First Come First Serve (FCFS) is a Non-Preemptive scheduling algorithm. FIFO (First In First Out) strategy assigns priority to process in the order in which they request the processor.
The process that requests the CPU first is allocated the CPU first. This is easily implemented with a FIFO queue for managing the tasks. As the process come in, they are put at the end of the queue. As the CPU finishes each task, it removes it from the start of the queue and heads on to the next task.
ALGORITHM
Start the process
Declare the array size
Get the number of processes to be inserted
Get the value
Start with the first process from it’s initial position let other process to be in queue
Calculate the total number of burst time
Display the values
Stop the process
Below is the source code for C program to perform First Come First Serve Algorithm which is successfully compiled and run on Windows System to produce desired output as shown below :
SOURCE CODE : :
#include<stdio.h>
#include<conio.h>
int main()
{
int n,i,j,sum=0;
int arrv[10],ser[10],start[10];
int finish[10],wait[10],turn[10];
float avgturn=0.0,avgwait=0.0;
start[0]=0;
printf("Enter the number of processes:");
scanf("%d",&n);
for(i=0;i<n;i++)
{
printf("Enter the arriwal and service time of %d process:",i+1);
scanf("%d%d",&arrv[i],&ser[i]);
}
for(i=0;i<n;i++)
{
sum=0;
for(j=0;j<i;j++)
sum=sum+ser[j];
start[i]=sum;
}
for(i=0;i<n;i++)
{
finish[i]=ser[i]+start[i];
wait[i]=start[i];
turn[i]=ser[i]+wait[i];
}
for(i=0;i<n;i++)
{
avgwait+=wait[i];
avgturn+=turn[i];
}
avgwait/=n;
avgturn/=n;
printf("\narraival service Start Finish Wait Turn\n");
for(i=0;i<n;i++)
printf("%d\t%d\t%d\t%d\t%d\t%d\n",arrv[i],ser[i],start[i],
finish[i],wait[i],turn[i]);
printf("\nAverage waiting time=%f",avgwait);
printf("\nAverage turn around time=%f",avgturn);
return 0;
}
OUTPUT : :
Enter the number of processes:5
Enter the arriwal and service time of 1 process:3 7
Enter the arriwal and service time of 2 process:7
77
Enter the arriwal and service time of 3 process:2
4
Enter the arriwal and service time of 4 process:4
2
Enter the arriwal and service time of 5 process:
5
4
arraival service Start Finish Wait Turn
3 7 0 7 0 7
7 77 7 84 7 84
2 4 84 88 84 88
4 2 88 90 88 90
5 4 90 94 90 94
Average waiting time=53.799999
Average turn around time=72.599998
What is First Come First Serve (FCFS) Algorithm?
First Come First Serve (FCFS) is a Non-Preemptive scheduling algorithm. FIFO (First In First Out) strategy assigns priority to process in the order in which they request the processor.
The process that requests the CPU first is allocated the CPU first. This is easily implemented with a FIFO queue for managing the tasks. As the process come in, they are put at the end of the queue. As the CPU finishes each task, it removes it from the start of the queue and heads on to the next task.
ALGORITHM
Below is the source code for C program to perform First Come First Serve Algorithm which is successfully compiled and run on Windows System to produce desired output as shown below :
SOURCE CODE : :
OUTPUT : :
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