Course Outline • Prerequisites – COMPXXXX Data structuresand algorithms • Stacks, queues, hash tables, lists, trees, heaps,. Introduction – COMPXXXX Microprocessor and Interfacing • Assembly programming • Mapping of high-level procedural language to assembly language COMP3231/9201/3891/9283 • Interrupts (Extended) Operating Systems – You are expected to be competent programmers!!!! • We will be using the C programming language Kevin Elphinstone – The dominant language for OS implementation. – Need to understand pointers, pointer arithmetic, explicit memory allocation. 2 Why does this fail? Lectures • Common for all courses(3231/3891/9201/9283) void func(int *x, int *y) • Wednesday, 1-3pm, ElecEng G25 { • Thursday, 1-2pm, Webster Theatre A *x = 1; *y = 2; – Extended OS Thursday 2-3pm Webster 250 • starts in week2 } – The lecture notes will be available on the course web site void main() • Available prior to lectures, when possible. { • Slide numbersfor note taking – The lecture notes and textbook are NOT a substitute for int *a, *b; attending lectures. func(a,b); printf(“%d %d\n”,*a,*b); } 3 4 Tutorials Assignments • Start in week 2 • Assignmentsform a substantial component of your assessment. • A tutorial participation mark will • They are challenging!!!! contribute to your final assessment. – Because operating systemsare challenging – Participation meansparticipation, NOT • We will be using OS/161, attendance. – an educational operating system – Comp3891/9283 studentsexcluded – developed by the SystemsGroup At Harvard – It containsroughly 20,000 linesof code and – Comp9201 optional comments • You will only get participation marks in your enrolled tutorial. 5 6 1 Assignments Assignments • Assignmentsare in pairs • Don’t under estimate the time needed to do the – Info on how to pair up available soon assignments. • We usually offer advanced versionsof the • If you start a couple daysbefore they are due, you assignments will be late. – Available bonus marks are small compared to amount of • To encourage you to start early, effort required. – Bonus 10% of max mark of the assignment for finishing a – Student should do it for the challenge, not the marks. week early – Attempting the advanced component is not a valid excuse – To iron out any potential problems with the spec, 5% bonus for failure to complete the normal component of the for finishing within 48 hours of assignment release. assignment – See course handout for exact details • Extended OS students(COMP3891/9283) are • Read the fine print!!!! expected to attempt the advanced assignments 7 8 Assignments Assignments • Three assignments • Late penalty – due roughly week 3, 6, 11 – 4% of total assignment value per day • The first one is trivial • Assignment isworth 20% • You get 18, and are 2 dayslate – It’sa warm up to have you familiarize • Final mark = 18 – (20*0.04*2) = 16 (16.4) yourself with the environment and easy marks. • Assignments are only accepted up to – Do not use it asa gauge for judging the one week late. 8+ days = 0 difficulty of the following assignments. 9 10 Assignments Plagiarism • To help you with the assignments • We take cheating seriously!!! – We dedicate a tutorial per-assignment to • We systematically check for plagiarised code discussissuesrelated to the assignment – Penaltiesare generally sufficient to make it difficult – Prepare for them!!!!! to pass 11 12 2 Cheating Statistics Exams Session 1998/S1 1999/S1 2000/S1 2001/S1 2001/S2 2002/S1 2002/S2 2003/S1 2003/S2 enrolment 178 410 320 300 107 298 156 333 133 • There is NO mid-session suspected cheaters 10(6%) 26(6%) 22(7%) 26(9%) 20(19%) 15(5%) ???(?%) 13 (4%) ???(?%) • The final written exam is 2 hours full penalties * * * * 2 6 9 14 10 9 5 2 1 reduced penalties 7 15 7 7 5 4 2 2 9 • Supplementary exams are oral . cheaters failed 4 10 16 16 10 12 5 4 ? cheaters – Supplementariesare available according to suspended 0 0 1 0 0 1 0 0 0 UNSW & school policy, not asa second chance. *Note: Full penalty0 FL not applied prior to 2001/S1 13 14 Assessment 3891/9283 • Exam Mark • ClassMark • No tutorial participation component Component Component • Assignment marks scaled to 100 – Max mark of 100 – Max mark of 100 • Based solely on the • 10% tutorial final exam participation • 90% Assignments 15 16 9201 Undergrad Assessment • Optional tutorial participation, we’ll • The final assessment is the harmonic award the better mark of mean of the exam and class – Tutorial participation included asfor component. comp3231 • If E >= 40, – Classmarked based solely on the assignments 2EC M = E + C 17 18 3 Postgrads (9201/9283) Assessment • Maximum of a 50/50 weighted harmonic mean and a 20/80 harmonicmean • If E < 40 – Can weight final mark heavily on exam if you can’t commit the time to the assignments – You are rewarded for seriously attempting the assignments 2EC M = min44, • if E >= 40, E + C 2EC 5EC M = max( E+C , E+4C ) 19 20 Harmonic Mean (Class Mark = 100 - Exam Mark) Final M ark = 50 100 100 90 90 80 80 70 70 Harm 50/50 60 60 Arith 50/50 Harm 50/50 50 50 Arith 20/80 Harm 20/80 Final Mark Final 40 Harm 20/80 40 30 30 20 20 ExamMark Required to Pass 10 10 0 0 0 10 20 30 40 50 60 70 80 90 100 0 10 20 30 40 50 60 70 80 90 100 Exam Mark Class Mark 21 22 Assessment Textbook • You need to perform reasonably • Andrew consistently in both exam and class Tanenbaum, components. Modern Operating • Harmonic mean only has significant Systems, 3rd effect with significant variation. Edition, Prentice Hall • Reserve the right to scale, and scale courses individually if required. – Warning: We have not scaled in the past. 23 24 4 References Consultations/Questions • A. Silberschatz and P.B. Galvin, Operating System Concepts , • Questionsshould be directed to the forum. th th th 5 , 6 , or 7 edition, Addison Wesley • Admin related queriesto NicholasFitzroy-Dale • William Stallings, Operating Systems: Internals and Design Principles, 4th or 5 th edition, Prentice Hall. [email protected] • A. Tannenbaum, A. Woodhull, Operating Systems--Design and • Personal queriescan be directed to me Implementation , 2 nd edition Prentice Hall [email protected] • John O'Gorman, Operating Systems , MacMillan, 2000 • We reserve the right to ignore email sent directly to • Uresh Vahalla, UNIX Internals: The New Frontiers , Prentice us(including tutors) if it should have been directed to Hall, 1996 the forum. • McKusick et al., The Design and Implementation of the 4.4 BSD Operating System , Addison Wesley, 1996 • Consultation Times – TBA 25 26 Course Outline Course Outline • “the course aims to educate students in • Processes and threads the basic concepts and components of • Concurrency control operating systems, the relevant • Memory Management characteristics of hardware, and the tradeoffs between conflicting objectives • File Systems faced by operating systems in efficiently • I/O and Devices supporting a wide range of • Security applications.” • Scheduling 27 28 Learning Outcomes • High-level understand what is an Introduction to Operating operating system and the role it plays Systems • Appreciate the evolution of operating systems tracks the evolution of Chapter 1 – 1.3 hardware, and that evolution is repeated in each new hardware era. 30 5 What is an Operating System? 31 32 Viewing the Operating System as an Abstract Disk Users Machine • Extends the basic hardware with added Memory functionality • Provides high-level abstractions CPU – More programmer friendly – Common core for all applications Network • It hides the details of the hardware Bandwidth – Makesapplication code portable 33 34 Dated View: the Operating Viewing the Operating System System as the Privileged as a Resource Manager Privileged Mode Component • Responsible for allocating resourcesto users and processes Operating System • Must ensure – No Starvation – Progress Requests Applications – Allocation isaccording to some desired policy • First-come, first-served; Fair share; Weighted fair share; (System Calls) limits (quotas), etc User Mode – Overall, that the system isefficiently used Applications Applications 35 36 6 The Operating System is Why Study Operating Privileged Systems? • Applicationsshould not be able to interfere or bypass • There are many interesting problemsin the operating system operating systems. – OS can enforce the “extended machine” • For a complete, top-to-bottom view of a – OS can enforce its resource allocation policies system. – Prevent applications from interfering with each other • Understand performance implicationsof application behaviour. • Note: Some Embedded OSshave no privileged component, e.g. PalmOS • Understanding and programming large, – Can implement OS functionality, but cannot enforce it. complex, software systemsisa good skill to • Note: Some operating systemsimplement significant acquire. OS functionality in user-mode, e.g. User-mode Linux 37 38 Second Generation Machines (A brief) Operating System History • Largely parallelshardware Batch Systems development • IBM 7094 • First Generation machines – 0.35 MIPS, 32K x 36-bit memory – Vacuum tubes – 3.5 million dollars – Plug boards • Programming via wiring • Batching used to more • Userswere simultaneously efficiently use the designers, engineers, and hardware programmers – Share machine amongst • “single user” many users • difficult to debug (hardware) – One at a time – No Operating System – Debugging a pain • Drinkcoffee until jobs finished 39 40 Batch System Issue: Keeping Batch Operating Systems Systems Busy • Reading tapesor punch cardswastime • Sometimes called “resident