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240-323, Part I Operating - System Structures

Department of Computer Engineering, PSU Wannarat Suntiamorntut. 240-323, Part I Operating - System Structures. Department of Computer Engineering, PSU Wannarat Suntiamorntut. System Components. Process Management - process : a program in execution, job

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240-323, Part I Operating - System Structures

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  1. Department of Computer Engineering, PSU Wannarat Suntiamorntut 240-323, Part I Operating - System Structures

  2. Department of Computer Engineering, PSU Wannarat Suntiamorntut System Components • Process Management • - process : a program in execution, job • - process needs certain resources : CPU time, memory • file, I/O device • - process is not program!!! • - program is a passive entity, whereas a process is an • active entity. • - process is unit of work in system : • --> Operating system process • --> User process

  3. Department of Computer Engineering, PSU Wannarat Suntiamorntut System Components - Os is responsible for the following activities : * created/deleted processes * mange resource requirements of a process during its execution : CPU time, memory, I/O, ... * avoid interface between process * achieve cooperation between process

  4. Department of Computer Engineering, PSU Wannarat Suntiamorntut System Components • Main-Memory Management • - Keep track of which parts of memory are • currently being used and by whom. • - Decide which processes are to be loaded into • memory when memory space becomes available. • - Allocate and deallocate memory space as needed.

  5. Department of Computer Engineering, PSU Wannarat Suntiamorntut System Components • File Management • - Created/ deleted files or directories • - map files onto secondary storage • - backup files on stable storage media • - manipulate files or directories

  6. Department of Computer Engineering, PSU Wannarat Suntiamorntut System Components • I/O System Management • - memory management component including • buffering, caching, and spooling. • - general device-driver interface • - drivers for specific hardware devices

  7. Department of Computer Engineering, PSU Wannarat Suntiamorntut System Components • Secondary-Storage Management • - Free-space management • - Storage allocation • - Disk scheduling

  8. Department of Computer Engineering, PSU Wannarat Suntiamorntut System Components • Networking • Distributed system is a collection of processors • that has its own local memory and clock, communicate • with one another through various lines.

  9. Department of Computer Engineering, PSU Wannarat Suntiamorntut System Components • Protection System • Controlling the access of programs, processes or • users to the resources defined by computer system. • Command-Interpreter System • - Interface between user and OS. • - As same as command-line interpreter (shell). • - Get next command statement and execute it.

  10. Department of Computer Engineering, PSU Wannarat Suntiamorntut Operating-System Services • OS services are provided for the convenience • of programmer. • Program execution • System loads program into main memory, • executes, and terminate (abnormal, normal). • I/O Operations • files or I/O devices • File-system manipulation • Copy or delete files • Communication

  11. Department of Computer Engineering, PSU Wannarat Suntiamorntut Operating-System Services • OS services are provided for multiusers • Resource allocation • CPU cycle, main memory, file storage, I/O • Accounting • status of user • Protection • Information for each users, Security

  12. Department of Computer Engineering, PSU Wannarat Suntiamorntut System Calls • System call provided directed access to OS by • programmers (assembly). • System call can be used from high level languages such • as copy file use : • - Interactive system must be work in sequence. • - bath system to define the parameter (file name)

  13. Department of Computer Engineering, PSU Wannarat Suntiamorntut System Calls : Copy file Start Receive names of files Prompt messg Pass para. Put in parameter Read character Error Open file Loop read input file Write output Terminate normally Close both file

  14. Department of Computer Engineering, PSU Wannarat Suntiamorntut System Calls • System call can provided into • - process control • - file manipulation • - device manipulation • - information manipulation • - communications

  15. Department of Computer Engineering, PSU Wannarat Suntiamorntut Application Program Resident system program MS-DOS device drivers ROM BIOS device drivers System structure • Simple Structure : small, simple and limited systems

  16. Department of Computer Engineering, PSU Wannarat Suntiamorntut USERS Shell and commands compilers and interpreters system libraries System call interface to kernel Signals terminal handling character I/O system terminal drivers File system swapping block I/O system disk and tape CPU scheduling page replacement demand paging virtual memory Kernel interface to kernel Terminal controller device controller memory controller disk and tape UNIX System structure

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