chucun.zip_LRU_chucun

#include <stdio.h> #include <stdlib.h> #include <unistd.h> #define TRUE 1 #define FALSE 0 #define INVALID -1 #define NUL 0 #define total_instruction 320 /*指令流长*/ #define total_vp 32 /*虚页长*/ #define clear_period 50 /*清零周期*/ typedef struct{ /*页面结构*/ int pn,pfn,counter,time; }pl_type; pl_type pl[total_vp]; /*页面结构数组*/ struct pfc_struct{ /*页面控制结构*/ int pn,pfn; struct pfc_struct *next; }; typedef struct pfc_struct pfc_type; pfc_type pfc[total_vp],*freepf_head,*busypf_head,*busypf_tail; int diseffect,a[total_instruction]; int page[total_instruction], offset[total_instruction]; void initialize(); void FIFO(); void LRU(); void OPT(); int main() { int S,i; srand((int)getpid()); S=(int)rand()%390; for(i=0;i<total_instruction;i+=1) /*产生指令队列*/ { a[i]=S; /*任选一指令访问点*/ a[i+1]=a[i]+1; /*顺序执行一条指令*/ a[i+2]=(int)rand()%390; /*执行前地址指令m’*/ a[i+3]=a[i+2]+1; /*执行后地址指令*/ S=(int)rand()%390; } for(i=0;i<total_instruction;i++) /*将指令序列变换成页地址流*/ { page[i]=a[i]/10; offset[i]=a[i]%10; } for(i=4;i<=32;i++) /*用户内存工作区从4个页面到32个页面*/ { printf("%2d page frames",i); FIFO(i); LRU(i); OPT(i); printf("\n"); } return 0; } void FIFO(total_pf) /*FIFO(First in First out)ALGORITHM*/ int total_pf; /*用户进程的内存页面数*/ { int i; pfc_type *p, *t; initialize(total_pf); /*初始化相关页面控制用数据结构*/ busypf_head=busypf_tail=NUL; /*忙页面队列头，对列尾链接*/ for(i=0;i<total_instruction;i++) { if(pl[page[i]].pfn==INVALID) /*页面失效*/ { diseffect+=1; /*失效次数*/ if(freepf_head==NUL) /*无空闲页面*/ { p=busypf_head->next; pl[busypf_head->pn].pfn=INVALID; /*释放忙页面队列中的第一个页面*/ freepf_head=busypf_head; freepf_head->next=NUL; busypf_head=p; } p=freepf_head->next; /*按方式调新页面入内存页面*/ freepf_head->next=NUL; freepf_head->pn=page[i]; pl[page[i]].pfn=freepf_head->pfn; if(busypf_tail==NUL) busypf_head=busypf_tail=freepf_head; else { busypf_tail->next=freepf_head; busypf_tail=freepf_head; } freepf_head=p; } } printf("FIFO:%d",diseffect); } void LRU(total_pf) int total_pf; { int min,minj,i,j,present_time; initialize(total_pf);present_time=0; for(i=0;i<total_instruction;i++) { if(pl[page[i]].pfn==INVALID) /*页面失效*/ { diseffect++; if(freepf_head==NUL) /*无空闲页面*/ { min=32767; for(j=0;j<total_vp;j++) if(min>pl[j].time&&pl[j].pfn!=INVALID) { min=pl[j].time; minj=j; } freepf_head=&pfc[pl[minj].pfn]; pl[minj].pfn=INVALID; pl[minj].time=-1; freepf_head->next=NUL; } pl[page[i]].pfn=freepf_head->pfn; pl[page[i]].time=present_time; freepf_head=freepf_head->next; } else pl[page[i]].time=present_time; present_time++; } printf("LRU:%d",diseffect); } void OPT(total_pf) /*OPT(Optimal Replacement)ALGORITHM*/ int total_pf; { int i,j,max,maxpage,d,dist[total_vp]; pfc_type *t; initialize(total_pf); for(i=0;i<total_instruction;i++) { if(pl[page[i]].pfn==INVALID) { diseffect++; if(freepf_head==NUL) { for(j=0;j<total_vp;j++) if(pl[j].pfn!=INVALID) dist[j]=32767; else dist[j]=0; d=1; for(j=i+1;j<total_instruction;j++) { if(pl[page[j]].pfn!=INVALID) dist[page[j]]=d; d++; } max=-1; for(j=0;j<total_vp;j++) if(max<dist[j]) { max=dist[j];maxpage=j;} freepf_head=&pfc[pl[maxpage].pfn]; freepf_head->next=NUL; pl[maxpage].pfn=INVALID; } pl[page[i]].pfn=freepf_head->pfn; freepf_head=freepf_head->next; } } printf("OPT:%d",diseffect); } void initialize(total_pf) /*初始化相关数据结构*/ int total_pf; /*用户进程的内存页面数*/ { int i; diseffect=0; for(i=0;i<total_vp;i++) { pl[i].pn=i;pl[i].pfn=INVALID; /*置页面控制结构中的页号，页面为空*/ pl[i].counter=0;pl[i].time=-1; /*页面控制结构中的访问次数为0，时间为-1*/ } for(i=1;i<total_pf;i++) { pfc[i-1].next=&pfc[i];pfc[i-1].pfn=i-1;/*建立pfc[i-1]和pfc[i]之间的连接*/ } pfc[total_pf-1].next=NUL;pfc[total_pf-1].pfn=total_pf-1; freepf_head=&pfc[0]; /*页面队列的头指针为pfc[0]*/ }