Highest response ratio next

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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 which are estimated to have short run times.

Priority = (time waiting + estimated run time)/ estimated run time = 1 + (time waiting / estimated run time).