Operating System Concepts Ku-Yaw Chang [email protected] Assistant Professor, Department of...

Operating System Operating System ConceptsConcepts

Ku-Yaw ChangKu-Yaw [email protected]@mail.dyu.edu.tw

Assistant Professor, Department of Assistant Professor, Department of Computer Science and Information EngineeringComputer Science and Information Engineering

Da-Yeh UniversityDa-Yeh University

22Ku-Yaw ChangKu-Yaw Chang Chapter 1 IntroductionChapter 1 Introduction

Chapter 1 IntroductionChapter 1 Introduction

An An Operating SystemOperating System (OS) (OS) A program that manages the computer hardwareA program that manages the computer hardware Provides a basis for application programsProvides a basis for application programs Acts as an intermediary between a user of a Acts as an intermediary between a user of a

computer and the computer hardwarecomputer and the computer hardware

Some operating systems are designed to beSome operating systems are designed to be ConvenientConvenient EfficientEfficient Some combination of the aboveSome combination of the above



To understand how they have developedTo understand how they have developed Trace the development of operating systemsTrace the development of operating systems Operating system variationsOperating system variations

Parallel systemsParallel systems

Real-time systemsReal-time systems

Embedded systemsEmbedded systems



1.1. What is an Operating What is an Operating System?System?

2.2. Mainframe SystemsMainframe Systems

3.3. Desktop SystemsDesktop Systems

4.4. Multiprocessor Multiprocessor SystemsSystems

5.5. Distributed Systems Distributed Systems

6.6. Clustered SystemClustered System

7.7. Real-Time SystemsReal-Time Systems

8.8. Handheld SystemsHandheld Systems

9.9. Feature MigrationFeature Migration

10.10. Computing Computing EnvironmentsEnvironments

11.11. SummarySummary

12.12. ExercisesExercises


1.1 What Is an Operating System?1.1 What Is an Operating System?

A computer system can be divided into:A computer system can be divided into: The The hardwarehardware The The operating systemoperating system The The application programsapplication programs The The usersusers


Abstract view of the componentsAbstract view of the componentsof a computer systemof a computer system


Computer System ComponentsComputer System Components

1.1. HardwareHardware – provides basic computing resources (CPU, – provides basic computing resources (CPU, memory, I/O devices).memory, I/O devices).

2.2. Operating systemOperating system – controls and coordinates the use of – controls and coordinates the use of the hardware among the various application programs the hardware among the various application programs for the various users.for the various users.

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

4.4. UsersUsers (people, machines, other computers). (people, machines, other computers).


Two ViewpointsTwo Viewpoints

1.1.1 User View1.1.1 User ViewPCPC

Monopolize its resourcesMonopolize its resources Maximize the workMaximize the work Designed for ease of use - Designed for ease of use - convenientconvenient

Mainframe or minicomputerMainframe or minicomputer TerminalTerminal Share resources and may exchange informationShare resources and may exchange information Maximize resource utilization – Maximize resource utilization – efficientefficient

WorkstationWorkstation Compromise between individual usability and resource utilizationCompromise between individual usability and resource utilization

Embedded computerEmbedded computer Little or no user viewLittle or no user view


Two ViewpointsTwo Viewpoints

1.1.2 System View1.1.2 System View

Resource allocatorResource allocator manages and allocates resources.manages and allocates resources.

Control programControl program controls the execution of user programs and controls the execution of user programs and

operations of I/O devices .operations of I/O devices .

KernelKernel the one program running at all times (all else the one program running at all times (all else

being application programs)being application programs)


1.1.3 System Goals1.1.3 System Goals

TradeoffsTradeoffs ConvenienceConvenience EfficiencyEfficiency

Operating systems have also evolved over Operating systems have also evolved over time.time. Graphical User Interfaces (GUIs)Graphical User Interfaces (GUIs)


1.2 Mainframe Systems1.2 Mainframe Systems

First computers used to tackle many First computers used to tackle many commercial and scientific applicationscommercial and scientific applications Batch systemsBatch systems Multiprogrammed SystemsMultiprogrammed Systems Time-Sharing SystemsTime-Sharing Systems


1.2.1 Batch Systems1.2.1 Batch Systems

Early computerEarly computer Physically enormous machine run from a consolePhysically enormous machine run from a console

Input devicesInput devicesCard readersCard readers

Tape drivesTape drives

User prepared a job and submitted it to the User prepared a job and submitted it to the computer operatorcomputer operator

At some time later, the output appeared.At some time later, the output appeared.

Output devicesOutput devicesLine PrinterLine Printer

Tape drivesTape drives

Card punchesCard punches


1.2.1 Batch Systems1.2.1 Batch Systems

First rudimentary operating systemFirst rudimentary operating system Always resident in memoryAlways resident in memory

To speed up processingTo speed up processing BatchBatch similar jobs similar jobs Automatic job sequencing – transfers control Automatic job sequencing – transfers control

from one job to anotherfrom one job to another

Introduction of disk technologyIntroduction of disk technology Keep all jobs on diskKeep all jobs on disk Job schedulingJob scheduling


Memory LayoutMemory Layoutfor a Simple Batch Systemfor a Simple Batch System


1.2.2 Multiprogrammed Systems1.2.2 Multiprogrammed Systems

Increase CPU utilizationIncrease CPU utilization Keep several jobs in memory simultaneouslyKeep several jobs in memory simultaneously CPU is multiplexed among them. CPU is multiplexed among them.


Memory LayoutMemory Layoutfor a Multiprogramming Systemfor a Multiprogramming System


1.2.2 Multiprogrammed Systems1.2.2 Multiprogrammed Systems

Job schedulingJob scheduling All the jobs enter the system are kept in the All the jobs enter the system are kept in the

job pooljob poolProcesses residing on disk awaiting for allocation Processes residing on disk awaiting for allocation of main memoryof main memory

If there is not enough room for all the jobs, the If there is not enough room for all the jobs, the system must choose among them.system must choose among them.

CPU schedulingCPU scheduling If several jobs are ready to run at the same If several jobs are ready to run at the same

time, the system must choose among them.time, the system must choose among them.


1.2.3 Time-Sharing Systems1.2.3 Time-Sharing Systems

Multiprogrammed, batch systemsMultiprogrammed, batch systems Utilize system resources effectivelyUtilize system resources effectively

CPU, memory, peripheral devicesCPU, memory, peripheral devices Do not provide user interaction with computer Do not provide user interaction with computer

system.system.

Time-sharing (Multitasking)Time-sharing (Multitasking) system system A logical extension of multiprogrammingA logical extension of multiprogramming Switch CPU among multiple jobs frequentlySwitch CPU among multiple jobs frequently

The user can interact with each program while it is The user can interact with each program while it is running.running.



Response timeResponse time The amount of time it takes to start respondingThe amount of time it takes to start responding

(not output that response)(not output that response)

An interactive (hands-on) computer systemAn interactive (hands-on) computer system Direct communicationDirect communication The response time should be short – typically with 1 The response time should be short – typically with 1

second or so.second or so.



A time-sharing systemA time-sharing system Allow many users to share the computer Allow many users to share the computer

simultaneouslysimultaneously Switch rapidly from one user to the nextSwitch rapidly from one user to the next Give each user the impression that the entire Give each user the impression that the entire

computer system is dedicated to his/her usecomputer system is dedicated to his/her use



Multiprogramming and time sharing Multiprogramming and time sharing systems are the central themes of modern systems are the central themes of modern operating systemsoperating systems Process and Thread conceptsProcess and Thread concepts Virtual / Physical memoryVirtual / Physical memory File systemFile system


1.3 Desktop Systems1.3 Desktop Systems

Personal computers (PCs)Personal computers (PCs) Computer system dedicated to a single user.Computer system dedicated to a single user.

Appear in the 1970sAppear in the 1970s Maximizing user convenience and Maximizing user convenience and

responsivenessresponsivenessInstead of maximizing CPU and peripheral Instead of maximizing CPU and peripheral utilizationutilization

May run several different types of operating May run several different types of operating systems (Windows, MacOS, UNIX, Linux)systems (Windows, MacOS, UNIX, Linux)


1.4 Multiprocessor Systems1.4 Multiprocessor Systems

More than one CPU in close communicationMore than one CPU in close communication Also known as Also known as parallel systemsparallel systems or or tightly coupled systemstightly coupled systems

Processors shareProcessors share Computer busComputer bus ClockClock

Main AdvantagesMain Advantages Increased throughputIncreased throughput Economy of scaleEconomy of scale Increased reliabilityIncreased reliability

graceful degradationgraceful degradation

fault tolerantfault tolerant

MemoryMemory Peripheral devicesPeripheral devices


1.4 Multiprocessor Systems1.4 Multiprocessor Systems

Symmetric multiprocessing (SMP)Symmetric multiprocessing (SMP) Each processor runs an identical copy of the Each processor runs an identical copy of the

operating system.operating system. Many processes can run simultaneously without Many processes can run simultaneously without

performance deterioration.performance deterioration. Most modern operating systems support SMP.Most modern operating systems support SMP.

Asymmetric multiprocessingAsymmetric multiprocessing Each processor is assigned a specific task; master Each processor is assigned a specific task; master

processor schedules and allocated work to slave processor schedules and allocated work to slave processors.processors.

More common in extremely large systemsMore common in extremely large systems


Symmetric Multiprocessing Symmetric Multiprocessing ArchitectureArchitecture







5.5. Distributed SystemsDistributed Systems









1.5 Distributed Systems1.5 Distributed Systems

Depends on network functionalityDepends on network functionality TCP/IP is the most common network protocolTCP/IP is the most common network protocol

Local-area network (LAN)Local-area network (LAN) Within a room, a floor, or a buildingWithin a room, a floor, or a building

Wide-area network (WAN)Wide-area network (WAN) Between buildings, cities, or countriesBetween buildings, cities, or countries

Metropolitan-area network (MAN)Metropolitan-area network (MAN) Buildings within a cityBuildings within a city

Small-area network (SAN)Small-area network (SAN) Short distance of several feet : BlueToothShort distance of several feet : BlueTooth


1.5.1 Client-Server Systems1.5.1 Client-Server Systems

Centralized systemsCentralized systems TerminalsTerminals

Supplanted by PCsSupplanted by PCs Server systemsServer systems

Satisfy requests generated by client systemsSatisfy requests generated by client systems

Two categories (broadly)Two categories (broadly) Compute-server systemsCompute-server systems File-server systemsFile-server systems


General Structure ofGeneral Structure ofa Client-Server Systema Client-Server System


1.5.2 Peer-to-Peer Systems1.5.2 Peer-to-Peer Systems

Distribute the computation among several Distribute the computation among several physical processors.physical processors.

Loosely coupled systemLoosely coupled system each processor has its own local memoryeach processor has its own local memory processors communicate with one another through processors communicate with one another through

various communications lines, such as high-speed various communications lines, such as high-speed buses or telephone lines.buses or telephone lines.

Network operating systemNetwork operating system Provide features such as file sharing across the Provide features such as file sharing across the

networknetwork


1.6 Clustered Systems1.6 Clustered Systems

Gather multiple CPUs to accomplish Gather multiple CPUs to accomplish computational workcomputational work Provide Provide high availabilityhigh availability

General accepted definitionGeneral accepted definition Clustered computers Clustered computers share storageshare storage and are and are

closely linked via LAN networkingclosely linked via LAN networking



AsymmetricAsymmetric clustering clustering one server runs the application while other one server runs the application while other

servers standby.servers standby.

SymmetricSymmetric clustering clustering all N hosts are running the application.all N hosts are running the application.



Parallel clustersParallel clusters Multiple hosts to access the same data on the Multiple hosts to access the same data on the

shared storageshared storageMost OSs lack such supportMost OSs lack such support

Clustering over a WANClustering over a WAN Global clusters – the machines could be Global clusters – the machines could be

anywhere in the worldanywhere in the world

Cluster technology is rapidly changing.Cluster technology is rapidly changing. Storage-Area-Networks (SANs)Storage-Area-Networks (SANs)


1.7 Real-Time Systems1.7 Real-Time Systems

Well-defined, fixed time constraintsWell-defined, fixed time constraints Processing Processing mustmust be done within the defined be done within the defined

constraints, or the system will fail.constraints, or the system will fail.

Often used as a control device in a Often used as a control device in a dedicated applicationdedicated application Weapon systemsWeapon systems Medical imaging systemsMedical imaging systems Industrial control systemsIndustrial control systems


Two FlavorsTwo Flavors

Hard real-time systemHard real-time system Secondary storage limited or absent, data stored in Secondary storage limited or absent, data stored in

short term memory, or read-only memory (ROM)short term memory, or read-only memory (ROM) Conflicts with time-sharing systems, not supported by Conflicts with time-sharing systems, not supported by

general-purpose operating systemsgeneral-purpose operating systems

Soft real-time systemSoft real-time system Limited utility in industrial control of roboticsLimited utility in industrial control of robotics Useful in applications (multimedia, virtual reality) Useful in applications (multimedia, virtual reality)

requiring advanced operating-system featuresrequiring advanced operating-system features


1.8 Handheld Systems1.8 Handheld Systems

Personal Digital Assistants (PDAs)Personal Digital Assistants (PDAs) PalmPalm

Cellular telephonesCellular telephones

Limited sizeLimited size Small amount of memorySmall amount of memory Slow processorSlow processor Small display screensSmall display screens


Migration of Migration of OS Concepts and FeaturesOS Concepts and Features


1.10 Computing Environments1.10 Computing Environments

Traditional computingTraditional computing

Web-based computingWeb-based computing

Embedded computingEmbedded computing


SummarySummary

P.23 – P.24P.23 – P.24


ExercisesExercises

1.31.3

1.41.4

1.51.5

1.91.9

1.101.10

The EndThe End

Operating System Concepts Ku-Yaw Chang [email protected] Assistant Professor, Department of...

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