FlexDriver: A Network Driver for Your Accelerator

We propose a new system design for connecting hardware and FPGA accelerators to the network, allowing the accelerator to directly control commodity Network Interface Cards (NICs) without using the CPU. This enables us to solve the key challenge of leveraging existing NIC hardware offloads such as virtualization, tunneling, and RDMA for accelerator networking. Our approach supports a diverse set of use cases, from direct network access for disaggregated accelerators to inline-Acceleration of the network stack, all without the complex networking logic in the accelerator. To demonstrate the feasibility of this approach, we build FlexDriver (FLD), an on-Accelerator hardware module that implements a NIC data-plane driver. Our main technical contribution is a mechanism that compresses the NIC control structures by two orders of magnitude, allowing FLD to achieve high networking scalability with low die area cost and no bandwidth interference with the accelerator logic. The prototype for NVIDIA Innova-2 FPGA SmartNICs showcases our design's utility for three different accelerators: A disaggregated LTE cipher, an IP-defragmentation inline accelerator, and an IoT cryptographic-Token authentication offload. These accelerators reach 25 Gbps line rate and leverage the NIC for RDMA processing, VXLAN tunneling, and traffic shaping without CPU involvement.