FCFS Scheduling Algorithm in C language with Gantt Chart

This Post Informs you about Non-Preemptive scheduling algorithm, (FCFS) First Comes and First Serve. with Programmatic view along with Gantt chart.

FCFS Scheduling Algorithm in C language with Gantt Chart..

• FCFS Scheduling Algorithm basically gives 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 quickly implemented with a FIFO(First Comes Firts Serve) queue for handling all the tasks. As the process come in, they are put at the last of the  queue. As the CPU complate each task  it will removes from the beginning of the queue and heads on to the next upcomming task.

Certain Term Related to the FCFS Algorithm

1. Turnaround Time :- turnaround time is the total time taken between the submission of a process for execution and the return of the complete output to the user.
2. Throughput Time :- Number of processes completed per unit time.
3. Waiting Time :– The sum of the periods spent waiting in the ready queue.

C Program for FCFS Scheduling Algorithm in c language with Gantt Chart

#include 
#include 
#include 
#define MAX 100

typedef struct
{
    int pid;
    int b_time;
    int w_time;
    int t_time;
} Process;

void print_table(Process p[], int n);
void print_gantt_chart(Process p[], int n);

int main()
{
    Process p[MAX];
    int i, j, n;
    int sum_w_time = 0, sum_t_time;
    printf("Enter total number of process: ");
    scanf("%d", &n);
    printf("Enter burst time for each process:\n");
    for(i=0; i<n; i++) {
        p[i].pid = i+1;
        printf("P[%d] : ", i+1);
        scanf("%d", &p[i].b_time);
        p[i].w_time = p[i].t_time = 0;
    }

    
    p[0].t_time = p[0].b_time;

    for(i=1; i<n; i++) {
        p[i].w_time = p[i-1].w_time + p[i-1].b_time;
        p[i].t_time = p[i].w_time + p[i].b_time;
    }

    for(i=0; i<n; i++) {
            sum_w_time += p[i].w_time;
            sum_t_time += p[i].t_time;
    }

    // print table
    puts(""); // Empty line
    print_table(p, n);
    puts(""); // Empty Line
    printf("Total Waiting Time      : %-2d\n", sum_w_time);
    printf("Average Waiting Time    : %-2.2lf\n", (double)sum_w_time / (double) n);
    printf("Total Turnaround Time   : %-2d\n", sum_t_time);
    printf("Average Turnaround Time : %-2.2lf\n", (double)sum_t_time / (double) n);

    // print Gantt chart
    puts(""); // Empty line
    puts("          GANTT CHART          ");
    puts("          ***********          ");
    print_gantt_chart(p, n);
    return 0;
}


void print_table(Process p[], int n)
{
    int i;

    puts("+*****+*************+*************+*****************+");
    puts("| PID | Burst Time | Waiting Time | Turnaround Time |");
    puts("+*****+************+**************+*****************+");

    for(i=0; i<n; i++) {
        printf("| %2d  |     %2d     |      %2d      |        %2d       |\n"
               , p[i].pid, p[i].b_time, p[i].w_time, p[i].t_time );
        puts("+-----+------------+--------------+-----------------+");
    }

}

void print_gantt_chart(Process p[], int n)
{
    int i, j;
    printf(" ");
    for(i=0; i<n; i++) {
        for(j=0; j<p[i].b_time; j++) printf("--");
        printf(" ");
    }
    printf("\n|");
    
    for(i=0; i<n; i++) {
        for(j=0; j<p[i].b_time - 1; j++) printf(" ");
        printf("P%d", p[i].pid);
        for(j=0; j<p[i].b_time - 1; j++) printf(" ");
        printf("|");
    }
    printf("\n ");
    for(i=0; i<n; i++) {
        for(j=0; j<p[i].b_time; j++) printf("--");
        printf(" ");
    }
    printf("\n");

    printf("0");
    for(i=0; i<n; i++) {
        for(j=0; j<p[i].b_time; j++) printf("  ");
        if(p[i].t_time > 9) printf("\b");
        printf("%d", p[i].t_time);

    }
    printf("\n");
    getch();
}