Operating Systems Vivek Pai Lecture 1 Sep 12, 2002

COS Operating Systems, Vivek Pai2 Introduction Who I am  Vivek Pai  PhD 99/00, Rice  Research: OS, networking, high- performance apps Why I do this  Fun  Interesting  Design opportunities  “Profitable”

Sep 12, 2002COS Operating Systems, Vivek Pai3 About this course… Principles  OS design  Some theory  Rationale  Practice Not trade school Goals  Understand OS decisions  Basis for future learning  Get hands dirty Not “elite hacker”

Sep 12, 2002COS Operating Systems, Vivek Pai4 Expect (Some) Pain Fast pace Lots of projects (programming) Hard material Course changing based on feedback Not the end of the world – course favorably received last year, under much more trying circumstances

Sep 12, 2002COS Operating Systems, Vivek Pai5 What Works & Doesn’t Works  Solid C background  Flexible approach  Grasping Prereqs  Open mind  Einstein  Feedback sheets Doesn’t  Schedule overload  Missing background  Mathematical precision

Sep 12, 2002COS Operating Systems, Vivek Pai6 Why So Many Grades?  Programming projects  Midterm & final exams  Quizzes ( see me about health/school absences ) Intended to reduce pressure/anxiety More data points = less noise Somewhat generous extra credit

Sep 12, 2002COS Operating Systems, Vivek Pai7 Some Relief Grades based on mean/deviation People have done generally well in the past 25 / 38 As 17 / 11 Bs 4 / 7 Cs Honor System  Use common sense  Ask for clarification  Cooperation OK  Work is your own (pairs for labs)

Sep 12, 2002COS Operating Systems, Vivek Pai8 There Is No Magic This Is Engineering  Tradeoffs  Constraints  Optimizations  Imperfection Nothing’s Permanent  High rate of change  Lots of inertia  Cost/benefit analyses  Human error

Sep 12, 2002COS Operating Systems, Vivek Pai9 Mechanics – Info  My home page  Course home page  Newsgroup  Precepts  Design reviews

Sep 12, 2002COS Operating Systems, Vivek Pai10 Mechanics – Grading  Assigned readings  20% quizzes  20% midterm  20% final  40% projects – some extra credit  Late policy: 6 hours: 91% 12 hours: 84% 24 hours: 71% 48 hours: 50%

Sep 12, 2002COS Operating Systems, Vivek Pai11 Mechanics - People  See web site – it’s up to date!  Basically –Me – quizzes, exams –TAs – precepts, labs –Office hours – T, W, Th or by Appt

Sep 12, 2002COS Operating Systems, Vivek Pai12 Mechanics – Readings Modern Operating Systems Tannenbaum Different from last time Available at Ustore Various readings – will be available from my home page (course web site)

Sep 12, 2002COS Operating Systems, Vivek Pai13 Mechanics - Projects  6 projects, 2 themes –Build parts of a mini-OS –Write applications that interact with OS  2 weeks each  Uses Linux, sort of  Partners – be decent to each other Option – one big project – only for the brave

Sep 12, 2002COS Operating Systems, Vivek Pai14 Send Me Your Details  Name  Year  Major  address  Phone #  Picture via URL  Why you’re taking the class  What you’d like/hope to learn

Sep 12, 2002COS Operating Systems, Vivek Pai15 What Is an OS?

Sep 12, 2002COS Operating Systems, Vivek Pai16 What Is an OS? “Code” that:  Sits between programs & hardware  Sits between different programs  Sits betweens different users But what does it do?

Sep 12, 2002COS Operating Systems, Vivek Pai17 What Is an OS? Resources  Allocation  Protection  Reclamation  Virtualization Services  Abstraction  Simplification  Convenience  Standardization Makes computers simpler

Sep 12, 2002COS Operating Systems, Vivek Pai18 What Is an OS? Resources  Allocation  Protection  Reclamation  Virtualization Finite resources Competing demands Examples:  CPU  Memory  Disk  Network

Sep 12, 2002COS Operating Systems, Vivek Pai19 What Is an OS? Resources  Allocation  Protection  Reclamation  Virtualization You can’t hurt me I can’t hurt you Implies some degree of safety & security

Sep 12, 2002COS Operating Systems, Vivek Pai20 What Is an OS? Resources  Allocation  Protection  Reclamation  Virtualization The OS giveth The OS taketh away Voluntary at run time Implied at termination Involuntary Cooperative

Sep 12, 2002COS Operating Systems, Vivek Pai21 What Is an OS? Resources  Allocation  Protection  Reclamation  Virtualization Illusion of infinite, private resources Memory versus disk Timeshared CPU More extreme cases possible (& exist)

Sep 12, 2002COS Operating Systems, Vivek Pai22 Mechanism & Policy Mechanism – tool to achieve some effect Policy – decisions on how to use tool Examples:  All users treated equally  All program instances treated equally  Preferred users treated better  No deterministic behavior at all

Sep 12, 2002COS Operating Systems, Vivek Pai23 Is There a Perfect OS?

Sep 12, 2002COS Operating Systems, Vivek Pai24 Is Any OS Complete? Portability Security Fairness Robustness Efficiency Interfaces

Sep 12, 2002COS Operating Systems, Vivek Pai25 History Lessons 60’s-70’s - Mainframes  Rise of IBM 70’s - 80’s – Minicomputers  Rise of Digital Equipment 80’s - 90’s – PCs  Rise of Intel, Microsoft Now – Post-PC  Distributed applications

Sep 12, 2002COS Operating Systems, Vivek Pai26 Historical Comparison MainframeMiniMicro System $/ worker 10:1 – 100:1 10:1 – 1:1 1:10-1:100 GoalSystem utilization Overall cost Productivity TargetCapacityFeaturesEase of Use

Sep 12, 2002COS Operating Systems, Vivek Pai27 Constant Employment?  New hardware  New features  New approaches Examples: Palm, Java, WWW

Sep 12, 2002COS Operating Systems, Vivek Pai28 May You Live in Interesting Times…  Processors double in 18 months  Disk doubling every 12 months  Global bandwidth every 6 months  “Sweet spot” constantly decaying Do people ever double?

Sep 12, 2002COS Operating Systems, Vivek Pai29 Send To  Name  Year  Major  address  Phone #  Picture via URL  Why you’re taking the class  What you’d like/hope to learn Consider this a grade

Sep 12, 2002COS Operating Systems, Vivek Pai30 And Now For Something Completely Different…