FSCTL_QUERY_VOLUME_NUMA_INFO control code

The FSCTL_QUERY_VOLUME_NUMA_INFO control code finds the current Non-Uniform Memory Architecture (NUMA) node index for a volume.

To perform this operation, call the DeviceIoControl function with the following parameters.

BOOL
   WINAPI
   DeviceIoControl( (HANDLE)       hDevice,
                    (DWORD)        FSCTL_QUERY_VOLUME_NUMA_INFO, // dwIoControlCode
                    (LPDWORD)      lpInBuffer,      // input buffer
                    (DWORD)        nInBufferSize,   // size of input buffer
                    (LPDWORD)      lpOutBuffer,     // output buffer
                    (DWORD)        nOutBufferSize,  // size of output buffer
                    (LPDWORD)      lpBytesReturned, // number of bytes returned
                    (LPOVERLAPPED) lpOverlapped );  // OVERLAPPED structure

Parameters

• hDevice [in]: A handle to the device. To obtain a device handle, call the CreateFile function.

This can also be a handle to a file or directory in the device as well. This FSCTL would return the NUMA node for the volume that contains the file or directory.

• dwIoControlCode [in]: The control code for the operation. Use FSCTL_QUERY_VOLUME_NUMA_INFO for this operation.

• lpInBuffer [in]: Not used with this operation; set to NULL

• nInBufferSize [in]: Not used with this operation; set to zero.

• lpOutBuffer [out]: A pointer to a buffer that receives a FSCTL_QUERY_VOLUME_NUMA_INFO_OUTPUT structure which specifies a Non Uniform Memory Architecture (NUMA) volume's current node.

• nOutBufferSize [in]: The size of the output buffer, in bytes.

• lpBytesReturned [out]: A pointer to a variable that receives the size of the data stored in the output buffer, in bytes.

  If the output buffer is too small, the call fails, GetLastError returns ERROR_INSUFFICIENT_BUFFER, and lpBytesReturned is zero.

  If lpOverlapped is NULL, lpBytesReturned cannot be NULL. Even when an operation returns no output data and lpOutBuffer is NULL, DeviceIoControl makes use of lpBytesReturned. After such an operation, the value of lpBytesReturned is meaningless.

  If lpOverlapped is not NULL, lpBytesReturned can be NULL. If this parameter is not NULL and the operation returns data, lpBytesReturned is meaningless until the overlapped operation has completed. To retrieve the number of bytes returned, call GetOverlappedResult. If the hDevice parameter is associated with an I/O completion port, you can retrieve the number of bytes returned by calling GetQueuedCompletionStatus.

• lpOverlapped [in]: A pointer to an OVERLAPPED structure.

  If hDevice was opened without specifying FILE_FLAG_OVERLAPPED, lpOverlapped is ignored.

  If hDevice was opened with the FILE_FLAG_OVERLAPPED flag, the operation is performed as an overlapped (asynchronous) operation. In this case, lpOverlapped must point to a valid OVERLAPPED structure that contains a handle to an event object. Otherwise, the function fails in unpredictable ways.

  For overlapped operations, DeviceIoControl returns immediately, and the event object is signaled when the operation has been completed. Otherwise, the function does not return until the operation has been completed or an error occurs.

Return value

If the operation completes successfully, DeviceIoControl returns a nonzero value.

If the operation fails or is pending, DeviceIoControl returns zero. To get extended error information, call GetLastError.

Requirements

See also

DeviceIoControl

FSCTL_QUERY_VOLUME_NUMA_INFO_OUTPUT