Operating Systems
Vivek Pai
Lecture 1
Sep 12, 2002
Introduction
Who I am
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Why I do this
Vivek Pai
PhD 99/00, Rice
Research: OS,
networking, highperformance apps
Sep 12, 2002
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Fun
Interesting
Design
opportunities
“Profitable”
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About this course…
Goals
Principles
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OS design
Some theory
Rationale
Practice
Not trade school
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Understand OS
decisions
Basis for future
learning
Get hands dirty
Not “elite hacker”
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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
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What Works & Doesn’t
Works
 Solid C background
 Flexible approach
 Grasping Prereqs
 Open mind
 Einstein
 Feedback sheets
Sep 12, 2002
Doesn’t
 Schedule overload
 Missing
background
 Mathematical
precision
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Why So Many Grades?
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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
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Some Relief
Grades based on
mean/deviation
People have done
generally well in the
past
25 / 38 As
17 / 11 Bs
4 / 7 Cs
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Honor System
 Use common sense
 Ask for clarification
 Cooperation OK
 Work is your own
(pairs for labs)
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There Is No Magic
This Is Engineering
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Tradeoffs
Constraints
Optimizations
Imperfection
Nothing’s Permanent
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High rate of change
Lots of inertia
Cost/benefit
analyses
Human error
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Mechanics – Info
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My home page
Course home page
Newsgroup
Precepts
Design reviews
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Mechanics – Grading
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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%
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Mechanics - People
See web site – it’s up to date!
 Basically
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– Me – quizzes, exams
– TAs – precepts, labs
– Office hours – T, W, Th or by Appt
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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)
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Mechanics - Projects
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6 projects, 2 themes
– Build parts of a mini-OS
– Write applications that interact with OS
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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
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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:
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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
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Finite resources
Competing demands
Examples:
 CPU
 Memory
 Disk
 Network
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What Is an OS?
Resources
 Allocation
 Protection
 Reclamation
 Virtualization
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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
Sep 12, 2002
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 & 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
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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 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
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Historical Comparison
Mainframe
Mini
Micro
System $/ 10:1 –
100:1
worker
Goal
System
utilization
10:1 –
1:1
1:10-1:100
Overall
cost
Productivity
Target
Features Ease of
Use
Sep 12, 2002
Capacity
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Constant Employment?
New hardware
 New features
 New approaches
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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
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Do people ever double?
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Send To vivek@cs…
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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
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And Now For
Something Completely
Different…
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