Chapter 4 - Type of scheduling processes

4.1.2.Describe the various type of scheduling processes:

Scheduling and Queuing :-

Processor management is concerned with the internal priorities of programs already in memory.
When one program finishes processing and space becomes available, a queuing routine and a scheduler are involved to load a program into memory based on the program's external priority.
Once a program is in the memory, the dispatcher uses the program’s internal priority to determine its access to the processor.

Interrupts. An interrupt is an electronic signal. Hardware senses the signal, saves key control information for the currently executing program, and starts the operating system’s interrupt handler routine.

Types of Scheduling :-
- Long term scheduling is determine which programs admitted to system for processing and controls degree of multiprogramming.
- Medium term scheduling is part of swapping function between main memory and disk - based on how many processes the OS wants available at any one time.
- Short term scheduling is executes most frequently, to decide which process to execute next – Invoked whenever event occurs that interrupts current process or provides an opportunity to preempt current one in favor of another.

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