operating systems vivek pai lecture 1 sep 13, 2001

Operating Systems

Vivek Pai

Lecture 1

Sep 13, 2001

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IntroductionWho I am

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

networking, high-performance apps

Why I do this

Fun Interesting Design

opportunities “Profitable”

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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”

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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

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

Doesn’t Schedule overload Missing background Mathematical

precision

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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

Fairly generous extra credit

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Some ReliefGrades based on

mean/deviation

People did generally well last time

38 As

11 Bs

7 Cs

Honor System Use common sense Ask for clarification Cooperation OK Work is your own

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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

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

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Mechanics – Grading Assigned readings 15% participation (quizzes) 15% midterm 15% final 55% projects Some extra credit Late policy TBA

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Mechanics – PeopleVivek Pai, room 3228-2086, vivek@csOffice hours: after class

Brian Lai, room 4148-5388, lai@csOffice hours: TBA

Ping Ruan, room 2178-0451, ryuan@csOffice hours: TBA

Precept time/location

TBA

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Mechanics – ReadingsOperating System Design & Implementation

Tannenbaum & Woodhill, 2nd Edition

Same as last time

Available at Ustore

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

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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

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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

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What Is an OS?

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What Is an OS?“Code” that:

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

But what does it do?

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What Is an OS?Resources Allocation Protection Reclamation Virtualization

Services Abstraction Simplification Convenience Standardization

Makes computers simpler

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What Is an OS?Resources Allocation Protection Reclamation Virtualization

Finite resources

Competing demands

Examples: CPU Memory Disk Network

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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

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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

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What Is an OS?Resources Allocation Protection Reclamation Virtualization

Illusion of infinite, private resources

Memory versus disk

Timeshared CPU

More extreme cases possible (& exist)

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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

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Is There a Perfect OS?

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Is Any OS Complete?Portability

Security

Fairness

Robustness

Efficiency

Interfaces

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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

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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

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Constant Employment? New hardware New features New approaches

Examples: Palm, Java, WWW

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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?

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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