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Types of Schedulers

 

What are schedulers?

A scheduler is a type of system software that allows us to handle process scheduling.

There are three types of schedulers:

  1. Short-term scheduler
  2. Medium-term scheduler
  3. Long-term scheduler

Short-term scheduler 

Short-term scheduler or CPU scheduler is used to boost the system performance. It decides which of the ready processes are supposed to be executed.

Medium-term scheduler

Medium-term scheduler temporarily removes processes from the main memory and stores them in the secondary memory or the other way round. This process is also known as swapping in or out.

Long-term scheduler

A long-term scheduler, also known as the admission scheduler, decides which processes are supposed to be admitted in the main memory.  

Short-term Scheduler vs Medium-term Scheduler vs Long-term Scheduler 

 

 

Short-term SchedulerMedium-term SchedulerLong-term Scheduler
It is also known as “CPU Scheduler.”It is also known as “Swapping Scheduler.”It is also known as “Admission Scheduler.”
It offers less control.It reduces the level of multiprogramming.It offers more control.
It offers the fastest speed.It offers medium speed.It offers comparatively lesser speed.
It is minimal in time-sharing.It is minimal or absent in time-sharing.It is present in time-sharing systems.
It selects processes that are ready to execute.It helps to send the process back to memory and vice versa.It decides which processes will be admitted in the ready queue (main memory).

 

References:

Operating system scheduler types.