Tom Anderson How This Course Fits in the UW CSE Curriculum CSE 333 Systems Programming Project experience in CC How to use the operating system interface CSE 451 Operating Systems How to make a single computer work reliably ID: 1010585
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1. Operating Systems: Principles and PracticeTom Anderson
2. How This Course Fits in the UW CSE CurriculumCSE 333: Systems ProgrammingProject experience in C/C++How to use the operating system interfaceCSE 451: Operating SystemsHow to make a single computer work reliablyHow an operating system works internallyCSE 452: Distributed Systems (winter 2015)How to make a set of computers work reliably, despite failures of some nodes
3. Project: OS/161Build an operating system That can boot on a multiprocessorWe give you some basic building blocksThree assignments, that build on each otherThreads, user programs, virtual memoryWork in groups of 2-3 (recommend 3!)Instructions on web pageDownload and browse code before sectionBring laptop or smartphone to sectionAssignment 0 due next Friday
4. Problem SetsThree assignments spread over quarterPractice for finalDone individually
5. Main Points (for today)Operating system definitionSoftware to manage a computer’s resources for its users and applicationsOS challengesReliability, security, responsiveness, portability, …OS historyHow are OS X, Windows 8, and Linux related?
6. What is an operating system?Software to manage a computer’s resources for its users and applications
7. Operating System RolesReferee:Resource allocation among users, applicationsIsolation of different users, applications from each otherCommunication between users, applicationsIllusionistEach application appears to have the entire machine to itselfInfinite number of processors, (near) infinite amount of memory, reliable storage, reliable network transportGlueLibraries, user interface widgets, …
8. Example: File SystemsRefereePrevent users from accessing each other’s files without permissionEven after a file is deleting and its space re-usedIllusionistFiles can grow (nearly) arbitrarily largeFiles persist even when the machine crashes in the middle of a saveGlueNamed directories, printf, …
9. QuestionWhat (hardware, software) do you need to be able to run an untrustworthy application?
10. QuestionHow should an operating system allocate processing time between competing uses?Give the CPU to the first to arrive?To the one that needs the least resources to complete? To the one that needs the most resources?
11. Example: web serviceHow does the server manage many simultaneous client requests?How do we keep the client safe from spyware embedded in scripts on a web site?How do make updates to the web site so that clients always see a consistent view?
12. OS ChallengesReliabilityDoes the system do what it was designed to do?AvailabilityWhat portion of the time is the system working?Mean Time To Failure (MTTF), Mean Time to RepairSecurityCan the system be compromised by an attacker?Privacy Data is accessible only to authorized users
13. OS ChallengesPortabilityFor programs:Application programming interface (API)Abstract virtual machine (AVM)For the operating systemHardware abstraction layer
14. OS ChallengesPerformanceLatency/response timeHow long does an operation take to complete?ThroughputHow many operations can be done per unit of time?OverheadHow much extra work is done by the OS?FairnessHow equal is the performance received by different users?PredictabilityHow consistent is the performance over time?
15. OS History
16. Computer Performance Over Time
17. Early Operating Systems:Computers Very ExpensiveOne application at a timeHad complete control of hardwareOS was runtime libraryUsers would stand in line to use the computerBatch systemsKeep CPU busy by having a queue of jobsOS would load next job while current one runsUsers would submit jobs, and wait, and wait, and
18. Time-Sharing Operating Systems:Computers and People ExpensiveMultiple users on computer at same timeMultiprogramming: run multiple programs at same timeInteractive performance: try to complete everyone’s tasks quicklyAs computers became cheaper, more important to optimize for user time, not computer time
19. Today’s Operating Systems:Computers CheapSmartphonesEmbedded systemsLaptopsTabletsVirtual machinesData center servers
20. Tomorrow’s Operating SystemsGiant-scale data centersIncreasing numbers of processors per computerIncreasing numbers of computers per userVery large scale storage
21. TextbookLazowska, Spring 2012: “The text is quite sophisticated. You won't get it all on the first pass. The right approach is to [read each chapter before class and] re-read each chapter once we've covered the corresponding material… more of it will make sense then. Don't save this re-reading until right before the mid-term or final – keep up.”