1 / 14

Operating System Structures

Operating System Structures. Chapter 3. Operating System Structures. OS Design Constraints OS Basic Functions OS Structures. Design Constraints. Performance Protection & Security Correctness Maintainability Commercial factors. Performance.

herve
Download Presentation

Operating System Structures

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Operating System Structures Chapter 3 A. Berrached:CMS:UHD

  2. Operating System Structures • OS Design Constraints • OS Basic Functions • OS Structures A. Berrached:CMS:UHD

  3. Design Constraints • Performance • Protection & Security • Correctness • Maintainability • Commercial factors A. Berrached:CMS:UHD

  4. Performance • People use computers for the potential of rapid information processing • There are several measures of performance • throughput • response time • The OS is an overhead function => should not use too much of machine resources • Provide an environment in which programmers can produce solutions in a cost-effective manner ==> trade off A. Berrached:CMS:UHD

  5. Correctness & Maintainability • Correctness - refers to whether OS functions meet their requirements. • Correctness is the most basic requirement on which all other requirement are based- e.g. security depends on correct operation of OS => trusted vs un-trusted software • Maintainability - refers to the ease with which software can be changed/extended, bugs can be fixed, etc. A. Berrached:CMS:UHD

  6. OS Basic Functions • Device management • Process & resource management • Memory Management • File Management A. Berrached:CMS:UHD

  7. Device Management • OS Manages the allocation, sharing and isolation of I/O devices (disks, tapes, terminals, etc.) • Most Operating Systems treat all devices in the same general manner • UNIX treats them all like files • Chapters 4 & 5 discuss Device Management A. Berrached:CMS:UHD

  8. Process & Resource Management • A process is the basic unit of computation • Resources are the elements needed by a process so that it can execute • CPU, Memory, I/O devices, data etc. • OS provides a set of process management mechanisms: for process creation , blocking, resumption, termination ,etc A. Berrached:CMS:UHD

  9. Process & Resource Management • OS manages computer resources so that multiple processes can execute simultaneously • CPU scheduling • resource allocation, sharing & process synchronization • resource allocation • Chapters 6 - 10 A. Berrached:CMS:UHD

  10. Memory Management • Allocation and use of the primary memory resource • memory allocation among competing processes • enforce memory isolation and sharing • Most modern OS support virtual memory. • Virtual memory allows processes to access data in secondary storage as if it were in main memory. • Chapter s11&12 A. Berrached:CMS:UHD

  11. File Management • Information that need to be saved "permanently" must be stored in a secondary storage device e.g. a disk, tape, etc. • Files are an abstraction of secondary storage devices • File manager is responsible for • managing the file system: file & directory creation and manipulation • mapping files into physical storage devices A. Berrached:CMS:UHD

  12. Basic OS Functions A. Berrached:CMS:UHD

  13. OS Structures-Simple Approach • MS-DOS - written to provide the most functionality in the least space • not divided into modules • Although MS-DOS has some structures, its interfaces and levels of functionality are not well separated. • application programs are able to access BIOS routines directly (bypassing DOS). A. Berrached:CMS:UHD

  14. OS Structures--UNIX • UNIX -- modular • UNIX consists of two separate parts: • System programs (Shells and commands, compilers and interpreters, system libraries) • The kernel: part of OS that is most critical to its correct operation (trusted) • provides CPU scheduling, memory management, file management, and other operating system functions. A. Berrached:CMS:UHD

More Related