Highest response ratio next

Highest response ratio next (HRRN) scheduling is a non-preemptive discipline, similar to shortest job next (SJN), in which the priority of each job is dependent on its estimated run time, and also the amount of time it has spent waiting. Jobs gain higher priority the longer they wait, which prevents indefinite postponement (process starvation). In fact, the jobs that have spent a long time waiting compete against those estimated to have short run times.

$Priority = \frac{waiting\ time + estimated\ run\ time}{estimated\ run\ time} = 1 + \frac{waiting\ time}{estimated\ run\ time}$

Developed by Brinch Hansen to correct certain weaknesses in Shortest job next including the difficulty in estimating run time.

References

William Stallings: Operating systems: internals and design principles. 4th ed., Prentice-Hall, 2001, ISBN 0-13-031999-6.

This article is issued from Wikipedia - version of the 10/30/2016. The text is available under the Creative Commons Attribution/Share Alike but additional terms may apply for the media files.

Highest response ratio next

See also

References