An Analytical Model for Thread-core Mapping for Tiled CMPs

Modern computing chips are composed of multiple, simple, low-power processing cores. Increasing the number of processing cores in a single chip brings the opportunity to exploit the inherent massive level of thread parallelism and further improved performance. However, efficient allocation of applications (threads) to available cores is a complicated process. Failing to do so, the mapping can be the limiting factor for achieving better performance on a tiled chip-multiprocessor (CMP). In this paper, we propose a mathematical formulation based on mixed integer linear program (MILP) to map application threads on cores at worst-case scenario by keeping into account the spatial topology of a two-dimensional mesh (2D-mesh) Networks-on-Chip (NoC). Our model allows evaluating in absolute term the performance of different mapping and routing algorithms. The proposed analytical model is general enough to consider a different optimising policy from energy to latency and a different number of memory controllers. In the experiments, we have shown that the proposed approach can achieve up to 40% reduction over the traditional zig-zag heuristic, therefore showing that there is a range for improving application mapping.