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Lecture Operating systems: A concept-based approach: Chapter 4 - Dhananjay M. Dhamdhere

Chapter 4 - Structure of operating systems. This chapter discusses three methods of structuring an operating system. The layered structure of operating systems simplifies coding, the kernel-based structure provides ease of implementation on different computer systems, and the microkernel-based structure permits modification of an operating system’s features to adapt to changes in the computing environment and also provides ease of implementation on different computer systems. | Chapter 4 Structure of Operating Systems Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Introduction Operation of an OS Structure of an Operating System Operating Systems with Monolithic Structure Layered Design of Operating Systems 4. Operating Systems, by Dhananjay Dhamdhere Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Introduction (continued) Virtual Machine Operating Systems Kernel-Based Operating Systems Microkernel-Based Operating Systems Case Studies 4. Operating Systems, by Dhananjay Dhamdhere Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Operation of an OS When a computer is switched on, boot procedure analyzes its configuration—CPU type, memory size, I/O devices, and details of other hardware Loads part of OS in memory, initializes data structures, and hands it control of computer system During operation of the computer, interrupts caused by: An event: I/O completion; end of a time slice System call made by a process | Chapter 4 Structure of Operating Systems Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Introduction Operation of an OS Structure of an Operating System Operating Systems with Monolithic Structure Layered Design of Operating Systems 4. Operating Systems, by Dhananjay Dhamdhere Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Introduction (continued) Virtual Machine Operating Systems Kernel-Based Operating Systems Microkernel-Based Operating Systems Case Studies 4. Operating Systems, by Dhananjay Dhamdhere Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Operation of an OS When a computer is switched on, boot procedure analyzes its configuration—CPU type, memory size, I/O devices, and details of other hardware Loads part of OS in memory, initializes data structures, and hands it control of computer system During operation of the computer, interrupts caused by: An event: I/O completion; end of a time slice System call made by a process (software interrupt) Interrupt servicing routine: Performs context save Activates event handler Scheduler selects a process for servicing 4. Operating Systems, by Dhananjay Dhamdhere Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Operation of an OS (continued) 4. Operating Systems, by Dhananjay Dhamdhere Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Operation of an OS (continued) 4. Operating Systems, by Dhananjay Dhamdhere Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Structure of an Operating System Policies and Mechanisms Portability and Extensibility of Operating Systems 4. Operating Systems, by Dhananjay Dhamdhere Copyright © 2008 Operating Systems, by Dhananjay Dhamdhere Policies and Mechanisms In determining how OS will perform a function, designer needs to think at two distinct levels: Policy: Principle under which OS performs function Decides what should be done Mechanism: Action needed to implement a .