Process Queue Burst time Arrival time P1 6 2 P2 2 5 P3 8 1 P4 3 0 P5 4 4 Step 1) At time 1, Process P3 arrives. If a process with even a shorter burst time arrives, the current process is removed or preempted from execution, and the shorter job is allocated CPU cycle.Ĭonsider the following five process: Process Queue Burst time Arrival time P1 6 2 P2 2 5 P3 8 1 P4 3 0 P5 4 4 Step 0) At time0, P4 arrives and starts execution. Step 11) Lets calculate the average waiting time for above example. Step 7) At time10, P2 is executing and P3 and P5 are in the waiting queue. Step 5) At time 5, process P2 arrives and is added to the waiting queue. Step 4) At time 4, process P5 arrives and is added to the waiting queue. Process P1 is executed because its burst time is less compared to P3. Step 2) At time 2, process P1 arrives and is added to the waiting queue. Process Queue Burst time Arrival time P1 6 2 P2 2 5 P3 8 1 P4 3 0 P5 4 4 Step 0) At time0, P4 arrives and starts execution. Non-Preemptive SJF In non-preemptive scheduling, once the CPU cycle is allocated to process, the process holds it till it reaches a waiting state or terminated.Ĭonsider the following five processes each having its own unique burst time and arrival time.
It improves job output by offering shorter jobs, which should be executed first, which mostly have a shorter turnaround time. It can improve process throughput by making sure that shorter jobs are executed first, hence possibly have a short turnaround time. This algorithm method is helpful for batch-type processing, where waiting for jobs to complete is not critical. There are basically two types of SJF methods: Non-Preemptive SJF Preemptive SJF In this Operating System tutorial, you will learn: What is Shortest Job First Scheduling Characteristics of SJF Scheduling Non-Preemptive SJF Preemptive SJF Advantages of SJF DisadvantagesCons of SJF Characteristics of SJF Scheduling It is associated with each job as a unit of time to complete.
It significantly reduces the average waiting time for other processes awaiting execution. In this article, we are going to learn about implementation of shortest job first (SJF) Non-preemptive scheduling algorithm using C program.įor the batch system of long-term scheduling, a burst time estimate can be obtained from the job description. We are using two for loops to sort processes in ascending order based on their burst time and then calculate waiting time and total time.
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