OPT, LRU, FIFO页面调度算法的模拟

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#include <iostream>#include <cstdlib>#include <ctime>#include <deque>#include <map>#include <algorithm>using namespace std;int findLRU(map<int, int> managedMap);deque<int> fifo;map<int, int> lru;map<int, int>opt;const int LEN = 1000;//要访问的页面总数const int BLOCKNO = 3;  //物理块数const int INF = 999999; //用于opt算法中在后续找不到该元素所用int main() {//初始化测试以数据srand((unsigned)time(NULL));int testData[LEN];//int testData[LEN] = {2,3,2,1,5,2,4,5,3,2,5,2};for (int i = 0; i < LEN; i++) {testData[i] = rand() % 5 + 1;}//初始化测试数据完毕int success=0;//命中次数int fail = 0;//缺页次数 + 物理块数//FIFO算法for (int i = 0; i < LEN; i++) {auto pos = find(fifo.cbegin(), fifo.cend(), testData[i]);if (pos != fifo.cend())success++;else {fail++;if (fifo.size() < BLOCKNO) {fifo.push_back(testData[i]);}else {fifo.pop_front();fifo.push_back(testData[i]);}}}cout << "测试数据：[" << testData[0];for (int i = 1; i <= LEN-1; i++) {cout << ", " << testData[i];}cout << "]" << endl<<endl;cout << "使用"<<BLOCKNO<<"个物理块"<<endl;cout << "FIFO算法" << endl;cout << "\t缺页数：" << fail - BLOCKNO;cout << "\t缺页率" << (double)fail / LEN;cout << "\t命中率" << (double)success / LEN<<endl<<endl;success = 0;fail = 0;//LRU算法 lru的map，map->first代表页面值，每过一个循环map->second全部都会+1，那么越久没用到的它的second就越大，那么替换的时候//就把second最大的替换出去for (int i = 0; i < LEN; i++) {auto pos = lru.find(testData[i]);if (pos != lru.end()) {success++;lru[testData[i]] = 0;}else {fail++;if (!(lru.size() < BLOCKNO)) {lru.erase(findLRU(lru));}lru[testData[i]] = 0;}map<int, int>::iterator it=lru.begin();for (; it != lru.end(); it++) {it->second++;}}cout << "LRU算法" << endl;cout << "\t缺页数：" << fail - BLOCKNO;cout << "\t缺页率" << (double)fail / LEN;cout << "\t命中率" << (double)success / LEN<<endl<<endl;success = 0;fail = 0;//OPT算法   与lru相同这个也用map实现，first含义与lru相同，second代表的是下一个相同的页面出现的位置，这个位置越远那么他越先被//替换，这个算法是命中率最高的，但在实际情况中是无法实现的。我们只能假装模拟一下for (int i = 0; i < LEN; i++) {auto pos = opt.find(testData[i]);if (pos != opt.end()) {success++;}else {fail++;if (!(opt.size() < BLOCKNO)) {opt.erase(findLRU(opt));}}//更新second数据int nextPos = -1;for (int j = i + 1; j < LEN; j++) {if (testData[j] == testData[i]) {nextPos = j;break;}}if (nextPos == -1)nextPos = INF;opt[testData[i]] = nextPos;}cout << "OPT算法" << endl;cout << "\t缺页数：" << fail - BLOCKNO;cout << "\t缺页率" << (double)fail / LEN;cout << "\t命中率" << (double)success / LEN;return 0;}int findLRU(map<int, int> managedMap) {int max = -1;int index;map<int, int> ::iterator it=managedMap.begin();for (; it != managedMap.end(); it++) {if (it->second > max) {max = it->second;index = it->first;}}return index;}
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