Exercise Program - 4.a IMPLEMENTATION OF FCFS SCHEDULING ALGORITHM

AIM:

To write a C program in Linux operating systems for implementing the first come first serve scheduling algorithm.

ALGORITHM:

Step 1: Start the program.

Step 2: Read the needed variables and the number of process.

Step 3: Read the burst time for all process.

Step 4: Read the arrival time (AT).

Step 5: Calculate the waiting time and turn around time and display it.

Step 6: Calculate the average waiting time and average total turnaround time and display it.

Step 7: Stop the program.

PROGRAM:

#include

#include

typedef struct pcb

{

int pid, bt, bt_bal, tat, wt;

} PCB;

int main()

{

PCB pr[10];

int i,j,k,n,tq;

int sum_bt=0,sum_tat=0,sum_wt=0;

int gantt[3][50];

printf("\n\nFCFS Scheduling \n");

printf("\nEnter the no. of process : ");

scanf("%d",&n);

for(i=0;i

{

printf("\nEnter burst time of the process %d: ",i+1);

pr[i].pid = i+1;

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

}

k=0;

for( i=0;i

{

sum_bt += pr[i].bt;

pr[i].tat = sum_bt;

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

sum_wt += pr[i].wt;

sum_tat += pr[i].tat;

gantt[0][k] = pr[i].pid;

gantt[1][k] = sum_bt;

gantt[2][k] = sum_bt - pr[i].bt;

k++;

}

printf("\n\nFCFS Scheduling \n");

printf("PID: ");

for( i=0; i

printf("%4d",gantt[0][i]);

printf("\nBTime:");

for( i=0; i

printf("%4d",pr[i].bt);

printf("\n\nGANTT Chart\n\n");

printf("PID: ");

for( i=0; i

printf("%4d",gantt[0][i]);

printf("\nTime: ");

for( i=0; i

printf("%4d",gantt[1][i]);

printf("\n\nWTime:");

for( i=0; i

printf("%4d",gantt[2][i]);

printf("\n\nTotal waiting time = %d\n",sum_wt);

printf("Average waiting time = %.2f\n",(float)sum_wt/n);

printf("\nTotal turn around time = %d\n",sum_tat);

printf("Average turn around time = %.2f\n\n",(float)sum_tat/n);

return 0;

}

SAMPLE OUTPUT:

[it65@AntiViruS ~]$ cc fcfs.c

[it65@AntiViruS ~]$ ./a.out

FCFS Scheduling

Enter the no. of process : 3

Enter burst time of the process 1: 24

Enter burst time of the process 2: 3

Enter burst time of the process 3: 3

FCFS Scheduling

PID: 1 2 3

BTime: 24 3 3

GANTT Chart-

PID: 1 2 3

Time: 24 27 30

WTime: 0 24 27

Total waiting time = 51

Average waiting time = 17.00

Total turn around time = 81

Average turn around time = 27.00

RESULT:

Thus the Linux program for implementing first come first serve scheduling algorithm has been executed and the output is verified successfully.