1 Ó1998 Morgan Kaufmann Publishers Chapter 8 I/O Systems.

11998 Morgan Kaufmann Publishers

Chapter 8I/O Systems


5 Components of Any Computer


“What’s This Stuff Good For?”


Motivation for Input/Output


I/O Design Issues


Outline


I/O System Performance


Simple Producer-Server Model


Throughput vs. Respond Time


Throughput Enhancement


I/O Benchmarks for Perf. Measure (1/2)


I/O Benchmarks for Perf. Measure (2/2)


Outline


I/O Device Examples and Speeds


Magnetic Disk


Disk History (1/2)


Disk History (2/2)


1-inch Disk Drive!


Storage Technology Drivers


Historical Perspective


Technology Trends


Disk Device Technology


Photo of Disk Head, Arm, Actuator


Magnetic Disk Characteristic


Typical Numbers of a Magnetic Disk


Recent Example: Barracuda 180


Disk Device Performance

※Assumes average seek distance is random


Example


Areal Density


Data Rate: Inner vs. Outer Tracks


Disk Performance Model/Trends


Reliability and Availability


Disk Arrays


Disk Summary


Outline


What Is a Bus?


Advantages of Buses


Disadvantage of Buses


The General Organization of a Bus


Master versus Slave


Buses According to Functionality


A Computer System with One Bus:Backplane Bus


A Two-Bus System


A Three-Bus System


Main Components of Intel Chipset


Buses According to Clocking


Simple Synchronous Protocol


Simple Synchronous Protocol (Write)


Asynchronous Handshake (Read)


Asynchronous Handshake (Write)


Multiple Potential Bus Masters:Need Arbitration


Daisy Chain Bus Arbitration


Centralized Parallel Arbitration


Increasing the Bus Bandwidth


Increasing Transaction Rate onMultimaster Bus


Summary of Bus Options


Bus Summary


Outline


What Need to Make I/O Work?


Instruction Set Architecture for I/O


Memory Mapped I/O


Processor-I/O Speed Mismatch


Processor Checks Status before Acting


Polling: Programmed I/O


Alternative to Polling?


I/O Interrupt


Interrupt Driven Data Transfer


Questions Raised about Interrupts


Improving Data Transfer Performance


What is DMA (Direct Memory Access)?


Delegating I/O from CPU: DMA


Delegating I/O from CPU: IOP


Responsibilities of Operating System


Functions OS Must Provide


OS: I/O Requirements


Summary

1 Ó1998 Morgan Kaufmann Publishers Chapter 8 I/O Systems.

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Transcript of 1 Ó1998 Morgan Kaufmann Publishers Chapter 8 I/O Systems.