The model-based methodology has proven to be effective for fast and low-cost development of embedded software In the model-based development process, transforming a software structural model that describes the underlying application, to an implementable runtime model is a critical issue. Since the designed software will finally run on the target platform, non-functional issues like schedulability, timing constraints and resource requirements have to be considered during the transformation. In this paper, we propose a generic runtime model architecture that can best satisfy the non-functional requirements of the system, and a generic transformation method to convert a structural model to a runtime model in such an architecture. The transformation approach is based on the notion of end-to-end computations performed by the system in response to external stimuli. We demonstrate the advantages and effectiveness of the proposed method by constructing a software runtime model for a combined electronic throttle and air-fuel ratio control system.