This chart shows the function of each of the three types of schedulers (long-term, short-term, and medium-term) for each of three types of operating systems (batch, interactive, and real-time).
| batch | interactive | real-time | |
|---|---|---|---|
| long-term | job admission based on characteristics and resource needs | sessions and processes normally accepted unless capacity reached | processes either permanent or accepted at once |
| medium-term | usually none-jobs run remain in storage done | processes swapped when necessary | processes never swapped |
| short-term | processes scheduled by priority; continue until wait voluntarily, request service, or are terminated | processes scheduled on rotating basis;continue until service requested, time quantum expires, or pre-empted | scheduling based on strict priority immediate pre-emption; may time-share processes with equal priorities |
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