Compare and contrast short term, long term and medium term scheduling.
1 Answer


Long Term Scheduler

  • The process are stored in mass storage device (typically disk). The long term scheduler selects a process from this pool and loads it into main memory for execution.
  • Controls degree of multiprogramming.
  • Executes less frequently.
  • It should select a mix of 1/O bound and CPU bound processes.


Short Term Scheduler

  • Selects among the processes that are ready to execute and allocates CPU to one of them.

  • Executes frequently.


Medium Term Scheduler

It removes process from memory hence reducing degree of multiprogramming. The process is swapped out and later ,swapped in by medium term scheduler.


Long-Term Scheduler Short-Term Scheduler Medium-Term Scheduler
It is a job scheduler It is a CPU scheduler It is a process swapping
Speed is lesser than short term scheduler Speed is fastest among other two Speed is in between both
short and long term scheduler.
It controls the degree of multiprogramming It provides lesser control
over degree of multiprogramming
It reduces the degree of
It is almost absent orminimal in time sharing system It is also minimal in time sharing system It is a part of Time sharing systems.
It selects processes from pool
and loads them into memory for execution
It selects those processes which are
ready to execute
It can re-introduce the process into memory
and execution can be continued.
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