• Like
  • Save
Upcoming SlideShare
Loading in...5




Operating system subject PPT

Operating system subject PPT



Total Views
Views on SlideShare
Embed Views



0 Embeds 0

No embeds



Upload Details

Uploaded via as Microsoft PowerPoint

Usage Rights

© All Rights Reserved

Report content

Flagged as inappropriate Flag as inappropriate
Flag as inappropriate

Select your reason for flagging this presentation as inappropriate.

  • Full Name Full Name Comment goes here.
    Are you sure you want to
    Your message goes here
Post Comment
Edit your comment

    Ossvv12013 Ossvv12013 Presentation Transcript

    • Operating Systems-EC426 Introduction Mr. S. V. Viraktamath, Faculty, Dept. of E&CE, SDMCET, Dharwad. svvmath@gmail.com
    • Introduction • What is an Operating System? – It is a program that manages computer hardware. – A program that acts as an intermediary between a user of a computer and the computer hardware. • Operating system goals: – Execute user programs and make solving user problems easier. – Make the computer system convenient to use. • Use the computer hardware in an efficient manner. 1/20/2014 SVV SDSMCET SVV SDMCET OS -2013 5
    • What is an OS • A program, C or C++ • Loads and runs other programs • Application programs might wish to: – Draw on the screen – Interact via a keyboard, mouse etc – Access the hard disk (files) – Communicate with other application programs • The OS should provide a consistent way to do this – Works on whatever hardware you have. 1/20/2014 SVV SDSMCET SVV SDMCET OS -2013 6
    • Introduction • Why to study the OS subject? – It is there in syllabus! – U work on Computer in any Job….. – Without OS difficult to work.. – Any s/w u design it runs on OS (Application) – New ―smart‖ devices need new OSs, U can write OS – High-performance servers are an OS issue – Resource consumption is an OS issue – Security is an OS issue 1/20/2014 SVV SDSMCET SVV SDMCET OS -2013 7
    • Current Technology DoCoMo video phone Laptop Mobile phone / PDA Best friend! Personal digital assistant (PDA) Thanks to M. Sloman for slides
    • Introduction • Topics includes 1. 2. 3. 4. 5. 6. 7. 8. 1/20/2014 Introduction to OS OS structure Process scheduling Process issues Storage Management Virtual Memory OS securities Case study SVV SDMCET OS -2013 9
    • Text books • Abraham Silberschatz, Peter Baer Galvin, Greg Gagne- ―Operating system Concepts‖, 6th Edition, Jhon Wiley & sons 2002, 2003. • Milan Milankovic, ―Operating system concepts and design‖, 2nd edition, MC Graw Hill 1992. • Harvey M Dietal ―Operating systems‖, Addison Wesley 1990 • D M Dhamdhere, ―Operating systems- A Concept based approach‖, Tata MC Hill 2002. 1/20/2014 SVV SDMCET OS -2013 10
    • Introduction • What do you think you are going to study in this subject? • Aim of the subject? 1/20/2014 SVV SDSMCET SVV SDMCET OS -2013 11
    • Introduction • Aim of the subject – Will not teach you how to use OS. – Examines the way OS works. – Which OS? Ex. Bike working/ parts.. – Algorithms & Data structures inside OS. – Problems/Solutions. ….. 1/20/2014 SVV SDMCET OS -2013 12
    • Introduction • Computer system can be divided into 4 components –Hardware –OS –Application Programs –Users 1/20/2014 SVV SDSMCET SVV SDMCET OS -2013 13
    • Computer System Components 1. Hardware – provides basic computing resources (CPU, memory, I/O devices). 2. Operating system – controls and coordinates the use of the hardware among the various application programs for the various users. 3. Applications programs – define 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). 1/20/2014 SVV SDMCET OS -2013 14
    • Abstract View of System Components 1/20/2014 SVV SDMCET OS -2013 15
    • Abstract View of System Components • A computer system consists of – hardware – system programs – application programs 1/20/2014 SVV SDMCET OS -2013 16
    • Introduction • What do you mean by system programming and Application programming? • OS can be explored from two view points – User View – System View 1/20/2014 SVV SDMCET OS -2013 17
    • User View • User View varies by the interface being used –Most comp are PCs • OS designed – –Ease of use –Some attention to performance –No attention to resource utilization • Monopolies resources. 1/20/2014 SVV SDMCET OS -2013 18
    • User View – Mainframe/Mini computer • Other users are accessing comp. • OS design- to maximize resource utilization • Resources - CPU time, Mem, I/O… – Workstations • Connected to N/W of other workstations & servers. • OS Design -compromise between usability and resource utilization. • Users have dedicated resources & some are shared-file servers, print servers. 1/20/2014 SVV SDMCET OS -2013 19
    • User View – Recently – Hand held computers • Come in to Fashion. • These are stand alone. • Some r connected to n/w, wire/wireless. • OS designed for individual/ Single user. – Some comp. no user view • Embedded systems, automobiles- numeric key pad, indicator lights -on or off. 1/20/2014 SVV SDMCET OS -2013 20
    • System View • OS as a resource allocator (Not simple Deadlock) – Many resources Ex. CPU time, memory space, file storage space, I/o devices and so on.. – OS acts as a manager of resources. • OS as a control program – It controls the improper use of the computers. – Concerned with operation and control of I/O devices. 1/20/2014 SVV SDMCET OS -2013 21
    • System View • • • • • OS is a pgm –most intimate with hardware Resource Allocator Manager Control program No complete definition for the OS. 1/20/2014 SVV SDMCET OS -2013 22
    • Goals of an OS • Fundamental goal of OS – To execute user programs & to make solving user programs easier. • Common definition – The OS is one program running at all times on the computer (Kernel) with all else being application programs. 1/20/2014 SVV SDMCET OS -2013 23
    • System Goals • Primary goal of some OS is convenience for the user. (small PCs) • Primary goal of other OS is efficient operation of comp system. (Large, shared, multi user expensive comps) • Convenience and Efficiency are some times contradictory. • Past Efficiency/Utilization was imp. • (As time changes goals changes!) 1/20/2014 SVV SDMCET OS -2013 24
    • Summary • • • • • What is the OS. Why to study the OS subject. Topics. Computer – 4 components. OS two views. – User Views. • PC, Main frame, Workstations, Handheld comps, Embedded – System View. • Resource allocator, Manager, Control program. – System goals. • Convenience and efficient/Utilization 1/20/2014 SVV SDMCET OS -2013 25
    • Evolution of OS: • Mainframe systems – Batch systems – Multiprogrammed systems – Time sharing systems • • • • • • Desktop systems Multiprocessor systems Distributed systems Clustered systems Real time systems Hand held systems 1/20/2014 SVV SDMCET OS -2013 26
    • First generation • What did the first operating system look like? 1945 to 1955 • No operating system • Human operators (Ex. Telephone) SVV SDMCET OS -2013
    • Batch Processing: • Why utilization? • IBM 7094 system costing $2,000,000, Life of 5 years, 24hrs use, 365days per year then $45.66 per hour! • Operational cost, cooling, paper, programmers ….. Rich wont work for money, Money work for them 1/20/2014 SVV SDSMCET 28
    • Batch Processing: • Common I/P devices were card readers and tape drives. • Common O/P devices were line printers, tape drives, card punches. • Operators were hired, he used to collect all the programs. (cards) • At some later time (minutes, hours, days) o/p, dump of memory and reg contents for debugging. 1/20/2014 29
    • Batch Processing: • OS was simple, its work is to transfer control from one job to next. • Jobs with similar needs are batched together, operator sort the programs. • Job batches of ―Fortran Jobs, Cobol jobs‖. • Jobs executed sequentially – one job at a time. • Cards -comprising of the program, the data, & some control information, ―Job header‖ control cards were used to define 1/20/2014 SVV SDSMCET 30
    • Batch Processing Programmer Operator Impersonal computing • Disadvantage: CPU idle, speed of mechanical I/O is less. • Card reader speed 1200cards/min, microsecond range. • Next technology Disks resulted. 1/20/2014 SVV SDSMCET CPU 31
    • Memory Layout for a Simple Batch System 1/20/2014 SVV SDMCET OS -2013 32
    • Multiprogramming: • • • • Why >1 program? Single user cannot keep –CPU I?O Busy Multiprogramming increases CPU utilization. Multiprogramming is a technique to execute number of programs simultaneously by a single processor. • In Multiprogramming, number of processes reside in main memory at a time. • 1/20/2014 SVV SDMCET OS -2013 33
    • Multiprogramming: • The OS picks and begins to executes one of the jobs in the main memory. • If any I/O wait happened in a process, then CPU switches from that job to another job. • Single pgm CPU--I/O— CPU --I/O – I/O wait-- CPU wait I/O wait-CPU wait • Hence CPU in not idle at any time. 1/20/2014 SVV SDMCET OS -2013 34
    • Multiprogramming: • Idea-Life situation: A lawyer does not work on only one client at a time. Other Ex. • How OS select the job if many are ready? Topic 6Hrs - cpu scheduling • More than one program--needs memory management. 1/20/2014 SVV SDMCET OS -2013 35
    • Multiprogramming OS Job 1 Job 2 Job 3 Job 4 • Figure depicts the layout multiprogramming system. of • The main memory consists of 5 jobs at a time, the CPU executes one by one. Advantages: • Efficient memory utilization • Throughput increases Job 5 1/20/2014 • CPU is never idle, so performance increases. SVV SDSMCET 36
    • Time Sharing Systems: • Multiprogramming environment –did not provide user interaction • MP and BP systems – offline-- poor user service • Computing becomes online – Video terminals .i.e. Key board and monitor screen; quick service to user • Time sharing is logical extension of multiprogramming, switch from program to program very fast, user can interact. • Many users share computer simultaneously. • User get impression –it is dedicated to her use. (SHE) 1/20/2014 SVV SDMCET OS -2013 37
    • Time Sharing Systems: • Program Vs Process Vs processor • Process?- A program loaded in to memory and executing is commonly referred to as a process. • When process go for I/O CPU can execute other program. • All user must receive reasonable service 1/20/2014 SVV SDMCET OS -2013 38
    • Time Sharing Systems: • Two provisions are made to ensure this – programs not assigned priorities – programs prevented from consuming unreasonable amount of cpu time • These provisions are implemented using the techniques – Round-robin scheduling – Time slice • RR Scheduling: Schedules the user program – only after all other programs get their turn on the CPU • Time slice: It is used to prevent monopolization of CPU by a program 1/20/2014 SVV SDMCET OS -2013 39
    • Time Sharing Systems: • Timesharing systems are more complex than Multi-programmed • Several jobs in the memory- Need Memory Management (Topic 5Hrs), Protection • Jobs may have to be swapped (disk back up). • Virtual Memory concept (Topic5Hrs). 1/20/2014 SVV SDMCET OS -2013 40
    • Desktop Systems: • PCs appeared in 1970s, Neither multiuser nor multitasking. • Goals of OS have changed with time • Instead of maximizing CPU and peripheral Utilization, the system opt for user convenience and responsiveness. • PC. OSs -MS windows, OS/2, Apple Macintosh OS, MacOS X, Unix, Linux... 1/20/2014 SVV SDMCET OS -2013 41
    • Desktop Systems • Hardware cost reduces individual use, Utilization was not prime concern. • Other design decision still apply – File protection (Internet). • MS-DOS lack of security-easy to destroy by worm or virus. 1/20/2014 SVV SDMCET OS -2013 42
    • Multiprocessor Systems • Most of the systems single processor. • Multi processor systems/parallel systems/tightly coupled systems-more than one processor –sharing comp bus, clock, sometimes memory and peripherals • Main Adv – Increased through put – Economy of scale – Increased reliability 1/20/2014 SVV SDSMCET SVV SDMCET OS -2013 43
    • – Increased through put • If one processor takes 10 sec then 10 processors takes ? – Economy of scale • Save money – instead of N separate processors • Share data no need of duplication • Share resources – Increased reliability • fail of one processer/10. • Graceful degradation/Fault tolerant. • Expensive –Duplication 1/20/2014 SVV SDMCET OS -2013 44
    • Multiprocessor Systems • Symmetric multiprocessing (SMP) (Peer to Peer) – Each processor runs an identical copy of the operating system. – Many processes can run at once without performance deterioration. – Most modern operating systems support SMP 1/20/2014 SVV SDMCET OS -2013 45
    • Multiprocessor Systems • Asymmetric multiprocessing (Master-slave) – Each processor is assigned a specific task; master processor schedules and allocated work to slave processors. – More common in extremely large systems 1/20/2014 SVV SDMCET OS -2013 46
    • Distributed Systems • Distribute the computation among several physical processors. LAN/WAN… • Loosely coupled system – each processor has its own local memory; processors communicate with one another through various communications lines, such as high-speed buses or telephone lines. • Advantages of distributed systems. – – – – 1/20/2014 Resources Sharing Computation speed up – load sharing Reliability Communications SVV SDMCET OS -2013 47
    • Distributed Systems • Requires networking infrastructure. • Local area networks (LAN) or Wide Area Networks (WAN) • May be either client-server or peer-to-peer systems. • General Structure of Client-Server 1/20/2014 SVV SDMCET OS -2013 48
    • Clustered Systems • Like parallel systems; Defn: Not concrete • Clustering allows two or more systems to share storage. • Provides high reliability. • Asymmetric clustering: one server runs the application while other servers standby. • Symmetric clustering: all N hosts are running the application. 1/20/2014 SVV SDMCET OS -2013 49
    • Real-Time Systems • Often used as a control device in a dedicated application such as controlling scientific experiments, medical imaging systems, industrial control systems, and some display systems. • Well-defined fixed-time constraints. • Real-Time systems may be either hard or soft real-time. 1/20/2014 SVV SDMCET OS -2013 50
    • Real-Time Systems • Hard real-time: – Secondary storage limited or absent, data stored in short term memory, or read-only memory (ROM) – Conflicts with time-sharing systems, not supported by general-purpose operating systems. • Soft real-time – Limited utility in industrial control of robotics – Useful in applications (multimedia, virtual reality) requiring advanced operating-system features. 1/20/2014 SVV SDMCET OS -2013 51
    • Handheld Systems • Personal Digital Assistants (PDAs) • Cellular telephones • Issues: – Limited memory – Slow processors – Small display screens. 1/20/2014 SVV SDMCET OS -2013 52
    • 1/20/2014 SVV SDMCET OS -2013 53