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Operating Systems

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Why Bother? • We do not know:

• Who is Linus Trovalds• Who is Andrew Tanenbaum• What does the “red devil” logo represent• How Bill Gates made his $$$ ….• What is this fuss about “open-source” software

• In addition, we want to learn: • What is an Operating System (OS)• How it manages computer hardware

• IMO, “the” most important subject in a IT degree:• We are doing one!

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A Simple Definition of OS• A complex layer of software between applications and the

computer hardware (my own definition)• An operating system (OS) is a computer program that manages

the hardware and software resources of a computer (wikipedia)• Its hard to agree on an authoritative definition:

• The bad news is that it is not possible (IMO)

• The good news is that it is not important

Applications like Internet Explorer

Operating System

Computer Hardware

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What Needs Learning?• Background:

• Computer architecture -- what exactly is managed by the OS

• Evolution of OS • Processes:

• How OS is executing applications

• Memory:• How memory is managed

• Scheduling:• How are multiple applications managed

• Input, output, and file systems:• How do computers store data on hard disk

• Networking:• How do two computers talk to each other

• Security:• How to ensure that your data is safe

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Text Book

• “Operating Systems”, 5th Edition by William Stallings

Currently its not available in the library but we have ordered it

• We might have to live with the 4th edition!

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• This book is very simple and “simple is good”• If time allows, we will cover the whole book• The slides for this books are freely available:

• I will use customized slides in the class and will upload it on my website

• Do not expect that slides will help you in exams• I’ll be testing your concepts!• Do not expect a question like:

• “define operating system and give two examples”

• I will recommend that you read through the book (Chapter by Chapter): • Try to understand the OS concepts!

Why this Book?

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Rules of the Game• Grading Policy:

• I will upload it on the course website

• We’ll have normal stuff like 2 OHTs, 1 final exams, quizzes, and assignments

• In addition, I’d like every student to present something interesting about OS or its applications in the class: • List of topics will be uploaded soon

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Anyway .. .. ..• Early computers (1940s era) had no OS• Things got interesting in 1964:

• IBM developed System/360 hardware• OS/360 was developed with the aim of “one OS for

IBM hardware”• OS/360 evolved in Multics, which inspired UNIX in

1970s

• And UNIX changed everything!

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Tanenbaum and Minix• Professor of CS at Vrije Universiteit, Amsterdam in the

Netherlands• Wrote Minix for research and teaching purposes• http://www.cs.vu.nl/~ast/• http://en.wikipedia.org/wiki/Andrew_S._Tanenbaum

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Linus and Linux• Linus Trovalds is the guy who

wrote Linux when he was a student in Finland:• Evolved out of Minix

• He is the ultimate authority of Linux OS:• Current estimates suggest that

he has 2% contribution to Linux

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Linus vs. Tanenbaum• Background:

• Linux has “monolithic” kernel• Minix is based on “microkernel” approach

• AST posted an email “Linux is obsolete”: • “ … the debate is essentially over. Microkernels have won …”• “ … portability …”

• Reply from Linus:• “… look at who makes money off minix, and who gives linux out for free …”• “… your job is being a professor and researcher. That's one hell of a good excuse for some of the brain-

damages of minix …”• “.. From a theoretical (and aesthetical) standpoint linux looses ..“• “.. Linux wins heavily on points of being available now ..”

• Linus vs. Tanenbaum:• http://people.fluidsignal.com/~luferbu/misc/Linus_vs_Tanenbaum.html

• More on :• http://en.wikipedia.org/wiki/Tanenbaum-Torvalds_debate and Google

• Today, Linux is much widely adopted than other non-M$ (Microsoft) Oses:• Of course Windows is the clear market leader

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Some Linux Distributions• Red Hat Fedora Linux• Debian• Gentoo• SuSE • Slackware• Ubuntu• Knoppix• Many more …

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How Bill Gates made his $$$• In terms of market-share, M$ Windows is the

big boy in OSes …• I’ll let you find out more about this …

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Steve Jobs - The Apple Guy

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Open Source Software• Open source refers to any computer software whose

source code is available under a license (or arrangement such as the public domain) that permits users to study, change, and improve the software, and to redistribute it in modified or unmodified form (Wikipedia)

• Open Source Initiative: http://www.opensource.org/• Free Software Foundation: http://www.fsf.org/• GNU (GNU’s Not Unix) Project: http://www.gnu.org/• According to GNU:

• “Free software” is a matter of liberty, not price. To understand the concept, you should think of “free” as in “free speech”, not as in “free coke”

• How will companies make money then?

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Now About Me• Name: Aamir Shafi• Computer Software Engr. from MCS (2003)

• Did my final year project at NIIT

• Ph.D. from the Institute of Cosmology and Gravitation at the University of Portsmouth, UK (2006)

• Ph.D. Supervisors: • Mark Baker • Bryan Carpenter

• Thesis Title: “Nested Parallelism for Multicore Systems Using Java”

• Taking care of the Center for High Performance Scientific Computing

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Research Interests• Research, development, and evaluation of parallel

programming libraries, languages, and paradigms• Also interested in scientific computing and simulations:

• Ported a cosmological simulation code to Java

• I’m the developer and maintainer of MPJ Express: • A Java HPC library• http://acet.rdg.ac.uk/projects/mpj/• http://mpj-express.org

• My old outdated website:• http://acet.rdg.ac.uk/~mas

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Parallel Computing Workshop• At NIIT, we will be conducting a three day

workshop on parallel computing: • More details on: http://www.niit.edu.pk/hpsc

• All BIT-7 students are encouraged to attend this workshop: • Registration

• High Performance Computing or Parallel Computing or Scientific Computing is a very specialized area:• Probably our only chance to get into NASA or ESA …

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Lets Start Parallel Computing • Get to know Parallel Computing:

• http://www.llnl.gov/computing/tutorials/parallel_comp/

• Get to know Message Passing Interface (MPI):• http://www.llnl.gov/computing/tutorials/mpi

• Get to know OpenMP:• http://www.llnl.gov/computing/tutorials/openMP/

• Try running a “Hello World” MPJ Express program: • Download and install MPJ Express from

(http://acet.rdg.ac.uk/projects/mpj)

• Need help: • See me in the HPC lab

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My Take on Research• In CS, research and development are strongly

tied together• Normally researchers in HPC are excellent

programmers: • Fortran, C, or Java

• A simple definition of research is “better understanding of things”

• Research could be very frustrating and challenging at times

• Good research always start with a lot of reading and thorough literature review

• Anyway, its an OS class …

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Summary• Covered some popular UNIX-based OSes• Reminded ourselves the importance of

operating systems• Linux is a good OS, and deserves “a try” from

us• Center for High Performance Scientific

Computing is up and running: • Maybe you could join us while we are starting

• Next week we will talk about “computer architecture and evolution of OS” -- basically Chapter 1 and 2 of Stallings book