SJF Scheduling Visualizer

Simulate and visualize Shortest Job First CPU scheduling algorithm to understand how processes are executed based on their burst time.

Configuration

What is SJF Scheduling?

Shortest Job First (SJF) is a CPU scheduling algorithm that selects the process with the smallest execution time first. SJF is optimal in terms of average waiting time for a given set of processes, but it requires knowledge of the CPU burst time in advance. The non-preemptive version of SJF will let a process run to completion once it starts execution.

Key Concepts

  • Arrival Time: Time at which a process enters the ready queue.
  • Burst Time: Time required by a process for CPU execution.
  • Completion Time: Time at which a process completes execution.
  • Turnaround Time: Time taken from submission to completion (Completion Time - Arrival Time).
  • Waiting Time: Time a process waits in the ready queue (Turnaround Time - Burst Time).

How the Algorithm Works

1. Process Arrival

Processes arrive at the system at their respective arrival times and are placed in a ready queue.

2. Job Selection

From the available processes in the ready queue, the process with the shortest burst time is selected for execution.

3. Process Completion

The selected process executes until completion. Once finished, the CPU is assigned to the next process with the shortest burst time among those available.

4. Performance Metrics

After all processes complete execution, metrics like average waiting time and average turnaround time are calculated to evaluate the scheduler's performance.

Advantages & Limitations

Advantages

  • ✓ Provides minimum average waiting time
  • ✓ Favors short processes, improving system throughput
  • ✓ Better than FCFS for interactive systems

Limitations

  • ✗ Requires prior knowledge of CPU burst time
  • ✗ May lead to starvation of longer processes
  • ✗ Cannot be implemented perfectly in practice