Backported from X.org:

 commit 9f9268821b13038556fbc029df54ab0e9b2aa77f
 Author: Mathieu Bérard <mathieu.berard@crans.org>
 Date:   Mon Aug 11 13:52:38 2008 -0400

    The smart scheduler is not optional.
Backported-to-NX-by: Mike Gabriel <mike.gabriel@das-netzwerkteam.de>