Differencing dispatcher and scheduler

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Properties DISPATCHER SCHEDULER

Definition:

  • Dispatcher is a module that gives control of CPU to the process selected by short term scheduler
  • Scheduler is something which selects a process among various processes

Types:

  • There are no different types in dispatcher.It is just a code segment.
  • There are 3 types of scheduler i.e. Long-term, Short-term, Medium-term

Dependency:

  • Working of dispatcher is dependent on scheduler.Means dispatcher have to wait until scheduler selects a process.
  • Scheduler works independently. It works immediately when needed

Algorithm:

  • Dispatcher has no specific algorithm for its implementation
  • Scheduler works on various algorithm such as FCFS, SJF, RR etc.

Time Taken:

  • The time taken by dispatcher is called dispatch latency.

  • Time taken by scheduler is usually negligible.Hence we neglect it
    .
    Functions:

  • Dispatcher is also responsible for:Context Switching, Switch to user mode, Jumping to proper location when process again restarted

  • The only work of scheduler is selection of processes.