Slide 1-1 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1

Slide 1-2 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 1 Introduction

Slide 1-3 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Why Study Operating Systems? Understand the model of operation –Easier to see how to use the system –Enables you to write efficient code Learn to design an OS Even so, OS is pure overhead of real work Application programs have the real value to person who buys the computer

Slide 1-4 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 What is an Operating System? A program or collection of programs that act as intermediary between the user of a computer and the computer hardware. Operating system goals: –Make the computer convenient to use. –Use computer resources in an efficient manner. –Coordinate among the various users and programs that are competing for computing resources.

Slide 1-5 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Perspectives of the Computer Application Software System Software Hardware (a)End User View (b) Application Programmer View (c) OS Programmer View Application Software Application Software System Software System Software Hardware cut save print send malloc() fork() open() read-disk track-mouse start-printer

Slide 1-6 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1

Slide 1-7 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Operating System Definition OS provides an interface between the computer hardware and users, applications and system software. OS manages computer resources. OS controls and coordinates the use of the computing resources among the various users/programs: –resource sharing among computer users/programs –protect users from each others

Slide 1-8 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 System Software Independent of individual applications, but common to all of them Examples –C library functions –A window system –A database management system –Resource management functions –The OS

Slide 1-9 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Using the System Software Loader OS Database Management System Database Management System Window System Window System Application Programmer System Software Libraries Compiler Hardware Command Line Interpreter Command Line Interpreter Libraries Software API

Slide 1-10 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Application Software, System Software, and the OS Hardware Resources Trusted OS (Abstract Resources ) Software-Hardware Interface OS Interface System Software (More Abstract Resources ) API Application Software Human-Computer Interface

Slide 1-11 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 The OS as Resource Manager Process: An executing program Resource: Anything that is needed for a process to run –Memory –Space on a disk –The CPU “An OS creates resource abstractions” “An OS manages resource sharing”

Slide 1-12 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Resource Abstraction load(block, length, device); seek(device, 236); out(device, 9) write(char *block, int len, int device, int track, int sector) {... load(block, length, device); seek(device, 236); out(device, 9);... } write(char *block, int len, int device,int addr);fprintf(fileID, “%d”, datum);

Slide 1-13 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Disk Abstractions load(…); seek(…); out(…); void write() { load(…); seek(…) out(…) } int fprintf(…) {... write(…) … } (a) Direct Control (b) write() abstraction (c) fprintf() abstraction Application Programmer OS Programmer

Slide 1-14 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Abstract Resources Hardware Resources OS OS Resources (OS Interface) Middleware Abstract Resources (API) Application User Interface

Slide 1-15 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Abstract Machines Program Result Program Result Program Result … … Idea Physical Machine Abstract Machines …

Slide 1-16 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Resource Sharing Space- vs time-multiplexed sharing To control sharing, must be able to isolate resources OS usually provides mechanism to isolate, then selectively allows sharing –How to isolate resources –How to be sure that sharing is acceptable Concurrency

Slide 1-17 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 The OS as a Conductor The OS coordinates the sharing and use of all the components in the computer

Slide 1-18 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Multiprogramming … Abstract Machine P i OS Resource Sharing P i Memory P k Memory P j Memory … Time-multiplexed Physical Processor Abstract Machine P j Abstract Machine P k Space-multiplexed Physical Memory

Slide 1-19 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Multiprogramming(2) Technique for sharing the CPU among runnable processes –Process may be blocked on I/O –Process may be blocked waiting for other resource, including the CPU While one process is blocked, another might be able to run Multiprogramming OS accomplishes CPU sharing “automatically” – scheduling Reduces time to run all processes

Slide 1-20 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 How Multiprogramming Works Process 1 Process 2 Process 3 Process 4 Space-multiplexed Memory Time-multiplexed CPU

Slide 1-21 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Speeding Up the Car Wash Vacuum Inside WashDry Vacuum Inside WashDry (a) The Sequential Car Wash (b) The Parallel Car Wash

Slide 1-22 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Multiprogramming Performance Time Using the processor I/O operation 0titi P i ’s Total Execution Time, t i (a) P i ’s Use of Machine Resources Time P1P1 P2P2 PiPi PNPN … … (a) All Processes’ Use of Machine Resources

Slide 1-23 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 OS Strategies Batch processing Timesharing Personal computer & workstations Process control & real-time Network Distributed Small computers

Slide 1-24 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Batch Processing Job 19 Input SpoolerOutput Spooler Job 3 Input Spool Output Spool

Slide 1-25 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Batch Processing(2) Uses multiprogramming Job (file of OS commands) prepared offline Batch of jobs given to OS at one time OS processes jobs one-after-the-other No human-computer interaction OS optimizes resource utilization Batch processing (as an option) still used today

Slide 1-26 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 A Shell Script Batch File cc -g -c menu.c cc -g -o driver driver.c menu.o driver test_out lpr -PthePrinter test_out tar cvf driver_test.tar menu.c driver.c test_data test_out uuencode driver_test.tar driver_test.tar >driver_test.encode

Slide 1-27 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Timesharing Systems Physical Machine Abstract Machines … Command Result

Slide 1-28 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Timesharing Systems(2) Uses multiprogramming Support interactive computing model (Illusion of multiple consoles) Different scheduling & memory allocation strategies than batch Tends to propagate processes Considerable attention to resource isolation (security & protection) Tend to optimize response time

Slide 1-29 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Personal Computers CPU sharing among one person’s processes Power of computing for personal tasks –Graphics –Multimedia Trend toward very small OS OS focus on resource abstraction Rapidly evolved to “personal multitasking” systems

Slide 1-30 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Process Control & Real-Time Computer is dedicated to a single purpose Classic embedded system Must respond to external stimuli in fixed time Continuous media popularizing real-time techniques An area of growing interest

Slide 1-31 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Networks LAN (Local Area Network) evolution 3Mbps (1975)  10 Mbps (1980)  100 Mbps (1990)  1 Gbps (2000) High speed communication means new way to do computing –Shared files –Shared memory –Shared procedures/objects –???

Slide 1-32 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Distributed OS Wave of the future Distributed OS App Multiple Computers connected by a Network

Slide 1-33 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Distributed Systems Distribute the computation among several physical processors. Multiprocessor system: Tightly coupled systems – processors share memory and a clock; communication usually takes place through the shared memory. Loosely coupled systems – each processor has its own local memory; processors communicate with one another through various communication lines Advantages of distributed systems: –Resource sharing, Computation speed up –Reliability, Communication

Slide 1-34 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Parallel Systems Multiprocessor systems with more than one CPU in close communication. Tightly coupled systems – processors share memory and a clock; communication usually takes place through the shared memory. Advantages of parallel systems: –Increased throughput –Increased reliability

Slide 1-35 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Small Computers PDAs, STBs, embedded systems became commercially significant Have an OS, but –Not general purpose –Limited hardware resources –Different kinds of devices Touch screen, no keyboard Graffiti –Evolving & leading to new class of Oses PalmOS, Pocket PC (WinCE), VxWorks, …

Slide 1-36 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Evolution of Modern OS Modern OS Batch Timesharing PC & Wkstation Network OS Real-Time Memory Mgmt Protection Scheduling Files Devices Memory Mgmt Protection Scheduling System software Human-Computer Interface Client-Server Model Protocols Scheduling Small Computer Network storage, Resource management

Slide 1-37 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Examples of Modern OS UNIX variants (e.g. Linux) -- have evolved since 1970 Windows NT/2K -- has evolved since 1989 (much more modern than UNIX –Win2K = WinNT, V5 Research OSes – still evolving … Small computer OSes – still evolving … Book provides Linux examples This course will use Windows NT as the main example

Slide 1-38 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 The Microsoft OS Family Win32 API Windows CE (Pocket PC) Windows CE (Pocket PC) Windows 95/98/Me Windows NT/2000/XP Win32 API Subset Win32 API SubSet

Slide 1-39 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Microsoft Windows NT Heavily window-oriented Foundation behavior is windows- independent –We will focus on the foundation –Use only the “MS-DOS prompt” -- cmd.exe OS API NT Kernel NT User Interface and Graphics NT Executive

Slide 1-40 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Windows NT (cont) OS API has text orientation (like UNIX) Object-oriented implementation Heavy use of threads Broad spectrum of synchronization tools Modern I/O system

Slide 1-41 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Applications VxWorks Runtime System VxWorks Organization VxWorks Configurable Core OS Extension VxWorks Configurable Core OS Extension Wind Microkernel

Slide 1-42 Copyright © 2004 Pearson Education, Inc. Operating Systems: A Modern Perspective, Chapter 1 Windows CE Organization