When we apply Shortest Job First (SJF) scheduling Policy/algorithm, Process (P₂) faces partial starvation and waits for the longer time to execute. Which one of the following algorithms addresses this problem?

The correct answer is Highest Response Ratio Next.

Key Points

• Shortest Job First (SJF) scheduling algorithm selects the process with the smallest execution time. This can lead to issues such as starvation, where longer processes keep getting delayed by shorter processes.
• The Highest Response Ratio Next (HRRN) algorithm addresses the starvation problem by considering the waiting time of the processes. It calculates the response ratio for each process using the formula:
  • Response Ratio = (Waiting Time + Burst Time) / Burst Time
• The process with the highest response ratio is selected next for execution. This ensures that even processes with longer burst times get a chance to execute after waiting for a sufficient period.
• By considering both the waiting time and the burst time, HRRN balances the needs of both short and long processes, mitigating the risk of starvation.

Additional Information

• The HRRN algorithm dynamically adjusts the priority of processes based on their waiting time, making it more flexible and fair compared to static scheduling algorithms.
• This algorithm is particularly useful in systems where processes have varying burst times, as it ensures a more equitable distribution of CPU time.
• Other scheduling algorithms like Round Robin and Priority Scheduling also aim to address different aspects of process scheduling, but HRRN specifically targets the starvation problem in SJF.
• HRRN is a non-preemptive scheduling algorithm, meaning once a process starts executing, it runs to completion before the next process is selected.