Prerequisite – Process Schedulers
1. Short-Term Scheduler :
Short term scheduler is also known as CPU scheduler. Its main objective is to boost the system performance according to certain set criteria. Short term scheduler helps to select the group of processes that are ready to execute and allocate CPU to each one of them. Unlike Middle term scheduler, it executes more frequently i.e within a few seconds. Short term scheduler has less control over DOM (Degree of Multi-programming).
2. Middle-Term Scheduler :
Middle term scheduler is also known as the Swapping scheduler. Its main objective is to swap out the suspended processes from the main memory. If a running process make I/O request it becomes suspended. A suspended process will not show any progress towards completion so it should be moved to secondary storage, hence providing space for new processes. Unlike Short term scheduler, it’s execution is not quite frequent. Middle term scheduler reduced the DOM (Degree of Multi-programming).
Difference between Short-Term and Medium-Term Scheduler :
|S.No.||SHORT-TERM SCHEDULER||MIDDLE-TERM SCHEDULER|
|1.||Short-Term scheduler is also known as CPU Scheduler.||Middle-Term scheduler is also known as Swapping Scheduler.|
|2.||Speed of Short-Term scheduler is very fast as compared to middle-Term scheduler.||Its speed is less than Short-Term scheduler.|
|3.||It provides less control over Degree of programming.||It reduces the Degree of Programming.|
|4.||Its presence in Time sharing system is very minimal.||Middle-term scheduler is a part of Time sharing system.|
|5.||In short-term scheduler, there occurs transition of process from ready to executing state.||In middle-term scheduler, no process transition state occurs.|
|6.||Its function is to selects those processes which are ready to execute.||Its function is to reintroduce process back in the memory.|
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