Morgan Kaufmann Publishers April 27, 2017 January 25, 2016 Shambhu Upadhyaya (www.cse.buffalo.edu/faculty/shambhu) lecture slides: http://www.cse.buffalo.edu/faculty/shambhu/cse34116/ Chapter 1 — Computer Abstractions and Technology

Copyright/Acknowledgments Morgan Kaufmann Publishers April 27, 2017 Copyright/Acknowledgments The lecture material for this course has been adapted in part from UC Berkeley, Penn State, Publisher and Previous Semesters of Offerings at UB Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 Overview Administrative Matters (5 minutes) Course Style, Philosophy and Structure (15 min) Intro to Computer Architecture (30 minutes) Chapter 1 — Computer Abstractions and Technology — 3 Chapter 1 — Computer Abstractions and Technology

Course Administration Instructor: Shambhu Upadhyaya (shambhu@buffalo.edu) 329 Davis Hall Office Hours: Tuesdays 9:30 am – 11:00 am TAs: Hayreddin Ceker and Aleksey Charapko Labs: UNIX/Linux accounts for all More info. will be provided later Materials: http://www.cse.buffalo.edu/faculty/shambhu/cse34116 Newsgroup: sunyab.cse.341 (may not use) Blackboard: UBlearns Text: Computer Organization and Design: The Hardware/Software Interface, Fifth Edition, Patterson and Hennessy Chapter 1 — Computer Abstractions and Technology — 4

Textbook purchase options Paperback or eBook University Bookstore on campus New, used, rental Greeks and Sneaks Bookstore, 2 blocks from UB South campus (on Main street) Patterson Computer Org & Design, 5th Edition Amazon Chapter 1 — Computer Abstractions and Technology — 5

Course Exams Reduce the pressure of taking exams Midterms: Friday Feb 26th, Friday March 25th, Monday May 2nd 50 minutes to take 45 minute test ( in class) Our goal: test knowledge vs. speed writing All mid-terms closed book, no cheat sheets Necessary sheets will be provided No final exam Chapter 1 — Computer Abstractions and Technology — 6

Course Workload Reasonable workload (if you have good work habits) No final exam: Only 3 mid-terms Every recitation feeds into the project and lecture Project teams have 2-3 members (exact no. TBD) Science/Design units: 3 Science, 2 Design Chapter 1 — Computer Abstractions and Technology — 7

Homework Assignments and Project Assignments consist of two parts Homeworks – Individual Effort: Exercises from the text book Projects – Team Effort: Lab assignments Homework assignments go out on Fridays Assignments due in 10 days (Mondays) at beginning of lecture Brief (15 minute) quiz on assignment material in lecture or recitations (several of them) Must understand assignment to do quiz No late assignments! Recitations will help solve problems Homeworks will not be graded, but checked for completeness Solution will be posted on UBlearns Chapter 1 — Computer Abstractions and Technology — 8

My Goal Show you how to understand modern computer architecture in its rapidly changing form Show you how to design by leading you through the process on challenging design problems Learn how to test things Keep interactive So... ask questions come to office hours See the TA(s) Chapter 1 — Computer Abstractions and Technology — 9

Project/Lab Summary Verilog installed on Unix SPIM available on Unix, Windows Lab assignments 2-3 Projects Written report Code submission, if necessary Chapter 1 — Computer Abstractions and Technology — 10

Grading Grade breakdown No late homeworks or labs Three Midterm Exams: 55% (combined) Homeworks: 10% Projects: 20% Quizzes: 15% No late homeworks or labs Chapter 1 — Computer Abstractions and Technology — 11

Morgan Kaufmann Publishers April 27, 2017 Course Problems Can’t make midterm Tell us early and we will schedule alternate time, if appropriate Forgot to turn in homework … Computer/my cute dog ate whatever … No late homeworks or labs What is cheating? Common examples of cheating: running out of time on an assignment and take from another and copy, borrow solution “just to take a look”, peeking during exam, ... Cheating will be met with an ‘F’ for the course Studying together in groups is not discouraged Work must be your own Better off to skip an assignment (rather than copying) But it doesn’t help on quiz (15% of grade) anyway Dog: Courtesy….Google images Chapter 1 — Computer Abstractions and Technology — 12 Chapter 1 — Computer Abstractions and Technology

Project Simulates Industrial Environment Project teams have 2-3 members in same discussion section Must work in groups in “the real world” Communicate with colleagues (team members) Communication problems are natural What have you done? What answers you need from others? You must document your work!!! Everyone must keep an on-line notebook Communicate with supervisor (TAs) How is the team’s plan? Short progress reports are required What is the team’s game plan? What is each member’s responsibility? Chapter 1 — Computer Abstractions and Technology — 13

The Instruction Set: a Critical Interface Morgan Kaufmann Publishers April 27, 2017 The Instruction Set: a Critical Interface software instruction set hardware Computer organization/computer architecture lays the foundation for the entire IT industry – Patterson The datacenter/cloud is a computer, your cell phone is a computer, your automobile is a computer Intel and Microsoft come to your mind – intel builds the heart of the computer, microsoft builds the breath. Why do you want to know computer architecture? – describes the inner workings of the computer Chapter 1 — Computer Abstractions and Technology — 14 Chapter 1 — Computer Abstractions and Technology

How Do the Pieces Fit Together? Morgan Kaufmann Publishers April 27, 2017 How Do the Pieces Fit Together? Application Operating System Compiler Firmware Instruction Set Architecture Memory system Instr. Set Proc. I/O system Datapath & Control Digital Design Circuit Design For class handout Coordination of many levels of abstraction Under a rapidly changing set of forces Design, measurement, and evaluation Chapter 1 — Computer Abstractions and Technology — 15 Chapter 1 — Computer Abstractions and Technology

How Do the Pieces Fit Together? Morgan Kaufmann Publishers April 27, 2017 How Do the Pieces Fit Together? Application Operating CSE 421 System CSE 443 Compiler Firmware Instruction Set Architecture Memory system Instr. Set Proc. I/O system CSE 241 & 341 & 490 Datapath & Control Digital Design CSE 379 Circuit Design CSE 493 & 452 For lecture CSE 443 – Intro. To language processors Coordination of many levels of abstraction Under a rapidly changing set of forces Design, measurement, and evaluation Chapter 1 — Computer Abstractions and Technology — 16 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers Computer Abstractions and Technology April 27, 2017 Chapter 1 Computer Abstractions and Technology Chapter 1 — Computer Abstractions and Technology

The Computer Revolution Morgan Kaufmann Publishers April 27, 2017 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 — 18 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 Classes of Computers Personal 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 Chapter 1 — Computer Abstractions and Technology — 19 Chapter 1 — Computer Abstractions and Technology

Classes of Computers Supercomputers Embedded computers High-end scientific and engineering calculations Highest capability but represent a small fraction of the overall computer market Embedded computers Hidden as components of systems Stringent power/performance/cost constraints Chapter 1 — Computer Abstractions and Technology — 20

Morgan Kaufmann Publishers April 27, 2017 The PostPC Era Y- Chapter 1 — Computer Abstractions and Technology — 21 Chapter 1 — Computer Abstractions and Technology

The PostPC Era Personal Mobile Device (PMD) Cloud computing Battery operated Connects to the Internet Hundreds of dollars Smart phones, tablets, electronic glasses Cloud computing Warehouse Scale Computers (WSC) Software as a Service (SaaS) Portion of software run on a PMD and a portion run in the Cloud Amazon and Google Chapter 1 — Computer Abstractions and Technology — 22

Morgan Kaufmann Publishers April 27, 2017 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 — 23 Chapter 1 — Computer Abstractions and Technology

Understanding Performance Morgan Kaufmann Publishers April 27, 2017 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 — 24 Chapter 1 — Computer Abstractions and Technology

Eight Great Ideas Design for Moore’s Law Use abstraction to simplify design Make the common case fast Performance via parallelism Performance via pipelining Performance via prediction Hierarchy of memories Dependability via redundancy §1.2 Eight Great Ideas in Computer Architecture Chapter 1 — Computer Abstractions and Technology — 25

Morgan Kaufmann Publishers April 27, 2017 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 §1.3 Below Your Program Chapter 1 — Computer Abstractions and Technology — 26 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 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 — 27 Chapter 1 — Computer Abstractions and Technology

Components of a Computer Morgan Kaufmann Publishers April 27, 2017 Components of a Computer §1.4 Under the Covers Same components for all 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 — 28 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 Touchscreen PostPC device Supersedes keyboard and mouse Resistive and Capacitive types Most tablets, smart phones use capacitive Capacitive allows multiple touches simultaneously Chapter 1 — Computer Abstractions and Technology — 29 Chapter 1 — Computer Abstractions and Technology

Through the Looking Glass Morgan Kaufmann Publishers April 27, 2017 Through the Looking Glass LCD screen: picture elements (pixels) Mirrors content of frame buffer memory Chapter 1 — Computer Abstractions and Technology — 30 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 Opening the Box Capacitive multitouch LCD screen 3.8 V, 25 Watt-hour battery Computer board Chapter 1 — Computer Abstractions and Technology — 31 Chapter 1 — Computer Abstractions and Technology

Inside the Processor (CPU) Morgan Kaufmann Publishers April 27, 2017 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 — 32 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 Inside the Processor Apple A5 Chapter 1 — Computer Abstractions and Technology — 33 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 Abstractions The BIG Picture 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 Chapter 1 — Computer Abstractions and Technology — 34 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 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 — 35 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 Networks Communication, resource sharing, nonlocal access Local area network (LAN): Ethernet Wide area network (WAN): the Internet Wireless network: WiFi, Bluetooth Chapter 1 — Computer Abstractions and Technology — 36 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 Technology Trends Electronics technology continues to evolve Increased capacity and performance Reduced cost §1.5 Technologies for Building Processors and Memory DRAM capacity Year Technology Relative performance/cost 1951 Vacuum tube 1 1965 Transistor 35 1975 Integrated circuit (IC) 900 1995 Very large scale IC (VLSI) 2,400,000 2013 Ultra large scale IC 250,000,000,000 8Gigabit ICs are now available - 2014 Chapter 1 — Computer Abstractions and Technology — 37 Chapter 1 — Computer Abstractions and Technology

Semiconductor Technology Silicon: semiconductor Add materials to transform properties: Conductors Insulators Switch Chapter 1 — Computer Abstractions and Technology — 38

Morgan Kaufmann Publishers April 27, 2017 Manufacturing ICs Yield: proportion of working dies per wafer Chapter 1 — Computer Abstractions and Technology — 39 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 Intel Core i7 Wafer 300mm wafer, 280 chips, 32nm technology Each chip is 20.7 x 10.5 mm Chapter 1 — Computer Abstractions and Technology — 40 Chapter 1 — Computer Abstractions and Technology

Integrated Circuit Cost Morgan Kaufmann Publishers April 27, 2017 Integrated Circuit Cost Nonlinear relation to area and defect rate Wafer cost and area are fixed Defect rate determined by manufacturing process Die area determined by architecture and circuit design Chapter 1 — Computer Abstractions and Technology — 41 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 Defining Performance §1.6 Performance Which airplane has the best performance? Chapter 1 — Computer Abstractions and Technology — 42 Chapter 1 — Computer Abstractions and Technology

Response Time and Throughput Morgan Kaufmann Publishers April 27, 2017 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 — 43 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 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 — 44 Chapter 1 — Computer Abstractions and Technology

Measuring Execution Time Morgan Kaufmann Publishers April 27, 2017 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 — 45 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 CPU Clocking Operation of digital hardware governed by a constant-rate clock Clock period Clock (cycles) Data transfer and 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 — 46 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 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 — 47 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 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 — 48 Chapter 1 — Computer Abstractions and Technology

Instruction Count and CPI Morgan Kaufmann Publishers April 27, 2017 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 — 49 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 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 — 50 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 CPI in More Detail If different instruction classes take different numbers of cycles Weighted average CPI Relative frequency Chapter 1 — Computer Abstractions and Technology — 51 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 CPI Example Alternative compiled code sequences using instructions in classes A, B, C Class A B C CPI for class 1 2 3 IC in sequence 1 IC in sequence 2 4 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 — 52 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 Performance Summary The BIG Picture Performance depends on Algorithm: affects IC, possibly CPI Programming language: affects IC, CPI Compiler: affects IC, CPI Instruction set architecture: affects IC, CPI, Tc Chapter 1 — Computer Abstractions and Technology — 53 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 Power Trends §1.7 The Power Wall In CMOS IC technology Intel 4004 (108 KHz) in 1971 Intel 8008 (800 KHz) in 1972 Intel 8080 (2M MHz) in 1974 Intel 8086 (5 MHz) in 1978 ×30 5V → 1V ×1000 Chapter 1 — Computer Abstractions and Technology — 54 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 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 — 55 Chapter 1 — Computer Abstractions and Technology

Uniprocessor Performance Morgan Kaufmann Publishers April 27, 2017 Uniprocessor Performance §1.8 The Sea Change: The Switch to Multiprocessors Constrained by power, instruction-level parallelism, memory latency Chapter 1 — Computer Abstractions and Technology — 56 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 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 — 57 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 SPEC CPU Benchmark Programs used to measure performance Supposedly typical of actual workload Standard Performance Evaluation Corp (SPEC) Develops benchmarks for CPU, I/O, Web, … SPEC CPU2006 Elapsed time to execute a selection of programs Negligible I/O, so focuses on CPU performance Normalize relative to reference machine Summarize as geometric mean of performance ratios CINT2006 (integer) and CFP2006 (floating-point) Chapter 1 — Computer Abstractions and Technology — 58 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 CINT2006 for Intel Core i7 920 Chapter 1 — Computer Abstractions and Technology — 59 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 SPEC Power Benchmark Power consumption of server at different workload levels Performance: ssj_ops/sec Power: Watts (Joules/sec) Chapter 1 — Computer Abstractions and Technology — 60 Chapter 1 — Computer Abstractions and Technology

SPECpower_ssj2008 for Xeon X5650 Morgan Kaufmann Publishers April 27, 2017 SPECpower_ssj2008 for Xeon X5650 Chapter 1 — Computer Abstractions and Technology — 61 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 Pitfall: Amdahl’s Law Improving an aspect of a computer and expecting a proportional improvement in overall performance §1.10 Fallacies and Pitfalls Example: multiply accounts for 80s/100s How much improvement in multiply performance to get 5× overall? Can’t be done! Corollary: make the common case fast Chapter 1 — Computer Abstractions and Technology — 62 Chapter 1 — Computer Abstractions and Technology

Fallacy: Low Power at Idle Morgan Kaufmann Publishers April 27, 2017 Fallacy: Low Power at Idle Look back at i7 power benchmark At 100% load: 258W At 50% load: 170W (66%) At 10% load: 121W (47%) Google data center Mostly operates at 10% – 50% load At 100% load less than 1% of the time Consider designing processors to make power proportional to load Chapter 1 — Computer Abstractions and Technology — 63 Chapter 1 — Computer Abstractions and Technology

Pitfall: MIPS as a Performance Metric Morgan Kaufmann Publishers April 27, 2017 Pitfall: MIPS as a Performance Metric MIPS: Millions of Instructions Per Second Doesn’t account for Differences in ISAs between computers Differences in complexity between instructions CPI varies between programs on a given CPU Chapter 1 — Computer Abstractions and Technology — 64 Chapter 1 — Computer Abstractions and Technology

Morgan Kaufmann Publishers April 27, 2017 Concluding Remarks 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 §1.9 Concluding Remarks Chapter 1 — Computer Abstractions and Technology — 65 Chapter 1 — Computer Abstractions and Technology