Operating Systems Vivek Pai Lecture 1 Sep 12, 2002.

Operating Systems

Vivek Pai

Lecture 1

Sep 12, 2002

Sep 12, 2002 COS 318 - Operating Systems, Vivek Pai 2

IntroductionWho I am

Vivek Pai PhD 99/00, Rice Research: OS,

networking, high-performance apps

Why I do this

Fun Interesting Design

opportunities “Profitable”


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”


Expect (Some) PainFast 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


What Works & Doesn’tWorks Solid C background Flexible approach Grasping Prereqs Open mind Einstein Feedback sheets

Doesn’t Schedule overload Missing background Mathematical

precision


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


Some ReliefGrades 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)


There Is No MagicThis Is Engineering

Tradeoffs Constraints Optimizations Imperfection

Nothing’s Permanent

High rate of change Lots of inertia Cost/benefit

analyses Human error


Mechanics – Info My home page Course home page Newsgroup Precepts Design reviews


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%


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


Mechanics – ReadingsModern Operating Systems

Tannenbaum

Different from last time

Available at Ustore

Various readings – will be available from my home page (course web site)


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


Send Me Your Details Name Year Major E-mail address Phone # Picture via URL Why you’re taking the class What you’d like/hope to learn


What Is an OS?


What Is an OS?“Code” that:

Sits between programs & hardware Sits between different programs Sits betweens different users

But what does it do?


What Is an OS?Resources Allocation Protection Reclamation Virtualization

Services Abstraction Simplification Convenience Standardization

Makes computers simpler



Finite resources

Competing demands

Examples: CPU Memory Disk Network



You can’t hurt me

I can’t hurt you

Implies some degree of safety & security



The OS giveth

The OS taketh away

Voluntary at run time

Implied at termination

Involuntary

Cooperative



Illusion of infinite, private resources

Memory versus disk

Timeshared CPU

More extreme cases possible (& exist)


Mechanism & PolicyMechanism – 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


Is There a Perfect OS?


Is Any OS Complete?Portability

Security

Fairness

Robustness

Efficiency

Interfaces


History Lessons60’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


Historical ComparisonMainframe Mini Micro

System $/

worker

10:1 – 100:1

10:1 – 1:1

1:10-1:100

Goal System utilization

Overall cost

Productivity

Target Capacity Features Ease of Use


Constant Employment? New hardware New features New approaches

Examples: Palm, Java, WWW


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?


Send To vivek@cs… Name Year Major E-mail address Phone # Picture via URL Why you’re taking the class What you’d like/hope to learn

Consider this a grade


And Now For Something Completely Different…

Operating Systems Vivek Pai Lecture 1 Sep 12, 2002.

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