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Semaphores

Semaphores. The producer-consumer problem using semaphores. Producer/Consumer. Producer down(&empty); down(&mutex); insert_item(item); up(&mutex); up(&full);. N = 6 Semaphore mutex = 1 Semaphore full = 0 Semaphore empty = N. producer1. consumer1. producer2. consumer2. Run queue.

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Semaphores

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  1. Semaphores The producer-consumer problem using semaphores

  2. Producer/Consumer Producer down(&empty); down(&mutex); insert_item(item); up(&mutex); up(&full); N = 6 Semaphore mutex = 1 Semaphore full = 0 Semaphore empty = N producer1 consumer1 producer2 consumer2 Run queue Mutex queue Full queue Empty queue

  3. Producer/Consumer Producer down(&empty); down(&mutex); insert_item(item); up(&mutex); up(&full); N = 6 Semaphore mutex = 1 Semaphore full = 0 Semaphore empty = 5 down (&empty) producer1 consumer1 producer2 consumer2 Run queue Mutex queue Full queue Empty queue

  4. Producer/Consumer Producer down(&empty); down(&mutex); insert_item(item); up(&mutex); up(&full); N = 6 Semaphore mutex = 0 Semaphore full = 0 Semaphore empty = 5 down (&mutex) producer1 consumer1 producer2 consumer2 Run queue Mutex queue Full queue Empty queue

  5. Producer/Consumer Producer down(&empty); down(&mutex); insert_item(item); up(&mutex); up(&full); N = 6 Semaphore mutex = 0 Semaphore full = 0 Semaphore empty = 5 insert_item(item) producer1 consumer1 producer2 consumer2 Run queue Mutex queue X Full queue Empty queue

  6. Producer/Consumer N = 6 Semaphore mutex = 0 Semaphore full = 0 Semaphore empty = 5 … producer1 consumer1 producer2 consumer2 Run queue Quantum ends Mutex queue X Full queue Empty queue

  7. Producer/Consumer Consumer down(&full); down(&mutex); consume_item(); up(&mutex); up(&empty); N = 6 Semaphore mutex = 0 Semaphore full = 0 Semaphore empty = 5 down (&full) producer2 consumer2 producer1 Run queue Mutex queue X Full queue consumer1 Empty queue

  8. Producer/Consumer N = 6 Semaphore mutex = 0 Semaphore full = 0 Semaphore empty = 5 … producer2 consumer2 producer1 Run queue Mutex queue X Full queue consumer1 Empty queue

  9. Producer/Consumer Producer down(&empty); down(&mutex); insert_item(item); up(&mutex); up(&full); N = 6 Semaphore mutex = 0 Semaphore full = 0 Semaphore empty = 4 down (&empty) producer2 consumer2 producer1 Run queue Mutex queue X Full queue consumer1 Empty queue

  10. Producer/Consumer Producer down(&empty); down(&mutex); insert_item(item); up(&mutex); up(&full); N = 6 Semaphore mutex = 0 Semaphore full = 0 Semaphore empty = 4 down (&mutex) consumer2 producer1 Run queue Mutex queue producer2 X Full queue consumer1 Empty queue

  11. Producer/Consumer N = 6 Semaphore mutex = 0 Semaphore full = 0 Semaphore empty = 4 … consumer2 producer1 Run queue Mutex queue producer2 X Full queue consumer1 Empty queue

  12. Producer/Consumer Consumer down(&full); down(&mutex); consume_item(); up(&mutex); up(&empty); N = 6 Semaphore mutex = 0 Semaphore full = 0 Semaphore empty = 4 down (&full) producer1 Run queue Mutex queue producer2 X Full queue consumer1 consumer2 Empty queue

  13. Producer/Consumer N = 6 Semaphore mutex = 0 Semaphore full = 0 Semaphore empty = 4 … producer1 Run queue Mutex queue producer2 X Full queue consumer1 consumer2 Empty queue

  14. Producer/Consumer Producer down(&empty); down(&mutex); insert_item(item); up(&mutex); up(&full); N = 6 Semaphore mutex = 1 Semaphore full = 0 Semaphore empty = 4 up (&mutex) producer2 producer1 Run queue Mutex queue X Full queue consumer1 consumer2 Empty queue

  15. Producer/Consumer Producer down(&empty); down(&mutex); insert_item(item); up(&mutex); up(&full); N = 6 Semaphore mutex = 1 Semaphore full = 1 Semaphore empty = 4 up (&full) producer2 consumer1 producer1 Run queue Mutex queue X Full queue consumer2 Empty queue

  16. Producer/Consumer N = 6 Semaphore mutex = 1 Semaphore full = 1 Semaphore empty = 4 … producer2 consumer1 producer1 Run queue Quantum ends Mutex queue X Full queue consumer2 Empty queue

  17. Producer/Consumer N = 6 Semaphore mutex = 0 Semaphore full = 1 Semaphore empty = 4 down (&mutex) producer2 consumer1 producer1 Run queue Mutex queue X Full queue consumer2 Empty queue

  18. Producer/Consumer N = 6 Semaphore mutex = 0 Semaphore full = 1 Semaphore empty = 4 insert_item (item) producer2 consumer1 producer1 Run queue Mutex queue X Full queue consumer2 X Empty queue

  19. Producer/Consumer N = 6 Semaphore mutex = 1 Semaphore full = 1 Semaphore empty = 4 up (&mutex) producer2 consumer1 producer1 Run queue Mutex queue X Full queue consumer2 X Empty queue

  20. Producer/Consumer N = 6 Semaphore mutex = 1 Semaphore full = 2 Semaphore empty = 4 up (&full) producer2 consumer1 consumer2 producer1 Run queue Mutex queue X Full queue X Empty queue

  21. Producer/Consumer N = 6 Semaphore mutex = 1 Semaphore full = 2 Semaphore empty = 4 … producer2 consumer1 consumer2 producer1 Run queue Quantum ends Mutex queue X Full queue X Empty queue

  22. Producer/Consumer N = 6 Semaphore mutex = 1 Semaphore full = 1 Semaphore empty = 4 down (&full) producer2 consumer1 consumer2 producer1 Run queue Mutex queue X Full queue X Empty queue

  23. Producer/Consumer N = 6 Semaphore mutex = 0 Semaphore full = 1 Semaphore empty = 4 down (&mutex) producer2 consumer1 consumer2 producer1 Run queue Mutex queue X Full queue X Empty queue

  24. Producer/Consumer N = 6 Semaphore mutex = 0 Semaphore full = 1 Semaphore empty = 4 consume_item() producer2 consumer1 consumer2 producer1 Run queue Mutex queue X Full queue Empty queue

  25. Producer/Consumer N = 6 Semaphore mutex = 1 Semaphore full = 1 Semaphore empty = 4 up(&mutex) producer2 consumer1 consumer2 producer1 Run queue Mutex queue X Full queue Empty queue

  26. Producer/Consumer N = 6 Semaphore mutex = 1 Semaphore full = 1 Semaphore empty = 5 up(&empty) producer2 consumer1 consumer2 producer1 Run queue Mutex queue X Full queue Empty queue

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