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Operating Systems - David Vernon

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Processes<br />

Process Scheduling<br />

– ‘Shortest Job First’ Scheduling<br />

» Designed for batch systems<br />

» Scheduler runs the shortest job first<br />

» It minimizes the overall response time<br />

» How to estimate the length of a job?<br />

Estimate based on previous runs<br />

E.g. take weighted average of runs at time t i and t i-1<br />

t i+1 = w 1 i-1 t i-1 + w 1 i t i<br />

This is called aging<br />

Copyright © 2007 <strong>David</strong> <strong>Vernon</strong> (www.vernon.eu)

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