Answer:
Code implemented using C++ below
Explanation:
sambswas
answered this
#include<iostream>
#include<cstdlib>
#define CYCLES 100
using namespace std;
struct page_table_entry {
int page_num;
int last_access_time;
int first_access_time;
};
int num_of_frames;
int sequence;
struct page_table_entry *page_table;
void init() {
page_table = new page_table_entry[num_of_frames];
for (int i = 0; i < num_of_frames; i++) {
page_table[i].page_num = -1;
page_table[i].first_access_time = -1;
page_table[i].last_access_time = -1;
}
sequence = 0;
}
int get_random_page() {
sequence++;
return rand() % 10;
}
int request_frame_LRU() {
for (int i = 0; i < num_of_frames; i++)
if (page_table[i].page_num == -1) {
cout << "Empty frame found at location " << i << endl;
return i;
}
int target = 0;
for (int i = 1; i < num_of_frames; i++)
if (page_table[i].last_access_time < page_table[target].last_access_time)
target = i;
cout << "target frame is " << target << ", containing page " << page_table[target].page_num << endl;
return target;
}
int request_frame_FIFO() {
for (int i = 0; i < num_of_frames; i++)
if (page_table[i].page_num == -1){
cout << "Empty frame found at location " << i << endl;
return i;
}
int target = 0;
for (int i = 1; i < num_of_frames; i++)
if (page_table[i].first_access_time < page_table[target].first_access_time)
target = i;
cout << "target frame is " << target << ", containing page " << page_table[target].page_num << endl;
return target;
}
int search_page(int page) {
for (int i = 0; i < num_of_frames; i++) {
if (page_table[i].page_num == -1)
continue;
if (page_table[i].page_num == page) {
cout << "page " << page << " found at location " << i << endl;
return i;
}
}
cout << "page " << page << " not found" << endl;
return -1;
}
void LRU() {
init();
int miss = 0;
int hit = 0;
for (int i = 0; i < CYCLES; i++) {
int page = get_random_page();
cout << "Requested page is: " << page << endl;
int location = search_page(page);
if (location > 0) {
page_table[location].last_access_time = sequence;
hit ++;
}
else {
location = request_frame_LRU();
page_table[location].page_num = page;
page_table[location].first_access_time = sequence;
page_table[location].last_access_time = sequence;
miss++;
}
cout << endl;
}
double hit_ratio = (double)hit/(hit+miss);
cout << "######## LRU ########" << endl;
cout << "hits: " << hit << endl;
cout << "misses: " << miss << endl;
cout << "hit ratio: " << hit_ratio << endl;
cout << "for frame size " << num_of_frames << endl;
cout << "#######################" << endl << endl;
}
void FIFO() {
init();
int miss = 0;
int hit = 0;
for (int i = 0; i < CYCLES; i++) {
int page = get_random_page();
cout << "Requested page is: " << page << endl;
int location = search_page(page);
if (location > 0) {
page_table[location].last_access_time = sequence;
hit ++;
}
else {
location = request_frame_FIFO();
page_table[location].page_num = page;
page_table[location].first_access_time = sequence;
page_table[location].last_access_time = sequence;
miss++;
}
cout << endl;
}
double hit_ratio = (double)hit/(hit+miss);
cout << "######## FIFO ########" << endl;
cout << "hits: " << hit << endl;
cout << "misses: " << miss << endl;
cout << "hit ratio: " << hit_ratio << endl;
cout << "for frame size " << num_of_frames << endl;
cout << "#######################" << endl << endl;
}
int main() {
srand(time(NULL));
num_of_frames = rand() % 7 + 1;
LRU();
FIFO();
}
