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CS 35101 Computer Architecture Fall 2009 Lecture 01: Introduction

This course introduces students to computer architecture, including the hardware/software interface, program performance, and parallel processing. Topics covered include computer abstractions and technology, processor market, and understanding performance.

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CS 35101 Computer Architecture Fall 2009 Lecture 01: Introduction

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  1. CS 35101 Computer Architecture Fall 2009Lecture 01: Introduction Dr. Angela Guercio (www.personal.kent.edu/~aguercio) Course Web Page http://www.personal.kent.edu/~aguercio/Fall09/CS35101-600Fa09.html

  2. Course Administration • Instructor:Dr. Angela Guercio aguercio@kent.edu 424 Main Hall • Office Hrs: TR 10:00am - 10:55am 12:25pm - 1:55pm  4:55pm - 5:25pm other times are available by appointment • URL: http://www.personal.kent.edu/~aguercio/Fall09/CS35101-600Fa09.html • Text (Required): D. Patterson, J.Hennessy - Computer Organization and Design, 4th Edition, Morgan Kaufmann, 2009 • Slides: pdf on Flashline under My Courses

  3. The Syllabus: Requirements • Class attendance is required. • If you miss a class, let me know ahead of time • You cannot miss more than 4 classes without documentation • For >4 you must provide the documented reason. • You are responsible for bringing yourself up-to-date on class material and assignments • Penalty: drop of the grade (ex from A to B, from B to C, ect.) • Reading material before class is required • Read material once before class and again after class

  4. Course Content

  5. Course Goals

  6. The Exams • 2 Mid Term Exams and 1 Final Exam • 100 points each • No Make-up exams • Except in extreme case and only if I have been notified prior the exam has been issued • Homework and Projects must be returned by the deadline • Late penalty: 3 points per day

  7. The Grade • Participation 5% • Attendance 5% • Homework and Projects 40% • Exam 1 and 2 30% • Final Exam 20% • Check the syllabus for the grading scale

  8. Dates to Remember • Last day to withdraw before grade W is assigned, is Sept.13, 2009 • Last day to drop the class is Nov. 8, 2009 • Exam 1 is Thursday, Oct 1 • Exam 2 is Thursday, Nov 10 • Final Exam is Tuesday, Dec. 15 (1:00 pm – 3:00pm) • Thanksgiving Recess: Nov. 25 – Nov. 29 • Classes End: Dec. 15, 2009

  9. Others: more on the syllabus • Read the syllabus for: • Course Withdrawal • Academic Honesty Policy • Students with Disabilities • Classes Canceled – Campus Closings • Conduct • And other important issues

  10. Others: Security • Emergency: In case of an emergency please contact the security on campus. • Security phone on campus:  #53123 • Security cell phone (330) 705-0430 or, of course, 911. • I recommend that you program into your cell phone the previous numbers.

  11. Course Structure

  12. Questions you will be able to answer by the end of the course…. • How are programs written in high level language execute on the HW? • What is the interface between SW and HW? • How does SW instruct the HW? • What determine the performance of a program? • How can a programmer improve the performance • What technique can be use by HW to improve the performance?

  13. How Do the Pieces Fit Together? Application • Coordination of many levels of abstraction • Under a rapidly changing set of forces • Design, measurement, and evaluation Operating CS 33211 System Compiler Firmware Instruction Set Architecture Memory system Instr. Set Proc. I/O system Datapath & Control Digital Design Circuit Design

  14. Chapter 1 Computer Abstractions and Technology

  15. The Computer Revolution §1.1 Introduction • Progress in computer technology • Underpinned by Moore’s Law • Makes novel applications feasible • Computers in automobiles • Cell phones • Human genome project • World Wide Web • Search Engines • Computers are pervasive Chapter 1 — Computer Abstractions and Technology — 15

  16. Classes of Computers • Desktop computers • General purpose, variety of software • Subject to cost/performance tradeoff • Server computers • Network based • High capacity, performance, reliability • Range from small servers to building sized • Embedded computers • Hidden as components of systems • Stringent power/performance/cost constraints Chapter 1 — Computer Abstractions and Technology — 16

  17. The Processor Market Chapter 1 — Computer Abstractions and Technology — 17

  18. What You Will Learn • How programs are translated into the machine language • And how the hardware executes them • The hardware/software interface • What determines program performance • And how it can be improved • How hardware designers improve performance • What is parallel processing Chapter 1 — Computer Abstractions and Technology — 18

  19. Understanding Performance • Algorithm • Determines number of operations executed • Programming language, compiler, architecture • Determine number of machine instructions executed per operation • Processor and memory system • Determine how fast instructions are executed • I/O system (including OS) • Determines how fast I/O operations are executed Chapter 1 — Computer Abstractions and Technology — 19

  20. Below Your Program • Application software • Written in high-level language • System software • Compiler: translates HLL code to machine code • Operating System: service code • Handling input/output • Managing memory and storage • Scheduling tasks & sharing resources • Hardware • Processor, memory, I/O controllers §1.2 Below Your Program Chapter 1 — Computer Abstractions and Technology — 20

  21. Levels of Program Code • High-level language • Level of abstraction closer to problem domain • Provides for productivity and portability • Assembly language • Textual representation of instructions • Hardware representation • Binary digits (bits) • Encoded instructions and data Chapter 1 — Computer Abstractions and Technology — 21

  22. Components of a Computer §1.3 Under the Covers • Same components forall kinds of computer • Desktop, server,embedded • Input/output includes • User-interface devices • Display, keyboard, mouse • Storage devices • Hard disk, CD/DVD, flash • Network adapters • For communicating with other computers The BIG Picture Chapter 1 — Computer Abstractions and Technology — 22

  23. Anatomy of a Computer Output device Network cable Input device Input device Chapter 1 — Computer Abstractions and Technology — 23

  24. Anatomy of a Mouse • Optical mouse • LED illuminates desktop • Small low-res camera • Basic image processor • Looks for x, y movement • Buttons & wheel • Supersedes roller-ball mechanical mouse Chapter 1 — Computer Abstractions and Technology — 24

  25. Through the Looking Glass • LCD screen: picture elements (pixels) • Mirrors content of frame buffer memory Chapter 1 — Computer Abstractions and Technology — 25

  26. Opening the Box Chapter 1 — Computer Abstractions and Technology — 26

  27. Inside the Processor (CPU) • Datapath: performs operations on data • Control: sequences datapath, memory, ... • Cache memory • Small fast SRAM memory for immediate access to data Chapter 1 — Computer Abstractions and Technology — 27

  28. Inside the Processor • AMD Barcelona: 4 processor cores Chapter 1 — Computer Abstractions and Technology — 28

  29. Abstractions • Abstraction helps us deal with complexity • Hide lower-level detail • Instruction set architecture (ISA) • The hardware/software interface • Application binary interface • The ISA plus system software interface • Implementation • The details underlying and interface The BIG Picture Chapter 1 — Computer Abstractions and Technology — 29

  30. A Safe Place for Data • Volatile main memory • Loses instructions and data when power off • Non-volatile secondary memory • Magnetic disk • Flash memory • Optical disk (CDROM, DVD) Chapter 1 — Computer Abstractions and Technology — 30

  31. Networks • Communication and resource sharing • Local area network (LAN): Ethernet • Within a building • Wide area network (WAN: the Internet • Wireless network: WiFi, Bluetooth Chapter 1 — Computer Abstractions and Technology — 31

  32. Technology Trends • Electronics technology continues to evolve • Increased capacity and performance • Reduced cost DRAM capacity Chapter 1 — Computer Abstractions and Technology — 32

  33. Defining Performance §1.4 Performance • Which airplane has the best performance? Chapter 1 — Computer Abstractions and Technology — 33

  34. Response Time and Throughput • Response time • How long it takes to do a task • Throughput • Total work done per unit time • e.g., tasks/transactions/… per hour • How are response time and throughput affected by • Replacing the processor with a faster version? • Adding more processors? • We’ll focus on response time for now… Chapter 1 — Computer Abstractions and Technology — 34

  35. Relative Performance • Define Performance = 1/Execution Time • “X is n time faster than Y” • Example: time taken to run a program • 10s on A, 15s on B • Execution TimeB / Execution TimeA= 15s / 10s = 1.5 • So A is 1.5 times faster than B Chapter 1 — Computer Abstractions and Technology — 35

  36. Measuring Execution Time • Elapsed time • Total response time, including all aspects • Processing, I/O, OS overhead, idle time • Determines system performance • CPU time • Time spent processing a given job • Discounts I/O time, other jobs’ shares • Comprises user CPU time and system CPU time • Different programs are affected differently by CPU and system performance Chapter 1 — Computer Abstractions and Technology — 36

  37. CPU Clocking • Operation of digital hardware governed by a constant-rate clock Clock period Clock (cycles) Data transferand computation Update state • Clock period: duration of a clock cycle • e.g., 250ps = 0.25ns = 250×10–12s • Clock frequency (rate): cycles per second • e.g., 4.0GHz = 4000MHz = 4.0×109Hz Chapter 1 — Computer Abstractions and Technology — 37

  38. CPU Time • Performance improved by • Reducing number of clock cycles • Increasing clock rate • Hardware designer must often trade off clock rate against cycle count Chapter 1 — Computer Abstractions and Technology — 38

  39. CPU Time Example • Computer A: 2GHz clock, 10s CPU time • Designing Computer B • Aim for 6s CPU time • Can do faster clock, but causes 1.2 × clock cycles • How fast must Computer B clock be? Chapter 1 — Computer Abstractions and Technology — 39

  40. Instruction Count and CPI • Instruction Count for a program • Determined by program, ISA and compiler • Average cycles per instruction • Determined by CPU hardware • If different instructions have different CPI • Average CPI affected by instruction mix Chapter 1 — Computer Abstractions and Technology — 40

  41. CPI Example • Computer A: Cycle Time = 250ps, CPI = 2.0 • Computer B: Cycle Time = 500ps, CPI = 1.2 • Same ISA • Which is faster, and by how much? A is faster… …by this much Chapter 1 — Computer Abstractions and Technology — 41

  42. CPI in More Detail • If different instruction classes take different numbers of cycles • Weighted average CPI Relative frequency Chapter 1 — Computer Abstractions and Technology — 42

  43. CPI Example • Alternative compiled code sequences using instructions in classes A, B, C • Sequence 1: IC = 5 • Clock Cycles= 2×1 + 1×2 + 2×3= 10 • Avg. CPI = 10/5 = 2.0 • Sequence 2: IC = 6 • Clock Cycles= 4×1 + 1×2 + 1×3= 9 • Avg. CPI = 9/6 = 1.5 Chapter 1 — Computer Abstractions and Technology — 43

  44. Performance Summary • Performance depends on • Algorithm: affects IC, possibly CPI • Programming language: affects IC, CPI • Compiler: affects IC, CPI • Instruction set architecture: affects IC, CPI, Tc The BIG Picture Chapter 1 — Computer Abstractions and Technology — 44

  45. Power Trends §1.5 The Power Wall • In CMOS IC technology ×30 5V → 1V ×1000 Chapter 1 — Computer Abstractions and Technology — 45

  46. Reducing Power • Suppose a new CPU has • 85% of capacitive load of old CPU • 15% voltage and 15% frequency reduction • The power wall • We can’t reduce voltage further • We can’t remove more heat • How else can we improve performance? Chapter 1 — Computer Abstractions and Technology — 46

  47. Uniprocessor Performance §1.6 The Sea Change: The Switch to Multiprocessors Constrained by power, instruction-level parallelism, memory latency Chapter 1 — Computer Abstractions and Technology — 47

  48. Multiprocessors • Multicore microprocessors • More than one processor per chip • Requires explicitly parallel programming • Compare with instruction level parallelism • Hardware executes multiple instructions at once • Hidden from the programmer • Hard to do • Programming for performance • Load balancing • Optimizing communication and synchronization Chapter 1 — Computer Abstractions and Technology — 48

  49. Manufacturing ICs • Yield: proportion of working dies per wafer §1.7 Real Stuff: The AMD Opteron X4 Chapter 1 — Computer Abstractions and Technology — 49

  50. AMD Opteron X2 Wafer • X2: 300mm wafer, 117 chips, 90nm technology • X4: 45nm technology Chapter 1 — Computer Abstractions and Technology — 50

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