Reducing communication costs on Dynamic Networks-on-Chip through runtime relocation of tasks

Incremental on-line scheduling of tasks on reconfigurable devices may lead to suboptimal placements of tasks, in particular when communicating tasks and components have to be placed far apart due to the current device occupation. This includes computing modules, memories and peripherals and leads to high latency and high network bandwidth in Dynamic Networks-on-Chip, thus reducing the performance of applications. Relocation of tasks at runtime provides a way to optimize the placement of tasks with the goal of reducing communication distance between communication partners, resulting in an increase of performance of the whole system. In this work, we introduce a communication-aware on-line scheduler, as well as relocation strategies to cope with the drawback of device fragmentation. By selecting a feasible relocation task set, reordering the selected tasks and replace them, we are able to show an improvement of up to 25% in communication costs, with a lower rejection rate of tasks.