Priority based cpu scheduling in c program - Priority based cpu scheduling in operating system

Aim:To  implement Priority based cpu scheduling algorithm.

Program:

 #include<stdio.h>

#include<conio.h>

void main()

{

                int bt[10],wt[10],tt[10],pt[10],i,j,n,stt,swt=0,temp1,temp2;

                float awt,att;

                clrscr();

                printf("enter no of processes \n");

                scanf("%d",&n);

                printf("enter %d process times \n",n);

                for(i=0;i<n;i++)

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

                printf("enter %d process priorites \n",n);

                for(i=0;i<n;i++)

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

                printf("\n CPU time and priorities before sorting");

                for(i=0;i<n;i++)

                                printf("%d \t %d \n",bt[i],pt[i]);

                for(i=0;i<n;i++)

                {

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

                                {

                                                if(pt[i]>pt[j])

                                                {

                                                                temp1=bt[i];

                                                                bt[i]=bt[j];

                                                                bt[j]=temp1;

                                                                temp2=pt[i];

                                                                pt[i]=pt[j];

                                                                pt[j]=temp2;

                                                }

                                }

                }

                printf("\n CPU times and priorities after sorting \n");

                for(i=0;i<n;i++)

                                printf("%d \t %d \n",bt[i],pt[i]);

                tt[0]=bt[0];

                wt[0]=0;

                stt=0;

                for(i=1;i<n;i++)

                {

                                wt[i]=tt[i-1];

                                tt[i]=wt[i]+bt[i];

                                stt+=tt[i];

                                swt+=wt[i];

                }

                awt=(float)swt/n;

                att=(float)stt/n;

                printf("\n CPU time \t priority \t wtime \t ttime \n");

                for(i=0;i<n;i++)

                                printf("%d \t %d \t %d \t %d \n",bt[i],pt[i],wt[i],tt[i]);

                printf("\n average waiting time is %f",awt);

                printf("\n average turn around time is %f",att);

                getch();

}

Output:

Shortest Job First in c program - SJF in operating system

Aim: To Implement Shortest Job First cpu scheduling algorithm.

Program:

#include<stdio.h>

#include<conio.h>

void main()

{

                int n,bt[10],wt[10],tt[10],stt,swt=0,i,j,temp;

                float awt,att;

                clrscr();

                printf("enter no of process \n");

                scanf("%d",&n);

                printf("enter process cpu time \n");

                for(i=0;i<n;i++)

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

                printf("\n cpu time before sorting \n");

                for(i=0;i<n;i++)

                                printf("%d \t",bt[i]);

                for(i=0;i<n;i++)

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

                                {

                                                if(bt[i]>bt[j])

                                                {

                                                                temp=bt[i];

                                                                bt[i]=bt[j];

                                                                bt[j]=temp;

                                                }

                                }

                printf("\n cpu time after sorting \n");

                for(i=0;i<n;i++)

                                printf("%d \t",bt[i]);

                wt[0]=0;

                tt[0]=stt=bt[0];

                for(i=1;i<n;i++)

                {

                                wt[i]=tt[i-1];

                                tt[i]=wt[i]+bt[i];

                                swt+=wt[i];

                                stt+=tt[i];

                }

                awt=(float)swt/n;

                att=(float)stt/n;

                printf("cpu time \t waiting \t turn around \n");

                for(i=0;i<n;i++)

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

                printf("\n average waiting time is %f turn around time is %f \n",awt,att);

                getch();

}

Output:

First Come First Serve in c program - First Come First Serve(FCFS) in operating systems

AIM:To implement First Come First Serve process scheduling algorithm.

Program:

#include<stdio.h>

#include<conio.h>

void main()

{

                int n,bt[10],wt[10],tt[10],stt,swt=0,i;

                float awt,att;

                clrscr();

                printf("enter no of process \n");

                scanf("%d",&n);

                printf("enter process cpu time \n");

                for(i=0;i<n;i++)

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

                wt[0]=0;

                tt[0]=stt=bt[0];

                for(i=1;i<n;i++)

                {

                                wt[i]=tt[i-1];

                                tt[i]=wt[i]+bt[i];

                                swt+=wt[i];

                                stt+=tt[i];

                }

                awt=(float)swt/n;

                att=(float)stt/n;

                printf("cpu time \t waiting \t turn around \n");

                for(i=0;i<n;i++)

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

                printf("\n average waiting time is %f turn around time is %f \n",awt,att);

                getch();

}

Output: