Schedulers in Operating System

Jan 10 • Resources • 27448 Views • 22 Comments on Schedulers in Operating System

Schedulers in Operating System are the process which decides which task and process should be accessed and run at what time by the system resources. It is required to maintain the multi tasking capabilities of a computer and to keep its performance at the highest level by scheduling the process according to their preferences and need. The Schedulers in Operating System are the algorithms which help in the system optimisation for maximum performance. Lets have a look at different types of questions asked over this process of operating systems-

Important Questions with Answers on Schedulers in Operating System

Scheduling Process in OS

Scheduling Process in OS

Ques 1– Name the different types of schedulers ?
Answer 1- There are three types of scheduler. Categorization is based on the frequency of their operation. These three schedulers are:-
1. Long Term Scheduler
2. Middle Term Scheduler
3. Short Term Scheduler

Ques 2– Explain the role of long term scheduler ?
Answer 2- Long term scheduler are responsible for transferring a process to the ready queue and making it ready for CPU assignment. Since processes are not rapidly created therefore long term scheduler operate less frequently.

Ques 3- Explain the role of middle term scheduler ?
Answer 3- Sometimes when a process is waiting for CPU assignment and a process of higher priority arrives then the process in the ready queue is swapped out in a backing store and the higher priority process is swapped in and is assigned a CPU immediately.

Ques 4- Explain the role of short time scheduler ?
Answer 4- Short term scheduler selects a process from the ready queue according to the type of scheduling implemented by the operating system. After selecting a process from the queue it assigns it to the CPU. Since CPU rapidly switches from one process to another therefore short term scheduler operates more frequently.

Ques 5- How we can diagrammatically represent the working of scheduler ?
Answer 5- The diagrammatic representation of the working of the scheduler can be shown as-

Model of scheduler

Model of scheduler

Waiting for running– Short term scheduler.
Swap-in and Swap-out-Middle term scheduler.

Ques 6- Difference between short term and long term scheduler ?
Answer 6- Short term scheduler selects a process from the ready queue and assigns it to the CPU and it operates more frequently than long term scheduler while long term scheduler transfers a process into the ready queue and hence it occurs less frequently.

Ques 7- Does every operating system has all the types of schedulers?
Answer 7- No, windows and Unix does not have a long term scheduler as in these operating system as soon as processes are created they are automatically transferred to the ready queue.

Ques 8- Why short term scheduler execute at higher frequency than long term scheduler?
Answer 8- Since a process is created less frequently than the switching of the CPU from one process to another. Therefore, short term scheduler operate at higher frequency than long term scheduler.

Ques 9- What are the points that long term scheduler should consider while selecting a process?
Answer 9- There are two types of processes:
1. I/o Bound.
2. CPU Bound.
Therefore, Long term scheduler should select a proper mix from these different types of processes.

Ques 10- Explain the term swap-in and swap-out?
Answers 10- Swap-out is a process of swapping a process out from the ready queue to a backing store when a process of higher priority arrives and claims for the CPU while Swap-in is a process where swapped out process is transferred back to the ready queue from the backing store.

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22 Responses to Schedulers in Operating System

  1. Shubham mishra says:

    about sehudlers

  2. Shubham mishra says:

    about sehudlers

  3. Fahad Sheraz says:


  4. Fahad Sheraz says:
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  6. akashdeep singh says:


  7. akashdeep singh says:


  8. akashdeep singh says:


  9. akashdeep singh says:


  10. akashdeep singh says:


  11. Rehana parveen says:

    Msc IT

  12. Anonymous says:
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  19. wycliffe nzomo nzoli says:

    what are the functions of scheduler in operating system

  20. hadiza lawal abba says:

    i need an example of any scheduler of the first come first serve scheduling algorithm in java

  21. kalki says:

    what is sheduler?explain with diagram.what are the different types?

  22. abdulwahab says:

    when a process request for i/o,how many process switches take place

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