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.
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 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, 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. A nonsolution to the dining philosophers problem

6. Solution to dining philosophers problem (part 1)

7. Solution to dining philosophers problem (part 2)

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

24. Solution to dining philosophers problem (part 2)

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