Exploiting RapidWright in the Automatic Generation of Application-Specific FPGA Overlays

Overlay architectures implemented on FPGA devices have been proposed as a means to increase FPGA adoption in general-purpose computing. They provide the benefits of software such as flexibility and programmability, thus making it easier to build dedicated compilers. However, existing overlays are generic, resource and power hungry with performance usually an order of magnitude lower than bare metal implementations. As a result, FPGA overlays have been confined to research and some niche applications. In this paper, we introduce Application-Specific FPGA Overlays (AS-Overlays), which can provide bare-metal performance to FPGA overlays, thus opening doors for broader adoption. Our approach is based on the automatic extraction of hardware kernels from data flow applications. Extracted kernels are then leveraged for application-specific generation of hardware accelerators. Reconfiguration of the overlay is done with RapidWright which allows to bypass the HDL design flow. Through prototyping, we demonstrated the viability and relevance of our approach. Experiments show a productivity improvement up to 20x compared to the state of the art FPGA overlays, while achieving over 1.33x higher Fmax than direct FPGA implementation and the possibility of lower resource and power consumption compared to bare metal.