Please enable JavaScript.

Coggle requires JavaScript to display documents.

Process Synchronization (Semaphores (Two types (Counting (n), Binary (0…

- - - - Process A
        
        decrements acc
        
        State is saved and loaded
        
        Order matters, incorrect states
      - Process B
        
        increments acc
    - - To handle it
        
        Synchronization
- - - - code
        
        critical section
        
        changes in
        
        Variables
        
        tables
        
        files
        
        Must only allow 1 process to execute section
        
        problem
        
        Design protocol to cooperate
        
        each process must
        
        Request permission to execute
        
        entry section
        
        tell when it's finished
        
        Exit section
        
        Three requirements
        
        Mutual exlusion
        
        Progres
        
        Bounded waiting
        
        Two approaches
        
        Preemptive kernels
        
        Nonpreemptive kernels
        
        Essentially race free
        
        1 more item...
- - - - n
    - - 0,1
  - - - then it's woken up when it's time to execute
- - - - reading
      - writing
    - - Read or write
  - - - Starvation free
        
        Measures to avoid deadlocks
        
        Allow at most four philosophers at once
        
        Only picks up chopsticks if both are available
        
        assymetric
- - - - Priority number
- - - - condition variables
  - - - To protect only data that will be accesed shortly
    - - turns
  - - - Its disabled
  - - - named
      - unnamed
- - - - Sequence of atomic read writes
  - - - No variables, hence no race