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Switching to Blackboard

Switching to Blackboard. All assignments will be submitted through blackboard To access, you need to do the following: Get your UNET id and set a password. Contact UNET helpdesk or the IT helpdesk if necessary. Can also call 800 number on blackboard homepage. http://www.courses.maine.edu/

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Switching to Blackboard

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  1. Switching to Blackboard • All assignments will be submitted through blackboard • To access, you need to do the following: • Get your UNET id and set a password. Contact UNET helpdesk or the IT helpdesk if necessary. • Can also call 800 number on blackboard homepage. • http://www.courses.maine.edu/ • All future homework/projects must be submitted via the digital dropbox on blackboard.

  2. Proposed Schedule Modification • Reschedule preliminary 1 to Monday, October 4th. • Reschedule due date for project part 1 to Wednesday October 6th.

  3. Midterm • READING: • You are responsible for all of the material covered in the book • up to (but not including) Section 2.3.7 except for the following sections: • Chapter 1: 1.2.1, 1.2.2, 1.2.4, 1.2.5, 1.3, 1.5.8, 1.7 to the end of the chapter. • Chapter 2: 2.2.6, 2.3.7 to the end of the chapter. • Also responsible for all class slides!! • Please make sure you review the material carefully because large pieces of it is not covered in the book.

  4. Dining Philosophers (1) • Philosophers eat/think • Eating needs 2 forks • Pick one fork at a time • How to prevent deadlock

  5. Dining Philosophers A nonsolution to the dining philosophers problem

  6. Dining Philosophers Solution to dining philosophers problem (part 1)

  7. Dining Philosophers Solution to dining philosophers problem (part 2)

  8. 0 0 0 0 0 State Array S Array T T T T T Mutex = 1 NULL Mutex.queue P0: take_forks(0) down(mutex) ; test(0) ;

  9. 1 0 0 0 0 State Array S Array E T T T T Mutex = 0 NULL 2 1 1 1 1 Mutex.queue P0: take_forks(0) down(mutex) ; test(0) ;

  10. State Array S Array E T T T T Mutex = 0 NULL 1 0 0 0 0 Mutex.queue P0: take_forks(0) down(mutex) ; test(0) ; up(mutex) ; down(S[0]) ;

  11. 0 0 0 0 0 State Array S Array E T T T T Mutex = 1 NULL Mutex.queue P0: take_forks(0) down(mutex) ; test(0) ; up(mutex) ; down(S[0]) ; // falls through to //critical section Preempted

  12. 0 0 0 0 0 State Array S Array E T T T T Mutex = 1 NULL 1 1 1 1 1 Mutex.queue P0: take_forks(0) down(mutex) ; test(0) ; down(S[0]) ; Preempted P2: take_forks(2) ; down(mutex) ;

  13. 0 0 0 0 0 State Array S Array E T T T T Mutex = 0 NULL 1 1 1 1 1 Mutex.queue P0: take_forks(0) down(mutex) ; test(0) ; down(S[0]) ; Preempted P2: take_forks(2) ; down(mutex) ;

  14. 0 0 0 0 0 State Array S Array E T T T T Mutex = 0 NULL 1 1 1 1 1 Mutex.queue P0: take_forks(0) down(mutex) ; test(0) ; down(S[0]) ; Preempted P2: take_forks(2) ; down(mutex) ; test(2) ;

  15. 0 0 1 0 0 State Array S Array E T E T T Mutex = 0 NULL 1 1 2 1 1 Mutex.queue P0: take_forks(0) down(mutex) ; test(0) ; down(S[0]) ; Preempted P2: take_forks(2) ; down(mutex) ; test(2) ;

  16. 0 0 1 0 0 State Array S Array E T E T T Mutex = 0 NULL 1 1 2 1 1 Mutex.queue P0: take_forks(0) down(mutex) ; test(0) ; down(S[0]) ; Preempted P2: take_forks(2) ; down(mutex) ; test(2) ; up(mutex) ; down(S[2]) ;

  17. 0 0 0 0 0 State Array S Array E T E T T Mutex = 1 NULL 1 1 1 1 1 Mutex.queue P0: take_forks(0) down(mutex) ; test(0) ; down(S[0]) ; Preempted P2: take_forks(2) ; down(mutex) ; test(2) ; up(mutex) ; down(S[2]) ; //falls through semaphore //and enters critical section.

  18. 0 0 0 0 0 State Array S Array E T E T T Mutex = 1 NULL 1 1 1 1 1 Mutex.queue P0: take_forks(0) down(mutex) ; test(0) ; down(S[0]) ; Preempted P2: take_forks(2) ; down(mutex) ; test(2) ; up(mutex) ; down(S[2]) ; eat() !!! P3: take_forks(3) ; down(mutex) ; test(3) ; up(mutex) ; down(S[3]) ;

  19. 0 0 0 -1 0 State Array S Array E T E H T Mutex = 1 NULL 1 1 1 0 1 Mutex.queue S[3].queue P0: take_forks(0) down(mutex) ; test(0) ; down(S[0]) ; Preempted P2: take_forks(2) ; down(mutex) ; test(2) ; up(mutex) ; down(S[2]) ; eat() !!! P3: take_forks(3) ; down(mutex) ; test(3) ; up(mutex) ; down(S[3]) ; P3

  20. 0 0 0 -1 0 State Array S Array E T E H T Mutex = 1 NULL 1 1 1 0 1 Mutex.queue S[3].queue P0: take_forks(0) down(mutex) ; test(0) ; down(S[0]) ; Preempted P2: take_forks(2) ; down(mutex) ; test(2) ; up(mutex) ; down(S[2]) ; eat() !!! P3: take_forks(3) ; down(mutex) ; test(3) ; up(mutex) ; down(S[3]) ; P2: put_forks(2) ; down(mutex) ; set state[2] = Thinking. test(1) ; P3

  21. 0 0 0 -1 0 State Array S Array E T T H T Mutex = 0 NULL 1 1 1 0 1 Mutex.queue S[3].queue P0: take_forks(0) down(mutex) ; test(0) ; down(S[0]) ; Preempted P2: take_forks(2) ; down(mutex) ; test(2) ; up(mutex) ; down(S[2]) ; eat() !!! P3: take_forks(3) ; down(mutex) ; test(3) ; up(mutex) ; down(S[3]) ; P2: put_forks(2) ; down(mutex) ; set state[2] = Thinking. test(1) ; //left neighbor not //hungry. P3

  22. 0 0 0 -1 0 State Array S Array E T T H T Mutex = 0 NULL 1 1 1 0 1 Mutex.queue S[3].queue P0: take_forks(0) down(mutex) ; test(0) ; down(S[0]) ; Preempted P2: take_forks(2) ; down(mutex) ; test(2) ; up(mutex) ; down(S[2]) ; eat() !!! P3: take_forks(3) ; down(mutex) ; test(3) ; up(mutex) ; down(S[3]) ; P2: put_forks(2) ; down(mutex) ; set state[2] = Thinking. test(1) ; test(3) ; P3

  23. 0 0 0 0 0 Ready Queue P3 State Array S Array E T T T T Mutex = 0 NULL 1 1 1 1 1 Mutex.queue P0: take_forks(0) down(mutex) ; test(0) ; down(S[0]) ; Preempted P2: take_forks(2) ; down(mutex) ; test(2) ; up(mutex) ; down(S[2]) ; eat() !!! P3: take_forks(3) ; down(mutex) ; test(3) ; up(mutex) ; down(S[3]) ; P2: put_forks(2) ; down(mutex) ; set state[2] = Thinking. test(1) ; test(3) ;

  24. Dining Philosophers Solution to dining philosophers problem (part 2)

  25. Create Deadlock down(S[x]) ; up (mutex) ;

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