实验一处理机调度一、实验内容选择一个调度算法，实现处理机调度。
二、实验目的多道系统中，当就绪进程数大于处理机数时，须按照某种策略决定哪些进程优先占用处理机。
本实验模拟实现处理机调度，以加深了解处理机调度的工作。
三、实验题目1、设计一个按优先权调度算法实现处理机调度的程序；2、设计按时间片轮转实现处理机调度的程序。
PCB内容要求：进程名/PID；要求运行时间（单位时间）；优先权；状态：PCB指针；1、可随机输入若干进程，并按优先权排序；2、从就绪队首选进程运行：优先权-1要求运行时间-1要求运行时间=0时，撤销该进程3、重新排序，进行下轮调度；源代码：#include <stdio.h>#include <stdlib.h>#include <string.h>#include <windows.h>typedef struct pcb{char PID[50];int needTime;//需要运行时间int priority;//优先权char state[20];//进程状态struct pcb *next;}PCB;typedef struct{PCB* front;PCB* rear;}ProcessQueue;void SelectAlgorithm();void CreateQProcess(ProcessQueue &Q,char*,int time,int pri,char*);void ProcessSchedule();void InitQueue(ProcessQueue &Q);void visitQueue(ProcessQueue &Q);bool RunProcess(PCB* rp,ProcessQueue &Q);bool NonPreemptivePriority(ProcessQueue &Q);//非抢占式优先权调度void delProcess(PCB* delp);bool RunProcessPreem(PCB* rp,ProcessQueue &Q);//抢占式优先执行进程bool PreemptivePriority(ProcessQueue &Q);void RR(ProcessQueue &Q);int main(){int iSel;int i = 0;SelectAlgorithm();ProcessQueue readyQ;//就绪进程队列PCB newpcb;InitQueue(readyQ);printf("请选择调度算法：");do{scanf("%d",&iSel);} while (!(iSel == 1 || iSel == 2 || iSel == 3));while(i < 3){printf("请输入要创建的进程:\n");fflush(stdin);gets(newpcb.PID);fflush(stdin);scanf("%d",&newpcb.needTime);fflush(stdin);scanf("%d",&newpcb.priority);fflush(stdin);gets(newpcb.state);fflush(stdin);CreateQProcess(readyQ,newpcb.PID,newpcb.needTime,newpcb.priority,newpcb.state);printf("创建了一个进程\n");++i;}visitQueue(readyQ);//显示的是各个进程的优先权switch(iSel){case 1:while(NonPreemptivePriority(readyQ));//非抢占优先权调度break;case 2:PreemptivePriority(readyQ);//抢占式优先权调度break;case 3:RR(readyQ);break;}return 0;}void SelectAlgorithm(){printf("1.非抢占式优先权调度\n");printf("2.抢占式优先权调度\n");printf("3.时间片轮转调度\n");}void InitQueue(ProcessQueue &Q)//初始化进程队列{Q.front = Q.rear = (PCB*)malloc(sizeof(PCB));if(!Q.front) exit(-1);Q.front->next = NULL;}void CreateQProcess(ProcessQueue &Q,char* pid,int time,int pri,char* st)//指定进程入就绪队列，将优先权高的插在队列前面{PCB* p = (PCB*)malloc(sizeof(PCB));if(!p) exit(-1);strcpy(p->PID,pid); p->needTime = time;p->priority = pri; strcpy(p->state,st);p->next = NULL;PCB* q = Q.front->next, *old = Q.front;if(!q)//如果原队列为空{Q.rear->next = p;Q.rear = p;//q == NULL}else//如果原队列不为空{for(;q != NULL;){if(p->priority > q->priority){old->next = p;p->next = q;return;}q = q->next;old = old->next;if(q == NULL){Q.rear->next = p;Q.rear = q;//q == NULL}}}}void ProcessSchedule(){}void visitQueue(ProcessQueue &Q)//访问进程队列{PCB* p = (PCB*)malloc(sizeof(PCB));if(!p) exit(-1);p = Q.front->next;while(p != NULL){printf("%d,",p->priority);p = p->next;}printf("\n");int i = 0;}bool PreemptivePriority(ProcessQueue &Q){PCB* rprocess;if(!Q.front->next){printf("就绪队列中没有进程可以调度！\n");return false;}else{rprocess = Q.front->next;//选择优先权最高的进程Q.front->next = Q.front->next->next;//将进程移除就绪队列while(rprocess != NULL)//抢占式优先调度{RunProcessPreem(rprocess,Q);if(rprocess->needTime == 0){delProcess(rprocess);if((rprocess = Q.front->next) == NULL){printf("就绪队列中没有进程可以调度！\n");return false;}else{Q.front->next = Q.front->next->next;continue;}}if(Q.front->next != NULL){if(rprocess->priority < Q.front->next->priority)//判断运行了1个时间后还是否具有最高优先权{/*rprocess->next = Q.front->next->next;//正在运行中的进程因为优先权降低，重新进入就绪队列temp = Q.front->next;Q.front->next = rprocess;rprocess = temp;//rprocess保存运行进程*/CreateQProcess(Q,rprocess->PID,rprocess->needTime,rprocess->priority,rprocess->state);//正在运行中的进程因为优先权降低，重新进入就绪队列rprocess = Q.front->next;Q.front->next = Q.front->next->next;}}}}return true;}bool NonPreemptivePriority(ProcessQueue &Q)//非抢占式优先权调度{PCB* rprocess;//存放要调度运行的进程if(!Q.front->next){printf("就绪队列中没有进程可以调度！\n");return false;}else{rprocess = Q.front->next;Q.front->next = Q.front->next->next;//已经调度，从就绪队列中删除进程if(RunProcess(rprocess,Q)){delProcess(rprocess);printf("就绪队列状态:\n");visitQueue(Q);}return true;}}bool RunProcess(PCB* rp,ProcessQueue &Q)//执行进程{while(rp->needTime){printf("进程%s正在运行...\n",rp->PID);printf("PID[50]\tneedTime\tpriority\tstate[20]\n");printf("%s\t%d\t\t%d\t\t%s\n",rp->PID,rp->needTime,rp->priority,rp->state);Sleep(1000);--rp->needTime;}return true;}bool RunProcessPreem(PCB* rp,ProcessQueue &Q)//抢占式优先,RR执行进程{printf("进程%s正在运行...\n",rp->PID);printf("PID[50]\tneedTime\tpriority\tstate[20]\n");printf("%s\t%d\t\t%d\t\t%s\n",rp->PID,rp->needTime,rp->priority,rp->state);Sleep(1000);--rp->needTime;--rp->priority;return true;}void delProcess(PCB* delp)//撤销进程{free(delp);}void RR(ProcessQueue &Q){PCB* running = Q.front->next;PCB* old = Q.front;while(Q.front->next != NULL){if(running){RunProcessPreem(running,Q);if(running->needTime == 0)//撤销进程{old->next = running->next;delProcess(running);running = old->next;continue;}old = old->next;running = running->next;}else{old = Q.front;running = old->next;}}printf("就绪队列中没有进程可以调度！\n");}以下是使用时间片轮转算法的一次执行：选择算法3：进程输入，此处输入1，1，1，1，2，2，2，2，3，3，3，3测试。
