Windows中准确的系统cpu使用情况

Question

我正在将cpu使用情况监视器添加到进程监视器中，因此我选择使用NtQuerySystemInformation，因为它是最低的API，我可以使用它来进行更准确的计算，当cpu使用率较高但cpu接近时，下面的代码可以很好地工作空闲（10：30），它不会显示任务管理器中的使用率百分比，也不会显示低于26％的使用率，但是任务管理器将其显示为15％或接近百分比

这是我的代码：

double accurate_usage() {

  SYSTEM_INFO info = { 0 };
  GetSystemInfo(&info);
  DWORD proc_num = info.dwNumberOfProcessors;
  PSYSTEM_PROCESSOR_PERFORMANCE_INFORMATION old_values = new SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION[proc_num];
  PSYSTEM_PROCESSOR_PERFORMANCE_INFORMATION new_values = new SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION[proc_num];
  FILETIME old_time = { 0 }, new_time = { 0 };
  ULARGE_INTEGER uold_time = { 0 }, unew_time = { 0 };

  ULONG size;
  fNtQuerySystemInformation(SystemProcessorPerformanceInformation, old_values, sizeof(old_values[0]) * proc_num, &size);
  GetSystemTimeAsFileTime(&old_time);
  memcpy(&uold_time, &old_time, sizeof(FILETIME));
  Sleep(1000);
  fNtQuerySystemInformation(SystemProcessorPerformanceInformation, new_values, sizeof(old_values[0]) * proc_num, &size);
  GetSystemTimeAsFileTime(&new_time);
  memcpy(&unew_time, &new_time, sizeof(FILETIME));

  double percent = 0.0;
  for (DWORD i = 0; i < proc_num; ++i) {
      double current_percent = (new_values[i].KernelTime.QuadPart - old_values[i].KernelTime.QuadPart) +
      (new_values[i].UserTime.QuadPart - old_values[i].UserTime.QuadPart) - 
      (new_values[i].IdleTime.QuadPart - old_values[i].IdleTime.QuadPart);
      current_percent /= (unew_time.QuadPart - uold_time.QuadPart);
      current_percent /= proc_num;
      current_percent *= 100;
      percent += current_percent;
  }
  return percent;
}

Answer 1

工作代码：

double accurate_usage() {

  SYSTEM_INFO info = { 0 };
  GetSystemInfo(&info);
  DWORD proc_num = info.dwNumberOfProcessors;
  PSYSTEM_PROCESSOR_PERFORMANCE_INFORMATION old_values = new SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION[proc_num];
  PSYSTEM_PROCESSOR_PERFORMANCE_INFORMATION new_values = new SYSTEM_PROCESSOR_PERFORMANCE_INFORMATION[proc_num];
  FILETIME old_time = { 0 }, new_time = { 0 };
  ULARGE_INTEGER uold_time = { 0 }, unew_time = { 0 };

  ULONG size;
  fNtQuerySystemInformation(SystemProcessorPerformanceInformation, old_values, sizeof(old_values[0]) * proc_num, &size);
  GetSystemTimeAsFileTime(&old_time);
  memcpy(&uold_time, &old_time, sizeof(FILETIME));
  Sleep(1000);
  fNtQuerySystemInformation(SystemProcessorPerformanceInformation, new_values, sizeof(old_values[0]) * proc_num, &size);
  GetSystemTimeAsFileTime(&new_time);
  memcpy(&unew_time, &new_time, sizeof(FILETIME));

  double percent = 0.0;
  for (DWORD i = 0; i < proc_num; ++i) {
      double current_percent = (new_values[i].IdleTime.QuadPart - old_values[i].IdleTime.QuadPart) * 100 ;
      current_percent /= ((new_values[i].KernelTime.QuadPart + new_values[i].UserTime.QuadPart) - (old_values[i].KernelTime.QuadPart + old_values[i].UserTime.QuadPart));
      current_percent = 100 - current_percent;
      percent += current_percent;
  }
  return percent / 10;
}