操作系统--进程调度算法

#include<bits/stdc++.h>
#include<pthread.h>
using namespace std;
#define threadnum 20
#define timecut 25
pthread_mutex_t Device_mutex ;
struct PCB
{
int id;//process log
int priority;//youxianquan
int runtime;//use time
int waittime;//wait time
int arrivetime;
bool used;//book this pcb
}PCBS[threadnum];
void init()
{
for(int i=0;i<threadnum;i++)
{
PCBS[i].id = i+1;
PCBS[i].priority = 0;
PCBS[i].arrivetime = 1+rand()%60;
PCBS[i].runtime = 1+rand()%30;
PCBS[i].waittime = 0;
PCBS[i].used  = false;
}
}
void showinfo(PCB *T)
{
for(int i=0;i<threadnum;i++)
{
cout<<"id: "<<T[i].id<<" priority: "<<T[i].priority<<" arrivetime: "<<T[i].arrivetime<<" runtime: "<<T[i].runtime<<" waittime: "<<T[i].waittime<<endl;
}
}
bool cmpbyarrivetime(PCB a,PCB b)
{
return a.arrivetime<b.arrivetime;
}
bool cmpbyid(PCB a,PCB b)
{
return a.id<b.id;
}
bool cmpbyruntime(PCB a,PCB b)
{
return a.runtime<b.runtime;
}
void FCFS(PCB *T)
{
//int len = sizeof(T)/sizeof(PCB);
int sumtime = 0;
cout<<"the infomation before fcfs run"<<endl;
showinfo(T);
sort(T,T+threadnum,cmpbyarrivetime);
for(int i=0;i<threadnum;i++) T[i].priority = i+1;
T[0].waittime = 0;
sumtime+=T[0].runtime;
T[0].used = true;
for(int i=1;i<threadnum;i++)
{
if(T[i].arrivetime > sumtime) sumtime = T[i].arrivetime;
T[i].waittime = sumtime;
sumtime+=T[i].runtime;
T[i].used = true;
}
sort(T,T+threadnum,cmpbyid);
cout<<"the infomation after fcfs run"<<endl;
showinfo(T);
}
void SJF(PCB *T)//short first
{
int sumtime = 0;
int sumpcb = 0;
sort(T,T+threadnum,cmpbyarrivetime);
cout<<"the infomation before sfj run"<<endl;
showinfo(T);
vector<PCB> sfj;
sfj.clear();
sfj.push_back(T[0]);
T[0].used = true;
T[0].waittime = 0;
sumtime += T[0].runtime;
sumpcb++;
while(1)
{
if(sumpcb>=threadnum) break;
PCB S = sfj[sumpcb-1];
int truntime = 999;
int tipos=-1;
for(int i=0;i<threadnum;i++)
{
if(T[i].arrivetime < S.arrivetime+S.runtime&&(!T[i].used))
{
if(T[i].runtime < truntime)
{
truntime = T[i].runtime;
tipos  = i;
}
}
}
if(tipos!=-1)
{
T[tipos].used = true;
T[tipos].waittime=sumtime;
sfj.push_back(T[tipos]);
sumtime+=T[tipos].runtime;
sumpcb++;
}
else
{
for(int i=sumpcb;i<threadnum;i++)
{
if(!T[i].used)
{
sumtime = T[i].arrivetime;
T[i].used = true;
break;
}
}
}
}
for(int i=0;i<threadnum;i++)
{
T[i].id = sfj[i].id;
T[i].priority = i+1;
T[i].arrivetime = sfj[i].arrivetime;
T[i].runtime = sfj[i].runtime;
T[i].waittime = sfj[i].waittime;
}
sort(T,T+threadnum,cmpbyid);
cout<<"the infomation after sfj run"<<endl;
showinfo(T);
}
void HRRN(PCB *T)
{
int sumtime = 0;
sort(T,T+threadnum,cmpbyarrivetime);
cout<<"the infomation before hrrn run"<<endl;
showinfo(T);
//waittime /  runtime;
vector<PCB> PCBlist;
int sumpcb = 0;
PCBlist.push_back(T[0]);
sumtime+=T[0].runtime;
sumpcb++;
T[0].waittime = 0;
T[0].used = true;
while(1)
{
double rp = 0;
int tipos;
if(sumpcb>=threadnum) break;
for(int i=0;i<threadnum;i++)
{
if(!T[i].used)
{
if((sumtime-T[i].arrivetime)*1.0/T[i].runtime > rp){
rp = (sumtime-T[i].arrivetime)*1.0 / T[i].runtime;
tipos = i;
}
}
}
if(rp==0)
{
for(int i=0;i<threadnum;i++)
{
if(!T[i].used)
{
sumtime = T[i].arrivetime;
tipos = i;
}
}
}
T[tipos].used = true;
T[tipos].waittime = sumtime;
sumtime+=T[tipos].runtime;
sumpcb++;
// T[tipos].waittime = sumtime;
PCBlist.push_back(T[tipos]);
}
for(int i=0;i<threadnum;i++)
{
T[i].id = PCBlist[i].id;
T[i].priority = i+1;
T[i].waittime = PCBlist[i].waittime;
}
sort(T,T+threadnum,cmpbyid);
cout<<"the infomation after hrrn run"<<endl;
showinfo(T);
}
bool operator < (PCB a,PCB b)
{
double ax = a.waittime*1.0/a.runtime;
double bx = b.waittime*1.0/b.runtime;
return ax<bx;
}
bool cmpbywaitdivrun(PCB a,PCB b)
{
double ax = a.waittime*1.0/a.runtime;
double bx = b.waittime*1.0/b.runtime;
return ax>bx;
}

int main()
{
init();
FCFS(PCBS);
init();
SJF(PCBS);
init();
HRRN(PCBS);
}

 上述程序

FCFS：先到先服务算法

SJF：短作业优先调度算法

HRRN：响应比优先调度算法

轮盘调度算法：

#include <bits/stdc++.h>
using namespace std;
const int maxn = 20;
#define timecut 25
struct PCB
{
int id;//process log
int priority;//youxianquan
int runtime;//use time
int waittime;//wait time
int arrivetime;
bool used;//book this pcb
}PCBS[maxn];
void init()
{
for(int i=0;i<maxn;i++)
{
PCBS[i].id = i+1;
PCBS[i].priority = 0;
PCBS[i].arrivetime = 1+rand()%60;
PCBS[i].runtime = 1+rand()%30;
PCBS[i].waittime = 0;
PCBS[i].used  = false;
}
}
bool arivecmp(PCB a,PCB b)
{
return a.arrivetime < b.arrivetime;
}
void showinfo(PCB *T)
{
for(int i=0;i<maxn;i++)
{
cout<<"id: "<<T[i].id<<" priority: "<<T[i].priority<<" arrivetime: "<<T[i].arrivetime<<" runtime: "<<T[i].runtime<<" waittime: "<<T[i].waittime<<endl;
}
}
bool cmpid(PCB a,PCB b)
{
return a.id < b.id;
}
void RR(PCB *T)
{
sort(T,T+maxn,arivecmp);
cout<<"the infomation before RR runs"<<endl;
showinfo(T);
deque<PCB> QP;
vector<PCB> ans;
int sumpcb = 0;
int sumtime = 0;
for(int i=0;i<maxn;i++)
{
QP.push_back(T[i]);
}
while(!QP.empty())
{
PCB X = QP.front();
QP.pop_front();
if(X.runtime<=timecut)
{
X.waittime = sumtime;
X.used = true;
ans.push_back(X);
sumtime+=X.runtime;
}
else
{
X.runtime-=timecut;
QP.push_back(X);
sumtime+=timecut;
}
}
for(int i=0;i<maxn;i++)
{
T[i]= ans[i];
T[i].priority = i+1;
}
cout<<"the infomation after rr run"<<endl;
sort(T,T+maxn,cmpid);
showinfo(T);
}
int main()
{
init();
RR(PCBS);
}