Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-1 Chapter 1. Fundamentals of Computer Design Introduction –Performance Improvement due to (1). Advances in the technology (2). Innovation in computer design – : (1) and (2) made a major contribution to performance improvement –1970 ~ : 25% to 30% per year performance improvement for the mainframes and minicomputers. –1975~ : 35% per year performance improvement for microprocessors simply due to (1).

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-2 Performance Growth for Micro-processors

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-3 Changes in the Marketplaces Made a Successful Architecture The virtual elimination of assembly language reduced the need for object code compatibility The creation of standardized, vendor-independent operating system, such as Unix and Linux, lowered the cost and risk Consequence of the changes –Enable the development of RISCs to focus on Exploitation of instruction level parallelism Use of caches –Lead to 50% increase in performance per year

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-4 The Effect of the Growth rate in Computer Performance Significantly enhanced the capability available to computer users Lead to the dominance of microprocessor-based computers across the entire range of computer design. –Workstations and PCs have emerged as major products. –Servers replace minicomputers. –Multiprocessors replace mainframe computers and super computers. The advance of IC technology –Emergence of RSIC –Renewal of CISC such as x86 (IA32) microprocessors.

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-5 The Changing Face of Computing 1960sLarge mainframes »Business data processing and scientific computing 1970sMinicomputers »Time-sharing 1980sDesktop computing(personal computing) 1990sInternet and Word Wide Web (servers) 2000sEmbedded computing, mobile computing, and pervasive computing

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-6 Tasks of a Computer Designer Determine what attributes are important for a new machine, then design a machine to maximize performance while staying within cost constraints. Task aspects: Instruction set design, functional organization, logic design, and implementation. In the past, “Computer Architecture” often referred only to instruction set design. Other aspects of computer design were called “implementation”. In this book, “Computer Architecture” is intended to cover all three aspects of computer design: instruction set architecture, organization and hardware. “Instruction set architecture” refers to the actual programmable-visible instruction set. It serves as the boundary between the hardware and software.

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-7 “organization” includes the high-level aspects of a computer’s design, such as the memory system, the bus structure, and the internal CPU. NEC VR5432 and NEC VR 4122 have the same instruction set architecture but with different organization. “Hardware” would include the detailed logic design and packaging technology of the machine. –For example: different Pentium microprocessors running in different frequency have the same instruction set architecture and organization but with different hardware implementation Organization and hardware are two components of implementations.

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-8 Functional Requirements (Fig. 1.4) Application Area: –General purpose, scientific and server, commercial, embedded computing Level of Software Compatibility –At programming language, object code or binary code compatibility Operating System Requirements –Size of address space, memory management, protection Standards –Floating point, I/O bus, operating systems, networks, programming languages

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-9 Technology Trends A successful instruction set architecture must be designed to survive changes in computer implementation technology. Trends in implementation technology: –Integrated circuit logic technology: Transistor density: 35% increase per year, quadruple in 4 years. Die size: 10%~20% increase per year Transistor count/per chip: 55% increase per year. Transistor speed: scales more slowly. –DRAM: Density: 40%~60% increase per year recently. Cycle time : decrease 1/3 in 10 years. –Magnetic disk: Density: 100% increase per year recently. 30% increase per year, double in 3 years, prior to –Network technology Ethernet: 10M to 100M to 1G byte band width.

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-10 Scaling of IC Technology IC Process Technology –10um(1971)0.18um(2001) IC Technology and Computer Performance –Transistor performance –Wire delay –Power consumption

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-11 Cost, Price and Their Trends Cost reduction factors –Learning curve drives the cost down; manufacturing costs over time, i.e., yield improvement. –High volume (i.e. mass production) –Commodities are products sold by multiple vendors in large volumes and essentially identical, i.e., competition. –Price of DRAM (fig. 1.5) –Price of Pentium III (fig. 1.6) Cost of an integrated circuit –Cost of die =f(die area) –Computer designer affects die size both by what functions are included on the die and by the number of I/O pins. Distribution of cost in a system (fig. 1.9, 1.10)

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-12 Prices of DRAM

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-13 Price of Pentium III

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-14 Price for $1000 PC

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-15 Measuring and Reporting Performance “X is n times faster than Y” means The term “system performance” is used to refer to elapsed time on an unloaded system. CPU performance refers to user CPU time on an unloaded system. To evaluate a new system is to compare the execution time of her workload - the mixture of programs and operating system commands run on a machine.

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-16 Choosing Programs to Evaluate Performance Best case: Measure the execution time of a system’s workload General case: five levels of programs are used: –Real programs: C compiler, Tex, Spice, etc. –Modified (scripted) applications: A collection of real applications… –Kernels: small, key pieces from the real programs, ex., Livermore loops and Linpack. –Toy Benchmarks: 10 to 100 lines of code and produce a result the user already knows, ex., puzzle, quicksort,… –Synthetic benchmarks: try to match the average frequency of operations and operands of a large set of programs, ex., Whetstone and Drystone. Performance prediction accuracy: –Real programs is best, wile synthetic benchmarks is worst. and reporting performance results (fig. 1.9 &1.10)

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-17 Benchmark Suites SPEC (Standard Performance Evaluation Corporation) – Benchmark types –Desktop benchmarks –Server benchmarks –Embedded benchmarks

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-18 Desktop Benchmarks SPEC Benchmarks –SPEC CPU2000 (SPEC95, SPEC92, SPEC89) (Fig. 1.12) –Graphic benchmarks SPECviewperf SPECapc Window’s OS benchmarks (Fig. 1.11) –Business Winstone –CC Winstone –Winbench

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-19 Server Benchmarks SPEC –File server benchmarks: SPECSFS Measuring NFS performance –Web server benchmarks: SPECWeb Simulate multiple clients requesting both static and dynamic pages. TPC (Transaction-Processing Council) –TPC-A, TPC-C, TPC-H, TPC-R, TPC-W Simulate a business-oriented transactions (queries)

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-20 Embedded Benchmarks EDN Embedded Microprocessor Benchmark Consortium (EEMBC) (Fig. 1.13) –Automotive/industrial –Consumer –Networking –Office automation –Telecommunications

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-21 Reporting Performance Results Guiding Principle –The performance measurements should be reproducibility. Needs to tell –Hardware configurations –Software used Is source code modification for benchmarks allowed?

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-22 Comparing Performance Computer A Computer BComputer C P1 (secs)11020 P2 (secs) Total time Total execution time: A consistent summary measure Another metrics –Average execution time (arithmetic mean) –Harmonic mean –Weighted execution time: –Geometric mean:

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-23 Quantitative Principles of Computer Design Make the common case fast: A fundamental law, called Amdahl’s Law, can be used to quantify this principle. Amdahl’s Law –the performance improvement to be gained from using some faster mode of execution is limited by the fraction of the time the faster mode can be used. –Amdahl’s Law defines speedup as Example on pages 41 and 42

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-24 CPU Performance Equation –Dependency Clock cycle time - Hardware technology and organization CPI - Organization and instruction set architecture Instruction count - Instruction set architecture and compiler –Sometimes and overall –Example on page 44.

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-25 Measuring the Components of CPU Performance Clock cycle time: Timing simulator or timing verifiers IC(instruction count) –Direct measurement from running the applications on hardware –Instruction set simulator - slow but accurate –Instrumentation code approach: the binary program is modified by inserting some extra code into every basic block. Fast but need instruction set translation if simulated machine differs from simulating machine. CPI: very difficult to measure CPI = Pipeline CPI + Memory system CPI Basic block Label:xxx Branch *** Branch *** Label: xxx Branch *** Branch *** Label: xxx Label: xxx Use the CPU performance equations to compute performance

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-26 Principle of Locality Application of Amdahl’s Law –A program spends 90% of execution time in on 10% of the code. –Temporal locality: Recently accessed items are likely to be accessed in the near future. –Spatial locality: Items whose addresses are near one another tend to be referenced close together in time.

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-27 Put it All Together Performance and Price-Performance –Desktop computers –Server computers –Embedded processors

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-28 Price and Performance of Desktops (1)

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-29 Price and Performance of Desktops (2)

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-30 Price and Performance of Servers (1)

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-31 Price and Performance of Servers (2)

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-32 Price&Performance of Embedded Processors (1)

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-33 Price&Performance of Embedded Processors (2)

Rung-Bin Lin Chapter 1: Fundamental of Computer Design1-34 Price&Performance of Embedded Processors (3)