SJF Scheduling Calculator

Non-preemptive CPU scheduling. Among arrived processes, the shortest burst runs next.

PID	Arrival	Burst

What is SJF Scheduling?

SJF (Shortest Job First) is a CPU scheduling algorithm that selects the process with the shortest CPU burst time among the processes that are ready to run.

Is SJF Preemptive or Non-Preemptive?

SJF (Shortest Job First) is a non-preemptive scheduling algorithm. Once a process starts running, it continues until it completes. The process with the shortest burst time is selected from the available processes.

A related algorithm called Shortest Remaining Time First (SRTF) is the preemptive version of SJF.

How SJF Works

When the CPU becomes available, SJF checks the processes that have already arrived and selects the process with the shortest burst time. In non-preemptive SJF, the selected process continues until it finishes.

SJF Scheduling Formulas

Turnaround Time = Completion Time − Arrival Time

Waiting Time = Turnaround Time − Burst Time

Advantages and Disadvantages of SJF

Advantages of SJF	Disadvantages of SJF
Can produce a low average waiting time.	The exact burst time may not be known in advance.
Short processes can finish quickly.	Long processes may experience starvation.
Simple to understand for basic scheduling problems.	It can be difficult to use in some real-time systems.

SJF Scheduling Example

Suppose several processes have arrived and the CPU becomes available. If P1 has a burst time of 8, P2 has a burst time of 3, and P3 has a burst time of 5, SJF selects the shortest available process first.

The scheduling order depends on both the arrival time and burst time of the processes.

SJF vs FCFS

FCFS schedules processes according to arrival order, while SJF selects the shortest available burst. SJF can achieve a lower average waiting time, but it requires information about process burst times.

Related CPU Scheduling Calculators

Try the FCFS Calculator, Round Robin Calculator, or Priority Scheduling Calculator .