Differentiate between the long-term, short-term, and medium-term schedulers.

Before working on the difference between all three schedulers, let us recall the concept of process scheduler.

Process scheduler is a part of the Operating system which schedules the process. If the process is in ready, waiting and running state it schedules it correctly and is also responsible for the allocation of the CPU processor to a specific task within a time interval.

Also, when the task or process is completed it doesn't allow the CPU to sit idle. It will allocate the other task depending on its current state. If the process was in ready state it will allocate it to the CPU in this way it always keeps the CPU busy all of the time.

Characteristics of good process scheduler

The characteristics of a good process scheduler are as follows −

  • It increases the utilisation of the CPU as it keeps it busy all the time by assigning the ready state processes.

  • It has flexibility you can change your schedules easily

  • It allows revisiting or reviewing your projects.

  • By using this you can strictly follow the deadlines. For example − If you have a deadline for a project for SEP 10th then you can set the deadline for 10th SEP till 6pm or anything.

  • Also the tasks are not isolated; you can clearly see the relation among them or how they are interconnected to each other.

Types of Schedulers

There are three types of schedulers available which are as follows −

  • Long Term Scheduler

  • Short Term Scheduler

  • Medium Term Scheduler


The major differences between long term, medium term and short term scheduler are as follows −

Long term schedulerMedium term schedulerShort term scheduler
Long term scheduler is a job scheduler.Medium term is a process of swapping schedulers.Short term scheduler is called a CPU scheduler.
The speed of long term is lesser than the short term.The speed of medium term is in between short and long term scheduler.The speed of short term is fastest among the other two.
Long term controls the degree of multiprogramming.Medium term reduces the degree of multiprogramming.The short term provides lesser control over the degree of multiprogramming.
The long term is almost nil or minimal in the time sharing system.The medium term is a part of the time sharing system.Short term is also a minimal time sharing system.
The long term selects the processes from the pool and loads them into memory for execution.Medium term can reintroduce the process into memory and execution can be continued.Short term selects those processes that are ready to execute.

Updated on: 14-Sep-2023

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