Computer Abstractions and Technology

Chapter Objectives

1. be able to identify which ones are Hardware, or System Software, or Application software of a computer

2. be able to identify which ones are High-level languages, or Assembly language, or Machine language

3. be able to identify which ones are Operating systems, or Compilers, or Assemblers

4. be able to evaluate a computer’s performance based on its clock rate and CPI

What You Will Learn

nHow programs are translated into the machine language

nAnd how the hardware executes them

nThe hardware/software interface

nWhat determines program performance

nAnd how it can be improved

nHow hardware designers improve performance

nWhat is parallel processing

Understanding Performance

nAlgorithm

nDetermines number of operations executed

nProgramming language, compiler, architecture

nDetermine number of machine instructions executed per operation

nProcessor and memory system

nDetermine how fast instructions are executed

nI/O system (including OS)

nDetermines how fast I/O operations are executed

Eight Great Ideas

Below Your Program

Levels of Program Code

Inside the Processor (CPU)

nDatapath: performs operations on data

nControl: sequences datapath, memory, ...

nCache memory

nSmall fast SRAM memory for immediate access to data

Networks

nCommunication, resource sharing, nonlocal access

nLocal area network (LAN): Ethernet

nWide area network (WAN): the Internet

nWireless network: WiFi, Bluetooth

Manufacturing ICs

Integrated Circuit Cost

Defining Performance

Response Time and Throughput

nResponse time

nHow long it takes to do a task

nThroughput

nTotal work done per unit time

ne.g., tasks/transactions/… per hour

nHow are response time and throughput affected by

nReplacing the processor with a faster version?

nAdding more processors?

nWe’ll focus on response time for now…

Relative Performance

CPU Clocking

CPU Time

 CPU Time Example

Instruction Count and CPI

CPI Example

CPI in More Detail

CPI Example

Performance Summary

Concluding Remarks

nCost/performance is improving

nDue to underlying technology development

nHierarchical layers of abstraction

nIn both hardware and software

nInstruction set architecture

nThe hardware/software interface

nExecution time: the best performance measure

nPower is a limiting factor

        Use parallelism to improve performance