Virtualization of Hardware Accelerators in a Network-on-Chip.

Networks-on-Chip (NoCs) are beneficial for reconfigurable systems that require a high degree of parallel and scalable communication. NoCs are reusable as hardware accelerators can be exchanged via dynamic partial reconfiguration. Nevertheless, NoCs are not conceptualized for the use in a virtualized environment where applications from multiple virtual machines have to share reconfigurable resources. Many state-of-the-art works assign hardware accelerators exclusively to a single virtual machine, which limits the number of processed hardware tasks and leads to underutilization of FPGA area. Therefore, we provide a NoC virtualization layer that allows the execution of several pipelined hardware tasks agnostic of the location of the required hardware accelerators. The allocation of tasks to processing elements can be adapted to dynamically changing requirements, while unauthorized access is prohibited. Further, we provide a scheduler that schedules hardware tasks in spatial and temporal respect to processing elements in the NoC. The proposed heuristic considers task priorities, a possible reuse of accelerators and hop counts. In over-load conditions, the tasks with the lowest priorities are postponed. Our virtualization layer increases the number of tasks processed by 22.6% compared to an approach that grants exclusive access.