c++ - 使用 C++ 在 Windows 中检索 CPU 负载百分比总数

Question

我一直在开发这个工具来快速记录一些系统统计信息，例如内存信息和cpu 负载百分比(例如任务管理器中显示的内容)。我似乎已经处理了内存和日志记录部分，但是弄清楚 CPU 百分比非常困难:( 我找到了很多关于检查 CPU 信息的方法的信息，但在摘要之外几乎没有任何代码示例我找到了编译，或者评论很好，所以我很难找出一种方法来做到这一点。我已经阅读了很多关于获取 CPU 计时等的 stackoverflow 问题，但我没有能够把碎片拼在一起。

也许我没有捕获重点，但解决这个问题的一种流行方法似乎是查询 CPU 两次，每次检查之间至少间隔 200 毫秒，以帮助避免所谓的解决问题？是的!我该怎么做？ :( 我在语法上受到挑战 D:

我将分享我的源代码，这样你就可以看到我一直在做什么，直到现在。这一切都在一个 .cpp 中，我使用的是 VS2013 Express for C++，它仅适用于多核 CPU 的 Windows。

提前警告:我很抱歉代码中的所有注释:x 另外，如果您复制并运行此代码，它将生成一个名为 log.CSV 的 .CSV 文件

//included libraries/functionality for input/output
#include <iostream>
#include <fstream>
#include <windows.h>
using namespace std;

//creates a static variable to convert Bytes to Megabytes
#define MB 1048576


//main program code loop
int main()
{
    //Code block intiialization for the memory referenced in the Kernell
    MEMORYSTATUSEX memStat;
    memStat.dwLength = sizeof (memStat);
    GlobalMemoryStatusEx(&memStat);


    //loads the SYSTEMTIME
    SYSTEMTIME sysTime;
    //Retrieves data so that we have a way to Get it to output when using the pointers
    GetSystemTime(&sysTime);


    //setting the I/O for our log file to be "myfile"
    ofstream myfile;
    // ios::out means that we're outputting data to the file
    // ios::app means that all the data we're outputting goes to the end of that log file instead of the start
    myfile.open("log.csv", ios::out | ios::app);


    //a while loop that gathers and logs data every quarter of a second to gather 4 data points in one second
    int counter = 0;
    while (counter < 4)
    {
        //Timestamp + Memory Info, and eventually CPU Load percentage
        myfile << sysTime.wHour << ":" << sysTime.wMinute << ":" << sysTime.wMilliseconds << ", " << memStat.dwMemoryLoad << "%, " << memStat.ullTotalPhys / MB << ", " << memStat.ullAvailPhys / MB << ", " << memStat.ullTotalPageFile / MB << ", " << memStat.ullAvailPageFile / MB << ", " << memStat.ullTotalVirtual / MB << ", " << memStat.ullAvailVirtual / MB << ", " << memStat.ullAvailExtendedVirtual / MB << "\n";
        //250 millisecond sleep delay 
        Sleep(250);
        counter = counter + 1;
    }
        //close the log file before terminating the program
        myfile.close();

    return 0; //standard main() end of program terminator
}

编辑#2:

我遇到了这个

BOOL WINAPI GetSystemTimes(_Out_opt_  LPFILETIME lpIdleTime,_Out_opt_  LPFILETIME lpKernelTime,_Out_opt_  LPFILETIME lpUserTime);

它似乎得到了我需要的东西，但我不知道如何实际使用它，甚至不知道如何用它进行单元测试，在将它扔到我的其他 Source 之前，我更愿意这样做。 cpp

我完全迷路了。在过去的几个小时里，我尝试了各种各样的东西，但我什至无法编译一个简单的单元测试。

我觉得这条评论让我走上了正确的道路，但我实际上不知道如何处理它:How is CPU usage calculated?

编辑#3:

我正在展示 Jeremy Friesner 的代码的单元测试，以及我正在开发的完整的日志记录工具。

测试以监控 CPU 负载

#include <Windows.h>
#include <iostream>
using namespace std;

static float CalculateCPULoad();
static unsigned long long FileTimeToInt64();
float GetCPULoad();


int main()
{   
    int _c = 0;

    while (_c == 0)
    {
        cout << GetCPULoad() * 100 << "\n";
        Sleep(1000);
    }

    return 0;
}


static float CalculateCPULoad(unsigned long long idleTicks, unsigned long long totalTicks)
{
    static unsigned long long _previousTotalTicks = 0;
    static unsigned long long _previousIdleTicks = 0;

    unsigned long long totalTicksSinceLastTime = totalTicks - _previousTotalTicks;
    unsigned long long idleTicksSinceLastTime = idleTicks - _previousIdleTicks;


    float ret = 1.0f - ((totalTicksSinceLastTime > 0) ? ((float)idleTicksSinceLastTime) / totalTicksSinceLastTime : 0);

    _previousTotalTicks = totalTicks;
    _previousIdleTicks = idleTicks;
    return ret;
}

static unsigned long long FileTimeToInt64(const FILETIME & ft)
{
    return (((unsigned long long)(ft.dwHighDateTime)) << 32) | ((unsigned long long)ft.dwLowDateTime);
}

// Returns 1.0f for "CPU fully pinned", 0.0f for "CPU idle", or somewhere in between
// You'll need to call this at regular intervals, since it measures the load between
// the previous call and the current one.  Returns -1.0 on error.
float GetCPULoad()
{
    FILETIME idleTime, kernelTime, userTime;
    return GetSystemTimes(&idleTime, &kernelTime, &userTime) ? CalculateCPULoad(FileTimeToInt64(idleTime), FileTimeToInt64(kernelTime) + FileTimeToInt64(userTime)) : -1.0f;
}

已完成工具(全部进入您的 Source.cpp，然后编译并运行):

/*
Resource Links:
Calling memory info in c++:                             http://msdn.microsoft.com/en-us/library/aa366589%28VS.85%29.aspx
I/O file handling in c++:                               http://www.cplusplus.com/doc/tutorial/files/
Date and Time in c++:                                   http://www.tutorialspoint.com/cplusplus/cpp_date_time.htm
CPU Load Percent (Credit to Jeremy Friesner):           https://stackoverflow.com/questions/23143693/retrieving-cpu-load-percent-total-in-windows-with-c
Everything else (too many to list):                     https://stackoverflow.com/
*/


/*
Performance Snapshot Tool

Grabs CPU load percent and basic Memory info from the system,
and or the Windows Task manager

Designed to work with specifically Windows 7 and beyond

Ideology: Create a small executable program to retrieve and
write to a log file a data sample from system performance
in a single snapshot -- robust enough to be called multiple
times per boot

The compiled .exe will be called by another program to run at
an exact, specified time relative to the program that is
calling it

Does 5 checks per second, every 200 milliseconds for a "Snapshot"
of performance

Initial Code Author:    Anonymous
Current Author: Anonymous
Revision:           0.01
Date:               18/4/2014
*/


//included libraries/functionality for input/output
#include <iostream>
#include <fstream>
#include <windows.h>
using namespace std;

//creates a static variable to convert Bytes to Megabytes
#define MB 1048576

//functions to calculate and retrieve CPU Load information
static float CalculateCPULoad();
static unsigned long long FileTimeToInt64();
float GetCPULoad();


//main program code loop
int main()
{
    //Code block initialization for the memory referenced in the Kernel
    MEMORYSTATUSEX memStat;
    memStat.dwLength = sizeof (memStat);
    GlobalMemoryStatusEx(&memStat);


    //loads the SYSTEMTIME
    SYSTEMTIME sysTime;
    //Retrieves data so that we have a way to Get it to output when using the pointers
    GetSystemTime(&sysTime);


    //setting the I/O for our log file to be "myfile"
    ofstream myfile;
    // ios::out means that we're outputting data to the file
    // ios::app means that all the data we're outputting goes to the end of that log file instead of the start
    myfile.open("log.csv", ios::out | ios::app);


    //a while loop that gathers and logs data every quarter of a second to gather 4 data points in one second
    int counter = 0;
    while (counter < 5)
    {
        //Timestamp + Memory Info, and eventually CPU Load percentage
        myfile << sysTime.wHour << "." << sysTime.wMinute << "." << sysTime.wSecond << ", " << GetCPULoad() * 100 << "%, " << memStat.dwMemoryLoad << "%, " << memStat.ullTotalPhys / MB << ", " << memStat.ullAvailPhys / MB << ", " << memStat.ullTotalPageFile / MB << ", " << memStat.ullAvailPageFile / MB << ", " << memStat.ullTotalVirtual / MB << ", " << memStat.ullAvailVirtual / MB << ", " << memStat.ullAvailExtendedVirtual / MB << "\n";
        //250 millisecond sleep delay 
        Sleep(200);
        counter = counter + 1;
    }
        //close the log file before terminating the program
        myfile.close();

    return 0; //standard main() end of program terminator
}

static float CalculateCPULoad(unsigned long long idleTicks, unsigned long long totalTicks)
{
    static unsigned long long _previousTotalTicks = 0;
    static unsigned long long _previousIdleTicks = 0;

    unsigned long long totalTicksSinceLastTime = totalTicks - _previousTotalTicks;
    unsigned long long idleTicksSinceLastTime = idleTicks - _previousIdleTicks;


    float ret = 1.0f - ((totalTicksSinceLastTime > 0) ? ((float)idleTicksSinceLastTime) / totalTicksSinceLastTime : 0);

    _previousTotalTicks = totalTicks;
    _previousIdleTicks = idleTicks;
    return ret;
}

static unsigned long long FileTimeToInt64(const FILETIME & ft)
{
    return (((unsigned long long)(ft.dwHighDateTime)) << 32) | ((unsigned long long)ft.dwLowDateTime);
}

// Returns 1.0f for "CPU fully pinned", 0.0f for "CPU idle", or somewhere in between
// You'll need to call this at regular intervals, since it measures the load between
// the previous call and the current one.  Returns -1.0 on error.
float GetCPULoad()
{
    FILETIME idleTime, kernelTime, userTime;
    return GetSystemTimes(&idleTime, &kernelTime, &userTime) ? CalculateCPULoad(FileTimeToInt64(idleTime), FileTimeToInt64(kernelTime) + FileTimeToInt64(userTime)) : -1.0f;
}

Answer 1

随着时间的推移计算负载百分比很受欢迎的原因是因为 CPU 并没有真正的可变速度 - 在任何给定的时刻，CPU 内核要么以其额定时钟速率处理指令，要么处于空闲状态，所以瞬时测量只会给您 0% 或 100% (*)，这并不是您真正想要的。因此，为了计算有意义的负载百分比，您必须检查 CPU 在特定时间间隔内空闲的时间百分比。

无论如何，这是我在 Windows 下用于获取 CPU 使用率值的一些代码...只需定期调用 GetCPULoad()(例如每 250 毫秒或以您喜欢的任何速率)并乘以 100.0 即可获得百分比:

#include <Windows.h>

static float CalculateCPULoad(unsigned long long idleTicks, unsigned long long totalTicks)
{
   static unsigned long long _previousTotalTicks = 0;
   static unsigned long long _previousIdleTicks = 0;

   unsigned long long totalTicksSinceLastTime = totalTicks-_previousTotalTicks;
   unsigned long long idleTicksSinceLastTime  = idleTicks-_previousIdleTicks;

   float ret = 1.0f-((totalTicksSinceLastTime > 0) ? ((float)idleTicksSinceLastTime)/totalTicksSinceLastTime : 0);

   _previousTotalTicks = totalTicks;
   _previousIdleTicks  = idleTicks;
   return ret;
}

static unsigned long long FileTimeToInt64(const FILETIME & ft) {return (((unsigned long long)(ft.dwHighDateTime))<<32)|((unsigned long long)ft.dwLowDateTime);}

// Returns 1.0f for "CPU fully pinned", 0.0f for "CPU idle", or somewhere in between
// You'll need to call this at regular intervals, since it measures the load between
// the previous call and the current one.  Returns -1.0 on error.
float GetCPULoad()
{
   FILETIME idleTime, kernelTime, userTime;
   return GetSystemTimes(&idleTime, &kernelTime, &userTime) ? CalculateCPULoad(FileTimeToInt64(idleTime), FileTimeToInt64(kernelTime)+FileTimeToInt64(userTime)) : -1.0f;
}

(*) 好的，您可能会在多核系统上获得更高的分辨率；例如如果您测量四核 CPU 上的瞬时 CPU 使用率，您可能会发现在那个特定时刻，三个核心处于空闲状态，一个核心处于事件状态，并称其为 25% 负载......当然还有英特尔的SpeedStep 实际上改变 CPU 的时钟频率作为管理功耗的一种方式；但我们暂时忽略这些复杂性:)