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E ET 4250: Chapter 1

E ET 4250: Chapter 1. Computer Abstractions and Technology. Acknowledgements: Some s lides and lecture notes for this course adapted from Prof. Mary Jane Irwin @ Penn State, Morgan Kaufmann supplemental material for the course text. The Computer Revolution. §1.1 Introduction.

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E ET 4250: Chapter 1

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  1. EET 4250: Chapter 1 Computer Abstractions and Technology Acknowledgements: Some slides and lecture notes for this course adapted from Prof. Mary Jane Irwin @ Penn State, Morgan Kaufmann supplemental material for the course text.

  2. The Computer Revolution §1.1 Introduction EET 4250: Microcomputer Architecture - Chapter 1 • 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

  3. Classes of Computers EET 4250: Microcomputer Architecture - Chapter 1 • 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

  4. The Processor Market EET 4250: Microcomputer Architecture - Chapter 1

  5. What You Will Learn EET 4250: Microcomputer Architecture - Chapter 1 • 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

  6. Understanding Performance EET 4250: Microcomputer Architecture - Chapter 1 • 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

  7. 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 EET 4250: Microcomputer Architecture - Chapter 1

  8. Levels of Program Code EET 4250: Microcomputer Architecture - Chapter 1 • 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

  9. Inside the Processor (CPU) EET 4250: Microcomputer Architecture - Chapter 1 • Datapath: performs operations on data • Control: sequences datapath, memory, ... • Cache memory • Small fast SRAM memory for immediate access to data

  10. Inside the Processor EET 4250: Microcomputer Architecture - Chapter 1 AMD Barcelona: 4 processor cores

  11. Abstractions The BIG Picture EET 4250: Microcomputer Architecture - Chapter 1 • 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

  12. Technology Trends DRAM capacity EET 4250: Microcomputer Architecture - Chapter 1 • Electronics technology continues to evolve • Increased capacity and performance • Reduced cost

  13. Defining Performance §1.4 Performance EET 4250: Microcomputer Architecture - Chapter 1 Which airplane has the best performance?

  14. Response Time and Throughput EET 4250: Microcomputer Architecture - Chapter 1 • 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…

  15. Relative Performance • 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 EET 4250: Microcomputer Architecture - Chapter 1 Define Performance = 1/Execution Time “X is n time faster than Y”

  16. Measuring Execution Time EET 4250: Microcomputer Architecture - Chapter 1 • 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

  17. CPU Clocking 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 EET 4250: Microcomputer Architecture - Chapter 1 Operation of digital hardware governed by a constant-rate clock

  18. CPU Time EET 4250: Microcomputer Architecture - Chapter 1 • Performance improved by • Reducing number of clock cycles • Increasing clock rate • Hardware designer must often trade off clock rate against cycle count

  19. CPU Time Example EET 4250: Microcomputer Architecture - Chapter 1 • 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?

  20. Pitfall: Amdahl’s Law §1.8 Fallacies and Pitfalls • Example: multiply operations accounts for 80s/100s • How much improvement in multiply performance to get 8× overall? • Can’t be done! • Corollary: make the common case fast EET 4250: Microcomputer Architecture - Chapter 1 Improving an aspect of a computer and expecting a proportional improvement in overall performance

  21. Concluding Remarks §1.9 Concluding Remarks EET 4250: Microcomputer Architecture - Chapter 1 • Cost/performance is improving • Due to underlying technology development • Hierarchical layers of abstraction • In both hardware and software • Instruction set architecture • The hardware/software interface • Execution time: the best performance measure • Power is a limiting factor • Use parallelism to improve performance

  22. Assignment EET 4250: Microcomputer Architecture - Chapter 1 • Read Patterson & Hennessy • Ch. 2.1 – 2.8 • Labs/Assignments • Will start next week • Check course website for updates & preliminary info

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