[转载]VC实现CPU速度自测

简单说下原理:
在两个固定的时刻测出当前CPU的时钟计数,用这个计数除以间隔的时间就得到相应的频率值了。
需要说明的是为了获得当前CPU的内侧时钟值,要采用内嵌汇编的方式得到,这就要将当前的测试进程的优先级设定的较高,故采用了实时进程优先级:REALTIME_PRIORITY_CLASS,该优先级别高,并且有这种权限的进程中的所有线程要比其他进程中的所有线程的级别都高。

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用VC实现CPU速度自测
 
#include <windows.h>
#include <iostream>
using namespace std;
//测试速度的子程序
float MeasureSpeed(void);
int main(void)
{
    cout << "您的CPU的运行速度是: " << MeasureSpeed() << "MHz" << endl;
    system("pause");
    return 0;
}
float MeasureSpeed()
{
unsigned long int       ticks;          //先是存放计时次数,后存放固定时间间隔值
unsigned long int       stock0, stock1; //存放两固定时刻的CPU内置时钟值,值的含意为计数
unsigned long int       cycles;         //存放内置时钟值之差,好固定时段的计数值 
unsigned long int       freq[5] = {0,0,0,0,0}; //存放频率,为了提高精度,采用了相邻的测的5个频率的平均值
unsigned long int       nums = 0;       //循环次数
unsigned long int       total = 0;      //存放频率之和
    LARGE_INTEGER       t0,t1;
    LARGE_INTEGER       countfreq;
    //返回高精度的计数频率,即每秒多少次;
    if (!QueryPerformanceFrequency( &countfreq ) )
    {
        return 0.0f;
    }
    //返回特定进程的优先级;
    DWORD priority_class = GetPriorityClass(GetCurrentProcess());
    //返回特定线程的优先级;
    int   thread_priority = GetThreadPriority(GetCurrentThread());
    //将当前进程设成实时进程;
    SetPriorityClass(GetCurrentProcess(), REALTIME_PRIORITY_CLASS);
	//设定线程优先级;
  SetThreadPriority(GetCurrentThread(), THREAD_PRIORITY_TIME_CRITICAL);
    do
    {
        nums++;
        freq[4] = freq[3];
        freq[3] = freq[2];
        freq[2] = freq[1];
        freq[1] = freq[0];
	//返回高精度计数的值;
        QueryPerformanceCounter(&t0);
        t1.LowPart = t0.LowPart;
        t1.HighPart = t0.HighPart;
	//这句中的50和后面相同语句中的1000是一个经验值,起的作用是控制时间间隔,可以
	//调节这两个值来实现最佳时间间隔。
 while ( (unsigned long int)t1.LowPart - (unsigned long int)t0.LowPart<10)
        {
            QueryPerformanceCounter(&t1);
        }
        _asm
        {
rdtsc  //启动读取CPU的内置时钟,其返回值是个64位的整数,高32到EDX,低32到EAX里
 mov stock0, EAX //高位部份在短暂时间内是不会有变化的,故无需读出对比
	}
 t0.LowPart = t1.LowPart;        // 重置初始时刻
  t0.HighPart = t1.HighPart;
 while ((unsigned long int)t1.LowPart-(unsigned long int)t0.LowPart<1000 )
        {
            QueryPerformanceCounter(&t1);
        }
        _asm
        {
            rdtsc
            mov  stock1, EAX
	}
        cycles = stock1 - stock0;
        ticks = (unsigned long int) t1.LowPart - (unsigned long int) t0.LowPart;
        ticks = ticks * 1000000;
        ticks = ticks / countfreq.LowPart;
   if ( ticks % countfreq.LowPart > countfreq.LowPart/2 )
        {
            ticks++;            // 使数据收敛
        }
freq[0] = cycles / ticks;    // 求出频率,单位:MHz
        if ( cycles%ticks > ticks/2 )
        {
           freq[0]++;             // 使数据收敛
        }
   total = (freq[0] + freq[1] + freq[2] + freq[3] + freq[4]);
    } while ((nums < 5 ) || (nums < 100) && ( (abs(5 * freq[0] - total) < 5)
             || (abs(5 * freq[1]-total) < 5) || (abs(5 * freq[2] - total) < 5)
			 || (abs(5 * freq[3]-total) < 5) || (abs(5 * freq[4] - total) < 5)
			 ));
//条件循环,以确保循环不少于5次,在大于5次后确保达到一定的精度后退出
    if ( total/5  !=  ( total + 1 )/5 )
    {
        total ++;               // 使数据收敛
    }
    // 恢复进程及线程的优先级别;
    SetPriorityClass(GetCurrentProcess(), priority_class);
    SetThreadPriority(GetCurrentThread(), thread_priority);
    return float(total) / 5.0f;
}

上面的程序,可以做一定修改,循环中的控制语句也可以作适当的调整,来提高测试精度。调试环境VC6.0/XP

转载地址:http://blog.liuyixi.com/2009/07/02/vcshixiancpusuduzice/

posted @ 2012-05-13 23:08  Silence  阅读(498)  评论(0编辑  收藏  举报
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