CMPT 886: Special Topics in Operating Systems and Computer Architecture

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CMPT 886 Special Topics in Operating Systems and
Computer Architecture

• Dr. Alexandra Fedorova
• School of Computing Science
• SFU

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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 Oracle (Sun
  Microsystems), Intel, Google, Electronic Arts,
  STMicroelectronics

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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?

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Today

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

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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

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The Multicore Revolution

• Most new processors are multicore
• intel.com Most new processors are multicore
• 2006 75 for desktops, 85 for servers
• 2007 90 for desktop and mobile, 100 for
  servers
• Everyones doing it
• Oracle (Sun Microsystems Rock), Niagara 1,
  Niagara 2
• IBM Power4, Power5, Power6, Cell
• AMD Quad Core (Barcelona)
• Embedded ARM, STMicroelectronics

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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)

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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

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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
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Multicore vs. Unicore

• Multicore
• 1.6x throughput increase
• No power consumption increase
• Single-core
• Given the same power envelope
• Potentially 60 less throughput

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Transistor density still rising
Clock speed isnt
Transistors are used for parallelism multicore
processors
Source Sutter, The Free Lunch is over
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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?

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The Multicore Challenge

• Architecture
• We do not yet know whats 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

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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
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The Multicore Challenge

• Architecture
• We do not yet know whats 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

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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
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The Multicore Challenge

• Architecture
• We do not yet know whats 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

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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?

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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

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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

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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!

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What Is Expected from You

• Expect to work hard
• But youll 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

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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 youll need for the
  project

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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

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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

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Course Web Site

• Syllabus
• Wiki
• Multicore portal
• Technical documentation

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Administrivia

• Thursday Lab
• Sign up for paper presentations
• Meet graduate students