This work describes an approach to generate accurate system-level model of embedded software on a targeted Real-Time Operating System (RTOS). We design a RTOS emulation layer, called RTOS_SC, on top of the SystemC kernel. The system level model can be used for software optimization in the early stage of a processor design. The model precision is obtained by integrating key features which are provided in typical RTOS schedulers. We first discuss a case study which shows the impact of the implemented features on a priority-driven scheduler. We then present the abstraction of tasks scheduling and communication mechanisms. To validate the accuracy of our model we use the tasks response time metric with industrial-size examples such as MP3, Vocoder and Jpeg encoder. The experimental results show a significant improvement compared to existing RTOS models
