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COSC1078 Introduction to Information Technology Lecture 17 Memory and Deadlock

James Harland james.harland@rmit.edu.au. COSC1078 Introduction to Information Technology Lecture 17 Memory and Deadlock. Introduction. James Harland Email: james.harland@rmit.edu.au URL: www.cs.rmit.edu.au/~jah Phone: 9925 2045 Office: 14.10.1 Consultation: Mon 4.30-5.30,

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COSC1078 Introduction to Information Technology Lecture 17 Memory and Deadlock

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  1. Intro to IT James Harland james.harland@rmit.edu.au COSC1078 Introduction to Information TechnologyLecture 17Memory and Deadlock

  2. Intro to IT Introduction • James Harland • Email:james.harland@rmit.edu.au • URL:www.cs.rmit.edu.au/~jah • Phone:9925 2045 • Office:14.10.1 • Consultation:Mon 4.30-5.30, • Thu 11.30-12.30 • What colour is my office door? Carpet? Chair?

  3. Intro to IT Introduction to IT 1 Introduction 2Images 3Audio 4Video WebLearnTest 1 5 Binary Representation Assignment 1 6 Data Storage 7Machine Processing 8 Operating Systems WebLearn Test 2 9 ProcessesAssignment 2 10 Internet 11Internet Security WebLearn Test 3 12Future of IT Assignment 3, Peer and Self Assessment

  4. Intro to IT Overview • Questions? • Assignments 2 & 3 • Peer and Self Assessment • Memory and Deadlock • Questions?

  5. Assignments 2&3 Assignment 2: Due this week () No single`right’ answer Main issue is to justify options to Granny Assignment 3: start thinking about research topic Lecture 17: Review Intro to IT

  6. SE Fundamentals Tutorials • Held each week • Classes of up to 24 • Tutor will answer questions related to materials • Good place for individual feedback • Peer and self assessment • Peer learning groups (5 or 6) • Assessed on process, not product • Assessed in last tutorial • Trial assessments in weeks 4 and 8

  7. SE Fundamentals Self and Peer Assessment • How well has each person contributed to the group? • Evaluated over the entire semester • Assessed on process, not product • Work out a grade for each person (CR, DI etc) • Then convert this to a mark out of 20 • Submit list of marks to tutor with justifications • Repeat previous step until the tutor is satisfied • See guidelines in Blackboard material

  8. Processes Executing in Context Processor Memory Disk 00 CC ROM Program Counter RAM BB CC Instruction Register Lecture 17: Memory and Deadlock Intro to IT

  9. Processes Executing in Context Processor Memory Disk 00 BB ROM Program Counter RAM BB Instruction Register Lecture 17: Memory and Deadlock Intro to IT

  10. Processes Executing in Context Processor Memory Disk 00 FF ROM Program Counter RAM FF Instruction Register Lecture 17: Memory and Deadlock Intro to IT

  11. Processes Executing in Context Processor Memory Disk 00 BB ROM Program Counter RAM BB Instruction Register Lecture 17: Memory and Deadlock Intro to IT

  12. ``Thomas, you wouldn’t! Naughty!’’ Processor Memory Disk 00 BB ROM Program Counter RAM BB Instruction Register Lecture 17: Memory and Deadlock Intro to IT

  13. ``Thomas, you wouldn’t! Naughty!’’ Processor Memory Disk 00 BB ROM Program Counter RAM BB Instruction Register Lecture 17: Memory and Deadlock Intro to IT

  14. ``Thomas, you wouldn’t! Naughty!’’ Processor Memory Disk 00 BB ROM Program Counter RAM BB Instruction Register Lecture 17: Memory and Deadlock Intro to IT

  15. Software • `Programs should be able to do anything!’ (???) • Programs should be able to do anything reasonable • What is reasonable? • Not changing OS, not deleting other processes from memory, not playing with other people’s things, … Lecture 17: Memory and Deadlock Intro to IT

  16. Memory Management Disk Memory STOP IT! Mine! Mine! Mine! Lecture 17: Memory and Deadlock Intro to IT

  17. Memory Management Disk Memory HMM ... sandbox Lecture 17: Memory and Deadlock Intro to IT

  18. Virtual Memory • What if memory requirements exceed memory size? • Pretend we have more! • Shuffle required parts (pages) between disk and memory • Not every memory cell is needed all the time… Lecture 17: Memory and Deadlock Intro to IT

  19. Virtual Memory Virtual Memory Physical Memory Disk Processsor Lecture 17: Memory and Deadlock Intro to IT

  20. Co-ordination and locking MINE! MINE! MINE! Works fine for one resource … Lecture 17: Memory and Deadlock Intro to IT

  21. Deadlock BORING! Deadlock: neither can get both resources Lecture 17: Memory and Deadlock Intro to IT

  22. Deadlock requirements Deadlock requires: Competition for nonshareable resources Processes request multiple resources sequentially Resources cannot be forcibly retrieved Avoid deadlock by preventing 1 or 2 Detect and correct deadlock by falsifying 3 Lecture 17: Memory and Deadlock Intro to IT

  23. Deadlock avoidance Spooling makes nonshareable resources look like shareable ones … Lecture 17: Memory and Deadlock Intro to IT

  24. Operating Systems • Highly complex software systems • 30-40 million lines of code • Lots of processes associated with them • Probably most sophisticated software ever written • Not many of them around … Lecture 17: Memory and Deadlock Intro to IT

  25. Operating Systems Lecture 17: Memory and Deadlock Intro to IT

  26. Intro to IT Conclusion • Work on Assignment 2 (and 3?) • Research Topic for Assignment 3 • Finish reading book!

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