OS Organization Chapter 6 Part II: Deadlock Prevention

  1. Deadlock: Design conditions that create the swamps for deadlock to occur:
    • mutual exclusion
    • hold and wait
    • no resource preemption
  2. Deadlock: The Scheduling condition that go to the swamps
    circular wait (necessary and sufficient for deadlock to occur)
  3. Deadlock: What conditions are need for the possibility of deadlock?
    • Mutual Exclusion
    • No preemption
    • Hold and Wait
  4. Deadlock: What conditions are need for the existence  of deadlock?
    • Mutual Exclusion
    • No preemption
    • Hold and Wait
    • Circular Wait
  5. Deadlock to be possible: Only one process may use a resource at a time. No process may access a resource unit that has been allocated to another process. Name the condition of policy(?)
    Mutual exclusion
  6. Deadlock to be possible: A process may hold allocated resources while awaiting assignment of other resources. Name the condition of policy(?)
    Hold and Wait
  7. Deadlock to be possible: No resource can be forcibly removed from a process holding it. Name the condition of policy(?)
    No preemption.
  8. The three conditions of policy: mutual exclusion, hold and wait, and no preemption are said to be ___?___ but not ___?___  for a deadlock to occur.
    they are necessary but not sufficient for a deadlock to occur.
  9. Deadlock Prevention: The strategy of deadlock prevention is, simply put, to:
    ..., to design a system in such a way that the possibility of deadlock is excluded.
  10. Deadlock to exist: For deadlock to exist this condition of policy is needed(?).
    Circular Wait (necessary and sufficient for a deadlock to exist)
  11. Deadlock to exist: Define Circular Wait:
    A closed chain of processes exists, such that each process holds at least one resource needed by the next process in the chain.
  12. Deadlock Prevention: In deadlock prevention mutual exclusion cannot be disallowed. If access to a resource requires mutual exclusion, then mutual exclusion must be supported by the OS.(T/F)
    TRUE
  13. Deadlock Prevention: In deadlock prevention, the hold and wait condition can be prevented by requiring that a process request all of its required resources at one time, and blocking the process until all requests can be granted simultaneously. This approach is inefficient in three ways:
    1) A process may be held up for a long time waiting for all of its resource requests to be filled, when in fact it could have proceeded with only some of the resources.

    2) Second, resources allocated to a process may remain unused for a considerable period, during which time they are denied to other processes.

    3)Also a process may not know in advance, all the resources it will require.
Author
geschw66
ID
319831
Card Set
OS Organization Chapter 6 Part II: Deadlock Prevention
Description
From WUSTL Operating System Organization class SPRING 2016
Updated