Chapter11-OS7e - Chapter 11 I/O Management and Disk...

Info iconThis preview shows pages 1–17. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Chapter 11 I/O Management and Disk Scheduling Seventh Edition By William Stallings Operating Systems: Internals and Design Principles Operating Systems: Operating Systems: Internals and Design Principles Internals and Design Principles n artifact can be thought of as a meeting pointan interface in todays terms between an inner environment, the substance and organization of the artifact itself, and an outer environment, the surroundings in which it operates. If the inner environment is appropriate to the outer environment, or vice versa, the artifact will serve its intended purpose. THE SCIENCES OF THE ARTIFICIAL, External devices that engage in I/O with computer systems can be grouped into three categories: Devices differ in a number of areas: Three techniques for performing I/O are: Programmed I/O the processor issues an I/O command on behalf of a process to an I/O module; that process then busy waits for the operation to be completed before proceeding Interrupt-driven I/O the processor issues an I/O command on behalf of a process if non-blocking processor continues to execute instructions from the process that issued the I/O command if blocking the next instruction the processor executes is from the OS, which will put the current process in a blocked state and schedule another process Direct Memory Access (DMA) a DMA module controls the exchange of data between main memory and an I/O module Techniques for Performing I/O Efficiency Major effort in I/O design Important because I/O operations often form a bottleneck Most I/O devices are extremely slow compared with main memory and the processor The area that has received the most attention is disk I/O Generality Desirable to handle all devices in a uniform manner Applies to the way processes view I/O devices and the way the operating system manages I/O devices and operations Diversity of devices makes it difficult to achieve true generality Use a hierarchical, modular approach to the design of the I/O function Functions of the operating system should be separated according to their complexity, their characteristic time scale, and their level of abstraction Leads to an organization of the operating system into a series of layers Each layer performs a related subset of the functions required of the operating system Layers should be defined so that changes in one layer do not require changes in other layers Perform input transfers in advance of requests being made and perform output transfers some time after the request is made No Buffer No Buffer Without a buffer, the OS directly accesses the device when it needs Single Buffer Single Buffer Operating system assigns a buffer in main memory for an I/O request...
View Full Document

This note was uploaded on 12/14/2011 for the course CS 490 taught by Professor Weisskop during the Fall '11 term at University of Alabama - Huntsville.

Page1 / 62

Chapter11-OS7e - Chapter 11 I/O Management and Disk...

This preview shows document pages 1 - 17. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online