DHL: Enabling Flexible Software Network Functions with FPGA Acceleration

Network function virtualization (NFV) aims to run software network functions (NFs) in commodity servers. As CPU is general-purpose hardware, one has to use many CPU cores to handle complex packet processing at line rate. Owing to its performance and programmability, FPGA has emerged as a promising platform for NFV. However, the programmable logic blocks on an FPGA board are limited and expensive. Implementing the entire NFs on FPGA is thus resource-demanding. Further, FPGA needs to be reprogrammed when the NF logic changes which can take hours to synthesize the code. It is thus inflexible to use FPGA to implement the entire NFV service chain. We present dynamic hardware library (DHL), a novel CPU-FPGA co-design framework for NFV with both high performance and flexibility. DHL employs FPGA as accelerators only for complex packet processing. It abstracts accelerator modules in FPGA as a hardware function library, and provides a set of transparent APIs for developers. DHL supports running multiple concurrent software NFs with distinct accelerator functions on the same FPGA and provides data isolation among them. We implement a prototype of DHL with Intel DPDK. Experimental results demonstrate that DHL greatly reduces the programming efforts to access FPGA, brings significantly higher throughput and lower latency over CPU-only implementation, and minimizes the CPU resources.