Trade-offs in the Configuration of a Network on Chip for Multiple Use-Cases

Systems on chip (SoC) are becoming increasingly complex, with a large number of applications integrated on the same chip. Such a system often supports a large number of use-cases and is dynamically reconfigured when platform conditions or user requirements change. Networks on chip (NoC) offer the designer unsurpassed runtime flexibility. This flexibility stems from the programmability of the individual routers and network interfaces. When a change in use-case occurs, the application task graph and the network connections change. To mitigate the complexity in programming the many registers controlling the NoC, an abstraction in the form of a configuration library is needed. In addition, such a library must leave the modified system in a consistent state, from which normal operation can continue. In this paper we present the facilities for controlling change in a reconfigurable NoC. We show the architectural additions and the many trade-offs in the design of a run-time library for NoC reconfiguration. We qualitatively and quantitatively evaluate the performance, memory requirements, predictability and reusability of the different implementations