • Architecture • We do not yet know what’s the best way to build these processors • Resource sharing • We need to manage more shared resources than before • Programmability • Everyone must run multithreaded applications now, and this is hard

14. Example I (Architecture) Core 0 Core 0 Core 4 Core 0 ? ? Core 1 Core 1 Core 5 Core 2 Core 2 Core 6 Core 3 Core 3 Core 7 Core 0 ? Core 1 Core 2 Core 4 Core 3 Core 5

15. The Multicore Challenge • Architecture • We do not yet know what’s the best way to build these processors • Resource sharing • We need to manage more shared resources than before • Programmability • Everyone must run multithreaded applications now, and this is hard

16. Resource Sharing Core 0 Core 0 L2 cache L1 cache L1 cache Core 1 L2 cache L1 cache L3 cache Core 0 L2 cache L1 cache Core 1 L2 cache L1 cache

17. The Multicore Challenge • Architecture • We do not yet know what’s the best way to build these processors • Resource sharing • We need to manage more shared resources than before • Programmability • Everyone must run multithreaded applications now, and this is hard

18. Programmability • How do you write multithreaded code? • Is it easy? • In the past, writing multithreaded code is the prerogative of experienced programmers • Now everyone has to do it • Can we make this easier?

19. Summary • Multicore systems • They are everywhere: servers, desktops, small devices • Must understand them • Plenty of research on multicore systems • System software (OS, compilers, runtimes) • Architecture • Analytical modeling • Applications

20. Class Structure • Learn about multicore research • Read and critique papers • Paper summaries, presentations • Learn how to do multicore research • Discuss papers, think about new ideas • Analyze papers • Learn how to use research tools (1 homework) • Do multicore research • A research project

21. Research Project • A unique experience: getting a project done from start to end • Goal: generate a publication • Previous years: 2-4 publications out of 4-6 projects • Gives you confidence as a grad student • Improves your resume • Challenging! You will learn a lot!

22. What Is Expected from You • Expect to work hard • But you’ll be glad you did this later • Papers will be difficult to read at first (3-5 hours/paper) • Will get easy later • Reward: You will be comfortable at leading your own research in this area

23. Final Project • You can choose from a list of existing topics • Or create your own • Some projects are very well specified (like an undergraduate course project) • Others are more open-ended (hint: an opportunity to be creative) • We have systems and tools you’ll need for the project

24. Final Project (cont.) • Commit toa project proposal in early February • Complete the project by mid-April • You have only 2.5months • Have to work hard! • Expect to dedicate ≈30 hrs/week

25. Will I Succeed in this Course? • You have to work independently! • You have to be entrepreneurial! • Take full responsibility for your project • I will help, but I cannot do it for you • I do not have all the answers • Maybe there is no answer – the goal is to learn • I will stress methodology • You will succeed, if you are prepared to work hard • What you can or cannot do now does not matter – what matters is how well you learn • The course is designed to train you

26. Course Web Site • Syllabus • Wiki • Multicore portal • Technical documentation

27. Administrivia • Thursday Lab • Sign up for paper presentations • Meet graduate students