获取电脑实时CPU使用率

要求：实现一个计算电脑实时CPU占有率的测试程序，将多种方法获取结果显示在对话框上，动态显示。

实现：

1、新建基于对话框的MFC应用程序，Dialog上添加控件，为控件添加CSting类型变量m_RateResult1、m_RateResult2、m_RateResult3，

      

2、创建线程类（Thread.h和Thread.cpp），在 ####Dlg.cpp 文件中的初始化函数 OnInitDialog() 中创建计算CPU利用率的线程

    // TODO: 在此添加额外的初始化代码

    _beginthread(&CThread::InitCalcuPdh, 0, this);
    _beginthread(&CThread::InitCalcuGet, 0, this);
    _beginthread(&CThread::InitCalcuNt,  0, this);

3、线程类中计算CPU利用率

方式一：使用Performance Data Helper（PDH）性能数据助手，获取CPU利用率

void CThread::InitCalcuPdh(void *pDlg)
{
    CCalculateCPURateDlg *pItemDlg = (CCalculateCPURateDlg *)pDlg;
    if (pItemDlg == NULL)
    {
        return;
    }

    while(1)
    {
        //打开查询（query）句柄
        HQUERY query;
        PDH_STATUS status = PdhOpenQuery(NULL, NULL, &query);
        if (status != ERROR_SUCCESS)
        {
            pItemDlg->MessageBox(L"Open Query Error", NULL, MB_OK);
            continue;
        }
            
        //在查询中加入计数器(counter)
        HCOUNTER counter;
        //counter = (HCOUNTER *)GlobalAlloc(GPTR, sizeof(HCOUNTER));
        status = PdhAddCounter(query, LPCWSTR(L"\Processor Information(_Total)\% Processor Time"), NULL, &counter);
        if (status != ERROR_SUCCESS)
        {
            pItemDlg->MessageBox(L"Add Counter Error", NULL, MB_OK);
            continue;
        }

        //收集query的数据,在两条PdhCollectQueryData()语句之间加入一条Sleep(1000)语句
        PdhCollectQueryData(query);
        Sleep(1000);
        PdhCollectQueryData(query);

        //获得格式化（可以显示的）数据
        PDH_FMT_COUNTERVALUE pdhValue;
        DWORD dwValue;
        status = PdhGetFormattedCounterValue(counter, PDH_FMT_DOUBLE, &dwValue, &pdhValue);
        if (status != ERROR_SUCCESS)
        {
            pItemDlg->MessageBox(L"Get Value Error", NULL, MB_OK);
            continue;
        }
        pItemDlg->m_RateResult1.Format(L"%.0lf%%", pdhValue.doubleValue);

        SendMessage(pItemDlg->m_hWnd, WM_UPDATEDATA, FALSE, FALSE); 
        PdhCloseQuery(query);
    }
}

方式二：使用windows 自带的API（GetSystemTimes）获取CPU利用率

__int64 DiffFileTime(FILETIME time1, FILETIME time2)
{
    __int64 a = time1.dwHighDateTime << 32 | time1.dwLowDateTime;
    __int64 b = time2.dwHighDateTime << 32 | time2.dwLowDateTime;
    return (b - a);
}
void CThread::InitCalcuGet(void *pDlg)
{
    CCalculateCPURateDlg *pItemDlg = (CCalculateCPURateDlg *)pDlg;
    if (pItemDlg == NULL)
    {
        return;
    }

    while(1)
    {
        double cpurate;
        __int64 idle, kernel, user;
        FILETIME preidleTime, idleTime;      //空闲时间
        FILETIME prekernelTime, kernelTime;  //内核态时间
        FILETIME preuserTime, userTime;      //用户态时间

        //计算CPU使用率，需要收集两份样本，中间用Sleep()函数间隔1s
        GetSystemTimes(&preidleTime, &prekernelTime, &preuserTime);
        Sleep(1000);
        GetSystemTimes(&idleTime, &kernelTime, &userTime);

        idle = DiffFileTime(preidleTime, idleTime);
        kernel = DiffFileTime(prekernelTime, kernelTime);
        user = DiffFileTime(preuserTime, userTime);

        if (kernel + user == 0)
            cpurate = 0.0;
        else
            cpurate = abs((kernel + user - idle) * 100 / (kernel + user));//（总的时间-空闲时间）/总的时间=占用cpu的时间就是使用率
        
        pItemDlg->m_RateResult2.Format(L"%.0lf%%", cpurate);
        SendMessage(pItemDlg->m_hWnd, WM_UPDATEDATA, FALSE, FALSE); 
    }
}

方式三：使用windows API（NtQuerySystemInformation）获取CPU利用率

typedef struct _UINT64_DELTA
{
    ULONG64 Value;
    ULONG64 Delta;
} UINT64_DELTA, *PUINT64_DELTA;

#define UpdateDelta(DltMgr, NewValue) 
((DltMgr)->Delta = (NewValue) - (DltMgr)->Value, 
(DltMgr)->Value = (NewValue), (DltMgr)->Delta)

void CThread::InitCalcuNt(void *pDlg)
{
    CCalculateCPURateDlg *pItemDlg = (CCalculateCPURateDlg *)pDlg;
    if (pItemDlg == NULL)
    {
        return;
    }

    while(1)
    {
        double cpu_rate;
        ULONG64 total_time = 0;
        ULONG64 sys_time = 0;
        static SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION CpuInformation[1024];
        static SYSTEM_INFO sys_info;

        static UINT64_DELTA cpu_kernel_delta;
        static UINT64_DELTA cpu_user_delta;
        static UINT64_DELTA cpu_idle_delta;
        static SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION cpu_totals;
        memset(&cpu_totals, 0, sizeof(SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION));

        GetSystemInfo(&sys_info);

        NtQuerySystemInformation(
            SystemProcessorPerformanceInformation,
            &CpuInformation,
            sizeof(SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION) * (ULONG)sys_info.dwNumberOfProcessors,
            NULL
            );

        for (int i = 0; i < (int)sys_info.dwNumberOfProcessors; i++)
        {
            SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION& cpu_info = CpuInformation[i];

            // KernelTime includes idle time.
            LONGLONG dpc_time = cpu_info.Reserved1[0].QuadPart;
            LONGLONG interrupt_time = cpu_info.Reserved1[i].QuadPart;
            cpu_info.KernelTime.QuadPart -= cpu_info.IdleTime.QuadPart;
            cpu_info.KernelTime.QuadPart += dpc_time + interrupt_time;

            cpu_totals.Reserved1[0].QuadPart += dpc_time;
            cpu_totals.IdleTime.QuadPart += cpu_info.IdleTime.QuadPart;
            cpu_totals.Reserved2 += cpu_info.Reserved2;
            cpu_totals.Reserved1[1].QuadPart += cpu_info.Reserved1[1].QuadPart;
            cpu_totals.KernelTime.QuadPart += cpu_info.KernelTime.QuadPart;
            cpu_totals.UserTime.QuadPart += cpu_info.UserTime.QuadPart;
        }

        UpdateDelta(&cpu_kernel_delta, cpu_totals.KernelTime.QuadPart);
        UpdateDelta(&cpu_user_delta, cpu_totals.UserTime.QuadPart);
        UpdateDelta(&cpu_idle_delta, cpu_totals.IdleTime.QuadPart);

        total_time = cpu_kernel_delta.Delta + cpu_user_delta.Delta + cpu_idle_delta.Delta;
        sys_time = cpu_kernel_delta.Delta + cpu_user_delta.Delta;

        if (total_time)
            cpu_rate = sys_time * 100.0 / total_time;
        else
            cpu_rate = 0.0;
        pItemDlg->m_RateResult3.Format(L"%.0lf%%", cpu_rate);
        Sleep(1000);

        SendMessage(pItemDlg->m_hWnd, WM_UPDATEDATA, FALSE, FALSE); 
    }
}

4、stdafx.h 中添加

#pragma comment(lib,"pdh.lib")
#pragma comment(lib,"ntdll.lib")
#include <Pdh.h>
#include <PdhMsg.h>
#include <Windows.h> 
#include <Winternl.h>

错误：

1、在线程中调用UpdateData函数，在Debug模式下编译可以通过，但运行时会触发中断

原因：MFC对象不支持多线程操作，不能供多个线程进程使用。子线程调用pDlg-> UpdateData(FALSE)时主线程（界面线程）会阻塞，更新必须由它完成，这样就形成死锁。更改界面的操作最好用主线程（界面线程），要想在子线程（工作线程）里执行界面的操作，可以通过向主线程发送消息来解决。

解决：

####Dlg.h 中添加

#define WM_UPDATEDATA  10000+1

afx_msg LRESULT OnUpdateData(WPARAM wParam, LPARAM lParam);

####Dlg.cpp 中添加

ON_MESSAGE(WM_UPDATEDATA, OnUpdateData) 

LRESULT CCalculateCPURateDlg::OnUpdateData(WPARAM wParam, LPARAM lParam) 
{ 
    UpdateData(wParam); 
    return 0; 
} 

Thread.cpp 中添加

SendMessage(pItemDlg->m_hWnd, WM_UPDATEDATA, FALSE, FALSE);

2、在某些环境中exe文件运行失败

解决：Release使用MT选项编译，Debug使用MTd选项编译（同时属性页中选择在静态库中使用MFC）

参考博客：

https://www.cnblogs.com/einyboy/archive/2012/06/13/2548243.html

http://www.cnblogs.com/hbccdf/p/get_sys_cpu_usage_and_mem_usage.html