Why is shortest job first scheduling algorithm optimal?
Table of Contents
- 1 Why is shortest job first scheduling algorithm optimal?
- 2 What is the problem with the shortest job first scheduling algorithm?
- 3 Which is the most optimal scheduling algorithm FCFS first come first served SJF shortest job first RR Round Robin none of the mentioned?
- 4 What is shortest job first scheduling?
- 5 What are the drawbacks/cons of SJF algorithm?
Why is shortest job first scheduling algorithm optimal?
SJF is a scheduling algorithm that assigns to each process the length of its next CPU burst/execution time. SJF is provably optimal, in that for a given set of processes and their CPU bursts/execution times it gives the least average waiting time for each process.
What is the problem with the shortest job first scheduling algorithm?
Disadvantages/Cons of SJF SJF can’t be implemented for CPU scheduling for the short term. It is because there is no specific method to predict the length of the upcoming CPU burst. This algorithm may cause very long turnaround times or starvation. Requires knowledge of how long a process or job will run.
Why is SJF is practically not implementable?
Shortest Job First (SJF) is an optimal scheduling algorithm as it gives maximum Throughput and minimum average waiting time(WT) and turn around time (TAT) but it is not practically implementable because Burst-Time of a process can’t be predicted in advance.
Which scheduling algorithm results the smallest average wait time?
Shortest-Job-First
4.2 Shortest-Job-First (SJF) Scheduling The average waiting time is ( 3 + 16 + 9 + 0 ) / 4 = 7.0 ms. If we were using the FCFS scheduling, then the average waiting time would be 10.25 ms. SJF is optimal in that it gives the minimum average waiting time for a given set of processes.
Which is the most optimal scheduling algorithm FCFS first come first served SJF shortest job first RR Round Robin none of the mentioned?
| Q. | Which is the most optimal scheduling algorithm? |
|---|---|
| B. | sjf – shortest job first |
| C. | rr – round robin |
| D. | none of the mentioned |
| Answer» b. sjf – shortest job first |
What is shortest job first scheduling?
What is Shortest Job First Scheduling? Shortest Job First (SJF) is an algorithm in which the process having the smallest execution time is chosen for the next execution. This scheduling method can be preemptive or non-preemptive. It significantly reduces the average waiting time for other processes awaiting execution.
What is shortest job first in Java?
Shortest Job First (SJF) is an algorithm in which the process having the smallest execution time is chosen for the next execution. This scheduling method can be preemptive or non-preemptive.
Which method gives the lowest average waiting time for a process?
SJF method gives the lowest average waiting time for a specific set of processes. It is appropriate for the jobs running in batch, where run times are known in advance. For the batch system of long-term scheduling, a burst time estimate can be obtained from the job description.
What are the drawbacks/cons of SJF algorithm?
Here are some drawbacks/cons of SJF algorithm: Job completion time must be known earlier, but it is hard to predict. It is often used in a batch system for long term scheduling. SJF can’t be implemented for CPU scheduling for the short term.