About Me Bhuvan Urgaonkar Operating Systems Assistant Professor, - - PDF document

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Operating Systems Operating Systems CSE 411 CSE 411

Introduction Introduction and Overview and Overview Sept. Sept. 6 2006 - Lecture 1 6 2006 - Lecture 1 Instructor: Instructor: Bhuvan Urgaonkar Bhuvan Urgaonkar

About Me

• Bhuvan Urgaonkar

– Assistant Professor, CSE

– Ph.D., Sept. 2005, Univ. of Mass. Amherst – Research areas

• Operating systems, Distributed systems, Computer networks

– Office hours: Thu 5-7 PM, or by appointment – Office: 338D, IST Building – Email: bhuvan @ cse

Welcome!

Administrative Stuff Teaching Assistants

• Yuan Fang

– Office hours: M 10-11 AM, W 11.30-12.30 PM, 346D – Email: yufang @ cse

• Arjun R. Nath

– Office hours: Tue 5-7 PM – Email: anath @ cse

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Online Resources and Text-book

• Course Web page:

– http://www.cse.psu.edu/~bhuvan/teaching/fall06/411/411.html

• All material will be available via ANGEL

– Please seek help from the TAs if needed

• Textbook

– Operating Systems Concepts, 7th ed. Silberschatz, Galvin, and Gagne

Course Mailing List

• Via ANGEL

– Use with care

• I will send a test email, please respond to my

email address if you don’t receive it by Friday

• Welcome to write to me or the TAs

– Make sure to include “411” in the subject

Grading

• Quizzes (approx. one per week): 15%

– Made available each Mon, due on Wed (midnight)

• Written home-works (5): 15%
• Projects (3): 35%
• Exams (3): 35%
• 90+: A, 75-89: (A, B], 65-74: (B, C], …

– Subject to change; will not make it stricter – No relative grading - relax :)

Grading

• Projects will be done in groups of 2

– One group of size 3 will be allowed if needed – If your partner drops the course …

• 2 Exams, each on a different subset of the material;

final exam comprehensive

• Late policy:

– Strict deadlines for quizzes and home-works – Loss @ 20% per extra day for projects – Inform TAs well in advance if there is a real reason for a delay in project submission – Same for conflict exams

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Grading

• Projects

– 50% grade on how functional your project is – The other 50% on your write-up and presentation

• We will give instructions on what we expect when we make the

projects available

• Quizzes:

– Online on ANGEL – Multiple-choice, mostly

Computing Resources

• Solaris or Linux accounts for projects
• Email me or the TAs if you don’t have an

account or have any doubts/problems

Academic Honesty

• Do all assignments on your own

– Quizzes, home-works, projects

• We will use software to compare project

source codes

– Both partners on each team are expected to know everything about each project

Assumed Background

• First course on algorithms and data structures
• Comfortable programming in C/C++

– Comfortable with a debugger like gdb

• Preliminary understanding of computer architecture

– We will cover some basics in this course

• Talk to me if you have doubts
• Background poll to be turned in by next Monday

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Before We Begin …

• Some advice

– Speak up in class, ask questions – Attend all classes

• Hint: Ideas concerning homeworks, exam questions, …

– Do all assignments on your own! – Make good use of office hours – Bring printouts to class and take notes on them – Read text-book soon after class

• Sections to read will be made available on the Web site alongside

lecture notes

• Even better: read before class and ask questions

Operating Systems: Introduction & Background

What is an Operating System (OS)?

• Literal meaning

– Software that helps operate a computer

• Lack of consensus on the term operate
• Overloaded term

– Software that runs on a computer when nothing else is running (e.g., right after it boots up => kernel)

• Very restrictive, what about dynamically loaded device drivers?

– Windows = Any other OS + Windows Media Player + …

• Very inclusive, why not everything else in the world?

What is an OS

• There is no single truth here

– Our OS somewhere between these extremes

• Definition using negation

– Applications

• Moving the burden to defining an application :)

– OS = all software minus applications

• Helps the applications use the computer
• Helps manage the resources of the computer

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Why do we need an OS?

• Why not provide this functionality in

hardware?

– Why this separate piece of software?

A Little Bit of History

The Dark Ages (1940s - 60s)

Hardware: expensive; humans: cheap

• Evolution of functionality

– Single user – Batch processing – Overlap of I/O and computation – Multi-programming

• 1. Single User
• One user at a time on console
• Computer executes one function at a time

– No overlap: computation & I/O

• User must be at console to debug

Multiple users => inefficient use of machine

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• 2. Batch Processing
• Execute multiple “jobs” in batch:

– Load program – Run – Print results, dump machine state – Repeat

• Users submit jobs (on cards or tape)
• Human schedules jobs
• A program loads & runs jobs

– The Operating System

More efficient use of machine, complicates debugging

• 3. Overlap I/O and Computation
• Before: machine waits for I/O to complete
• New approach:

– Allow CPU to execute while waiting – Add buffering

• Data fills “buffer” and then output

– and interrupt handling

• I/O events trigger a signal (“interrupt”)

More efficient use of machine, but still one job at a time

• 4. Multiprogramming
• Allow several programs to run at same time

– Run one job until I/O – Run another job, etc.

• OS manages interaction between programs:

– Which jobs to start – Protects program’s memory from others – Decides which to resume when CPU available

So what does an OS do?

• Two kinds of functionality

– Management of computer resources

• Sharing CPU between tasks
• Memory management

– Certain services to users

• Load programs, run them

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OS Complexity

• Increased functionality & complexity
• First OS failures

– Multics (GE & MIT): announced 1963, released 1969 – OS/360 released with 1000 known bugs

• Need to treat OS design scientifically
• Managing complexity becomes key to…

The Renaissance (1970s)

Hardware: cheap; humans: expensive

• Users share system via terminals
• The UNIX era

– Multics:

• army of programmers, six years

– UNIX:

• three guys, two years
• “Shell”: composable commands
• But: response time & thrashing

– Need for improved resource management

The Industrial Revolution (1980s)

Hardware very cheap; humans expensive

• Widespread use of PCs

– IBM PC: 1981, Macintosh: 1984

• Simple OS (DOS, MacOS)

– No multiprogramming, concurrency, memory protection, virtual memory, … – Later: networking, file-sharing, remote printing… – GUI added to OS

The Modern Era (1990s-now)

Hardware cheap; processing demands increasing

• “Real” operating systems on PCs

– NT (1991); Mac OS X; Linux

• Different modalities:

– Parallel: Multiple processors, one machine – Distributed: Multiple networked processors – Real-time: Strict or loose deadlines – Sensor networks: Many small computers

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OSes Today

• Active research area

– Top CS conferences, several distinguished researchers/groups – Intersects with theory/algos., software engg., architecture, distrib. comp.

• Major market presence

– Microsoft, Apple, HP, …

• New environments, new devices

– Web, P2P systems, Internet apps, sensor networks, mobile devices, multimedia, …

• New challenges

– Distributed systems, heterogeneous devices, ubiquitous computing, utility computing, mobile computing, autonomic computing

Outline of this Course Course Outline

• Resource Management (and some services an OS provides to

programmers)

– CPU management – Memory management – I/O management (emphasis: Disk)

• Cross-cutting design considerations and techniques

– Quality-of-service/fairness, monitoring, accounting, caching, software design methodology, security and isolation

• Advanced topics

– Distributed systems – Data centers, multi-media systems, real-time systems, virtual machines

• Next time:

– Background on Computer Architecture

• Do the following this week:

– Reply to me/TAs if you don’t receive a “welcome” email via ANGEL by Friday – Take the poll on ANGEL (just 4-5 questions, no grades) – Form project groups (2 per group) and send us email – Talk to the TAs if problem with ANGEL account or with CSE Solaris/Linux accounts