Strega : An HTTP Server for FPGAs

The computer architecture landscape is being reshaped by the new opportunities, challenges and constraints brought by the cloud. On the one hand, high-level applications profit from specialised hardware to boost their performance and reduce deployment costs. On the other hand, cloud providers maximise the CPU time allocated to client applications by offloading infrastructure tasks to hardware accelerators. While it is well understood how to do this for, e.g., network function virtualisation and protocols such as TCP/IP, support for higher networking layers is still largely missing, limiting the potential of accelerators. In this paper, we present S trega , an open-source 1 light-weight HTTP server that enables crucial functionality such as FPGA-accelerated functions being called through a RESTful protocol (FPGA-as-a-Function). Our experimental analysis shows that a single S trega node sustains a throughput of 1.7 M HTTP requests per second with an end-to-end latency as low as 16 μ s, outperforming nginx running on 32 vCPUs in both metrics, and can even be an alternative to the traditional OpenCL flow over the PCIe bus. Through this work, we pave the way for running microservices directly on FPGAs, bypassing CPU overhead and realising the full potential of FPGA acceleration in distributed cloud applications.