What is FCFS (First Come First Served)?



FCFS (fcfs meaning) stands for first come, first served. In the FCFS scheduling algorithm, the work that arrived in the ready queue first is assigned to the processor, then the work which came second, and so on. We can say the ready queue acts as the first in-first out (FIFO) queue, so the incoming jobs/processes are at the end of the queue.

FCFS full form (fcfs meaning)

FCFS is a non-preemptive scheduling algorithm in which a process either holds the processor until it terminates or performs Input and output operations. So if the processor is assigned a more extended job, there will be many shorter jobs to run and then wait. This algorithm is used in most batch operating systems.


It follows the non-preemptive approach, which means that it is only terminated after it has been completed as soon as a process controls the CPU.

  1. The process selection criterion is the arrival time. The dispatcher picks the first job in the ready queue, and that job will run until the end of its processor burst.
  2. The average waiting time is very long and therefore not optimal and leads to poor performance.

What is FCFS Scheduling?

Here we focus on FCFS planning. FCFS planning helps to organize processes efficiently for the processor.

Scheduling algorithms are responsible for ensuring that a process does not monopolize the processor. A method is an ongoing program. This process can be carried out in 3 different states “Ready,” “Blocked,” and “In progress.” The procedures are stored in the list of information that indicates the status of the process, the life of the CPU, etc.

How does the FCFS algorithm work?

The acronym [FCFS] (fcfs meaning) means that it’s easier to come first in processor scheduling algorithms to be served first. The workload is processed in order of arrival. And even if the state of the system or the resource requirements of individual processes are not taken into account, planning on a first-come, first-served basis can lead to poor returns.

This algorithm has a high response time from the CPU because it does not leave the CPU until it is completed. After all, it is a non-eviction (unsuitable) algorithm. First come, first served scheduling eliminates the notion of process priorities. Select the process for assigning the CPU, and preference is given to the one that takes the most time (the first in the queue).

Running the process only generates the processor for two reasons:

  1. To be blocked on purpose until an event occurs (printer, file, etc.)
  2. When the execution ends.


1.The FCFS algorithm is simple, easy to implement, and easy to understand.

2.Better for processes with a long burst duration, as no context switching is required between processes.

3.It is a fair algorithm because it does not take the priority into account. The processes that arrive first are served first.


1.A convoy effect occurs, i. H. All small processes must wait for an extensive process to leave the processor.

2.This is not preventive. The process does not free the CPU until it has finished and completed its task.

3.It is not suitable for interactive systems because it cannot guarantee a short response time.

4.The average wait time is high, and the execution time is unpredictable, resulting in poor performance.

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