Virtual networks -- distributed communication resource management

Abstract

Networks-on-Chip (NoC) enable scalability for future manycore architectures, facilitating parallel communication between multiple cores. Applications running in parallel on a NoC-based architecture can affect each other due to overlapping communication. Quality-of-Service (QoS) must be supported by the communication infrastructure to execute communication-, real-time- and safety-critical applications on such an architecture. Different strategies have been proposed to provide QoS for point-to-point connections. These strategies allow each node to set up a limited number of connections to other nodes. In this work Virtual Networks (VN) are proposed to enable QoS for regions of a NoC-based architecture. Virtual Networks overcome the limitation of point-to-point connections. A VN behaves like an exclusive physical network. Virtual Networks can be defined and configured during runtime. The size of the VN region and the assigned bandwidth can be adjusted depending on the application requirements. Virtual Networks enable the decoupling of local from global communication. Therefore, the communication of the application mapped into the region is assigned to a Virtual Network established in that specific region. This concept targets packet-switched networks with virtual channels and is realized by an intelligent hardware unit that manages the virtual channel reservation process at system runtime. Virtual Networks can be established and administrated independent of each other, enabling distributed communication resource management. The proposed concept is implemented as a cycle-accurate SystemC simulation model. The simulation results of executing communicating graphs obtained from real application highlight the usefulness of Virtual Networks by showing improved throughput and reduced delay in the respective scenarios. A hardware implementation demonstrates a low impact on area utilization and power consumption.