A brief overview of the challenges of the multicore roadmap

Multicore chips are widely seen as the solution to continue the race toward ever more processing power, or in short, the continuation of Moore's Law. However, this poses many difficult challenges at different abstraction levels, as the preservation of dependability in the physical layer (related to the reduction of dimensions), the consumption and dissipation of the energy, the selection of the physical architecture beyond the current symmetric multiprocessing, the definition of a distributed operating system, and last but not least, the automatic and seamlessly parallelization of applications. Although many problems have been studied separately for a long time by academics, finding a satisfactory trade-off is an open issue. We will begin by reviewing the different challenges. Then, we will focus on the problem of dependability in the physical layer, and especially on the Network on Chip (NoC). Here, the future is in the generalization of total self-healing to NoCs, i.e., in self-detection of errors, self-diagnosis of faults, and self-repair at runtime, while preserving the efficiency of communications in the presence of an increasing percentage of defective elements. We shall briefly discuss the numerous constraints which apply to self-healing NoCs, and make that numerous tradeoffs are possible. The subject is widely open.