In computer science, process scheduling is a fundamental concept that helps to manage and allocate resources efficiently in computer systems. The scheduling algorithm determines the order in which processes are executed on the CPU, and it plays a significant role in determining system performance. Among the many scheduling algorithms that have been developed, the First-Come-First-Serve (FCFS) algorithm is the simplest and most straightforward. In this article, we will explore the FCFS algorithm, its advantages and disadvantages, and how it can be improved to optimize process scheduling techniques.

First-Come-First-Serve Algorithm Overview

The FCFS algorithm is based on a simple concept: the first process that arrives is the first process that is executed. In other words, the order in which processes arrive is the same order in which they are executed. As a result, when a process is executing, no other process can execute, even if it has a higher priority. Only after the currently running process completes its execution, the next process in the queue is selected for execution.

Advantages of FCFS Algorithm

The FCFS algorithm has several advantages. Firstly, it is very easy to implement and understand. It does not require any complex logic, data structures, or calculations. All that is required is a queue to store incoming processes and a mechanism to execute them in the order of arrival. Secondly, the FCFS algorithm is fair to all processes since it executes them in the order in which they arrived. This means that no process is prioritized over another based on its priority level. Lastly, the FCFS algorithm tends to have a minimal setup and context-switching overhead. Once a process starts executing, it continues to execute until it is complete, which reduces the number of context switches required.

Disadvantages of FCFS Algorithm

Despite its simplicity and fair execution, the FCFS algorithm has several disadvantages. One major disadvantage is that it is non-preemptive, which means that a process cannot be stopped or interrupted while it is executing. If a long-running process is executing, all other processes must wait for it to complete, even if they have a higher priority. This can lead to increased waiting times, reduced system performance, and increased response times. Additionally, since the FCFS algorithm does not consider the process time or priority, it can lead to poor average waiting times.

Improving FCFS Algorithm

To overcome the limitations of the FCFS algorithm, several modifications can be made. One popular modification is to add a priority element to the algorithm. In this modified version, processes are still executed in the order in which they arrive, but the priority level can be used to determine which process is given preference. Processes with a higher priority are executed before those with lower priority, even if it arrives later. This modification can significantly improve the system's response time, especially if time-critical processes need to be executed immediately.

Another modification that can be made is to make the algorithm preemptive. In this modified version, a long-running process can be interrupted or preempted if a higher-priority process becomes available. This can help to reduce waiting times, improve system performance, and improve the average waiting times. However, adding preemption to the FCFS algorithm requires more complex logic, and the overhead associated with context switching increases.

Conclusion

The FCFS algorithm is a popular and straightforward process scheduling algorithm used in computer science. While it is easy to understand and implement, its non-preemptive nature can lead to poor system performance, long waiting times, and increased response times. However, by modifying the FCFS algorithm to add prioritization or preemption, it is possible to optimize the process scheduling techniques and improve the average waiting times. Ultimately, the choice of scheduling algorithm depends on the specific system requirements, but understanding the advantages and disadvantages of each algorithm can help to develop a more effective system.