Operating System - First Come First Served (FCFS)
- It is the simplest CPU Scheduling algorithm.
When the process request the CPU first, then the CPU will be allocated first.
This algorithm use the FIFO queue for ready queue management.
Its code is simple to write and easy to read.
This algorithm follows the nonpreemptive scheduling.
The average waiting time for this algorithm is quite long.
The performance of this algorithm is very low so that it is rarely used in the modern operating system.
For example consider the set of processes that arrive at time 0 and CPU-burst time given in millisecond:
If the processes arrive in the order P1,P2,P3, then the processes will be processed in FCFS order.
Following shows the Gantt Chart:
Suppose, the processes arrive in the different arrival time, then these processes will be served in FCFS order.
|Process||Arrival Time||CPU-Burst Time|