Page "Scheduling (computing)" Paragraph 17

The short-term scheduler ( also known as the CPU scheduler ) decides which of the ready, in-memory processes are to be executed ( allocated a CPU ) next following a clock interrupt, an I / O interrupt, an operating system call or another form of signal.

Thus the short-term scheduler makes scheduling decisions much more frequently than the long-term or mid-term schedulers-a scheduling decision will at a minimum have to be made after every time slice, and these are very short.

This scheduler can be preemptive, implying that it is capable of forcibly removing processes from a CPU when it decides to allocate that CPU to another process, or non-preemptive ( also known as " voluntary " or " co-operative "), in which case the scheduler is unable to " force " processes off the CPU.

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In most cases short-term scheduler is written in assembly because it is a critical part of the operating system.