操作系统实验——内存管理之页面置换算法

#include <stdio.h> #include <stdlib.h> #include <string.h> int N,jishu=0,lost=0,counter=0,time; const int page[5]={100,500,1000,2000,5000}; typedef struct MCB{ int time; char valid; int adress; }Mcb; int find(int adress,Mcb *mcb){ int j=0; for(int i=0;i<N;i++){ if(mcb[i].adress==adress){ j=i; break; } } return j; } void LRU (Mcb *mcb,const char *filename){ char buf[20]={0}; FILE *pfile=fopen(filename,"r"); fseek(pfile, 0L, SEEK_SET); if(pfile==NULL){ printf("打开文件失败"); } else{ size_t len=sizeof(buf); int f,adress; while(!feof(pfile)){ time++; memset(buf,0,len); fgets(buf,len,pfile); jishu++; size_t buf_len=strlen(buf); adress=atoi(buf); f = find(adress,mcb); if(f == 0){ lost++; if (counter<N) { mcb[counter].valid='v'; mcb[counter].time=time; mcb[counter].adress=adress; counter++; }else{ int j=0; for (int i = 0; i < N; ++i) { if (mcb[i].time<mcb[j].time) { j=i; } } mcb[j].adress=adress; mcb[j].time=time; } }else{ mcb[f].time=time; } } } fclose(pfile);//关闭文件 } void init(Mcb *mcb){ for(int i=0;i<N;i++){ mcb[i].valid='i'; mcb[i].time=-1; mcb[i].adress=-1; } } int main(){ char filename[100]; float lost_rate[5][6]; float temp=0; for (int i = 0; i < 5; ++i) { N=page[i]; for (int j = 0; j < 6; ++j) { switch(j){ case 0: strcpy(filename,"/Users/admin/Desktop/memory/workload1"); break; case 1: strcpy(filename,"/Users/admin/Desktop/memory/workload2"); break; case 2: strcpy(filename,"/Users/admin/Desktop/memory/workload3"); break; case 3: strcpy(filename,"/Users/admin/Desktop/memory/workload4"); break; case 4: strcpy(filename,"/Users/admin/Desktop/memory/workload5"); break; case 5: strcpy(filename,"/Users/admin/Desktop/memory/workload6"); break; } Mcb mcb[N]; init(mcb); LRU(mcb,filename); temp=(float) lost/jishu; lost_rate[i][j]=temp; printf("\n当页框大小为：%d ,访问文件为workload%d ,缺页率为：%5f\n",N,j+1,temp); lost=0; jishu=0; } float average=lost_rate[i][0]+lost_rate[i][1]+ lost_rate[i][2]+lost_rate[i][3]+ lost_rate[i][4]+lost_rate[i][5]; printf("当页框为%d时，平均缺页率为：%0.5f\n",N,average/6.0 ); } return 0; }