i/o system

Chapter 13: I/O Systems

Operating System Concepts – 9th Edition

Silberschatz, Galvin and Gagne ©2013

Chapter 13: I/O Systems
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Overview
I/O Hardware
Application I/O Interface
Kernel I/O Subsystem
Transforming I/O Requests to Hardware Operations
STREAMS
Performance

Operating System Concepts – 9th Edition

13.2

Silberschatz, Galvin and Gagne ©2013

Objectives
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Explore the structure of an operating system’s I/O subsystem

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Discuss the principles of I/O hardware and its complexity

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Provide details of the performance aspects of I/O hardware and software

Operating System Concepts – 9th Edition

13.3

Silberschatz, Galvin and Gagne ©2013

Overview
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I/O management is a major component of operating system design and operation
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Important aspect of computer operation
I/O devices vary greatly
Various methods to control them
Performance management
New types of devices frequent

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Ports, busses, device controllers connect to various devices

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Device drivers encapsulate device details
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Present uniform device-access interface to I/O subsystem

Operating System Concepts – 9th Edition

13.4

Silberschatz, Galvin and Gagne ©2013

I/O Hardware
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Incredible variety of I/O devices
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Storage
Transmission
Human-interface

Common concepts – signals from I/O devices interface with computer
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Port – connection point for device
Bus - daisy chain or shared direct access
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PCI bus common in PCs and servers, PCI Express (PCIe)

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expansion bus connects relatively slow devices

Controller (host adapter) – electronics that operate port, bus, device
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Sometimes integrated

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Sometimes separate circuit board (host adapter)

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Contains processor, microcode, private memory, bus controller, etc
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Some talk to per-device controller with bus controller, microcode, memory, etc

Operating System Concepts – 9th