程序代写代做代考 arm assembly compiler algorithm cache mips Rosetta Demostrator Project MASC, Adelaide University and Ashenden Designs

Rosetta Demostrator Project MASC, Adelaide University and Ashenden Designs

COMPUTER ORGANIZATION AND DESIGN
The Hardware/Software Interface

5th

Edition

Chapter 1

Computer Abstractions

and Technology

Chapter 1 — Computer Abstractions and Technology — 2

The Computer Revolution

 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

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(IC resources double every

______ months)

( ______’s law: memory capacity

doubles every ____ months)

(Allows ___________ medical care)

(Web 1.0  Web ___  Web ___ ( __________ web))

(gnome: ____ _______ _______ _____ ___________ ) *

Chapter 1 — Computer Abstractions and Technology — 3

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

Classes of Computers

 Supercomputers

 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 — 4

(Processor core: processor written in ____, allowing integration with other ___ on a single chip)

Chapter 1 — Computer Abstractions and Technology — 5

The PostPC Era

The PostPC Era

Chapter 1 — Computer Abstractions and Technology — 6

 Personal Mobile Device (PMD)

 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

(Wireless; apps; heptics and speech input)

(Public/Private/________)

Chapter 1 — Computer Abstractions and Technology — 7

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*

(Multicore microprocessor)

(Energy efficiency)

Chapter 1 — Computer Abstractions and Technology — 8

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

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

Chapter 1 — Computer Abstractions and Technology — 9

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(Design for the technology available when the design ________ )

(Information _______; OO design)

( ______ )

(Asking for forgiveness is better than asking for ____________ )

(Top: fastest/smallest/______ expensive)

Chapter 1 — Computer Abstractions and Technology — 10

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

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Chapter 1 — Computer Abstractions and Technology — 11

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

(Microprocessor

wIthout Pipeline _____ )

(Million Instructions Per ______ )

Chapter 1 — Computer Abstractions and Technology — 12

Components of a Computer

 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

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The BIG Picture

Chapter 1 — Computer Abstractions and Technology — 13

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 — 14

Through the Looking Glass

 LCD screen: picture elements (pixels)

 Mirrors content of frame buffer memory

Chapter 1 — Computer Abstractions and Technology — 15

Opening the Box*

Capacitive multitouch LCD screen

3.8 V, 25 Watt-hour battery

Computer board

(Wi-Fi, _________ )

(camera, _________)

(Gyroscope, _______meter)

(Speaker)

(iPad 2 A1395 tablet PC, _____ )

( _____ ARM cores, ___Hz, ______ DRAM

of ___nsec and $5/GB)

( ____ flash memory) (Power and I/O

controller)

(Most recent one (2016): ______ _______ )

Chapter 1 — Computer Abstractions and Technology — 16

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 — 17

Inside the Processor

 Apple A5*
(12.1 x 10.1 mm; _____ process; iPad 2; iPhone 4S; _____ )
( _______ SoC; ____Hz)

Chapter 1 — Computer Abstractions and Technology — 18

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

(HW obeying the architecture abstraction)

Chapter 1 — Computer Abstractions and Technology — 19

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)

( ___sec access time, $____/GB)

( ___sec access time, $____/GB; standard for

PMD; wear out after 500,000 _______ )

( _____ )
(SD( ______ Digital) card/

MMC( _________ card)

Chapter 1 — Computer Abstractions and Technology — 20

Networks

 Communication, resource sharing,

nonlocal access*

 Local area network (LAN): Ethernet*

 Wide area network (WAN): the Internet

 Wireless network: WiFi, Bluetooth*

(cost proportional to speed and _________ )

(a few ___; ____/sec)

(over 100’s km; ______ ______ )

(IEEE 802.___; ______/sec)

(IEEE 802.15.1; _____/sec)

Chapter 1 — Computer Abstractions and Technology — 21

Technology Trends

 Electronics

technology

continues to evolve

 Increased capacity

and performance

 Reduced cost

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

DRAM capacity

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( ________ transistors)

( __ times/3 yrs)

( __ times/3 yrs)

Semiconductor Technology

 Silicon: semiconductor

 Add materials to transform properties:

 Conductors

 Insulators

 Switch

Chapter 1 — Computer Abstractions and Technology — 22

Chapter 1 — Computer Abstractions and Technology — 23

Manufacturing ICs

 Yield: proportion of working dies per wafer

( ______ diameter; _______ long)
(< ______ thick) Chapter 1 — Computer Abstractions and Technology — 24 Intel Core i7 Wafer  300mm wafer, 280 chips, 32nm technology  Each chip is 20.7 x 10.5 mm ( __Cores; ___ Threads; ____GHz ; _____ Cache ) ($_____ ) Chapter 1 — Computer Abstractions and Technology — 25 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 2 area/2)) Diearea per (Defects(1 1 Yield area Diearea Wafer waferper Dies Yield waferper Dies waferper Cost die per Cost      (High volume reduces the cost of a chip due to higher _____ and lower __________ cost per die) Chapter 1 — Computer Abstractions and Technology — 26 Defining Performance  Which airplane has the best performance? 0 100 200 300 400 500 Douglas DC-8-50 BAC/Sud Concorde Boeing 747 Boeing 777 Passenger Capacity 0 2000 4000 6000 8000 10000 Douglas DC- 8-50 BAC/Sud Concorde Boeing 747 Boeing 777 Cruising Range (miles) 0 500 1000 1500 Douglas DC-8-50 BAC/Sud Concorde Boeing 747 Boeing 777 Cruising Speed (mph) 0 100000 200000 300000 400000 Douglas DC- 8-50 BAC/Sud Concorde Boeing 747 Boeing 777 Passengers x mph § 1 .6 P e rfo rm a n c e (Different for passenger and airplane designer) Chapter 1 — Computer Abstractions and Technology — 27 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… * (Important for _________ _____ ) (Important for _______ ___________ ) (Also called _________ time; depends on memory and disk access time, OS overhead, CPU speed, etc) ( ________ ) (Both response time and throughput _______ ) ( _________ increases) ( _______ ) ( _______ ) Chapter 1 — Computer Abstractions and Technology — 28 Relative Performance  Define Performance = 1/Execution Time  “X is n time faster than Y” n XY YX time Executiontime Execution ePerformancePerformanc  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 — 29 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 — 30 CPU Clocking*  Operation of digital hardware governed by a constant-rate clock Clock (cycles) Data transfer and computation Update state Clock period  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 (Clock cycle, clock rate) Chapter 1 — Computer Abstractions and Technology — 31 CPU Time  Performance improved by  Reducing number of clock cycles  Increasing clock rate  Hardware designer must often trade off clock rate against cycle count Rate Clock Cycles Clock CPU Time Cycle ClockCycles Clock CPUTime CPU   (for a program) (for a program) Chapter 1 — Computer Abstractions and Technology — 32 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? 4GHz 6s 1024 6s 10201.2 Rate Clock 10202GHz10s Rate ClockTime CPUCycles Clock 6s Cycles Clock1.2 Time CPU Cycles Clock Rate Clock 99 B 9 AAA A B B B          Chapter 1 — Computer Abstractions and Technology — 33 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 Rate Clock CPICount nInstructio Time Cycle ClockCPICount nInstructioTime CPU nInstructio per CyclesCount nInstructioCycles Clock     (Average) ( ___ ) ( ___________ ) Chapter 1 — Computer Abstractions and Technology — 34 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? 1.2 500psI 600psI A Time CPU B Time CPU 600psI500ps1.2I B Time Cycle B CPICount nInstructio B Time CPU 500psI250ps2.0I A Time Cycle A CPICount nInstructio A Time CPU         A is faster… …by this much Chapter 1 — Computer Abstractions and Technology — 35 CPI in More Detail  If different instruction classes take different numbers of cycles    n 1i ii )Count nInstructio(CPICycles Clock  Weighted average CPI          n 1i i i Count nInstructio Count nInstructio CPI Count nInstructio Cycles Clock CPI Relative frequency Chapter 1 — Computer Abstractions and Technology — 36 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 2 1 2 IC in sequence 2 4 1 1  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 (Which one is faster?) Chapter 1 — Computer Abstractions and Technology — 37 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 cycle Clock Seconds nInstructio cycles Clock Program nsInstructio Time CPU  (IC depends on the architecture, not ___________ ) (All the three factors need to be considered together for fair comparison) (If an algorithm uses more divides than multiplications, it will cause a ______ CPI) (The more indirect calls due to data abstraction, the ______ CPI) (Loop unrolling for ________ CPI) (IPC: Instructions per ______ _______ ) (Intel Core i7 Turbo mode) Chapter 1 — Computer Abstractions and Technology — 38 Power Trends  In CMOS IC technology* § 1 .7 T h e P o w e r W a ll FrequencyVoltageload CapacitivePower 2  × 1000 × 30 5V → 1V (Slow down due to the limit in _______ ) (dynamic energy consumption due to _________ ) (Joule/second) (depends on fanout and technology) Chapter 1 — Computer Abstractions and Technology — 39 Reducing Power  Suppose a new CPU has  85% of capacitive load of old CPU  15% voltage and 15% frequency reduction 0.520.85 FVC 0.85F0.85)(V0.85C P P 4 old 2 oldold old 2 oldold old new      The power wall  We can’t reduce voltage further*  We can’t remove more heat*  How else can we improve performance? (With too low voltage, too leaky; ___% of power consumption is static due to leakage) (Cooling fan, turning off part of chip, hundreds pins for power and ______, etc) (Warehouse scale computer) Chapter 1 — Computer Abstractions and Technology — 40 Uniprocessor Performance § 1 .8 T h e S e a C h a n g e : T h e S w itc h to M u ltip ro c e s s o rs Constrained by power, instruction-level parallelism, memory latency (SPECint benchmark) Chapter 1 — Computer Abstractions and Technology — 41 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 * (since _____ ) (Pipelining) (Scheduling) (The more processors, the more ________ ) Chapter 1 — Computer Abstractions and Technology — 42 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) n n 1i i ratio time Execution  (Workload: a set of ________ run on a computer, actual applications or mix of real programs) (Benchmark: a program selected for use in _________ computer performance) (‘89) (12 benchmarks) (17 benchmarks)    n 1 i ii Time Weight (For execution time) (For rate)   n 1 i i i Rate Weight 1 Chapter 1 — Computer Abstractions and Technology — 43 CINT2006 for Intel Core i7 920 (9770/508) (Reference independence with geometric mean) (0.44 ~ 2.66; difference of a factor of 5) Chapter 1 — Computer Abstractions and Technology — 44 SPEC Power Benchmark  Power consumption of server at different workload levels  Performance: ssj_ops/sec  Power: Watts (Joules/sec)                10 0i i 10 0i i powerssj_ops Wattper ssj_ops Overall (Operations per second) Chapter 1 — Computer Abstractions and Technology — 45 SPECpower_ssj2008 for Xeon X5650 (2.66GHz, 16MB, 100GB SSD) Chapter 1 — Computer Abstractions and Technology — 46 Pitfall: Amdahl’s Law  Improving an aspect of a computer and expecting a proportional improvement in overall performance § 1 .1 0 F a lla c ie s a n d P itfa lls 20 80 20  n  Can’t be done! unaffected affected improved T factor timprovemen T T   Example: multiply accounts for 80s/100s  How much improvement in multiply performance to get 5× overall?  Corollary: make the common case fast (Law of ___________ return; the return is limited by the portion of the improvement is applied) Chapter 1 — Computer Abstractions and Technology — 47 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 * (Energy-proportional computing) Chapter 1 — Computer Abstractions and Technology — 48 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 6 6 6 10CPI rate Clock 10 rate Clock CPIcount nInstructio count nInstructio 10time Execution count nInstructio MIPS         CPI varies between programs on a given CPU (Usually the larger the better) Chapter 1 — Computer Abstractions and Technology — 49 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 C o n c lu d in g R e m a rk s (Others are valid in a limited context or requires preconditions)