IOCTL_DISK_PERFORMANCE

Using the IOCTL_DISK_PERFORMANCE control code provides disk performance information.

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

BOOL DeviceIoControl(
  (HANDLE) hDevice,            // handle to device
  IOCTL_DISK_PERFORMANCE,      // dwIoControlCode operation
  NULL,                        // lpInBuffer; must be NULL
  0,                           // nInBufferSize; must be zero
  (LPVOID) lpOutBuffer,        // output buffer
  (DWORD) nOutBufferSize,      // size of output buffer
  (LPDWORD) lpBytesReturned,   // number of bytes returned
  (LPOVERLAPPED) lpOverlapped  // OVERLAPPED structure
);

Parameters

hDevice

[in] Handle to the object from which performance information is to be retrieved.. To obtain a device handle, call the CreateFile function.

dwIoControlCode

[in] Control code for the operation. This value identifies the specific operation to be performed and the type of device on which to perform it. Use IOCTL_DISK_PERFORMANCE to request this operation.

lpInBuffer

[in] Pointer to the input buffer. Not used; must be NULL.

nInBufferSize

[in] Size, in bytes, of the input buffer. Not used; must be zero.

lpOutBuffer

[out] Pointer to a buffer that will receive a DISK_PERFORMANCE data structure.

nOutBufferSize

[in] Size, in bytes, of the buffer pointed to by lpOutBuffer, which must be large enough to contain a DISK_PERFORMANCE data structure.

lpBytesReturned

[out] Pointer to a variable that receives the size, in bytes, of output data returned.

If the output buffer is too small to return any data, then the call fails, GetLastError returns the error code ERROR_INSUFFICIENT_BUFFER, and the returned byte count is zero.

If the output buffer is too small to hold all of the data but can hold some entries, then the operating system returns as much as fits, the call fails, GetLastError returns the error code ERROR_MORE_DATA, and lpBytesReturned indicates the amount of data returned. Your application should call DeviceIoControl again with the same operation, specifying a new starting point.

If lpOverlapped is NULL (nonoverlapped I/O), lpBytesReturned cannot be NULL.

If lpOverlapped is not NULL (overlapped I/O), lpBytesReturned can be NULL. If this is an overlapped operation, you can retrieve the number of bytes returned by calling the GetOverlappedResult function. If hDevice is associated with an I/O completion port, you can get the number of bytes returned by calling the GetQueuedCompletionStatus function.

lpOverlapped

[in] Pointer to an OVERLAPPED structure.

If hDevice was opened with the FILE_FLAG_OVERLAPPED flag, lpOverlapped must point to a valid OVERLAPPED structure. In this case, the operation is performed as an overlapped (asynchronous) operation. If the device was opened with the FILE_FLAG_OVERLAPPED flag and lpOverlapped is NULL, the function fails in unpredictable ways.

If hDevice was opened without specifying the FILE_FLAG_OVERLAPPED flag, lpOverlapped is ignored and DeviceIoControl does not return until the operation has been completed, or until an error occurs.

Return Values

If the operation succeeds, DeviceIoControl returns a nonzero value.

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

Remarks

This device I/O control operation is for disk devices.

Requirements

  Windows NT/2000: Requires Windows NT 3.1 or later.
  Windows 95/98: Unsupported.
  Header: Declared in Winioctl.h.

See Also

Device Input and Output Overview, Device Input and Output Control Codes, DeviceIoControl, DISK_PERFORMANCE