—After their success in the high performance and desktop market, Graphic Processing Units (GPUs), that can be used for general purpose computing are introduced for embedded systems on a chip (SOCs). Due to some advanced architectural features, like massive simultaneous multithreading, static performance analysis and high-level timing simulation are difficult to apply to code running on these systems. This paper extends a method for performance simulation of GPUs. The method uses automated performance annotations in the application’s OpenCL C source code, and an extended performance model for derivation of a kernels runtime from metrics produced by the execution of annotated kernels. The final results are then generated using a probabilistic resource conflict model. The model reaches an accuracy of 90% on most test cases and delivers a higher average accuracy than previous methods.