Write the simulation program to implement demand paging and show the page scheduling and total number of page faults for the following given page reference string. Give input n as the number of memory frames. Reference String: 2,5,2,8,5,4,1,2,3,2,6,1,2,5,9,8 Implement MRU

 

#include <stdio.h>

#include <stdlib.h>

// Function to find the index of the page that is most recently used

int findMRUPage(int frames[], int recent[], int numFrames) {

    int maxIndex = 0;

    int maxRecent = recent[frames[0]];

    for (int i = 1; i < numFrames; i++) {

        if (recent[frames[i]] > maxRecent) {

            maxRecent = recent[frames[i]];

            maxIndex = i;

        }

    }

    return maxIndex;

}

// Function to simulate demand paging with MRU page replacement

void demandPagingMRU(int referenceString[], int n, int numFrames) {

    int frames[numFrames];

    int pageFaults = 0;

    int recent[numFrames]; // Index indicating how recently each page was used

    for (int i = 0; i < numFrames; i++) {

        frames[i] = -1; // Initialize frames to empty

        recent[i] = -1; // Initialize recent index to -1 (never used)

    }

    printf("Page Schedule:\n");

    for (int i = 0; i < n; i++) {

        int page = referenceString[i];

        int found = 0;

        for (int j = 0; j < numFrames; j++) {

            if (frames[j] == page) {

                recent[j] = i; // Update the recent index

                found = 1;

                break;

            }

        }

        if (!found) {

            int mruIndex = findMRUPage(frames, recent, numFrames);

            frames[mruIndex] = page;

            recent[mruIndex] = i;

            pageFaults++;

            printf("Page %d -> ", page);

            for (int j = 0; j < numFrames; j++) {

                if (frames[j] == -1) {

                    printf("M ");

                } else {

                    printf("%d ", frames[j]);

                }

            }

            printf(" (Page Fault)\n");

        } else {

            printf("Page %d -> ", page);

            for (int j = 0; j < numFrames; j++) {

                if (frames[j] == -1) {

                    printf("M ");

                } else {

                    printf("%d ", frames[j]);

                }

            }

            printf("\n");

        }

    }

    printf("\nTotal Page Faults: %d\n", pageFaults);

}

int main() {

    int numFrames;

    int n;

    printf("Enter the number of memory frames: ");

    scanf("%d", &numFrames);

    printf("Enter the number of pages in the reference string: ");

    scanf("%d", &n);

    int referenceString[n];

    printf("Enter the reference string (separated by spaces): ");

    for (int i = 0; i < n; i++) {

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

    }

    demandPagingMRU(referenceString, n, numFrames);

    return 0;

}