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Question number: 466

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Describe in Detail

What are shore, long and medium-term scheduling?


    • Long Term Scheduler

    • Long term scheduler determines which programs are admitted to the system for processing.

    • It controls the degree of multiprogramming.

    • It is also called a job scheduler.

    • A long-term scheduler determines which programs are admitted to the system for processing.

    • It selects processes from the queue and loads them into memory for execution.

    • Process loads into the memory for CPU scheduling.

  • Medium Term Scheduler

    • Medium term scheduling is part of the swapping function.

    • This relates to processes that are in a blocked or suspended state.

    • They are swapped out of real-memory until they are ready to execute.

    • The swapping-in decision is based on memory-management criteria.

    • It removes the processes from the memory.

  • It reduces the degree of multiprogramming.

  • The medium-term scheduler is in-charge of handling the swapped out-processes.

  • A running process may become suspended if it makes an I/O request.

  • Suspended processes cannot make any progress towards completion.

  • In this condition, to remove the process from memory and make space for other processes, the suspended process is moved to the secondary storage.

  • This process is called swapping, and the process is said to be swapped out or rolled out.

  • Swapping may be necessary to improve the process mix.

  • Short Term Scheduler

  • Short term scheduler, also known as a dispatcher executes most frequently, and makes the finest-grained decision of which process should execute next.

  • This scheduler is invoked whenever an event occurs.

  • It may lead to interruption of one process by preemption.

  • It is also called as CPU scheduler.

  • Its main objective is to increase system performance in accordance with the chosen set of criteria.

  • It is the change of ready state to running state of the process.

  • CPU scheduler selects a process among the processes that are ready to execute and allocates CPU to one of them.

  • Short-term schedulers, also known as dispatchers, make the decision of which process to execute next.

  • Short-term schedulers are faster than long-term schedulers.

Image of The Schedulers

Image of the Schedulers

Given the image is define the shore, long and medium-term scheduling