Multicore Systems – Challenges for the Real-Time Software Developer

International audienceMulticore systems have become the norm for desktop computer systems. The percentage of multicore systems in the embedded domain is still marginal, but growing at an incredible pace such that multicore will become the norm in the embedded area as well. How- ever, embedded systems have additional requirements with respect to safety, reliability, and real-time behaviour. The use of parallel multicore systems introduces new challenges to the embedded systems developer who has to fulfil these requirements when developing new software or porting existing code to multicore systems.This paper gives an overview over typical problems that arise with the use of multicore systems. Unfortunately, a multicore system in many cases does not behave the same as a single core system with multithreading. These differences may result in severe program errors. A good understanding of the sources of these errors is required. It will be explained how problems on multicore systems can be avoided. Mechanisms present in different programming languages such as C/C++ and Java will be presented. An important role is played by the memory model provided by the language implemen- tation and how this may manifest in false program behaviour. The memory model permits different compiler and CPU optimisation on atomic and non-atomic operations, and allow different semantics of the volatilemodifier