LRU Page Replacement Algorithm in C

Here you will get the program for lru page substitution calculation in C.

Least Recently Used (LRU) page substitution calculation chips away at the idea that the pages that are vigorously utilized in past directions are probably going to be utilized intensely in next guidelines. What’s more, the page that is utilized less is probably going to be utilized less in future.

At whatever point a page issue happens, the page that is least as of late utilized is expelled from the memory outlines. Page issue happens when a referenced page in not found in the memory outlines.

Underneath program tells the best way to actualize this calculation in C.

Program for LRU Page Replacement Algorithm in C

#include<stdio.h>
 
int findLRU(int time[], int n){
	int i, minimum = time[0], pos = 0;
 
	for(i = 1; i < n; ++i){
		if(time[i] < minimum){
			minimum = time[i];
			pos = i;
		}
	}
	
	return pos;
}
 
int main()
{
    int no_of_frames, no_of_pages, frames[10], pages[30], counter = 0, time[10], flag1, flag2, i, j, pos, faults = 0;
	printf("Enter number of frames: ");
	scanf("%d", &no_of_frames);
	
	printf("Enter number of pages: ");
	scanf("%d", &no_of_pages);
	
	printf("Enter reference string: ");
	
    for(i = 0; i < no_of_pages; ++i){
    	scanf("%d", &pages[i]);
    }
    
	for(i = 0; i < no_of_frames; ++i){
    	frames[i] = -1;
    }
    
    for(i = 0; i < no_of_pages; ++i){
    	flag1 = flag2 = 0;
    	
    	for(j = 0; j < no_of_frames; ++j){
    		if(frames[j] == pages[i]){
	    		counter++;
	    		time[j] = counter;
	   			flag1 = flag2 = 1;
	   			break;
   			}
    	}
    	
    	if(flag1 == 0){
			for(j = 0; j < no_of_frames; ++j){
	    		if(frames[j] == -1){
	    			counter++;
	    			faults++;
	    			frames[j] = pages[i];
	    			time[j] = counter;
	    			flag2 = 1;
	    			break;
	    		}
    		}	
    	}
    	
    	if(flag2 == 0){
    		pos = findLRU(time, no_of_frames);
    		counter++;
    		faults++;
    		frames[pos] = pages[i];
    		time[pos] = counter;
    	}
    	
    	printf("\n");
    	
    	for(j = 0; j < no_of_frames; ++j){
    		printf("%d\t", frames[j]);
    	}
	}
	
	printf("\n\nTotal Page Faults = %d", faults);
    
    return 0;
}

Output

Enter number of frames: 3
Enter number of pages: 6
Enter reference string: 5 7 5 6 7 3

5 -1 -1
5 7 -1
5 7 -1
5 7 6
5 7 6
3 7 6

Total Page Faults = 4

Video Output

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