【操作系统】编程模拟FIFO，LRU，NUR，OPT页面置换算法

#include<stdio.h>
#include<stdlib.h>
#include<time.h>
#define random(x) (rand()%x)#define LOG 1 //1-show log 2-no show
#define TYPE 10 //page types
#define NUM 20 //page nums
#define SIZE 5 //cache sizestruct page{
int id;//page id
int time=0;//different meaning in different algorithm
};
struct page pageList[NUM],cache[SIZE];//page needs,page cachevoid init(){//random data init
printf("PageList:\n");
srand((unsigned)time(NULL));
for(int i=0;i<NUM;i++)
printf("%d ",pageList[i].id=random(TYPE));
printf("\n");
}void cacheClear(){//clear the cache
for(int i=0;i<SIZE;i++){
cache[i].id=-1;
cache[i].time=0;
}
}int cacheHit(int i){//find cache hit or not
for(int j=0;j<SIZE;j++)
if(cache[j].id==pageList[i].id){
if(LOG)
printf(" hit ");
return j;
}
if(LOG)
printf(" ");
return -1;
}int cacheRoom(){//find cache have free room or not
for(int i=0;i<SIZE;i++)
if(cache[i].id==-1)
return i;
return -1;
}void cacheShow(){//show the cache pages
if(LOG) {
printf("cache: ");
for(int i=0;i<SIZE;i++)
if(cache[i].id==-1){
printf("N\t");
}else
printf("%d\t",cache[i].id);
printf("\n");
}
}void cacheTimeAdd(){//add the pages time in cache
for(int i=0;i<SIZE;i++)
cache[i].time++;
}int FIFOfun(){//FIFO replace
int maxtime=cache[0].time,t=0;
for(int i=1;i<SIZE;i++)
if(maxtime<cache[i].time){
maxtime=cache[i].time;
t=i;
}
return t;
}double FIFO(){//time in FIFO:live time
double ret;
if(LOG)
printf("\nFIFO:\n");
cacheClear();
int hitsum=0;
for(int i=0;i<NUM;i++){
if(LOG)
printf("input:%d\t",pageList[i].id);
int hit=cacheHit(i);
if(hit==-1){//if not hit
int room=cacheRoom();
if(room!=-1)// if have free room
cache[room]=pageList[i];//use room save page
else//if have not free room
cache[FIFOfun()]=pageList[i];//use FIFO to replace
}else{//if hit
hitsum++;
}
cacheShow();
cacheTimeAdd();
}
if(LOG) {
printf("PageReplacement:%d\n",hitsum);
printf("PageFault:%d\n",NUM-hitsum);
}
printf("HitRate:%lf\n",ret=(double)hitsum/NUM);
return ret;
}double LRU(){//time:from last use to now
double ret;
if(LOG)
printf("\nLRU:\n");
cacheClear();
int hitsum=0;
for(int i=0;i<NUM;i++){
if(LOG)
printf("input:%d\t",pageList[i].id);
int hit=cacheHit(i);
if(hit==-1){//if not hit
int room=cacheRoom();
if(room!=-1)//if have free room
cache[room]=pageList[i];//use free room to save page
else//if have not free room
cache[FIFOfun()]=pageList[i];//use LRU ,because time have different meaning ,function is same as FIFO
}else{//if hit
hitsum++;
cache[hit].time=0;//LRU：every hit reflash time
}
cacheShow();
cacheTimeAdd();
}
if(LOG){
printf("PageReplacement:%d\n",hitsum);
printf("PageFault:%d\n",NUM-hitsum);
}
printf("HitRate:%lf\n",ret=(double)hitsum/NUM);
return ret;
}double NUR(){//time:notuse-0 use-1
double ret;
if(LOG)
printf("\nNUR:\n");
cacheClear();
int hitsum=0,clockcur=0;//cur of the cache
for(int i=0;i<NUM;i++){
if(LOG)
printf("input:%d\t",pageList[i].id);
int loop=1,ishit=0;
for(int j=0;j<SIZE;j++){ //first loop to find hit or not
if(cache[j].id==pageList[i].id){
clockcur=j;
cache[clockcur].time=1;
clockcur=(clockcur+1)%SIZE;
ishit=1;
loop=0;// if hit ，there not next loop
break;
}
}
while(loop){//next loop to find one to replace
loop=0;
if(cache[clockcur].id==-1){ //id==-1,free room,loop end
cache[clockcur]=pageList[i];
cache[clockcur].time=1;
}else if(cache[clockcur].time==0){//time==0,replace,loop end
cache[clockcur]=pageList[i];
cache[clockcur].time=1;
}else{ //time==1,change time to 0,loop continue
cache[clockcur].time=0;
loop=1;
}
clockcur=(clockcur+1)%SIZE;
}
if(ishit){//show hit
hitsum++;
if(LOG)
printf(" hit ");
}else{
if(LOG)
printf(" ");
}
cacheShow();
}
if(LOG){
printf("PageReplacement:%d\n",hitsum);
printf("PageFault:%d\n",NUM-hitsum);
}
printf("HitRate:%lf\n",ret=(double)hitsum/NUM);
return ret;
}int OPTfun(int i){//OPT replace
int arr[SIZE];//save cache page next use
for(int j=0;j<SIZE;j++){
arr[j]=INT_MAX;
for(int k=i+1;k<NUM;k++){
if(cache[j].id==pageList[k].id){
arr[j]=k;
break;
}
}
}
int arrmax=arr[0],t=0;//find the longest next use
for(int j=1;j<SIZE;j++){
if(arr[j]>arrmax){
arrmax=arr[j];
t=j;
}
}
return t;
} double OPT(){
double ret;
if(LOG)
printf("\nOPT:\n");
cacheClear();
int hitsum=0;
for(int i=0;i<NUM;i++){
if(LOG)
printf("input:%d\t",pageList[i].id);
int hit=cacheHit(i);
if(hit==-1){//if not hit
int room=cacheRoom();
if(room!=-1)//if have free room
cache[room]=pageList[i];//use free room to save
else// not free room
cache[OPTfun(i)]=pageList[i];//use OPT replace
}else{//if hit
hitsum++;
}
cacheShow();
cacheTimeAdd();
}
if(LOG){
printf("PageReplacement:%d\n",hitsum);
printf("PageFault:%d\n",NUM-hitsum);
}
printf("HitRate:%lf\n",ret=(double)hitsum/NUM);
return ret;
}int main(){
int alltime=LOG?1:100;
double arr[4]={0,0,0,0};
for(int i=0;i<alltime;i++){
init();
arr[0]+=FIFO();
arr[1]+=LRU();
arr[2]+=NUR();
arr[3]+=OPT();
}
printf("\n");
printf("FIFO:%lf\n",arr[0]/alltime);
printf("LRU:%lf\n",arr[1]/alltime);
printf("NUR:%lf\n",arr[2]/alltime);
printf("OPT:%lf\n",arr[3]/alltime);
return 0;
}