Applying end-to-end path delay analysis to multi-rate automotive systems developed using legacy tools

The end-to-end path delay analysis is used to predict timing behavior of multi-rate automotive embedded systems. Some of the assumptions used by the existing analysis may not be strictly followed by some legacy tools due to optimizations applied during the development of these systems. As a result, the existing analysis may not be applicable in some cases. In this paper we identify one such case. That is, the case in which all the tasks in a multi-rate task chain have equal priorities despite the fact that they have different periods. Furthermore, the chain contains at least one single-rate sub-chain. We also propose a preliminary solution that makes the existing analysis applicable to this case. However, the proposed solution is pessimistic. Currently, we are working on minimizing the pessimism.