To write a C program to implement Page Replacement technique using FIFO
- Start the program.
- Get the number of pages and their sequence from the user
- Get the number of available page frames from the user.
- In FIFO, on the basics of first in first out, replace the pages respectively, then find number of page faults occurred.
- Compare all frames with incoming page�6. If the incoming page is already available in page frame, set the match flag to indicate ‘no need of page replacement’.
- If the incoming page is not available in all frames, then remove the page which is loaded into the memory long back and give space for new incoming page.
- Increment the ‘number of Page faults counter
- Print the number of page faults.
- Stop the program.
#include<stdio.h>
int main()
{
int i,j,n,a[50],frame[10],no,k,avail,count=0;
printf("\n ENTER THE NUMBER OF PAGES:\n");
scanf("%d",&n);
printf("\n ENTER THE PAGE NUMBER :\n");
for(i=1;i<=n;i++)
scanf("%d",&a[i]);
printf("\n ENTER THE NUMBER OF FRAMES :");
scanf("%d",&no);
for(i=0;i<no;i++)
frame[i]= -1;
j=0;
printf("\tRef string\t Page Frames\n");
for(i=1;i<=n;i++)
{
printf("%d\t\t\t",a[i]);
avail=0;
for(k=0;k<no;k++)
if(frame[k]==a[i])
avail=1;
if (avail==0)
{
frame[j]=a[i];
j=(j+1)%no;
count++;
for(k=0;k<no;k++)
printf("%d\t",frame[k]);
}
printf("\n");
}
printf("\nPage Fault Is %d",count);
return 0;
}
Thus the implementation of FIFO page replacement is successfully executed.
To write a C program to implement Page Replacement technique using LRU
- Start the program
- Get the number of pages and their sequence from theuser
- Get the number of available page frames from theuser.
- In LRU replace the page that has not been used for the longest period oftime.
- Compare all frames with incoming page�6. If the incoming page is already available in page frame, set the match flag to indicate ‘no need of page replacement’.
- If the incoming page is not available in all frames, then remove the page which has not been used for the longest period oftime.
- Increment the ‘number of Page faults’ counter
- Print the number of page faults.
- Stop the program.
#include<stdio.h>
main()
{
int q[20],p[50],c=0,c1,d,f,i,j,k=0,n,r,t,b[20],c2[20];
printf("Enter no of pages: \n");
scanf("%d",&n);
printf("Enter the reference string: \n");
for(i=0;i<n;i++)
scanf("%d",&p[i]);
printf("Enter no of frames: \n");
scanf("%d",&f);
q[k]=p[k];
printf("\t\n\t %d\n",q[k]);
c++;
k++;
for(i=1;i<n;i++)
{
c1=0;
for(j=0;j<f;j++)
{
if(p[i]!=q[j])
c1++;
}
if(c1==f)
{
c++;
if(k<f)
{
q[k]=p[i];
k++;
for(j=0;j<k;j++)
printf("\t%d",q[j]);
printf("\n");
}
else
{
for(r=0;r<f;r++)
{
c2[r]=0;
for(j=i-1;j<n;j--)
{
if(q[r]!=p[j])
c2[r]++;
else
break;
}
}
for(r=0;r<f;r++)
b[r]=c2[r];
for(r=0;r<f;r++)
{
for(j=r;j<f;j++)
{
if(b[r]<b[j])
{
t=b[r];
b[r]=b[j];
b[j]=t;
}
}
}
for(r=0;r<f;r++)
{
if(c2[r]==b[0])
q[r]=p[i];
printf("\t%d",q[r]);
}
printf("\n");
}
}
}
printf("\nThe no of page faults is %d",c);
}
Thus the implementation of LRU page replacement is successfully executed.
To write a C program to implement Page Replacement technique using OPR
- Start the program.
- Take the input of pages as an array.
- Look for the page allocated is present in near future, if no then replace that page in the memory with new page,
- If page already present increment hit, else increment miss.
- Repeat till we reach the last element of the array.
- Print the number of hits and misses.
- Stop the program.
#include<stdio.h>
int main()
{
int i,j,n,a[50],frame[10],no,k,avail,count=0;
printf("\n ENTER THE NUMBER OF PAGES:\n");
scanf("%d",&n);
printf("\n ENTER THE PAGE NUMBER :\n");
for(i=1;i<=n;i++)
scanf("%d",&a[i]);
printf("\n ENTER THE NUMBER OF FRAMES :");
scanf("%d",&no);
for(i=0;i<no;i++)
frame[i]= -1;
j=0;
printf("\tref string\t page frames\n");
for(i=1;i<=n;i++)
{
printf("%d\t\t",a[i]);
avail=0;
for(k=0;k<no;k++)
if(frame[k]==a[i])
avail=1;
if (avail==0)
{
frame[j]=a[i];
j=(j+1)%no;
count++;
for(k=0;k<no;k++)
printf("%d\t",frame[k]);
}
printf("\n");
}
printf("Page Fault Is %d",count);
return 0;
}
Thus the implementation of OPR page replacement is successfully executed.
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