Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Slide 3-1 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Slide 3-2 Operating System Organization Copyright © 2004 Pearson Education, Inc. 3 Operating Systems: A Modern Perspective, Chapter 3 Purpose of an OS Coordinate Use of the Abstractions Processes The Abstractions Create the Abstractions Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Slide 3-3 OS Requirements • Provide resource abstractions – Process abstraction of CPU/memory use • Address space • Thread abstraction of CPU within address space – Resource abstraction • “Anything a process can request that can block the process if it is unavailable” • NT uses “object abstraction” to reference resources – File abstraction of secondary storage use Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Slide 3-4 Slide 3-5 DOS -- Resource Abstraction Only Program Program Libraries Program OS Services ROM Routines Processor(s) Copyright © 2004 Pearson Education, Inc. Main Memory Operating Systems: A Modern Perspective, Chapter 3 Devices Slide 3-6 OS Requirements (cont) • Provide resource abstractions • Manage resource sharing – – – – Time/space-multiplexing Exclusive use of a resource Isolation Managed sharing Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Slide 3-7 Abstraction & Sharing Process Program State Process Program State Process Program State Libraries OS Services • Abstraction • Manage sharing Processor(s) Copyright © 2004 Pearson Education, Inc. Main Memory Operating Systems: A Modern Perspective, Chapter 3 ROM Routines Devices Slide 3-8 OS Design Constraints • • • • • • Performance Protection and security Correctness Maintainability Commercial factors Standards and open systems Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Performance • The OS is an overhead function should not use too much of machine’s resources • Minimum functionality is to implement abstractions • Additional function must be traded off against performance – DOS: one process – UNIX: low level file system Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Slide 3-9 Protection & Security Slide 3-10 • Multiprogramming resource sharing • Therefore, need software-controlled resource isolation • Security policy: Sharing strategy chosen by computer’s owner • Protection mechanism: Tool to implement a family of security policies Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Correctness & Maintainability Slide 3-11 • Security depends on correct operation of software trusted vs untrusted software • Maintainability relates to ability of software to be changed • If either is sufficiently important, can limit the function of the OS – Guiding a manned spaceship – Managing a nuclear reactor Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Device Management Slide 3-12 Device-Independent Part Device-Dependent Part Device-Dependent Part Device Device Copyright © 2004 Pearson Education, Inc. Device-Dependent Part … Operating Systems: A Modern Perspective, Chapter 3 Device Process, Thread, and Resource Management Thread Abstraction Process Abstraction Multiprogramming Generic Resource Manager Other Primary Memory … Processor Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Abstract Resources Slide 3-13 Slide 3-14 Memory Management Isolation & Sharing Process Manager Block Allocation Virtual Memory Primary Memory Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Storage Devices Exclusive Access to a Resource Slide 3-15 Processor Process A Process B A’s Protected Object Supervisor Program Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Processor Modes • Mode bit: Supervisor or User mode • Supervisor mode – Can execute all machine instructions – Can reference all memory locations • User mode – Can only execute a subset of instructions – Can only reference a subset of memory locations Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Slide 3-16 Kernels Slide 3-17 • The part of the OS critical to correct operation (trusted software) • Executes in supervisor mode • The trap instruction is used to switch from user to supervisor mode, entering the OS Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Supervisor and User Memory User Process User Space Supervisor Process Supervisor Space Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Slide 3-18 Procedure Call and Message Passing Operating Systems send(…, A, …); receive(…, B, …); call(…); trap send/receive return; Copyright © 2004 Pearson Education, Inc. receive(…A, …); … send(…, B, …); Operating Systems: A Modern Perspective, Chapter 3 Slide 3-19 System Call Using the trap Instruction Slide 3-20 … fork(); … Trap Table fork() { … trap N_SYS_FORK() … } Kernel sys_fork() sys_fork() { /* system function */ … return; } Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 A Thread Performing a System Call User Space Kernel Space Thread fork(); sys_fork() { } Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 3 Slide 3-21 Basic Operating System Organization File Manager Process, Thread & Resource Manager Processor(s) Copyright © 2004 Pearson Education, Inc. Slide 3-22 Memory Manager Device Manager Main Memory Devices Operating Systems: A Modern Perspective, Chapter 3 Slide 3-23 The UNIX Architecture Interactive User Application … Programs OS System Call Interface Commands Device Driver Device Driver … Device Driver Copyright © 2004 Pearson Education, Inc. Driver Interface Libraries Trap Table Monolithic Kernel Module •Process Management •Memory Management •File Management •Device Mgmt Infrastructure Operating Systems: A Modern Perspective, Chapter 3 Slide 3-24 Microkernel Organization Process Process Process Libraries User Supervisor Server Server Server Device Drivers Microkernel Processor(s) Copyright © 2004 Pearson Education, Inc. Main Memory Operating Systems: A Modern Perspective, Chapter 3 Devices Windows NT Organization T Process T T T Process Slide 3-25 Process T T T T Process Management Memory Management File Management Subsystem Subsystem Device Mgmt Infrastructure T Libraries Subsystem User Supervisor NT Executive NT Kernel Hardware Abstraction Layer Processor(s) Copyright © 2004 Pearson Education, Inc. Main Memory Operating Systems: A Modern Perspective, Chapter 3 I/O Subsystem Devices Slide 3-26 Monitoring the Kernel T Process Task Manager T T T Process Process T T T T T pview Libraries pstat Subsystem Subsystem Subsystem User Supervisor NT Executive NT Kernel Hardware Abstraction Layer Processor(s) Copyright © 2004 Pearson Education, Inc. Main Memory Operating Systems: A Modern Perspective, Chapter 3 I/O Subsystem Devices