Edward Chang Electrical Computer Engineering

  ECE154 ECE154 Computer Architecture Computer Architecture

  Lecture #1 Lecture #1

  Edward Chang Electrical & Computer Engineering _{ECE154 Winter 2003 1/6/2003}

  1 ECE154 Team

  ECE154 Team l Instructor: Edward Chang l TAs

• – Chao, Chia-Tso – Gadepalli, S.

  l Office Hours and Contact Information

• – Check class Web site frequently
• – http://www.mmdb.ece.ucsb.edu/~ece154/

  Class Email Address l _{ECE154 Winter 2003} – ece154@mmdb.ece.ucsb.edu ₂

• – Basic digital logic
• – Assembly programming
• – Simple OS concepts

  1/6/2003 ^{ECE154 Winter 2003 3} Textbook and Prerequisite

  Textbook and Prerequisite l “Computer Architectures: A Quantitative

  Approach’’, 3 rd edition, J. Hennessy and D.

  Patterson l Prerequisite

• – HW: 20%; Midterms: 30%; Final: 50%
>– All deadlines are final, no exceptions
• – Regrading requests must be in writing

  ECE154 Winter 2003 ⁴ Assignments and Exams

  Assignments and Exams l

6 Homework Assignments

  l Midterm on 2/10 l Final on 3/12 l Grading

  l Policies

• – 8 – 9am 387 104
• – 12 – 1pm SNDCR 1637
• – 1 – 2pm 387 103
• – 2 – 3pm PHELP 1445

  1/6/2003 ^{ECE154 Winter 2003 5} Discussion Session Signup

  Discussion Session Signup l Four Sessions (Friday)

  ECE154 Winter 2003 ⁶ Course Outline

  Course Outline

• – Design process, constraints, tools
• – Execution Time vs. Throughput – CPU time equation
• – Amdhal’s law

  1/6/2003 ^{ECE154 Winter 2003 7} Today

  Today ’

  ’ s Outline s Outline l Class Goals l What is Computer Architecture

  l Performance

  l Basic Design Principles l Chip Cost

• – Instruction-set architecture
• – Hardware and software techniques for instruction-level parallelism
• – Memory hierarchy and IO storage
• – Multiprocessor and multimedia processors

  ECE154 Winter 2003 ⁸ Class Goals

  Class Goals l

  Understand how computer systems are organized and why they are organized that way l

  

Be conversant with techniques for analyzing performance

and comparing systems l

  Introduction to computer implementation techniques l

  Will discuss advanced topics Components of a General Purpose - Purpose - Components of a General

  Computer System Computer System

  Programmable Processor

l

• – CPU, DSP, microprocessor

  Memory

l

• – For program and data
• – Cache, DRAM, MEMS

  Storage

l

  Buses and Controllers

l

• – Connecting CPU, memory, storage _{ECE154 Winter 2003}
• – Connecting networks _1/6/2003
₉ Computer Architecture?

  Computer Architecture? _{ECE154 Winter 2003}

  10 History of Computer Systems History of Computer Systems l 1960s – 1970s

• – Mainframes and minicomputers

  Late 1970 l

• – Emergence of microprocessor

  Late 1980 l

• – C and compilers
• – Unix – RISC
_{ECE154 Winter 2003 1/6/2003}

  11 Relative Performance

  Relative Performance _{ECE154 Winter 2003}

  12

  

The Contribution of Architectural

The Contribution of Architectural

  Innovation Innovation l 2001 Statistics

• – Base circuit design performance: X – Architectural innovation: 15 X

  l ECE154 is about

• – Innovative architecture ideas
• – Measured by a quantitative approach
_{ECE154 Winter 2003 1/6/2003}

  13 Computer Categories

  

Computer Categories

l Desktops
• – Examples: PCs, workstations
• – Metrics: latency (graphics & IO)

  l Servers

• – Examples: Web, database servers
• – Metrics: throughput, reliability, scalability

  l Embedded Systems

• – Examples: PDAs, cell phones, set-top boxes _{ECE154 Winter 2003}
• – Metrics: complexity, power, latency
₁₄

  

Technology Trends

Technology Trends

  (Yearly Improvement) (Yearly Improvement) Integrated Circuit: logic l

• – 35% increase in density, 55% a chip
• – 15% speedup

  Integrated Circuit: memory l

• – 60% increase in density
• – 7% reduction in latency
• – 14% increase in throughput

  Magnetic Disks l

• – 100% increase in density
• – Access time improvement 33% in ten years

  Networking l

• – Little improvement in latency _{ECE154 Winter 2003}
• – Large improvement in bandwidth _1/6/2003
₁₅ Technology Trends

  

Technology Trends

(Yearly Improvement) (Yearly Improvement) l Feature Size (f)
• – Shrinks from 10 microns (1971) to 0.18 (2001)

  Device Size l

• – Shrinks quadratically with decrease in feature size

  Transistor Count l

• – Improves quadratically w.r.t. 1/f

  Transistor Performance l

• – Improves linearly w.r.t. 1/f
_{ECE154 Winter 2003}

  16 Performance Bottlenecks Performance Bottlenecks l Wires

• – No improvement
• – Pentium IV allocates 2 out of 20-stage pipeline for wire delay

  l Power

  2

• – Switching frequency * load capacitance * voltage

  st

• – The 1 microprocessor consumes 1/10 watt
• – 2GHz Pentium-4 consumes 100 watts
_{ECE154 Winter 2003 1/6/2003}

  17 Changing Technology Changes

  

Changing Technology Changes

Architecture Architecture _{ECE154 Winter 2003}

  18 Cost, Price, and Trends Cost, Price, and Trends

  Factors Affect Cost

l

• – Yield – Competition

  Price

l

• – Memory: Price = cost
• – CPU: Price = (1+k%) cost

  Computer Price

l

• – Dominated by processor,
• – Monitor
_{ECE154 Winter 2003 1/6/2003}

  19 Relative Performance

  Relative Performance _{ECE154 Winter 2003}

  20

  

Measuring Performance

Measuring Performance

l X performs N time better than Y
• – X runs N-times faster than Y – X takes 1/N time, compared to Y, to complete the task

• – X takes 1/N+1 time, compared to Y, to complete the task

• – X responds N-times faster than Y

  l Improve a system performance by N folds

• – Decrease its running time by N folds
• – Increase its throughput by N folds

  CAQA’s position l _{ECE154 Winter 2003} – Use Execution Time to measure performance _{1/6/2003 21} Execution Time

  

Execution Time

l Elapsed Time l Response Time l CPU Time
• – User CPU time and system CPU time
• – The choice of CAQA to measure processor performance (throughout Chapter 4)

  Many Benchmarks l

• – But none can be perpetually and universally applicable
₂₂ ECE154 Winter 2003

  1/6/2003 ^{ECE154 Winter 2003 23} Benchmark Examples

  Benchmark Examples

  ECE154 Winter 2003 ²⁴ Performance Summary

  Performance Summary l A is 10 times faster than B for program P1 l B is 10 times faster than A for program P2 l A is 10 times faster than C for program P1 l C is 10 times faster than A for program P2 l B is 10 times faster than C for program P1 l

  C is 10 times faster than B for program P2

  1/6/2003 ^{ECE154 Winter 2003 25} Execution Time

  Execution Time Total Time 1001 40 110 P2 1000 20 100

  20

  

10

  Computer C Computer

B

  Computer A

1 P1

• – if P1 and P2 are run equally in the workload

  ECE154 Winter 2003 ²⁶ Arithmetic Means

  Arithmetic Means l B is 9.1 faster than A for P1 + P2 l C is 25 times faster than A for P1 + P2 l C is 2.75 times faster than B for P1 + P2 l

  Arithmetic mean is fine

• – Σ
• – w

  1/6/2003 ^{ECE154 Winter 2003 27} Weighted Execution Time

  Weighted Execution Time l Weighted Arithmetic Mean

  w i

  × t i

  i : frequency of execution of the i th program

  ECE154 Winter 2003 ²⁸ Weights

  Weights .5 .091 .001 P2 1000 20 100 .5 .909 .999

  20

  10

  W(1) on C W(2) on B

  W(3) on A C B A Weightings Programs

1 P1

  1/6/2003 ^{ECE154 Winter 2003 29} Weighted Arithmetic Means

  Weighted Arithmetic Means

1 P1

  20 55 500.5 W(1)

  20

  18.19

  20

  10.09

  2 W(3) P2 1000 20 100

  20

  

10

  

C B A

91.91 W(2)

  ECE154 Winter 2003 ³⁰ Geometric Means

  Geometric Means l The Weighted Arithmetic Mean differs depending on which machine is the reference one. l Geometric Mean

  1/6/2003 ^{ECE154 Winter 2003 31} Geometric Mean

  0.02

  10.01

  5.05

  1.0 Arm

  1.0

  5.0

  50.0

  0.2

  

1.0

  10.0

  0.1

  

1.0

  1.0 P2 1.0 0.5 0.005

  2.0

  

1.0

  0.1

  20.0

  10.0

  1.0 P1

C B A C B A C B A

  

Normalized to C Normalized to B Normalized to A

  ECE154 Winter 2003 ³² Summary of Means

  5.05

  1.1

  

Geometric Mean

  1.0

  1.0

  2.75

  25.03

  0.36

  

1.0

  9.1

  0.04

  0.11

  1.0 TT

  1.58

  25.03

  1.58

  0.63

  

1.0

  1.0

  0.63

  1.0

  1.0 Geo

  1.0

  2.75

  

Summary of Means

  Design Principles Design Principles

  Make the Common Case Fast l

  Principle of Locality l

  Parallelism l _{ECE154 Winter 2003 1/6/2003}

  33 Make the Common Case Fast

  Make the Common Case Fast Amdahl’s Law l

• – The performance gain is limited by the

  fraction of time the faster mode can be used

  Example l

• – Meal time = Order time + Eating time
• – 40 mins = 20 mins + 20 mins
• – Speeding up eating alone cannot reduce the _{ECE154 Winter 2003}

  meal time to be under 20 mins ₃₄

  Make the Common Case Fast Make the Common Case Fast _{ECE154 Winter 2003 1/6/2003}

  35 Examples

  Examples

  IO time is 60% of the execution time, and l

  CPU time 40% Speeding up CPU 10 times achieves l overall speedup of

• – 1 / (0.6 + (0.4/10))
• – 1.56
_{ECE154 Winter 2003}

  36

  1/6/2003 ^{ECE154 Winter 2003 37} CPU Performance Equation

  CPU Performance Equation

  ECE154 Winter 2003 ³⁸ Computer Architecture?

  Computer Architecture?

• – Design to last through trends
• – Amdahl's law
• – CUP time formula
• – Make the common case fast
• – Locality – Parallelism

  1/6/2003 ^{ECE154 Winter 2003 39} Summary

  Summary l

  Computer Architecture

  l Performance Metrics

  l Design Principles

  ECE154 Winter 2003 ⁴⁰ References

  References l

  Textbook figures, publisher l

  Lecture notes, prof. Kozyrakis, Stanford