synar systems networking and architecture group cmpt 886: special topics in operating systems and...
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SYNAR Systems Networking and Architecture Group
CMPT 886: Special Topics in Operating Systems and Computer Architecture
Dr. Alexandra FedorovaSchool of Computing Science
SFU
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
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?
Conventional vs. Multicore
Core 0
Conventional processor•Single core•One thread at a time
Core 0
Core 1
Multicore processors•Several cores•Many threads simultaneously
Core 2
Core 3
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
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)
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
Superior Performance/Watt
• Example:– Reduce CPU clock frequency by 20%– Power consumption reduces by 50%!
Core 0 Core 10.8x frequency 0.8x frequency
• 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
Multicore vs. Unicore
• Multicore:– 1.6x throughput increase– No power consumption increase
• Single-core:– Given the same power envelope– Potentially 60% less throughput
Source: Sutter, The Free Lunch is over
Transistor density still
rising
Clock speed isn’t
Transistors are used for
parallelism: multicore
processors
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?
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
Example I (Architecture)
Core 0Core 0Core 1Core 2Core 3
Core 0
Core 1
Core 2
Core 3
Core 4
Core 5
Core 6
Core 7
? ?
Core 2
Core 3
Core 4
Core 5
?Core 0Core 1
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
Resource SharingCore 0
L2 cache
L1 cache
Core 0
Core 1L2 cache
L1 cache
L1 cache
Core 0
Core 1
L2 cacheL1 cache
L1 cacheL2 cache
L3 cache
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
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?
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
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
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!
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
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
Final Project (cont.)
• Commit to a 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
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