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-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|
Department of Computer Science
University of California at Davis
Davis, CA 95616-8562