Operating System Concepts 1.1 Silberschatz, Galvin …users.cs.fiu.edu/~ege/cop4610/Slides/ch1.pdf · Printer Disk)Significant increase in speed and ... processors share memory and

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Silberschatz, Galvin and Gagne ©20021.1Operating System Concepts

Chapter 1: Introduction

What is an Operating System?Mainframe SystemsDesktop SystemsMultiprocessor SystemsDistributed Systems Clustered SystemReal -Time SystemsHandheld SystemsComputing Environments


What is an Operating System?

A program that acts as an intermediary between a user of a computer and the computer hardware

Operating system goals:execute user programsmake solving user problems easiermake the computer system convenient to use

Use the computer hardware in an efficient manner


Computer System Components

1. Hardwareprovides basic computing resources (CPU, memory, I/O devices)

2. Operating systemcontrols and coordinates the use of the hardware among the various application programs for the various users

3. Applications programsdefine the ways in which the system resources are used to solve the computing problems of the users (compilers, database systems, video games, business programs)

4. Users(people, machines, other computers)

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Abstract View of System Components

•Terminal•PC•Workstation


System View

Resource allocatormanages and allocates resources.

Control programcontrols the execution of user programs and operations of I/O devices

Kernelthe one program running at all timesall else being application programs


Mainframe Systems

Reduce setup time by batching similar jobs

Automatic job sequencingautomatically transfers control from one job to anotherfirst rudimentary operating system

Resident monitorinitial control in monitor control transfers to job when job completes control transfers back to monitor

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Devices

Card reader20 cards/second !

Printer

DiskSignificant increase in speed and convenience

Job scheduling


Memory Layout for a Simple Batch System


Multi-programmed Batch Systems

• Several jobs are kept in main memory at the same time• CPU is multiplexed among them

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OS Features Needed for Multiprogramming

I/O routine supplied by the system

Memory managementsystem must allocate the memory to several jobs

CPU schedulingsystem must choose among several jobs ready to run

Allocation of devices


Time-Sharing Systems–Interactive Computing

CPU is multiplexed several jobs that are kept in memory and on diskCPU is allocated to a job only if the job is in memory

A job swapped in and out of memory to the diskVirtual memory systemJob becomes process

Direct user interactionoperating system runs job for useronce finished, it seeks next job from user

Users to access data and codeFile system


Desktop Systems

Personal computerscomputer system dedicated to a single user

I/O deviceskeyboards, mice, display screens, small printers.

User convenience and responsivenessadopt technology developed for larger system

individuals have sole use of computer and may not need advanced CPU utilization or protection features

operating system varies DOS, OS/2, Windows, MacOS, UNIX, Linux

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Parallel Systems

Multiprocessor systemsmore than one CPU in close communication

Tightly coupled systemprocessors share memory and a clockcommunication through the shared memory

Advantages of parallel system: Increased throughputEconomicalIncreased reliability

graceful degradationfail-soft systems


Parallel Systems (Cont.)

Symmetric multiprocessing (SMP)Each processor runs and identical copy of the operating systemMany processes can run at once without performance deterioration.Most modern operating systems support SMP

Asymmetric multiprocessingEach processor is assigned a specific taskMaster processor allocates work to slave processorsMore common in extremely large systems


Symmetric Multiprocessing Architecture

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Distributed Systems

Distribute the computation among several processors

Loosely coupled systemeach processor has its own local memoryprocessors communicate via high-speed buses or low-speed telephone lines.

Advantages of distributed systemsResources Sharing Computation speed up – load sharing ReliabilityCommunications


Distributed Systems (cont)

Requires networking infrastructure:Local area networks (LAN)Wide area networks (WAN)

client-serverComputer serverFile server

peer-to-peerEx: world-wide web


General Structure of Client-Server

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Distributed Systems

Operating system supportNetwork protocols

IP, TCP, UDPApplication protocols

ftp, http, sip

OS vs. NOS

True Distributed OS:User presents jobs to Dist-OSHigh degree of transparency


Clustered Systems

Clustering allows two or more systems to share storage

Higher degree of sharing of resourcesHigh-bandwidth connection

Provides high reliabilityAsymmetric clustering

one server runs the application while other servers standby

Symmetric clustering: all hosts are running the application


Real-Time Systems

Often used as a control device in a dedicated applicationcontrolling scientific experimentsmedical imaging systemsindustrial control systemssome display systems

Well-defined fixed-time constraintshard real-time: all tasks done on timesoft real-time: critical tasks have priority

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Real-Time Systems (Cont.)

Hard real-time:Secondary storage limited or absentdata stored in short term memoryor read-only memory (ROM)Conflicts with time-sharing systemsnot supported by general-purpose operating systems

Soft real-timeLimited utility in industrial control of roboticsUseful in applications (multimedia, virtual reality) requiring advanced operating-system features


Handheld Systems

Personal Digital Assistants (PDAs)Cellular telephones

Issues:Limited memorySlow processorsSmall display screens


Migration of Operating-System Concepts and Features

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Computing Environments

Traditional computingWeb-Based ComputingEmbedded Computing

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Operating System Concepts 1.1 Silberschatz, Galvin …users.cs.fiu.edu/~ege/cop4610/Slides/ch1.pdf · Printer Disk)Significant increase in speed and ... processors share memory and