SJF Scheduling Algorithm Program Operating System LAB

By | December 18, 2022

SJF Scheduling Algorithm Program – Operating System Practicals LAB.
Write a C Program to input burst times of N processes and find the Waiting times and Turn around times using SJF – Shortest Job First Scheduling Method in Operating system.

SJF Scheduling Algorithm Program - Operating System Practicals LAB.

Program Code

#include<stdio.h>
 
int main()
{
    int bt[20],p[20],wt[20],tat[20],i,j,n,total=0,pos,temp;
    float avg_wt,avg_tat;
    printf("Enter number of process:");
    scanf("%d",&n);
 
    printf("\nEnter Burst Time:\n");
    for(i=0;i<n;i++)
    {
        printf("p%d:",i+1);
        scanf("%d",&bt[i]);
        p[i]=i+1;           /*contains process number*/
    }
 
    /*sorting burst time in ascending order using selection sort*/
    for(i=0;i<n;i++)
    {
        pos=i;
        for(j=i+1;j<n;j++)
        {
            if(bt[j]<bt[pos])
                pos=j;
        }
 
        temp=bt[i];
        bt[i]=bt[pos];
        bt[pos]=temp;
 
        temp=p[i];
        p[i]=p[pos];
        p[pos]=temp;
    }
 
    wt[0]=0;            /*waiting time for first process will be zero */
    total = 0; 
    /*calculate waiting time for processes */
    for(i=1;i<n;i++)
    {
        wt[i]=wt[i-1]+bt[i-1];
        total+=wt[i];
    }
 
    avg_wt=(float)total/n;      /*average waiting time*/
    total=0;
 
    printf("\nProcess\t    Burst Time    \tWaiting Time\tTurnaround Time");
    for(i=0;i<n;i++)
    {
        tat[i]=bt[i]+wt[i];     /*calculate turnaround time*/
        total+=tat[i];
        printf("\np%d\t\t  %d\t\t    %d\t\t\t%d",p[i],bt[i],wt[i],tat[i]);
    }
 
    avg_tat=(float)total/n;     /*average turnaround time*/
    printf("\n\nAverage Waiting Time=%f",avg_wt);
    printf("\nAverage Turnaround Time=%f\n",avg_tat);
}

Output:

SJF Scheduling Algorithm Program Operating System Practicals LAB

Enter number of process:3

Enter Burst Time:
p1:24
p2:3
p3:3

Process Burst Time Waiting Time Turnaround Time
p2        3          0            3
p3        3          3            6
p1        24         6            30

Average Waiting Time=3.000000
Average Turnaround Time=13.000000

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