What is FCFS?

In an operating system, the task of the scheduler is to administer the workload of the processor in order to keep a balance in the amount of work for the processor in such a way that the throughput is maximized. There are different algorithms for this task. One of them is First Come First Served (FCFS) algorithm. FCFS is one of the easiest scheduling algorithms. In this algorithm, the scheduler assigns the processor tasks in the same order as they come. This method can be understood as a daily life queue. The first task arrived will be processed first and the task coming after that will be joining the queue by the end and so on.

The good thing about this algorithm is that it is easy to implement. While one of the negative points is that it is non-preemptive – means when a task is assigned to the processor it can’t be interrupted during the processing while in other “preemptive algorithms” the processing of task/process can be interrupted on the basis of priority and/or time. Another drawback is that parallel processing is not allowed.

Nowadays this algorithm is not implemented independently (due to slow response time) but still it is part of many other scheduling algorithms.