Types of Schedulers


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).


long-termjob admission based on characteristics and resource needssessions and processes normally accepted unless capacity reachedprocesses either permanent or accepted at once
medium-termusually none-jobs run remain in storage done processes swapped when necessaryprocesses never swapped
short-termprocesses 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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Page last modified on 5/2/99