QT获取cpu使用率

double getCpuUsage()
{

#ifdef Q_OS_WIN
    static FILETIME s_preIdleTime = { 0, 0 };
    static FILETIME s_preKernelTime = { 0, 0 };
    static FILETIME s_preUserTime = { 0, 0 };
    static bool isFirst = true;

    FILETIME idleTime;
    FILETIME kernelTime;
    FILETIME userTime;

    int idleCost = 0;
    int kernelCost = 0;
    int userCost = 0;

    double rate = 0.0;

    GetSystemTimes(&idleTime, &kernelTime, &userTime);

    idleCost = CompareFileTime(&s_preIdleTime, &idleTime);
    kernelCost = CompareFileTime(&s_preKernelTime, &kernelTime);
    userCost = CompareFileTime(&s_preUserTime, &userTime);

    s_preIdleTime = idleTime;
    s_preKernelTime = kernelTime;