使用 C++ 在 Windows 中检索 CPU 总负载百分比-C/C++问题

Retrieving CPU Load Percent total in Windows with C++(使用 C++ 在 Windows 中检索 CPU 总负载百分比)

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问题描述

我一直在研究这个工具来快速记录一些系统统计信息，如内存信息和cpu 负载百分比(如任务管理器中显示的内容).我似乎处理了内存和日志记录部分，但是计算 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 compile 或得到了很好的评论，所以我很难找到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，但我还没有能够将碎片拼凑在一起.

I've been working on this tool to quickly log some system stats, like memory info, and cpu load percentage (like what's shown in the Task Manager). I seem to have the memory and logging part taken care of, but figuring out the CPU percentage has been very tough :( I've found a lot info on methods to check CPU info, but outside of abstracts pretty much none of the code samples I've found compile, or are well commented, so it's been hard for me to hash out a way to do this. I've already read through a lot of stackoverflow questions about getting CPU timings and such, but I haven't been able to put the pieces together.

也许我忽略了这一点，但似乎一种流行的解决方法是通过在每次检查之间至少间隔 200 毫秒的时间查询 CPU 两次，以帮助避免称为...分辨率的问题?嗯是的！我他妈的怎么做?:(我在语法上受到挑战 D:

Maybe I'm missing the point, but it seems like a popular way to figure this out is by querying the CPU two times with at least 200ms between each check to help avoid problems with something called... resolution? So yeah! How the heck do I do that? :( I'm syntactically challenged 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.

I'm going to share my source code so you can see what exactly I've been up to, up until now. It's all in just one .cpp, I'm using VS2013 Express for C++, and it's only for Windows for multicore CPUs.

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

Warning in advance: I'm so sorry for all the comments in the code :x Also, if you copy this code and run it, it's going to generate a .CSV file called log.CSV

//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 << "
";
        //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);

它似乎正在获取我需要的东西，但我不知道如何实际使用它，甚至不知道如何使用它进行单元测试，我更喜欢在将其放入我的源的其余部分之前.cp

It seems like it is getting the stuff I need, but I don't know how to actually use it or even make a unit test out of it, which I'd prefer before throwing it in the rest of my Source.cpp

我完全迷路了.在过去的几个小时里，我尝试了各种方法，但我什至无法进行简单的单元测试编译.

I am completely lost. I've tried all sorts of things for the last few hours, but I can't even get a simple unit test compiling.

我觉得这条评论让我走上了正确的道路，但我实际上不知道该怎么做:CPU 使用率是如何计算的?

I feel like this comment has me on the right path, but I don't actually know what to do with it: How is CPU usage calculated?

编辑#3:

我正在展示 Jeremy Friesner 代码的单元测试，以及我正在开发的完整日志工具.

I'm showing a Unit Test for Jeremy Friesner's code, as well as the completed logging tool that I was working on.

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 << "
";
        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;
}

完成的工具(都进入你的Source.cpp，然后编译运行):

/*
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 << "
";
        //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;
}

推荐答案

计算负载百分比随时间推移而流行的原因是因为 CPU 并没有真正的可变速度——在任何给定时刻，CPU 内核要么是以额定时钟速率处理指令，或者它处于空闲状态，因此即时测量只会给您 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.

The reason it's popular to compute the load percentage over time is because CPUs don't really have variable speeds -- at any given instant, a CPU core is either processing instructions at its rated clock rate, or it's sitting idle, so an instantaneous measurement would only give you 0% or 100% (*), which isn't really what you want. So in order to calculate a meaningful load percentage, you have to examine what percentage of time the CPU was idle during a particular interval of time.

无论如何，这是我用来在 Windows 下获取 CPU 使用率值的一些代码……只需定期调用 GetCPULoad()(例如每 250 毫秒或您喜欢的任何速率)并乘以 100.0 即可获得百分比:

In any case, here's some code I use to get a CPU-usage value under Windows... just call GetCPULoad() at regular intervals (e.g. every 250mS or at whatever rate you like) and multiply by 100.0 to get a percentage:

#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，三个内核空闲，一个内核处于活动状态，并称其为 25% 负载……当然还有像英特尔这样的东西SpeedStep 实际改变 CPU 的时钟频率作为管理功耗的一种方式；但我们暂时会忽略这些并发症:)

(*) Okay, you might get a bit more resolution on a multicore system; e.g. if you measured instantaneous CPU usage on a quad-core CPU you might find that at that particular instant in time, three cores were idle and one core was active, and call that 25% load... and of course there are things like Intel's SpeedStep that actually varies the CPU's clock rate as a way to manage power consumption; but we'll ignore those complications for the time being :)

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