UML through its profiling mechanism is well adapted for the modeling of real-time software requirements and designs. It is becoming the de facto standard. On the other hand, several real-time schedulability analysis techniques have been proposed in the literature. One of the current research challenges is in bridging the gap between the UML/SPT models and the well-established real-time schedulability analysis techniques. In this paper, we propose an MDA-compliant approach addressing this issue. We develop an UML metamodel for a well-established schedulability analysis technique. We propose a rule-based transformation between the UML/SPT schedulability analysis sub-profile metamodel and this metamodel. We illustrate our approach with an example.