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A. Frank - P. Weisberg

Operating Systems

Introduction to

Operating System (OS)

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2 A. Frank - P. Weisberg

Slides Credits for all PPTs of OS course

The slides/diagrams in this course are an adaptation,combination, and enhancement of material from thefollowing resources and persons:

1. Slides of A. Silberschatz, P. B. Galvin and G. Gagne

(see book references ahead) with someenhancements by Y. Wiseman.

2. Slides of Mario Marchand of the University ofOttawa and Patricia Roy of Manatee Community

College based on W. Stallings (see book referenceahead) with some enhancements by O. Kremien andE. Gruengard.

3. Some diagrams from R. A. Finkel and Andrew S.Tanenbaum (see book references ahead).

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What is an Operating System (1)?

A modern computer consists of:

One or more processors

Main memoryDisks

Printers

Various input/output devices.

Managing all these varied components

requires a layer of softwarethe

Operating System (OS).

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What is an Operating System (2)?

An Operating System is a program that acts as

an intermediary/interface between a user of a

computer and the computer hardware.

OS goals:

Control/execute user/application programs.

Make the computer system convenient to use.

Ease the solving of user problems.

Use the computer hardware in an efficient manner.

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Where does the OS fit in?

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Services provided by an OS

Facilities for program creation

editors, compilers, linkers, debuggers, etc.

Program execution

loading in memory, I/O and file initialization.

Access to I/O and files

deals with the specifics of I/O and file formats.

System access

resolves conflicts for resource contention.

protection in access to resources and data.

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Why are Operating Systems Important?

Important to understand and know how to correctlyuse when writing user applications.

Large and complex systems that have a high

economic impact and result in interesting problemsof management.

Few actually involved in OS design andimplementation but nevertheless many general

techniques to be learned and applied. Combines concepts from many other areas of

Computer Science: Architecture, Languages,Data Structures, Algorithms.

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Course Syllabus (1)

Motivation for Operating Systems (OS)

Introduction

What's an Operating System?Computer/Operating System Overview

Evolution of Operating Systems

Functional/Protection Aspects

Operating System Structures

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Course Syllabus (2)

Concurrent Processes

Process Models and Management

Process Description and ControlTask/Thread Description and Control

Concurrency: Mutual Exclusion and

SynchronizationConcurrency: Deadlock and Starvation

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Course Syllabus (3)

Memory Management

Real Memory Management

Motivation for Virtual Memory (VM)Paging and Segmentation

Page Fetch, Placement and Replacement

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Course Syllabus (4)

Uniprocessor Scheduling

Levels of CPU Scheduling

Process Scheduling External Storage Management

File Systems/Management

Directories

File Allocation

Disk Scheduling

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Main Bibliography

1. A. Silberschatz, P. B. Galvin, and G. Gagne,

Operating Systems Concepts (with Java),

8th Edition, John Wiley & Sons, 2009.

http://codex.cs.yale.edu/avi/os-book/os8/index.php
http://codex.cs.yale.edu/avi/os-book/os8/index.phphttp://codex.cs.yale.edu/avi/os-book/os8/index.phphttp://codex.cs.yale.edu/avi/os-book/os8/index.phphttp://codex.cs.yale.edu/avi/os-book/os8/index.phphttp://codex.cs.yale.edu/avi/os-book/os8/index.phphttp://codex.cs.yale.edu/avi/os-book/os8/index.php

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Main Bibliography

3. W. Stallings,

Operating Systems:

Internals and Design

Principles,

7thed, Prentice Hall,

2012.

http://williamstallings.com/OperatingSyste

ms/
http://williamstallings.com/OS/OS5e.htmlhttp://williamstallings.com/OS/OS5e.htmlhttp://williamstallings.com/OS/OS5e.htmlhttp://williamstallings.com/OS/OS5e.htmlhttp://williamstallings.com/OS/OS5e.htmlhttp://williamstallings.com/OS/OS5e.htmlhttp://williamstallings.com/OS/OS5e.html

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Additional Bibliography

4. A. S. Tanenbaum,

Modern Operating

Systems, 3rd

Edition, Prentice-

Hall Intl., 2008.http://www.pearsonhigh

ered.com/educator/academic/product/0,,013600

6639,00%2ben-

USS_01DBC.html
http://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.htmlhttp://www.pearsonhighered.com/educator/academic/product/0,,0136006639,00%2ben-USS_01DBC.html

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5. A. S. Tanenbaum and A.

S. Woodhill, Operating

Systems: Design and

Implementation, 3rdEdition, Prentice-Hall

Intl., 2006.http://www.pearsonhighered.

com/educator/academic/product/0,,0131429388,00%2ben-

USS_01DBC.htm
http://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htmhttp://www.pearsonhighered.com/educator/academic/product/0,,0131429388,00%2ben-USS_01DBC.htm

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6. S. Toledo, Operating Systems, in Hebrew,Akademon, 2001.

http://www.tau.ac.il/~stoledo/osbook/

7. G. Nutt, ``Operating Systems: A ModernPerspective'', 2nd Edition Lab Update,

Addison-Wesley, 2002.

http://www.cs.colorado.edu/~nutt/osamp.html8. R. A. Finkel, An Operating Systems Vade

Mecum, Prentice-Hall Intl., 1988.
http://www.tau.ac.il/~stoledo/osbook/http://www.cs.colorado.edu/~nutt/osamp.htmlhttp://www.cs.colorado.edu/~nutt/osamp.htmlhttp://www.tau.ac.il/~stoledo/osbook/

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UNIX Bibliography (Internals)

9. R. Love, Linux Kernel Development, 2nd

Edition, Novell Press, 2005.

10. U. Vahalia, UNIX Internals: The NewFrontiers, Prentice-Hall Intl., 1995.

11. S. J. Leffler, et al, The Design and

Implementation of the 4.3BSD UNIX

Operating System, Addison-Wesley, 1989.

12. M. J. Bach, The Design of the UNIX

Operating System, Prentice-Hall Intl., 1986.

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UNIX Bibliography (Programming)

13. K. Haviland, et al, Unix SystemProgramming: A Programmer's Guide toSoftware Development, Addison-Wesley,

1999.14. W. R. Stevens, and S. A. Rago, Advanced

Programming in the UNIX Environment, 2nd

Edition, Addison-Wesley, 2008.15. D. P. Bovet, and M. Cesati, Understanding

the Linux Kernel, 3rded, OReilly Media,2008

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Computer Hardware Organization

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Computer System Components

1. Hardwareprovides basic computing resources

(CPU, Memory, I/O devices, Communication).

2. Operating Systemcontrols and coordinates the

use of the hardware among various applicationprograms for various users.

3. System & Application Programsways in which

the system resources are used to solve computing

problems of the users (Word processors, Compilers,

Web browsers, Database systems, Video games).

4. Users(People, Machines, other computers).

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Hierarchical view of computer system

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Static View of System Components

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Dynamic View of System Components

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Layers of a Computer System

End

User

Programmer

Operating-

System

Designer

Computer Hardware

Operating-System

Utilities

ApplicationPrograms

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Views of an Operating System

There are three classical views (in literature):

1. Resource Managermanages and allocates

resources.

2. Control programcontrols the execution of user

programs and operations of I/O devices.

3. Command ExecuterProvides an environment

for running user commands. But one more modern view: the Operating

System as a Virtual Machine.

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1. Resource Manager

Resource Manager:

Manages and protects multiple computer resources: CPU,

Processes, Internal/External memory, Tasks, Applications,

Users, Communication channels, etc Handles and allocates resources to multiple users or

multiple programs running at the same time and space

(e.g., processor time, memory, I/O devices).

Decides between conflicting requests for efficient and fairresource use (e.g., maximize throughput, minimize

response time).

Sort of a bottom-up view.

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27

OS as a Resource Manager

A. Frank - P. Weisberg

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Resource Manager oriented OS names

DEC RSXResource Sharing eXecutive

MIT MulticsMULTiplexed Information and

Computing Services

IBM MFT/MVTMultiple Fixed/Variable Tasks

IBM MVSMultiple Virtual Storage

DEC VMSVirtual Memory System

MVS TSOTime Sharing Option

CTSSCompatible Time Sharing System

IBM VMVirtual machine

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2. Control Program

Control Program:Manages all the components of a complex

computer system in an integrated manner.

Controls the execution of user programs andI/O devices to prevent errors and improperuse of computer resources.

Looks over and protects the computer:

Monitor, Supervisor, Executive, Controller,Master, Coordinator .

Sort of a black box view.

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Control program oriented OS names

Unisys MCPMaster Control Program

DR CP/MControl Program/Microcomputer

IBM VM/CPVM Control Program IBM AIXAdvanced Interactive eXecutive

DEC RSXResource Sharing eXecutive

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3. Command Executer

Command Executer:

Interfaces between the users and machine.

Supplies services/utilities to users.Provides the users with a convenient CLI

(Command Language Interface), also called

a Shell (in UNIX), for entering the usercommands.

Sort of a top-down view.

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Command Executer oriented OS names

IBM AIXAdvanced Interactive Executive

IBM VM/CMSConversational monitor

System

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Modern view: Virtual Machine (1)

Operating System as a Virtual Machine:

An interface between the user and hardware that

hides the details of the hardware (e.g., I/O).

Constructs higher-level (virtual) resources out oflower-level (physical) resources (e.g., files).

Definition: OS is a collection of software

enhancements, executed on the bare hardware,

culminating in a high-level virtual machine thatserves as an advanced programming environment.

virtual machine = software enhancement = extended

machine = abstract machine = layer = level = ring.

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Modern view: Virtual Machine (2)

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Definition of Operating System

There is no universally accepted definition.

Everything a vendor ships when you order an

operating system is good approximation but

varies widely.

The one program running at all times on the

computer is the Kernel.

Everything else is either a system program

(ships with the operating system) or an

application program.

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One Kernel Point of View

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What is the OS/Kernel?

Is the Operating System just the Kernel (notthe utilities and application programs)?!

The Command Line Interface (CLI) (or

command layer/interpreteror shell) allowsdirect command entry by the user.

The shell used to be in the kernel but now is a

(first between equals) utility outside of it:Easy to change/debug

Many of them (sh, bsh, csh, ksh, tcsh, wsh, bash)

Possible to switch between them (chsh)

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Utilities Shell

Kernel

Hardware

User

UNIX Shell and Utilities

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Bourne Shell (bsh)

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A very simplified Shell

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General UNIX Architecture (1)

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Other application programs

cc

Other application programs

Hardware

Kernel

sh whoa.out

date

we

grepedvi

ldas

comp

cppnroff

General UNIX Architecture (2)

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