1、实验目的
通过动态优先权算法的模拟加深对进程概念进程调度过程的理解。
2、实验内容
- 用C语言来实现对N个进程采用动态优先权优先算法的进程调度。
- 每个用来标识进程的进程控制块PCB用结构来描述，包括以下字段：
- 进程标识数 ID。
- 进程优先数 PRIORITY，并规定优先数越大的进程，其优先权越高。
- 进程已占用的CPU时间CPUTIME。
- 进程还需占用的CPU时间ALLTIME。当进程运行完毕时，ALLTIME变为0。•••• 进程的阻塞时间STARTBLOCK，表示当进程再运行STARTBLOCK个时间片后，将进入阻塞状态。
- 进程被阻塞的时间BLOCKTIME，表示已足赛的进程再等待BLOCKTIME个时间片后，将转换成就绪状态。
- 进程状态START。
- 队列指针NEXT，用来将PCB排成队列。
- 优先数改变的原则：
- 进程在就绪队列中呆一个时间片，优先数加1。
- 进程每运行一个时间片，优先数减3。
- 假设在调度前，系统中有5个进程，它们的初始状态如下：
ID 0 1 2 3 4
PRIORITY 9 38 30 29 0
CPUTIME 0 0 0 0 0
ALLTIME 3 3 6 3 4
STARTBLOCK 2 -1 -1 -1 -1
BLOCKTIME 3 0 0 0 0
STATE READY READY READY READY READY
- 为了清楚的观察各进程的调度过程，程序应将每个时间片内的情况显示出来，参照的具体格式如下：
RUNNING PROG：i
READY-QUEUE：-〉id1-〉id2
BLOCK-QUEUE：-〉id3-〉id4
= = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = == = =
ID 0 1 2 3 4
PRIORITY P0 P1 P2 P3 P4
CUPTIME C0 C1 C2 C3 C4
ALLTIME A0 A1 A2 A3 A4
STARTBLOCK T0 T1 T2 T3 T4
BLOCKTIME B0 B1 B2 B3 B4
STATE S0 S1 S2 S3 S4
实验代码
#include
#include
#include
using namespace std;
typedef int ID;
typedef int Priority;
typedef int Time;
enum State {
sready, sblocked, sruning, sstop
};
struct PCB{
ID id;
Priority priority;
Time cpu_time;
Time all_time;
Time start_block;
Time block_time;
State state;
public:
PCB(
ID id0,
Priority priority0,
Time cpu_time0,
Time all_time0,
Time start_block0,
Time block_time0,
State state0
): id(id0), priority(priority0), cpu_time(cpu_time0),
all_time(all_time0), start_block(start_block0),
block_time(block_time0), state(state0) {
}
};
struct cmp //��д�º���
{
bool operator() (PCB* a, PCB* b)
{
return a->priority < b->priority; //��
}
};
typedef priority_queue, cmp> mqueue;
const int width = 10;
void show_PCB(PCB* pcb) {
string state = "";
switch(pcb->state) {
case sready: state = "ready"; break;
case sblocked : state = "blocked";break;
case sruning : state = "runing";break;
case sstop: state = "stop";break;
defalut:state="unknown";break;
}
cout
<< left << setw(width) << setfill(' ') << pcb->id << "|"
<< left << setw(width) << setfill(' ') << pcb->priority << "|"
<< left << setw(width) << setfill(' ') << pcb->cpu_time << "|"
<< left << setw(width) << setfill(' ') << pcb->all_time << "|"
<< left << setw(width) << setfill(' ') << pcb->start_block << "|"
<< left << setw(width) << setfill(' ') << pcb->block_time << "|"
<< left << setw(width) << setfill(' ') << state << "|" << endl;
}
void show_queue(queue q){
cout
<< left << setw(7*width+7) << setfill('-') << "" << "\n"
<< left << setw(width) << setfill(' ') << "id" << "|"
<< left << setw(width) << setfill(' ') << "priority" << "|"
<< left << setw(width) << setfill(' ') << "cpuTime" << "|"
<< left << setw(width) << setfill(' ') << "allTime" << "|"
<< left << setw(width) << setfill(' ') << "startBlock" << "|"
<< left << setw(width) << setfill(' ') << "blockTime" << "|"
<< left << setw(width) << setfill(' ') << "state" << "|" << endl;
while(!q.empty()) {
PCB* t = q.front();
q.pop();
show_PCB(t);
}
cout << left << setw(7*width+7) << setfill('-') << "" << "\n";
}
void show_queue(mqueue q){
cout
<< left << setw(7*width+7) << setfill('-') << "" << "\n"
<< left << setw(width) << setfill(' ') << "id" << "|"
<< left << setw(width) << setfill(' ') << "priority" << "|"
<< left << setw(width) << setfill(' ') << "cpuTime" << "|"
<< left << setw(width) << setfill(' ') << "allTime" << "|"
<< left << setw(width) << setfill(' ') << "startBlock" << "|"
<< left << setw(width) << setfill(' ') << "blockTime" << "|"
<< left << setw(width) << setfill(' ') << "state" << "|" << endl;
while(!q.empty()) {
PCB* t = q.top();
q.pop();
show_PCB(t);
}
cout << left << setw(7*width+7) << setfill('-') << "" << "\n";
}
queue finished;
void run_a_time(mqueue& ready,mqueue& blocked,PCB* runing) {
mqueue t_ready, t_blocked;
runing = ready.top();
ready.pop();
runing->priority -= 3;
runing->cpu_time += 1;
runing->all_time -= 1;
runing->start_block -= 1;
if(runing->start_block == 0) {
t_blocked.push(runing);
runing->state = sruning;
} else {
if(runing->all_time > 0) {
t_ready.push(runing);
} else {
finished.push(runing);
runing->state = sstop;
}
}
mqueue t_queue = blocked;
while(!t_queue.empty()) {
PCB* t = t_queue.top();
t_queue.pop();
t->block_time -= 1;
if(t->block_time == 0) {
t_ready.push(t);
t->block_time = 0;
t->start_block = -1;
t->state = sready;
} else {
t_blocked.push(t);
t->state = sblocked;
}
}
t_queue = ready;
while(!t_queue.empty()) {
PCB* t = t_queue.top();
t_queue.pop();
t->priority += 1;
t->start_block -= 1;
if(t->start_block == 0) {
t_blocked.push(t);
t->state = sblocked;
} else {
t_ready.push(t);
t->state = sready;
}
}
ready = t_ready;
blocked = t_blocked;
}
int main() {
mqueue ready, blocked;
PCB* runing = nullptr;
PCB* pcbs[] = {
new PCB(0,9,0,3,2,3, sready),
new PCB(1,38,0,3,-1,0, sready),
new PCB(2,30,0,6,-1,0, sready),
new PCB(3,29,0,3,-1,0, sready),
new PCB(4,0,0,4,-1,0, sready)
};
int pcb_num = sizeof(pcbs)/sizeof(PCB*);
for(int i = 0; i < pcb_num; i++) {
ready.push(pcbs[i]);
}
show_queue(ready);
int clock_ = 1;
while(!ready.empty() || !blocked.empty()) {
cout << "clock = " << clock_ << endl;
run_a_time(ready, blocked, runing);
cout << "ready queue:" << endl;
show_queue(ready);
cout << "blocked queue:" << endl;
show_queue(blocked);
//system("pause");
clock_++;
}
show_queue(finished);
//delete
for(int i = 0; i < pcb_num; i++) {
delete pcbs[i];
}
}