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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
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Outline
What is an operating system The history of Operating System Hardware of operating system Important concepts of Operating System
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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
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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
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What Is An Operating System
Figure 1-1. Where the operating system fits in.
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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?
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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
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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
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The Operating System as an Extended Machine
Figure 1-2. Operating systems turn ugly hardware into beautiful abstractions.
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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
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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
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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?
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summary
Operating system is a software Is a complex software Runs in kernel mode Manages hardware Provide a friendly interface for application
programmer
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History of Operating Systems
Generations:
(194555) Vacuum Tubes (195565) Transistors and Batch Systems (19651980) ICs and Multiprogramming (1980Present) Personal Computers
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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
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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
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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.
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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
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Transistors and Batch Systems (4)
Figure 1-4. Structure of a typical FMS job.
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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
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Figure 1-5. A multiprogramming system with three jobs in memory.
3rd: ICs and Multiprogramming
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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
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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
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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
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Summary
4 generations OS Develops with hardware and user needs Multi-user, multi-programming, time-sharing
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Computer Hardware Review
Figure 1-6. Some of the components of a simple personal computer.
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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
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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
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CPU Pipelining
Figure 1-7. (a) A three-stage pipeline. (b) A superscalar CPU.
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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CPU Pipeline
Accelerate the execution Cause headaches to OS/compiler writers
For superscalar: instructions are often executed out of order
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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
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Figure 1-9. A typical memory hierarchy. The numbers are very rough approximations.
Memory (1)
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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
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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)
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-10. Structure of a disk drive.
Disks
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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
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Figure 1-11. (a) The steps in starting an I/O device and getting an interrupt.
I/O Devices
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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
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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
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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
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Processes Address spaces Files Input/Output Protection The shell Ontogeny recapitulates phylogeny
Large memories Protection hardware Disks Virtual memory
Operating System Concepts
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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
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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.
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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
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Figure 1-14. A file system for a university department.
Files (1)
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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)
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-16. Two processes connected by a pipe.
Files (3)
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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
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Figure 1-17. The 11 steps in making the system call read(fd, buffer, nbytes).
System Calls
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-18. Some of the major POSIX system calls.
System Calls for Process Management
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-18. Some of the major POSIX system calls.
System Calls for File Management (1)
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-18. Some of the major POSIX system calls.
System Calls for File Management (2)
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-18. Some of the major POSIX system calls.
Miscellaneous System Calls
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-19. A stripped-down shell.
A Simple Shell
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-20. Processes have three segments: text, data, and stack.
Memory Layout
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-21. (a) Two directories before linking /usr/jim/memo to asts directory. (b) The same directories after linking.
Linking
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-22. (a) File system before the mount. (b) File system after the mount.
Mounting
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-23. The Win32 API calls that roughly correspond to the UNIX calls of Fig. 1-18.
Windows Win32 API
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-25. Structure of the THE operating system.
Layered Systems
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-26. Structure of the MINIX 3 system.
Microkernels
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-27. The client-server model over a network.
Client-Server Model
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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Figure 1-29. (a) A type 1 hypervisor. (b) A type 2 hypervisor.
Virtual Machines (2)
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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The C language Header files Large programming projects The model of run time
The World According to C
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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
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Figure 1-30. The process of compiling C and header files to make an executable.
The Model of Run Time
Tanenbaum, Modern Operating Systems 3 e, (c) 2008 Prentice-Hall, Inc. All rights reserved. 0-13-6006639
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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
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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
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