Write a C program to implement the First-come, first-serve scheduling mechanisms.

Write a C program to implement the First-come, first-serve scheduling mechanisms.

Description of First-come, first-serve scheduling: First-come, first-serve scheduling(FCFS): In this, which process enter the ready queue first is served first. The OS maintains DS that is the ready queue. It is the simplest CPU scheduling algorithm. If a process request the CPU then it is loaded into the ready queue, which process is the head of the ready queue, connect the CPU to that process.

Algorithm for FCFS scheduling:

Step 1: Start the process

Step 2: Accept the number of processes in the ready Queue

Step 3: For each process in the ready Q, assign the process id and accept the CPU burst time

Step 4: Set the waiting of the first process as ‘0’ and its burst time as its turn around time

Step 5: for each process in the Ready Q calculate

(c) Waiting time for process(n)= waiting time of process (n-1) + Burst time of process(n-1)

(d) Turn around time for Process(n)= waiting time of Process(n)+ Burst time for process(n)

Step 6: Calculate

(e) Average waiting time = Total waiting Time / Number of process

(f) Average Turnaround time = Total Turnaround Time / Number of process

Step 7: Stop the process

/* Program to Simulate First Come First Serve CPU Scheduling Algorithm */

Program Code:

#include<stdio.h>

#include<conio.h>

#include<string.h>

void main()

{

int i,j,n,bt[10],compt[10],at[10], wt[10],tat[10];

float sumwt=0.0,sumtat=0.0,avgwt,avgtat;

clrscr();

printf("Enter number of processes: ");

scanf("%d",&n);

printf("Enter the burst time of %d process\n", n);

for(i=0;i<n;i++)

{

scanf("%d",&bt[i]);

}

printf("Enter the arrival time of %d process\n", n);

for(i=0;i<n;i++)

{

scanf("%d",&at[i]);

}

compt[0]=bt[0]-at[0];

for(i=1;i<n;i++)

compt[i]=bt[i]+compt[i-1];

for(i=0;i<n;i++)

{

tat[i]=compt[i]-at[i];

wt[i]=tat[i]-bt[i];

sumtat+=tat[i];

sumwt+=wt[i];

}

avgwt=sumwt/n;

avgtat=sumtat/n;

printf("----------------------------------\n");

printf("PN\tBt\tCt\tTat\tWt\n");

printf("----------------------------------\n");

for(i=0;i<n;i++)

{

printf("%d\t%2d\t%2d\t%2d\t%2d\n",i,bt[i],compt[i],tat[i],wt[i]);

}

printf("----------------------------------\n");

printf(" Avgwt = %.2f\tAvgtat = %.2f\n",avgwt,avgtat);

printf("-----------------------------------\n");

getch();

}

Program Output:

Enter number of processes: 5

Enter the burst time of 5 process

3 6 4 5 2

Enter the arrival time of 5 process

0 2 4 6 8

----------------------------------------

PN Bt Ct Tat Wt

----------------------------------------

0 3 3 3 0

1 6 9 7 1

2 4 13 9 5

3 5 18 12 7

4 2 20 12 10

---------------------------------------

Avgwt = 4.60 Avgtat = 8.60

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