用c++实现虚拟存储器实验:使用FIFO算法和最近最久未使用算法,模拟虚拟内存的页面调度和页面错误处理过程,比较不同算法的缺页率并显示输出调度过程、错误处理结果以及两个算法的缺页率
时间: 2024-04-03 20:36:40 浏览: 14
以下是使用FIFO算法和最近最久未使用算法实现虚拟存储器实验的C++代码。在本次实验中,我们使用一个整数向量表示内存页框,它的大小为3。我们还使用一个整数向量表示页面序列,它的大小为10,其中每个元素都是一个介于0和9之间的随机整数。在FIFO算法中,我们使用一个队列来维护内存页框,每次发生缺页时,我们将最老的页面弹出队列并将新页面推入队列。在最近最久未使用算法中,我们使用一个整数向量来存储当前内存页框中的页面,并记录每个页面最近一次被访问的时间。每次发生缺页时,我们选择最长时间未被访问的页面进行替换。
```cpp
#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
using namespace std;
// FIFO算法
void fifo_algorithm(vector<int>& memory_frames, const vector<int>& page_sequence) {
cout << "FIFO Algorithm" << endl;
queue<int> page_queue;
int page_faults = 0;
for (int i = 0; i < page_sequence.size(); i++) {
int page_number = page_sequence[i];
cout << "Accessing page " << page_number << endl;
if (find(memory_frames.begin(), memory_frames.end(), page_number) == memory_frames.end()) {
page_faults++;
if (memory_frames.size() < 3) {
memory_frames.push_back(page_number);
page_queue.push(page_number);
} else {
int oldest_page = page_queue.front();
page_queue.pop();
auto it = find(memory_frames.begin(), memory_frames.end(), oldest_page);
*it = page_number;
page_queue.push(page_number);
}
cout << "Page fault occurred" << endl;
} else {
cout << "Page already in memory" << endl;
}
cout << "Current state of memory frames: ";
for (auto frame : memory_frames) {
cout << frame << " ";
}
cout << endl;
}
double page_fault_rate = (double)page_faults / page_sequence.size();
cout << "Page fault rate: " << page_fault_rate << endl;
}
// 最近最久未使用算法
void lru_algorithm(vector<int>& memory_frames, const vector<int>& page_sequence) {
cout << "LRU Algorithm" << endl;
vector<pair<int, int>> last_access_times(3);
int page_faults = 0;
for (int i = 0; i < page_sequence.size(); i++) {
int page_number = page_sequence[i];
cout << "Accessing page " << page_number << endl;
auto it = find(memory_frames.begin(), memory_frames.end(), page_number);
if (it == memory_frames.end()) {
page_faults++;
if (memory_frames.size() < 3) {
memory_frames.push_back(page_number);
last_access_times[memory_frames.size() - 1] = {page_number, i};
} else {
int lru_page_index = 0;
for (int j = 1; j < last_access_times.size(); j++) {
if (last_access_times[j].second < last_access_times[lru_page_index].second) {
lru_page_index = j;
}
}
memory_frames[lru_page_index] = page_number;
last_access_times[lru_page_index] = {page_number, i};
}
cout << "Page fault occurred" << endl;
} else {
int page_index = distance(memory_frames.begin(), it);
last_access_times[page_index].second = i;
cout << "Page already in memory" << endl;
}
cout << "Current state of memory frames: ";
for (auto frame : memory_frames) {
cout << frame << " ";
}
cout << endl;
}
double page_fault_rate = (double)page_faults / page_sequence.size();
cout << "Page fault rate: " << page_fault_rate << endl;
}
int main() {
vector<int> memory_frames;
vector<int> page_sequence = {3, 2, 0, 3, 4, 2, 3, 1, 0, 4};
fifo_algorithm(memory_frames, page_sequence);
cout << endl;
memory_frames.clear();
lru_algorithm(memory_frames, page_sequence);
return 0;
}
```
在本代码中,我们使用了两个函数分别实现了FIFO算法和最近最久未使用算法。在主函数中,我们先使用FIFO算法运行一次实验,然后清除内存页框并使用LRU算法运行一次实验。在每个算法中,我们都输出了内存页框的当前状态,以及是否发生了页面缺失。最后,我们计算了每个算法的缺页率并将其输出。