进程调度时间片轮转例题_进程调度算法java

 
主程序的流程以及各程序模块之间的层次(调用)关系。
  

void Pop()//模仿时间轮转调度
	{
		struct _PCBNode node;
		unsigned int n = _PNode.size();
		unsigned int  i = 0;
		for(; i< n; ++i)// for循环找队列中到达时间大于当前时间时的进程
		{
			node = _PNode.front();_PNode.pop();
			if(node.arrive_time <= TIME)
			{
				break;
			}
			_PNode.push(node);

		}

		TIME = TIME+Time_Pice;//模拟进程运行中
		
		if(i == n)//没找到到达时间大于当前时间时的进程		{
			Display_PCB();
			return ;
		}

		node.cputime +=Time_Pice; //进程占有CPU运行的时间

		if(node.cputime >= node.need_time)//完成运行，进入完成队列
		{
			node.accomplish_Time = TIME;
			node.tag = true;
			node.turn_over_time  = node.accomplish_Time -node.arrive_time ;
			_CNode.push(node);  
			cout<<node.name<<"   run over"<<endl;
		}
		else
		{
			_PNode.push(node);
		}
		Display_PCB(); 
	}

四、总结与体会

  通过做本次实验，我模拟了CPU进程调度中的时间片轮转调度算法。时间片轮状调度算法可以实现进程共享CPU。在试验中，我发现时间片不能太大，否则会导致大部分的进程在一个时间片中就能运行完成，不能实现进程对CPU资源的共享。

附录：源程序

#include<iostream> #include<queue> #include<string> using namespace std; #define Time_Pice 2 struct _PCBNode { char name[20]; //进程名称 int arrive_time; //到达时间 int need_time; //服务时间 int cputime; //CPU已经执行的时间 int accomplish_Time; //完成时间 int turn_over_time; //周转时间 bool tag; //是否完成 }; class _PCB { public: void Push(struct _PCBNode& node) { _PNode.push(node); } void init_time() { TIME = 0; } bool empty() { return _PNode.empty(); } void Pop() { struct _PCBNode node; unsigned int n = _PNode.size(); unsigned int i = 0; for(; i< n; ++i) { node = _PNode.front();_PNode.pop(); if(node.arrive_time <= TIME) { break; } _PNode.push(node); } TIME = TIME+Time_Pice; if(i == n) { Display_PCB(); return ; } node.cputime +=Time_Pice; if(node.cputime >= node.need_time) { node.accomplish_Time = TIME; node.tag = true; node.turn_over_time = node.accomplish_Time -node.arrive_time ; _CNode.push(node); cout<<node.name<<" run over"<<endl; } else { _PNode.push(node); } Display_PCB(); } void Display_PCB() { cout<<" TIME "<<TIME<<endl; int n = _PNode.size(); if(n != 0) { cout<<"ready......."<<endl; cout<<"name arrive_time need_time cputime tag"<<endl; for(int i = 0;i<n; ++i) { struct _PCBNode node = _PNode.front();_PNode.pop(); if(node.arrive_time <= TIME) { cout<<node.name<<" "<<node.arrive_time<<" " <<node.need_time<<" "<<node.cputime <<" "<<node.tag <<endl; } _PNode.push(node); } cout<<endl; } n = _CNode.size(); if(n != 0) { cout<<"run over"<<endl; cout<<"name arrive_time need_time accomplish_Time turn_over_time tag"<<endl; for(int i = 0;i<n; ++i) { struct _PCBNode node = _CNode.front();_CNode.pop(); cout<<node.name<<" "<<node.arrive_time<<" " <<node.need_time<<" "<<node.accomplish_Time<<" "<< node.turn_over_time<<" "<<node.tag <<endl; _CNode.push(node); } cout<<endl; } cout<<"**************************************************"<<endl; } private: queue<struct _PCBNode> _PNode; queue<struct _PCBNode> _CNode; int TIME; }; void main() { _PCB pcb; pcb.init_time(); int PCB_Numble; char PCBname[20]; int arrive_time; int need_time; cout<<"input PCB_Numble : "; cin>>PCB_Numble; cout<<"input PCBname arrive_time need_time example A 0 5\n"; for(int i = 0; i<PCB_Numble; ++i) { cin>>PCBname>>arrive_time>>need_time; struct _PCBNode node; strcpy(node.name ,PCBname); node.arrive_time = arrive_time; node.need_time = need_time; node.accomplish_Time = 0; node.cputime = 0; node.tag = 0; pcb.Push(node); } pcb.Display_PCB(); while(!pcb.empty()) { pcb.Pop(); } }