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First Come First Served Process Scheduling FCFS in operating systems

Last modified on February 13th, 2019 at 5:42 pm

First Come First Served Scheduling (FCFS)

In this tutorial, we will try to learn the followings;

  • What is First Come First Served Scheduling?
  • Gantt Chart for FCFS
  • How to calculate turn around time?
  • FCFS Program in C++
  • Watch Video Lecture

Process arrives first always execute first.

FCFS is non-preemptive scheduling algorithm so processes priority does not matter.

  • If the process first arrived is a big process with a high burst time, then other processes with less burst time need to wait.
  • Average wait time is high.
  • Easy to implement.
  • Easy to understand.
ProcessBurst TimeArrival
P142nd
P223rd
P381st
P434th

Gantt Chart of First Come, First Served (FCFS) Scheduling

FCFS Algo in os
Figure: FCFS.
ProcessWaiting Time
P18
P212
P30
P414

Average Wait Time: (0+8+12+14) / 4 = 8.5

How to calculate turn around time?

TurnAroundTime=BurstTime+WaitingTime.

First Come First Served (FCFS) Program in C++

 

Prof. Fazal Rehman Shamil
Researcher, Publisher of International Journal Of Software Technology & Science ISSN: 2616-5325
Instructor, SEO Expert, Web Programmer and poet.
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