Lecture Operating systems: A concept-based approach (2/e): Chapter 12 - Dhamdhere

PROPRIETARY MATERIAL. © 2007 The McGraw­Hill Companies, Inc. All rights reserved. No part of this PowerPoint slide may be displayed, reproduced or distributed in any form or by any means, without the prior written permission of the publisher, or used beyond the limited distribution to teachers and educators permitted by McGraw­Hill for their individual course preparation. If you are a student using this PowerPoint slide, you are using it without permission. Chapter 12: Implementation Dhamdhere: Operating Systems— Copyright © 2008 Input Output Control System (IOCS) • The IOCS consists of two layers that provide efficient file processing and efficient device performance – Access Methods layer * Each access method provides efficient processing of files with a specific file organization, e.g., sequential file organization and direct file organization – Physical IOCS layer * Performs I/O operations on devices * Ensures efficient device performance Chapter 12: Implementation Dhamdhere: Operating Systems— Copyright © 2008 Physical organizations in Access methods and Physical IOCS • The physical IOCS reads data from disk into buffers or disk cache/file cache maintained in memory (or writes data), ensuring high device throughput • The access method moves the data between buffers or caches and the address space of the process, ensuring efficient file processing Chapter 12: Implementation Dhamdhere: Operating Systems— Copyright © 2008 Policies and Mechanisms • Policy – A guiding principle for implementing a functionality (e.g., priority-based scheduling) * It invokes mechanisms to perform various actions required to implement the functionality • Mechanism – Specific action in implementing a functionality Chapter 12: Implementation Dhamdhere: Operating Systems— Copyright © 2008 Layers of File system and IOCS • M: Mechanism module, P: Policy module • A policy module invokes mechanism modules of the same layer, which may invoke policy and mechanism modules of the lower layer Chapter 12: Implementation Dhamdhere: Operating Systems— Copyright © 2008 ... - tailieumienphi.vn