windows利用系统api获取的系统的cpu利用率为什么和任务管理器的不一致？

Question

windows利用系统api获取的系统的cpiweiu利用率为什么和任务管理器的不一致。
具体代码如下，我的电脑T480S，64位系统，运行的结果比任务管理器的第不少，大概低10%-25%

#include
#include
static bool getSystemCPUTime(ULONGLONG& totalTime, ULONGLONG& idleTime)
{
FILETIME ftSysIdle, ftSysKernel, ftSysUser;

if (!GetSystemTimes(&ftSysIdle, &ftSysKernel, &ftSysUser))
{
    return false;
}

ULARGE_INTEGER sysKernel, sysUser, sysIdle;
sysKernel.HighPart = ftSysKernel.dwHighDateTime;
sysKernel.LowPart = ftSysKernel.dwLowDateTime;
sysUser.HighPart = ftSysUser.dwHighDateTime;
sysUser.LowPart = ftSysUser.dwLowDateTime;
sysIdle.HighPart = ftSysIdle.dwHighDateTime;
sysIdle.LowPart = ftSysIdle.dwLowDateTime;

totalTime = sysKernel.QuadPart + sysUser.QuadPart;
idleTime = sysIdle.QuadPart;

return true;

}
int main()
{
unsigned int interval = 1000;
ULONGLONG totalPrev = 0, totalCurr = 0;
ULONGLONG idlePrev = 0, idleCurr = 0;
unsigned int totalCPUUsage = 0;

getSystemCPUTime(totalPrev, idlePrev);

while (true)
{

    Sleep(1000);

    if (getSystemCPUTime(totalCurr, idleCurr))
    {
        LONGLONG total = totalCurr - totalPrev;

        if (total > 0)
        {
            LONGLONG idle = idleCurr - idlePrev;
            totalCPUUsage = static_cast<unsigned int>(100 * (total - idle) / (total));
            std::cout << "cpu usage is " << totalCPUUsage << std::endl;
        }
    }

    totalPrev = totalCurr;
    idlePrev = idleCurr;
}

}

Answer 1

在windows中要看真实的进程占用cpu,内存等情况还是要以资源监视器为主，别看任务管理器了，例如redis，redis-server在windows的任务管理器中几乎
不怎么占内存，与实际情况完全背离，但是如果你去看资源监视器，就能看到他工作集的正常内存占用