C programming Simulate an example of an optimal algorithm fo

C programming

Simulate an example of an optimal algorithm for operating systems.

Solution

Let us take a case of optimal page replacement algorithm usd in memory managment by operating systemin this the page with the highest labels should be removed.

include<stdio.h>

#include<conio.h>

   int rs[3];

      void main()

       {

                void display();

                int z[12]={2,3,2,1,5,2,4,5,3,2,5,2},i,j,fs[3];

                   int max,found=0,we[3],index,k,l,flag1=0,flag2=0,pf=0,frsize=3;

                    clrscr();

                      for(i=0;i<3;i++)

                       {

                                rs[i]=-1;

                       }

                                for(j=0;j<12;j++)

                {

                   flag1=0;

                      flag2=0;

                                for(i=0;i<3;i++)

                     {

                                if(rs[i]==z[j])

                                {

                                    flag1=1;

                                      flag2=1;

                                                     break;

                                }

                     }

                       if(flag1==0)

                                {

                                for(i=0;i<3;i++)

                                       {

                                                if(rs[i]==-1)

                                                                {

                                                                     rs[i]=z[j];

                                                                                flag2=1;

                                                                                   break;

                                                                }

                                                }

                       }

                                if(flag2==0)

                                    {

                                       for(i=0;i<3;i++)

                                                we[i]=0;

                                                      for(i=0;i<rssize;i++)

                                                                       {

                                                                                for(k=j+1;k<12;k++)

                                                                                       {

                                                                                                if(rs[i]==z[k])

                                                                                                       {

                                                                                                                we[i]=k-j;

                                                                                                                      break;

                                                                                                       }

                                                                      }

                                                }

                                                found=0;

                                                     for(i=0;i<rssize;i++)

                                                                {

                                                                   if(we[i]==0)

                                                                                {

                                                                                index=i;

                                                                                    found=1;

                                                                                                break;

                                                                                }

                                                                }

                                                                    if(found==0)

                                                                                {

                                                                                max=we[0];

                                                                                     index=0;

                                                                                                for(i=1;i<rssize;i++)

                                                                                                   {

                                                                                                     if(max<we[i])

                                                                                                                {

                                                                                                                max=we[i];

                                                                                                                index=i;

                                                                                   }

                                                      }

                                }

                       fr[index]=p[j];

                       pf++;

                }

                   display();

}

                printf(\"\ no of page faults:%d\",pf);

                       getch();

}

void display()

{

int i;

printf(\"\ \");

for(i=0;i<3;i++)

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

}

here output of the above program

OUTPUT :

2 -1 -1

2 3 -1

2 3 -1

2 3 1

2 5 1

2 5 1

2 5 4

2 5 4

3 5 4

3 5 2

3 5 2

3 5 2

no of page faults : 4