Let us learn how to implement LFU Page Replacement Algorithm in C programming language. This code for Least Frequently Used Page Replacement makes use of Arrays.
What is LFU Page Replacement Algorithm?
In LFU Page Replacement method, the page with the minimum count is selected for replacement with the page that needs to enter into the system.
LFU is a cache algorithm which is used to manage computer’s memory. A counter is assigned to every block of memory that is loaded into the cache memory.
However, the LFU technique is hardly implemented these days but this algorithm is normally combined with other algorithms which make it a hybrid algorithm, and then it is implemented.
LFU algorithm is sometimes also combined with LRU replacement algorithm, and then implemented.
C Program To Implement LFU Page Replacement Algorithm in OS
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 | #include<stdio.h> int main() { int total_frames, total_pages, hit = 0; int pages[25], frame[10], arr[25], time[25]; int m, n, page, flag, k, minimum_time, temp; printf("Enter Total Number of Pages:\t"); scanf("%d", &total_pages); printf("Enter Total Number of Frames:\t"); scanf("%d", &total_frames); for(m = 0; m < total_frames; m++) { frame[m] = -1; } for(m = 0; m < 25; m++) { arr[m] = 0; } printf("Enter Values of Reference String\n"); for(m = 0; m < total_pages; m++) { printf("Enter Value No.[%d]:\t", m + 1); scanf("%d", &pages[m]); } printf("\n"); for(m = 0; m < total_pages; m++) { arr[pages[m]]++; time[pages[m]] = m; flag = 1; k = frame[0]; for(n = 0; n < total_frames; n++) { if(frame[n] == -1 || frame[n] == pages[m]) { if(frame[n] != -1) { hit++; } flag = 0; frame[n] = pages[m]; break; } if(arr[k] > arr[frame[n]]) { k = frame[n]; } } if(flag) { minimum_time = 25; for(n = 0; n < total_frames; n++) { if(arr[frame[n]] == arr[k] && time[frame[n]] < minimum_time) { temp = n; minimum_time = time[frame[n]]; } } arr[frame[temp]] = 0; frame[temp] = pages[m]; } for(n = 0; n < total_frames; n++) { printf("%d\t", frame[n]); } printf("\n"); } printf("Page Hit:\t%d\n", hit); return 0; } |
Output
If you have any doubts or compilation errors in this C program to implement Least Frequently Used Page Replacement Algorithm in operating system, let us know about it in the comment section below.
LFU is a cache eviction algorithm which is also known as least frequently used cache.
What is the purpose of the array arr?
The Least Frequently Used Page Replacement Algorithm is sometimes combined with the Least Recent Used Page Replacement Algorithm is known as LRFU Algorithm.
Amazing Program!! Thanks!
I run the program in a virtual machine, but I get error says”subscripted value is neither array nor pointer”
I know of this error that the compiler couldn’t read the values. Can someone tell me how can I remove this error?
I am gettting page hit as 0 in every output
Can you add page faults function?