Accurate timing analysis is key to efficient embedded system synthesis and integration. While industrial control software systems are developed using graphical models, such as Matlab/Simulink or ASCET/SD, exhaustive simulation is not suitable for verifying functional and timing behavior. Formal performance analysis is an alternative but can lead to wide timing intervals because of input data dependency and complex target architectures. Hence a designer might want to restrict the formal performance analysis to parts of the software system, called context or process modes.In this paper, we describe how to define and characterize such context information from graphical models. Further, we extend the formal performance analysis to consider contexts. Results from an automotive application demonstrate the applicability of our approach.