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CS 217 - Operating Systems Lectutre-01 Introduction and Overview Somia Razzaq NFC IET.

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Presentation on theme: "CS 217 - Operating Systems Lectutre-01 Introduction and Overview Somia Razzaq NFC IET."— Presentation transcript:

1 CS Operating Systems Lectutre-01 Introduction and Overview Somia Razzaq NFC IET

2 Goals for today What is an Operating System? And – what is it not? Why study Operating Systems? How the course will proceed? Course content Grading Regulations Interaction is important! Ask Questions! Note: Some slides and/or pictures in the following lectures are adapted from author slides by Silberschatz, Galvin, and Gagne and some from different instructor lectures taken from internet. 2

3 Computer System 1.Hardware 2.Operating system 3.Applications programs 4.Users

4 Purpose of a Computer System Computer systems consist of software and hardware that are combined to provide a tool to solve specific problems in an efficient manner Execute programs 4

5 Layered View of a Computer System

6 Computer System Hardware Keyboard Mouse Printer RAM/ROM HD Mem Bus System Bus Monitor CD Processor Floating Point Unit Integer Unit Cache Control Unit

7 What is an Operating System? A program that acts as an intermediary between a user of a computer and the computer hardware A program that allocates and de-allocates computer system resources in an efficient, fair, and secure mannera resource manager 7

8 Goals of Operating System 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 8

9 Technology Trends: Moores Law 2X transistors/Chip Every 1.5 years Called Moores Law Moores Law Microprocessors have become smaller, denser, and more powerful. Gordon Moore (co-founder of Intel) predicted in 1965 that the transistor density of semiconductor chips would double roughly every 18 months. 9

10 ManyCore Chips: The future is here ManyCore refers to many processors/chip 64? 128? Hard to say exact boundary How to program these? Use 2 CPUs for video/audio Use 1 for word processor, 1 for browser 76 for virus checking??? Parallelism must be exploited at all levels Intel 80-core multicore chip (Feb 2007) –80 simple cores –Two floating point engines /core –Mesh-like "network-on-a-chip –100 million transistors –65nm feature size Frequency Voltage Power Bandwidth Performance 3.16 GHz 0.95 V 62W 1.62 Terabits/s 1.01 Teraflops 5.1 GHz 1.2 V 175W 2.61 Terabits/s 1.63 Teraflops 5.7 GHz 1.35 V 265W 2.92 Terabits/s 1.81 Teraflops 10

11 Computer System Organization Computer-system operation One or more CPUs, device controllers connect through common bus providing access to shared memory Concurrent execution of CPUs and devices competing for memory cycles 11

12 Functionality comes with great complexity! Proc Caches Busses Memory I/O Devices: Controllers adapters Disks Displays Keyboards Networks Pentium IV Chipset 12

13 Sample of Computer Architecture Topics Instruction Set Architecture Pipelining, Hazard Resolution, Superscalar, Reordering, Prediction, Speculation, Vector, Dynamic Compilation Addressing, Protection, Exception Handling L1 Cache L2 Cache DRAM Disks, WORM, Tape Coherence, Bandwidth, Latency Emerging Technologies Interleaving Bus protocols RAID VLSI Input/Output and Storage Memory Hierarchy Pipelining and Instruction Level Parallelism Network Communication Other Processors 13

14 Example: Some Mars Rover (Pathfinder) Requirements Pathfinder hardware limitations/complexity: 20Mhz processor, 128MB of DRAM, VxWorks OS cameras, scientific instruments, batteries, solar panels, and locomotion equipment Many independent processes work together Cant hit reset button very easily! Must reboot itself if necessary Must always be able to receive commands from Earth Individual Programs must not interfere Better not crash antenna positioning software! Further, all software may crash occasionally Automatic restart with diagnostics sent to Earth Periodic checkpoint of results saved? Certain functions time critical: Need to stop before hitting something Must track orbit of Earth for communication 14 Why processor is so limited? What if you had to move the rover paying attention to every little component? Taking care of the motors, measuring soil/distances, coordinating with the controller at Earth…!

15 How do we tame complexity? Every piece of computer hardware is different Different CPU Pentium, PowerPC, ColdFire, ARM, MIPS Different amounts of memory, disk, … Different types of devices Mice, Keyboards, Sensors, Cameras, Fingerprint readers Different networking environment Cable, DSL, Wireless, Firewalls,… Questions: Does the programmer need to write a single program that performs many independent activities? Does every program have to be altered for every piece of hardware? Does a faulty program crash everything? Does every program have access to all hardware? 15

16 OS Tool: Virtual Machine Abstraction Software Engineering Problem: Turn hardware/software quirks what programmers want/need Optimize for convenience, utilization, security, reliability, etc… For Any OS area (e.g. file systems, virtual memory, networking, scheduling): Whats the hardware interface? (physical reality) Whats the application interface? (nicer abstraction) Application Operating System Hardware Physical Machine Interface Virtual Machine Interface 16

17 What does an Operating System do? Silerschatz and Galvin: An OS is Similar to a government Begs the question: does a government do anything useful by itself? Coordinator and Traffic Cop: Manages all resources Settles conflicting requests for resources Prevents errors and improper use of the computer Facilitator: Provides facilities that everyone needs Standard Libraries, Windowing systems Make application programming easier, faster, less error-prone Some features reflect both tasks: E.g. File system is needed by everyone (Facilitator) But File system must be Protected (Traffic Cop) 17

18 So what is this course all about? What well be covering? and How we shall proceed? 18

19 Tentative Course Outline Week #ModuleTopics 1Introduction Introduction to the course Operating System Concepts System Structures 2Process Concepts Process Scheduling Process Operations Inter process Communication Communication in Client Server Systems 3 Multithreaded Programming Overview Multithreading Models Thread Libraries 4Process Scheduling Basic Concepts Scheduling Criteria Scheduling Algorithms Thread Scheduling 19

20 Course Outline Week #ModuleTopics 5Synchronization Overview Critical Section Problem Semaphores Monitors 6Deadlocks System Model Deadlock Characterization Methods for handling Deadlocks Deadlock Prevention 7 Memory Management Background Swapping Contiguous Memory Allocation Paging 20

21 Course Outline Week #ModuleTopics 8Mid Term Exam 9Virtual Memory Demand Paging Copy-on-Write Page Replacement Allocation of Frames Thrashing 10File System File Concept Access Methods Directory and Disk Structure File System Mounting 11-12Secondary Storage Structure Overview of Mass Storage Structure Disk Structure Disk Scheduling RAID Structure Overview 21

22 Course Outline Week #ModuleTopics 12-13I/O Systems Overview Hardware Application I/O Interface Kernel I/O Subsystem Transforming Requests to Hardware Operations Streams 13-14Protection Goals Principles Domain Access Matrix Access Control 15Security The issue Threats Cryptography Authentication Defense 16Distributed Operating Systems An overview of Distributed Operating System Concepts 22

23 Tentative Lab Exercise Plan Lab #ModuleWeek Lab 1 Process Creation in Java RMI Example (Optional) Week 2 Lab 2Threads in JavaWeek 3 Lab 3Threads in Java (priority scheduling example)Week4 Lab 4Synchronization in JavaWeek 5 Lab 5Deadlock Example with handling of deadlocks in JavaWeek 6 Lab 6Memory Management ExerciseWeek 8 23

24 Textbook Operating System Concepts – 7/8 th Edition Silberschatz, Galvin, and Gagne (Textbook) Modern Operating Systems,3rd Edition, Tanenbaum A.S., 2008 (Reference) 24

25 Grading Scheme Quizzes 5% (unannounced/announced) Assignment5% Attendance/ Class participation5% Midterm Exam:30% Final Exam:50% Term Assignment 5% 25

26 Academic Dishonesty Policy Copying all or part of another person's work, or using reference material not specifically allowed, are forms of cheating and will not be tolerated. A student involved in an incident of cheating will be subject to strict disciplinary action as per the institutes policies. The instructor may take actions such as: require repetition of the subject work, assign a'zero' grade to the subject work, 26

27 Remember Interaction is important! 27

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