Problem with I/O priority management

The performance tuning Guidlines for Windows Server 2008 R2, sais that we can disable the I/O priority management for a disk by setting to zero the following registry setting:

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\DeviceClasses\{Device GUID}\DeviceParameters\Classpnp\IdlePrioritySupported.

My problem is that such a registry edit in my server's registry does not exist. I have to create it? If yes how?

Thanjs