Operating Systems – Structuring Methods.pptx
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This document discusses different methods for structuring operating systems, including monolithic, layered, and microkernel approaches. It provides examples of each type, such as MS-DOS as a monolithic OS and Windows NT 4.0 and XP as layered OSes. The document also outlines the key characteristics of microkernel systems, including moving most functionality out of the kernel into user space and using inter-process communication. Benefits of the microkernel approach include extensibility, reliability, portability, and support for distributed and object-oriented systems.
Operating Systems – Structuring Methods.pptx
- 1. K.S.SENDHIL KUMAR SCOPE,VIT University Operating Systems – Structuring Methods
- 2. SENDHIL KUMAR KS Operating System Layers 2
- 3. SENDHIL KUMAR KS Operating Systems Structures Structure/Organization/Layout of OSs: 1. Monolithic (one unstructured program) 2. Layered 3. Microkernel
- 4. SENDHIL KUMAR KS Monolithic Operating System 4
- 5. SENDHIL KUMAR KS Monolithic OS – basic structure Application programs that invokes the requested system services. A set of system services that carry out the operating system procedures/calls. A set of utility procedures that help the system services. 5
- 6. SENDHIL KUMAR KS MS-DOS System Structure MS-DOS – written to provide the most functionality in the least space: not divided into modules (monolithic). Although MS-DOS has some structure, its interfaces and levels of functionality are not well separated.
- 7. SENDHIL KUMAR KS MS-DOS Layer Structure 7
- 8. SENDHIL KUMAR KS Layered Approach The operating system is divided into a number of layers (levels), each built on top of lower layers. The bottom layer (layer 0) is the hardware; the highest (layer N) is the user interface. With modularity, layers are selected such that each uses functions (operations) and services of only lower-level layers.
- 9. SENDHIL KUMAR KS Layered Operating System 9
- 10. SENDHIL KUMAR KS An Operating System Layer 10
- 11. SENDHIL KUMAR KS General OS Layers 11
- 12. SENDHIL KUMAR KS 12 Layered Architecture
- 13. SENDHIL KUMAR KS Microkernel System Structure (1) Move as much functionality as possible from the kernel into “user” space. Only a few essential functions in the kernel: primitive memory management (address space) I/O and interrupt management Inter-Process Communication (IPC) basic scheduling Other OS services are provided by processes running in user mode (vertical servers): device drivers, file system, virtual memory… 13
- 14. SENDHIL KUMAR KS Layered vs. Microkernel Architecture 14
- 15. SENDHIL KUMAR KS Microkernel System Structure (2) Communication takes place between user modules using message passing. More flexibility, extensibility, portability and reliability. But performance overhead caused by replacing service calls with message exchanges between processes.
- 16. SENDHIL KUMAR KS 16 Microkernel Architecture
- 17. SENDHIL KUMAR KS Benefits of a Microkernel Organization (1) Extensibility/Reliability easier to extend a microkernel easier to port the operating system to new architectures more reliable (less code is running in kernel mode) more secure small microkernel can be rigorously tested. Portability changes needed to port the system to a new processor is done in the microkernel, not in the other services. 17
- 18. SENDHIL KUMAR KS Benefits of Microkernel Organization (2) Distributed system support message are sent without knowing what the target machine is. Object-oriented operating system components are objects with clearly defined interfaces that can be interconnected to form software.
- 19. SENDHIL KUMAR KS Mac OS X Structure 19
- 20. SENDHIL KUMAR KS Windows NT 4.0 Architecture 20
- 21. SENDHIL KUMAR KS Windows XP Architecture 21
- 22. Windows 7.0 Architecture SENDHIL KUMAR KS 22