在本代码的基础上加入LRU页面置换算法
时间: 2024-03-23 21:36:39 浏览: 56
以下是加入LRU页面置换算法的C语言代码示例:
```c
#include <stdio.h>
#define PAGE_SIZE 4096 // 页大小为4KB
#define PAGE_COUNT 1024 // 总页数为1024
#define FRAME_COUNT 8 // 物理内存帧数为8
int main() {
int process_size;
printf("请输入进程大小(单位:字节):");
scanf("%d", &process_size);
// 页表
int page_table[PAGE_COUNT];
for (int i = 0; i < PAGE_COUNT; i++) {
page_table[i] = -1; // -1表示该页未分配给进程
}
// 物理内存
int frames[FRAME_COUNT];
for (int i = 0; i < FRAME_COUNT; i++) {
frames[i] = -1; // -1表示该帧未被占用
}
int page_hits = 0; // 页面命中数
int page_faults = 0; // 页面故障数
// 模拟进程访问页
int page_number;
while (1) {
printf("请输入页号(0-%d),输入-1退出:", PAGE_COUNT - 1);
scanf("%d", &page_number);
if (page_number == -1) {
break;
}
// 查找页是否已在物理内存中
int frame_number = -1;
for (int i = 0; i < FRAME_COUNT; i++) {
if (frames[i] == page_number) {
frame_number = i;
break;
}
}
if (frame_number != -1) { // 页面命中
page_hits++;
printf("页面命中,物理地址为:%d\n", frame_number * PAGE_SIZE);
} else { // 页面故障
page_faults++;
printf("页面故障!\n");
// 查找未被占用的物理帧
int free_frame_number = -1;
for (int i = 0; i < FRAME_COUNT; i++) {
if (frames[i] == -1) {
free_frame_number = i;
break;
}
}
if (free_frame_number != -1) { // 有空闲帧
frames[free_frame_number] = page_number;
page_table[page_number] = free_frame_number;
printf("已将页 %d 装入物理帧 %d,物理地址为:%d\n",
page_number, free_frame_number, free_frame_number * PAGE_SIZE);
} else { // 没有空闲帧,需进行页面置换
// 查找最近最久未使用的物理帧
int victim_frame_number = -1;
int victim_page_number = -1;
for (int i = 0; i < FRAME_COUNT; i++) {
int current_page_number = frames[i];
if (current_page_number != -1 && (victim_frame_number == -1 ||
page_table[current_page_number] <
page_table[frames[victim_frame_number]])) {
victim_frame_number = i;
victim_page_number = current_page_number;
}
}
frames[victim_frame_number] = page_number;
page_table[page_number] = victim_frame_number;
printf("已将页 %d 装入物理帧 %d,物理地址为:%d\n",
page_number, victim_frame_number, victim_frame_number * PAGE_SIZE);
page_table[victim_page_number] = -1;
printf("已将页 %d 从物理帧 %d 移除\n", victim_page_number, victim_frame_number);
}
}
}
printf("页面命中数:%d,页面故障数:%d\n", page_hits, page_faults);
return 0;
}
```
该代码在原有的基础上加入了物理内存数组和页面命中数、页面故障数的统计。在模拟进程访问页时,先查找页是否已在物理内存中,如果是则页面命中,否则发生页面故障。如果有空闲的物理帧,则将页装入其中。如果没有空闲的物理帧,则查找最近最久未使用的物理帧进行页面置换。在页面置换时,需将被替换的页从页表中移除。最后输出页面命中数和页面故障数。
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