优先数，时间片算法

最新推荐文章于 2024-10-29 10:26:27 发布

原创最新推荐文章于 2024-10-29 10:26:27 发布 · 766 阅读

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CC 4.0 BY-SA版权

本文介绍了一个简单的进程调度算法演示程序，实现了优先级调度算法和时间片轮转调度算法。通过输入进程的各项参数，如进程名、优先级和所需CPU时间等，程序能够展示不同调度策略下进程的执行情况。

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#include "iostream.h"
#include "string.h"
const int prnum=5;
const int ROUND=3;
typedef enum flag{Ready,Run,Finish};

struct pcb
{ 
   public:
   char name[10];   //进程名
   int pri;         //进程优先数
   int round;       //进程轮转时间片
   int cputime;     //进程占用的CPU时间
   int needtime;    //进程到完成还要的CPU时间
   flag state;      //进程状态
   struct pcb *next;//链指针
};

typedef struct pcb plist;
typedef plist *link;

void main()
{
	int i;
    int chose;
    cout<<"该程序实现的是5个进程的两种调度算法"<<endl;
	while ((chose!=1)&&(chose!=2))
	{
	    cout<<"=================================="<<endl;
        cout<<" 请选择一种进程调度算法: "<<endl;
        cout<<" 1.优先数调度算法 "<<endl;
        cout<<" 2.循环时间片轮转调度算法 "<<endl;
     	cout<<"=================================="<<endl;
        cout<<"请选择(1或者2):";
        loop:cin>>chose;
        cout<<endl;
        if ((chose!=1)&&(chose!=2)) 
		{
         	cout<<"输入错误，请重新输入(1或者2):"<<endl;
            goto loop;
		}
        else cout<<"请分别按顺序输入5个进程的各项参数:"<<endl;;
	}
    void showlist(link,char*,int);    //显示进程队列
    void instlist(link,link);         //按优先数插入进程
    void appenlist(link,link);        //按就绪先后加入进程
    link gethead(link);               //取队首进程
    link ptr,head1,head2;
    head1=new plist;
    head1->next=NULL;                //就绪队首指针
    head2=new plist;
    head2->next=NULL;                //完成队首指针
    
   
//初始化进程队列
 cout<<"进程名 "<<"优先数 "<<"占用CPU时间 "<<"还需CPU时间"<<endl;
 for(i=0;i<prnum;i++)
 {
   ptr=new plist;   
   cin>>ptr->name>>ptr->pri>>ptr->cputime>>ptr->needtime; 
   ptr->round=ROUND;
   ptr->state=Ready;
   ptr->next=NULL;
   if(chose==1)
       instlist(head1,ptr);
   else
       appenlist(head1,ptr);
 }
 cout<<"\n"<<endl;
 while(head1->next!=NULL)
 { 
	 
     if(head1->next!=NULL)
		 showlist(head1,"就绪进程队列：",chose);
     if(head2->next!=NULL)
		 showlist(head2,"完成进程队列：",chose);
     ptr=gethead(head1);
     if(chose==1)
	 {
        ptr->cputime=ptr->cputime+3;
        ptr->needtime=ptr->needtime-3;
        ptr->state=Ready;
	 }
     else
	 {
        ptr->cputime=ptr->cputime+ptr->round;
        ptr->needtime=ptr->needtime-ptr->round;
        ptr->state=Ready;
	 }
     if(ptr->needtime<=0)
	 {
        ptr->needtime=0;
        ptr->state=Finish;
        appenlist(head2,ptr);
	 }
     else
	 {
        if(chose==1)
           instlist(head1,ptr);
        else
           appenlist(head1,ptr);
	 }
 }
 showlist(head2,"完成进程队列：",chose);
}

//按就绪先后加入进程
void appenlist(link head,link ptr1)
{
    link p;
    p=head;
    if(head->next==NULL)
		head->next=ptr1;
    else
	{
		while(p->next!=NULL)p=p->next;
		p->next=ptr1;
	}
};

//按优先数插入进程
void instlist(link head,link ptr1)
{
	link p1,p2;
	p1=head->next;
	p2=head;
	if(head->next==NULL)
	{
		head->next=ptr1;
	}
	else
	{ 
		while((p1->next!=NULL)&&((p1->pri)>=(ptr1->pri)))
		{
			p2=p1;
			p1=p1->next;
		}
		if((p1->pri) < (ptr1->pri))
		{
			p2->next=ptr1;
			ptr1->next=p1; 
		}
		else
		{
			p1->next=ptr1; 
		}
	}
};

//取队首进程
link gethead(link head)
{
	link ptr1;
	ptr1=head->next;
	head->next=ptr1->next;
	ptr1->next=NULL;
	ptr1->state=Run;
	return ptr1;
};

//显示进程队列
void showlist(link ptr1,char *msg,int k)
{
    
	ptr1=ptr1->next;
	cout<<msg<<endl; 
	if(k==1)
	{
		cout<<"进程名 "<<"优先数 "<<"占用CPU时间 "<<"还需CPU时间 "<<"进程状态 "<<endl;
		while(ptr1!=NULL)
		{
			cout<<"  "<<ptr1->name<<"      "<<ptr1->pri;
			cout<<"        "<<ptr1->cputime<<"        "<<ptr1->needtime;
			cout<<"        "<<ptr1->state<<endl;
			ptr1=ptr1->next;
		}
	}
	else
	{	
		cout<<"进程名 "<<"时间片 "<<"占用CPU时间 "<<"还需CPU时间 "<<"进程状态 "<<endl;
		while(ptr1!=NULL)
		{
			cout<<"  "<<ptr1->name<<"      "<<ptr1->round;
			cout<<"        "<<ptr1->cputime<<"        "<<ptr1->needtime;
			cout<<"        "<<ptr1->state<<endl;
			ptr1=ptr1->next;
		}
	}
};