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OS Process Scheduling Q & A #4
Question: What is Highest Response Ratio Next (HRN) Scheduling?
Answer:
HRN is non-preemptive scheduling algorithm.
In Shortest Job First scheduling, priority is given to shortest job, which may sometimes indefinite blocking of longer job.
HRN Scheduling is used to correct this disadvantage of SJF.
For determining priority, not only the job's service time but the waiting time is also considered.
In this algorithm, dynamic priorities are used instead of fixed priorities.
Dynamic priorities in HRN are calculated as
Priority = (waiting time + service time) / service time. So shorter jobs get preference over longer processes because service time appears in the denominator.
Longer jobs that have been waiting for long period are also give favorable treatment because waiting time is considered in numerator.
os_exams_questions_answers.htm
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