Q.7) Write the program to simulate FCFS CPU-scheduling. The
arrival
time and first CPU_burst for different n number of processes
should be
input to the algorithm. Assume that the fixed IO waiting time (2
units). The next CPU-burst should be generated randomly. The
output
should give Gantt chart, turnaround time and waiting time for
each
process. Also find the average waiting time and turnaround time.
#include <stdio.h>
float getMax();
int getfirst();
void showRQ();
void setStartRQ();
void setAllT();
void ganttChart();
typedef struct
{
float at;
float bt;
float done;
float st;
float wt;
float ft;
float tat;
} JobProcess;
JobProcess p[100];
int n, rediQ[100];
int getfirst()
{
int i = 0, j;
float least = getMax();
for (i = 0; i < n; i++)
if (p[i].at <= least && !p[i].done)
least = p[i].at;
for (i = 0; i < n; i++)
if (least == p[i].at && !p[i].done)
{
p[i].done = 1;
return i;
}
}
float getMax()
{
int i;
float max = 0;
for (i = 0; i < n; i++)
if (p[i].at > max)
max = p[i].at;
return max;
}
void FCFS()
{
int i;
for (i = 0; i < n; i++)
rediQ[i] = getfirst();
setStartT();
setAllT();
ganttChart();
showRQ();
}
void ganttChart()
{
int i;
printf("\nGANTT CHART\n");
for (i = 0; i < n; i++)
printf("-----------------------------------------------");
printf("\n|");
for (i = 0; i < n; i++)
printf("P%d\t ", rediQ[i] + 1);
printf("\n|");
for (i = 0; i < n; i++)
printf("------------------------------------------------");
printf("\n|");
for (i = 0; i < n; i++)
printf("%.1f\t", p[rediQ[i]].st);
printf("%.1f", p[rediQ[n - 1]].ft);
}
void setAllT()
{
int i;
for (i = 0; i < n; i++)
{
p[i].ft = p[i].st + p[i].bt;
p[i].wt = p[i].st - p[i].at;
p[i].tat = p[i].ft - p[i].at;
}
}
void setStartT()
{
int i;
p[rediQ[0]].st = p[rediQ[0]].at; // Arrival time is start time for
first process for (i = 1; i < n; i++)
{
p[rediQ[i]].st = p[rediQ[i - 1]].bt + p[rediQ[i - 1]].st;
if (p[rediQ[i]].st < p[rediQ[i]].at) // process start before arriving
p[rediQ[i]].st = p[rediQ[i]].at;
}
}
void showRQ()
{
int i;
printf("\n\n\t\t\t(time)\nProcess\tBurst\tArrival\tStart\tWait\
tFinish\tTurn_Arround\n");
for (i = 0; i < n; i++)
printf("P%d\t%.1f\t%.1f\t%.1f\t%.1f\t%.1f\t%.1f\
n",
i + 1, p[i].bt, p[i].at, p[i].st, p[i].wt, p[i].ft, p[i].tat);
float sum;
for (i = 0; i < n; i++)
sum += p[i].tat;
printf("\nAverage Turn Around Time : \t%.2f", sum / n);
sum = 0.0;
for (i = 0; i < n; i++)
sum += p[i].wt;
printf("\nAverage WaitingTime : \t\t%.2f\n", sum / n);
}
void main()
{
int i, rq[n];
printf("Enter the number of process ");
scanf("%d", &n);
for (i = 0; i < n; i++)
{
printf("Enter the Burst Time of Process %d\t", i + 1);
scanf("%f", &p[i].bt);
printf("Enter the Arrival Time of process %d\t", i + 1);
scanf("%f", &p[i].at);
p[i].done = 0;
printf("\n");
}
FCFS();
}
*****************************OUTPUT******************************
****
cs10@cs10-Lenovo-C20-30:~$ cd Documents/
cs10@cs10-Lenovo-C20-30:~/Documents$ cd kadam
cs10@cs10-Lenovo-C20-30:~/Documents/kadam$ gcc osprogram7.c
cs10@cs10-Lenovo-C20-30:~/Documents/kadam$ ./a.out
Enter the number of process 5
Enter the Burst Time of Process 1 6
Enter the Arrival Time of process 1 2
Enter the Burst Time of Process 2 4 5
Enter the Arrival Time of process 2
Enter the Burst Time of Process 3 3
Enter the Arrival Time of process 3 2
Enter the Burst Time of Process 4 3
Enter the Arrival Time of process 4 4
Enter the Burst Time of Process 5 7
Enter the Arrival Time of process 5 6
GANTT CHART
-----------------------------------------------------------------
-----------------------------------------------------------------
-----------------------------------------------------------------
----------------------------------------
|P1 P3 P4 P2 P5
|----------------------------------------------------------------
-----------------------------------------------------------------
-----------------------------------------------------------------
----------------------------------------------
|2.0 8.0 11.0 14.0 18.0 25.0
(time)
Process Burst Arrival Start Wait Finish
Turn_Arround
P1 6.0 2.0 2.0 0.0 8.0 6.0
P2 4.0 5.0 14.0 9.0 18.0 13.0
P3 3.0 2.0 8.0 6.0 11.0 9.0
P4 3.0 4.0 11.0 7.0 14.0 10.0
P5 7.0 6.0 18.0 12.0 25.0 19.0
Average Turn Around Time : 11.40
Average WaitingTime : 6.80
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