chapter 01

MODERN OPERATING SYSTEMSThird Edition

ANDREW S. TANENBAUM

Chapter 1Introduction

Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639

Outline

What is an operating system The history of Operating System Hardware of operating system Important concepts of Operating System

What Is An Operating System

A modern computer consists of:

One or more processors Main memory Disks Printers Various input/output devices

Managing all these components requires a layer of software the operating system

What is an Operating System? A modern computer is very complex.

Networking Disks Video/audio card .

It is impossible for every application programmer to understand every detail

A layer of computer software is introduced to provide a better, simpler, cleaner model of the resources and manage them

What Is An Operating System

Figure 1-1. Where the operating system fits in.


What is an Operating System? Users use various OS

Windows, Linux, Mac OS etc. User interacts with shell or GUI

part of OS? they use OS to get their work done

Is device driver part of OS?

What is an Operating System? On top of hardware is OS Most computers have two modes of

operation: Kernel mode and user mode OS runs in kernel mode, which has complete

access to all hardware and can execute any instruction

Rest of software runs in user mode, which has limited capability

Shell or GUI is the lowest level of user mode software

What is an operating system?

Two functions: From top to down: provide application

programmers a clean abstract set of resources instead of hardware ones

From down to top: Manage these hardware resources

The Operating System as an Extended Machine

Figure 1-2. Operating systems turn ugly hardware into beautiful abstractions.


As an extended machine Abstraction:

CPUprocess Storage - files Memory address space

4 types of people: Industrial engineer: design hardware Kernel designer Application programmer: OSs user End users

The Operating System as a Resource Manager

Allow multiple programs to run at the same time Manage and protect memory, I/O devices, and

other resources Includes multiplexing (sharing) resources in two

different ways: In time In space


As a resource manager

Modern OS runs multiple programs of multiple users at the same time Imagine what would happen if several programs

want to print at the same time? How to account the resource usage of each

process? Resources can be multiplexed:

How to ensure fairness and efficiency?

summary

Operating system is a software Is a complex software Runs in kernel mode Manages hardware Provide a friendly interface for application

programmer

History of Operating Systems

Generations:

(194555) Vacuum Tubes (195565) Transistors and Batch Systems (19651980) ICs and Multiprogramming (1980Present) Personal Computers


1st: vacuum tubes

Large and slow Engineers design, build, operate and

maintain the computer All programming is done with machine

language, or by wiring circuits using cables insert plugboards into the computer and

operate The work is mainly numerical calculations

2nd: transistors and batch systems Also called mainframes Computers are managed by professional operators Programmers use punch card to run programs;

operators operate (load compiler, etc ) and collect output to the user

Complains soon come: Human Operation between computer operation Lead to batch system Collect a batch of jobs in the input room, then read them

into a magnetic tape; the same for output

2nd: Transistors and Batch Systems (1)

Figure 1-3. An early batch system. (a) Programmers bring cards to 1401. (b)1401 reads batch of jobs onto tape.


Transistors and Batch Systems (2)

Figure 1-3. (c) Operator carries input tape to 7094. (d) 7094 does computing. (e) Operator carries output tape to

1401. (f) 1401 prints output. Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639

Transistors and Batch Systems (4)

Figure 1-4. Structure of a typical FMS job.


3rd: IC and Multiprogramming

OS/360: a dinosaur stuck in a tar pit Aims to adapts 1401/7904, covers all trades of life However, OS/360 introduces several key

techniques Multi-programming: solve the problem of CPU idling Spooling: simultaneous peripheral operation on line

Whenever a job finishes, OS load a new job from disk to the empty-partition

Figure 1-5. A multiprogramming system with three jobs in memory.

3rd: ICs and Multiprogramming


3rd: Ics and Multiprogramming

Problems: 3rd generation OS was well suited for big scientific

calculations and massive data processing But many programmers complain a lot for not

be able to debug quickly. Why? And the solution to this problem would be.? Timesharing:

A variant of multiprogramming Provide both fast interactive service but also fits big

batch work

3rd: IC and Multiprogramming

A system to be remembered: MULTICS A machine that would support hundreds of

simultaneous timesharing users like the electricity system (like a web server nowadays)

Introduces many brilliant ideas but enjoys no commercial success

Its step-child is the well-known and time-honored UNIX

System V/ FreeBSD, MINIX, Linux

4th: personal computers Computers have performance similar to 3rd

generation, but prices drastically different CP/M

First disk-based OS 1980, IBM PC, Basic Interpreter, DOS, MS-

DOS GUI--LisaApple: user friendly MS-DOS with GUI Win95/98/me

winNT/xp

Summary

4 generations OS Develops with hardware and user needs Multi-user, multi-programming, time-sharing

Computer Hardware Review

Figure 1-6. Some of the components of a simple personal computer.


Hardware: processor Brain of computer

Fetches instruction from memory and execute Cycle of CPU:

fetch, decode, execute CPU has registers to store variable and temporary

result: load from memory to register; store from register to memory

Program counter: next instruction to fetch Stack pointer: the top of the current stack PSW: program status word, priority, mode

A reference Adam Smith: Wealth of Nation

Of the Division of labor

One man draws out the wire, another straights it, a third cuts it, a fourth points it, a fifth grinds it at the top

One person could make up to forth-eight thousand pins in a day

CPU Pipelining

Figure 1-7. (a) A three-stage pipeline. (b) A superscalar CPU.


CPU Pipeline

Accelerate the execution Cause headaches to OS/compiler writers

For superscalar: instructions are often executed out of order

Figure 1-8. (a) A quad-core chip with a shared L2 cache. (b) A quad-core chip with separate L2 caches.

Multithreaded and Multicore Chips


Figure 1-9. A typical memory hierarchy. The numbers are very rough approximations.

Memory (1)


memory Memory is where computer fetch and store

data, ideally, it should be both chip/large The best people can do, is to construct a

memory hierarchy Cache lines:

Memory divided into cache lines; the mostly used ones are stored in caches

Cache hit, cache miss Cache: whenever there is disparity in usage or

speed; used to improve performance

Questions when dealing with cache:

When to put a new item into the cache. Which cache line to put the new item in. Which item to remove from the cache when a

slot is needed. Where to put a newly evicted item in the larger

memory.

Memory (2)


Figure 1-10. Structure of a disk drive.

Disks


Disks Cheap and large: two orders better than RAM Slow: three orders worse than RAM Mechanical movement to fetch data One or more platterrotate rpm Information is stored on concentric circles Arm, track, cylinder, sector Disk helps to implement Virtual Memory

When no enough memory is available, disks are used as the storage, and memory as cache

Figure 1-11. (a) The steps in starting an I/O device and getting an interrupt.

I/O Devices


I/O devices

Two parts: a controller and a device Controller: to provide a simpler interface to

OS Device driver: talks to controller, give

commands and accepts response Busy waiting/interrupt/DMA

Booting the Computer BIOSbasic input/output system

On the parentboard, low-level I/O software Checks RAM, keyboard and other basic devices Determine the boot device: floppy, CD-ROM, disk First sector of the boot-device is read into memory The sector contains program to check which

partition is active Then a secondary boot-loader is read into

memory and reads in operating system from the active partition

The Operating System Zoo

Mainframe operating systems Server operating systems Multiprocessor operating systems Personal computer operating systems Handheld operating systems Embedded operating systems Sensor node operating systems Real-time operating systems Smart card operating systems


Processes Address spaces Files Input/Output Protection The shell Ontogeny recapitulates phylogeny

Large memories Protection hardware Disks Virtual memory

Operating System Concepts


processes

Process Address space: 0-4G; executable program,

programs data, and its stack Other resources like: registers, files, alarms,

related processes, and other information A process is fundamentally a container that holds

information for a program to run

Processes

Figure 1-13. A process tree. Process A created two child processes, B and C. Process B created three child

processes, D, E, and F.


Address Space

The memory used by a process, in concept MOS allows multiple processes in memory

simultaneously Some processes need more memory than

physically available virtual memory

Figure 1-14. A file system for a university department.

Files (1)


Figure 1-15. (a) Before mounting, the files on the CD-ROM are not accessible. (b) After mounting, they are part of the file hierarchy.

Files (2)


Figure 1-16. Two processes connected by a pipe.

Files (3)


System calls

System calls is the interface users contact with OS and hardware

System calls vary from system to system, but the underlying concepts are similar

Figure 1-17. The 11 steps in making the system call read(fd, buffer, nbytes).

System Calls


Figure 1-18. Some of the major POSIX system calls.

System Calls for Process Management



System Calls for File Management (1)



System Calls for File Management (2)



Miscellaneous System Calls


Figure 1-19. A stripped-down shell.

A Simple Shell


Figure 1-20. Processes have three segments: text, data, and stack.

Memory Layout


Figure 1-21. (a) Two directories before linking /usr/jim/memo to asts directory. (b) The same directories after linking.

Linking


Figure 1-22. (a) File system before the mount. (b) File system after the mount.

Mounting


Figure 1-23. The Win32 API calls that roughly correspond to the UNIX calls of Fig. 1-18.

Windows Win32 API


Monolithic systems basic structure:

A main program that invokes the requested service procedure.

A set of service procedures that carry out the system calls.

A set of utility procedures that help the service procedures.

Operating Systems Structure


Figure 1-25. Structure of the THE operating system.

Layered Systems


Figure 1-26. Structure of the MINIX 3 system.

Microkernels


Figure 1-27. The client-server model over a network.

Client-Server Model


Figure 1-29. (a) A type 1 hypervisor. (b) A type 2 hypervisor.

Virtual Machines (2)


The C language Header files Large programming projects The model of run time

The World According to C


World according to C

Operating systems are large C programs consisting of many pieces written by many programmers

C language Data types, variables, control statements Header files: declaration, definition, macros For a large programming project

Figure 1-30. The process of compiling C and header files to make an executable.

The Model of Run Time


Large programming projects

C preprocessor: Gets the header, expand macros, handling

conditional compilation Compiler

.c -.o Linker

Combine all .o to an executable program; traditionally a.out

Gcc: preprocess-assemble-compile-link gcc -E hello.c o hello.i gcc -S hello.i -o hello.s gcc -c hello.s o hello.o gcc hello.o o hello

ldd hello

Slide 1Slide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Slide 44Slide 45Slide 46Slide 47Slide 48Slide 49Slide 50Slide 51Slide 52Slide 53Slide 54Slide 55Slide 56Slide 57Slide 58Slide 59Slide 60Slide 61Slide 62Slide 63Slide 64Slide 65Slide 66Slide 67Slide 68Slide 69Slide 70

chapter 01

Documents