用C++模拟操作系统进程调度的几种算法
********************************************
*****1.******* 先来先服务算法 **********
*****2.******** 时间片轮转 ************
*****3.******** 短作业优先 ************
*****4.******** 优先级调度 ************
*****5.******** 最短剩余时间 ***********
*****0.**********退出**********************
具体算法的细节想必读者可以从很多地方了解到，下面给出简单的实现代码：
#include
using namespace std;
#define MAX_PEOC_ID 65536
#define TIME_SLICE 2
//进程控制块
typedef struct PCB
{
char name[10];//进程名 id
char state; //进程状态 W/R
int ArriveTime; //进程到达时间
int StartTime; //进程开始时间
int FinshTime;//进程结束时间
int ServiceTime;//进程服务时间
float WholeTime; //周转时间
float Weight_WholeTime;//带权周转时间
double Average_WholeTime;//平均周转时间
double Average_Weight_WholeTime;//带权平均周转时间
int RunTime;//已经占用CPU时间
int NeedTime;//还要占用CPU时间
int Prio;//优先级
struct PCB *next;
}pcb;
double Sum_WholeTime=0,Sum_Weight_WholeTime=0;
int time=0;
int Proc_Num=0;
pcb *head = NULL;
pcb *tail=NULL;
void FCFS_RunProccess(pcb *proc)
{
proc->StartTime=time;
cout<<"时刻 "<name<ServiceTime;
proc->state='R';
proc->FinshTime=time;
proc->WholeTime=proc->FinshTime-proc->ArriveTime;
proc->Weight_WholeTime=proc->WholeTime/proc->ServiceTime;
Sum_WholeTime+=proc->WholeTime;
Sum_Weight_WholeTime+=proc->Weight_WholeTime;
proc->Average_WholeTime=Sum_WholeTime/Proc_Num;
proc->Average_Weight_WholeTime=Sum_Weight_WholeTime/Proc_Num;
printf(" 到达时间 开始时间 服务时间 完成时间 周转时间 带权周转时间\n");
printf("%6d %6d %6d %6d %8.1f %8.2f\n",
proc->ArriveTime,proc->StartTime,proc->ServiceTime,
proc->FinshTime,proc->WholeTime,proc->Weight_WholeTime);
//printf("共 %d 个进程\n",Proc_Num);
printf(" 平均周转时间 平均带权周转时间 \n");
printf(" %10.2f %10.2f\n",proc->Average_WholeTime,
proc->Average_Weight_WholeTime);
}
void FCFS()
{
pcb* cur_proc=head;
pcb*new_proc=NULL;
while(cur_proc)
{
if(cur_proc->state == 'W')
{
new_proc=cur_proc;
FCFS_RunProccess(new_proc);
}
cur_proc=cur_proc->next;
head=cur_proc;
free (new_proc);
new_proc=NULL;
}
}
void FCFS_CreateProccess()
{
cout<<"请输入进程的个数: ";
cin>>Proc_Num;
if(Proc_Num > MAX_PEOC_ID)
{
cout<<"sorry I can't give you PCB \n";
return;
}
for(int i=1;i<=Proc_Num;++i)
{
pcb*new_proc=NULL;
if((new_proc=(pcb*)malloc(sizeof(pcb))) == NULL)
{
perror("malloc");
return;
}
cout<<"请输入第"<>new_proc->name;
cout<<"请输入第"<>new_proc->ArriveTime;
cout<<"请输入第"<>new_proc->ServiceTime;
new_proc->next=NULL;
if(head == NULL)
{
new_proc->next=head;
head=new_proc;
tail=head;
time=new_proc->ArriveTime;
}
else
{
if(head->ArriveTime>new_proc->ArriveTime)
{
new_proc->next=head;
head=new_proc;
}
else
{
pcb* cur_proc=head;
while(cur_proc->next != NULL && cur_proc->next->ArriveTimeArriveTime)
{
cur_proc=cur_proc->next;
}
if(cur_proc->next==NULL)
{
tail=new_proc;
}
new_proc->next=cur_proc->next;
cur_proc->next=new_proc;
}
if(new_proc->ArriveTime < time)
{
time=new_proc->ArriveTime;
}
}
new_proc->StartTime=0;
new_proc->FinshTime=0;
new_proc->WholeTime=0;
new_proc->Weight_WholeTime=0;
new_proc->Average_Weight_WholeTime=0;
new_proc->Average_WholeTime=0;
new_proc->state= 'W';
new_proc->RunTime=0;
new_proc->NeedTime=0;
}
}
void ShortJobsCreateProccess()
{
cout<<"请输入进程的个数: ";
cin>>Proc_Num;
if(Proc_Num > MAX_PEOC_ID)
{
cout<<"sorry I can't give you PCB \n";
return;
}
for(int i=1;i<=Proc_Num;++i)
{
pcb*new_proc=NULL;
if((new_proc=(pcb*)malloc(sizeof(pcb))) == NULL)
{
perror("malloc");
return;
}
cout<<"请输入第"<>new_proc->name;
cout<<"请输入第"<>new_proc->ArriveTime;
cout<<"请输入第"<>new_proc->ServiceTime;
new_proc->next=NULL;
if(head == NULL)
{
new_proc->next=head;
head=new_proc;
tail=head;
time=new_proc->ArriveTime;
}
else
{
if(head->ServiceTime>new_proc->ServiceTime)
{
new_proc->next=head;
head=new_proc;
}
else
{
pcb* cur_proc=head;
while(cur_proc->next != NULL && cur_proc->next->ServiceTimeServiceTime)
{
cur_proc=cur_proc->next;
}
if(cur_proc->next==NULL)
{
tail=new_proc;
}
new_proc->next=cur_proc->next;
cur_proc->next=new_proc;
}
if(new_proc->ArriveTime < time)
{
time=new_proc->ArriveTime;
}
}
new_proc->StartTime=0;
new_proc->FinshTime=0;
new_proc->WholeTime=0;
new_proc->Weight_WholeTime=0;
new_proc->Average_Weight_WholeTime=0;
new_proc->Average_WholeTime=0;
new_proc->state= 'W';
new_proc->RunTime=0;
new_proc->NeedTime=0;
}
}
void PrioCreateProccess()
{
cout<<"请输入进程的个数: ";
cin>>Proc_Num;
if(Proc_Num > MAX_PEOC_ID)
{
cout<<"sorry I can't give you PCB \n";
return;
}
for(int i=1;i<=Proc_Num;++i)
{
pcb*new_proc=NULL;
if((new_proc=(pcb*)malloc(sizeof(pcb))) == NULL)
{
perror("malloc");
return;
}
cout<<"请输入第"<>new_proc->name;
cout<<"请输入第"<>new_proc->ArriveTime;
cout<<"请输入第"<>new_proc->ServiceTime;
cout<<"请输入第"<>new_proc->Prio;
new_proc->next=NULL;
if(head == NULL)
{
new_proc->next=head;
head=new_proc;
tail=head;
time=new_proc->ArriveTime;
}
else
{
if(head->Prio>new_proc->Prio)
{
new_proc->next=head;
head=new_proc;
}
else
{
pcb* cur_proc=head;
while(cur_proc->next != NULL && cur_proc->next->PrioPrio)
{
cur_proc=cur_proc->next;
}
if(cur_proc->next==NULL)
{
tail=new_proc;
}
new_proc->next=cur_proc->next;
cur_proc->next=new_proc;
}
if(new_proc->ArriveTime < time)
{
time=new_proc->ArriveTime;
}
}
new_proc->StartTime=0;
new_proc->FinshTime=0;
new_proc->WholeTime=0;
new_proc->Weight_WholeTime=0;
new_proc->Average_Weight_WholeTime=0;
new_proc->Average_WholeTime=0;
new_proc->state= 'W';
new_proc->RunTime=0;
new_proc->NeedTime=0;
}
}
void RR_RunProccess(PCB *proc)
{
proc->StartTime=time;
cout<<"时刻 "<name<RunTime+=TIME_SLICE;
time+=TIME_SLICE;
proc->NeedTime=proc->ServiceTime-proc->RunTime;
if(proc->NeedTime <=0)
{
cout<<"时刻 "<name<next;
free(proc);
proc=NULL;
if(head==NULL)
{
tail=head;
}
}
else
{
cout<<"时刻 "<name<RunTime<<"还需要执行"<NeedTime<next != NULL)
{
head=proc->next;
proc->next=NULL;
tail->next=proc;
tail=proc;
}
}
}
void RoundRobin()
{
pcb* cur_proc=head;
pcb* new_proc=NULL;
while(cur_proc)
{
if(cur_proc->state == 'W')
{
new_proc=cur_proc;
RR_RunProccess(new_proc);
}
cur_proc=head;
}
}
void Sort_By_NeedTime()
{
pcb* prev=head;
pcb*cur=head->next;
prev->next=NULL;
pcb*nxt=NULL;
if( cur && head->NeedTime <= cur->NeedTime)
{
cur->next=head;
head=cur;
}
else if(cur)
{
while(cur && prev->next != NULL && prev->next->NeedTime <= cur->NeedTime)
{
prev=prev->next;
}
nxt=cur->next;
cur->next=prev->next;
prev->next=cur;
cur=nxt;
}
}
void ShortNeed_Time_RunProccess(pcb *proc)
{
proc->StartTime=time;
cout<<"时刻 "<name<RunTime+=TIME_SLICE;
time+=TIME_SLICE;
proc->NeedTime=proc->ServiceTime-proc->RunTime;
if(proc->NeedTime <=0)
{
cout<<"时刻 "<name<next;
free(proc);
proc=NULL;
if(head==NULL)
{
tail=head;
}
}
else
{
cout<<"时刻 "<name<RunTime<<"还需要执行"<NeedTime<state == 'W')
{
new_proc=cur_proc;
ShortNeed_Time_RunProccess(new_proc);
}
cur_proc=head;
}
}
void main()
{
int select=1;
while(select)
{
cout<<"******************************************\n";
cout<<"*****1.******* 先来先服务算法 ************\n";
cout<<"*****2.******** 时间片轮转 ************\n";
cout<<"*****3.******** 短作业优先 ************\n";
cout<<"*****4.******** 优先级调度 ************\n";
cout<<"*****5.******** 最短剩余时间 ************\n";
cout<<"*****0.**********退出*********************\n";
cout<<"请选择:> ";
cin>>select;
switch(select)
{
case 1:
FCFS_CreateProccess();
FCFS();
break;
case 2:
FCFS_CreateProccess();
RoundRobin();
break;
case 3:
ShortJobsCreateProccess();
FCFS();
break;
case 4:
PrioCreateProccess();
FCFS();
break;
case 5:
ShortJobsCreateProccess();
ShortNeed_Time();
break;
default:
break;
}
}
}