process.cpp

操作系统 请求页式管理

#include<stdlib.h>
#include<stdio.h>


#define TRUE 1
#define FALSE 0
#define INVALID -1
#define null 0

#define total_instruction 320
#define total_vp 32
#define clear_period 50

typedef struct{
	int pn,pfn,counter,time;
}pl_type;//页面结构
pl_type pl[total_vp];

struct pfc_struct{
	int pn,pfn;
	struct pfc_struct *next;
};//页面控制结构

typedef struct pfc_struct pfc_type;
pfc_type pfc[total_vp], *freepf_head,/*空页面的头指针*/ *busypf_head,/*忙页面的头指针*/ *busypf_tail/*忙页面的尾指针*/;
//freepf_head为空闲的页面，busypf_head为使用的页面

int diseffect,  a[total_instruction];
int page[total_instruction],  offset[total_instruction];

void initialize(int total_pf);
void FIFO(int total);
void LRU(int total);

main()
{
	int S,i,j;

	srand(600);

	S=(float)319*rand()/32767+1;
	for(i=0;i<total_instruction;i+=4)
	{
		a[i]=S;
		a[i+1]=a[i]+1;
		a[i+2]=(float)a[i]*rand()/32767;
		a[i+3]=a[i+2]+1;
		S=(float)rand()*(318-a[i+2])/32767+a[i+2]+2;
	}
	for(i=0;i<total_instruction;i++)
	{
		page[i]=a[i]/10;
		offset[i]=a[i]%10;
	}
	for(i=4;i<=32;i++)
	{
		printf("%2d page frames ",i);
		FIFO(i);
		LRU(i);
		printf("\n");
	}
}

void FIFO(int total_pf)
{
	int i,j;
	pfc_type *p,*t;
	initialize(total_pf);
	busypf_head=busypf_tail=NULL;
	for(i=0;i<=total_instruction;i++)
	{
		if(pl[page[i]].pfn==INVALID)//此页面不在内存里需要掉入
		{
			diseffect+=1;
			if(freepf_head==NULL) //没有空闲空间
			{
				p=busypf_head->next;
				pl[busypf_head->pn].pfn=INVALID;//调出
				freepf_head=busypf_head;
				freepf_head->next=NULL;
				busypf_head=p;//指向下一个页
			}
			p=freepf_head->next;
			freepf_head->next=NULL;//将空闲空间取下
			freepf_head->pn=page[i];
			pl[page[i]].pfn=freepf_head->pfn;
			if(busypf_tail==NULL)//第一个页掉入内存
				busypf_head=busypf_tail=freepf_head;
			else
			{
				busypf_tail->next=freepf_head;
				busypf_tail=freepf_head;
			}
			freepf_head=p;
		}
	}
	printf("FIFO:%6.4f ",1-(float)diseffect/320);
}

void LRU(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)
		{
			diseffect++;
			if(freepf_head==NULL)
			{
				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=NULL;
			}
			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: %6.4f",1-(float)diseffect/320);
}


void initialize(int total_pf)
{
	int i;
	diseffect=0;
	for(i=0;i<=total_vp;i++)//初始化所有的32个页
	{
		pl[i].pn=i;
		pl[i].pfn=INVALID;
		pl[i].counter=0;
		pl[i].time=-1;
	}
	for(i=1;i<total_pf;i++)
	{
		pfc[i-1].next=&pfc[i];
		pfc[i-1].pfn=i-1;
	}
	pfc[total_pf-1].next=NULL;
	pfc[total_pf-1].pfn=total_pf-1;
	freepf_head=&pfc[0];
}