Thermal-Constrained Task Allocation for Interconnect Energy Reduction in 3-D Homogeneous MPSoCs

3-D technology that stacks silicon dies with through silicon vias (TSVs) is a promising solution to overcome the interconnect scaling problem in giga-scale integrated circuits (ICs). Thermal dissipation is a major challenge for 3-D integration and prior thermal-balanced task scheduling methods for 3-D multiprocessor system-on-chips (MPSoCs) typically balance power gradient across vertical stacks based on the assumption of strong thermal correlation among processing cores within a stack. On the other hand, 3-D MPSoCs typically employ network-on-chip (NoC) as the communication infrastructure which consumes a large portion of the energy budget. As TSVs consume much less energy than horizontal links in 3-D MPSoCs when transmitting the same amount data due to the reduced interconnect distance between vertical adjacent cores, it motivates to allocate heavily communicating tasks within the same vertical stack as much as possible, and thus traffic is restricted in the third dimension to reduce interconnect energy. However, aggregating active tasks within the same stack probably exacerbates the power density and result in hot spots. In this paper, we explore the tradeoff between thermal and interconnect energy when allocating tasks in 3-D Homogeneous MPSoCs, and propose an efficient heuristic. Experimental results show that the proposed technique can reduce interconnect energy by more than 25% on average with almost the same peak temperature when compared with prior thermal-balanced solutions.