Definition
First Come First Served (FCFS)
First Come First Served (FCFS) selects the process that has been in the Ready Queue the longest. It is the simplest scheduling strategy.
Properties
Selection
Process with the longest wait time in the Ready Queue is chosen.
Non-Preemptive
Once running, a process continues until it terminates or blocks for I/O.
Bias
Favours long, CPU-intensive processes over short or I/O-intensive ones.
Convoy Effect
Poor resource utilisation: I/O devices sit idle while processes wait for a long CPU burst.
Usage
Modern Systems
Rarely used standalone in modern systems but often serves as the underlying mechanism for specific priority levels in more complex schedulers.