ASNI: Redefining the Interface Between SmartNICs and Applications

With a budget of 300 CPU cycles per packet, Network Functions Virtualisation (NFV) scenarios require efficient packet exchange mechanisms between NICs and CPUs. However, even the latest kernel bypass techniques, such as DPDK, can eat up 20% of the budget. This paper investigates the strain on CPUs due to escalating network speeds and the ability to exchange more packet metadata due to NICs becoming more feature-fledged and ''Smart''. We advocate for NICs to adapt to software needs rather than rely on drivers as translators. We analyze different applications and compare multiple packet buffers and data organization models. We then develop an API for the datapath that will compile into different buffer management models according to the application's needs. Introducing ASNI, we explore the potential to tailor packet descriptors for different applications, offloading the driver's work from the datapath so that the application receives the packets precisely as it needs them. We advocate for a vision where only a minimal driver on the host is required, retrieving CPU cycles to applications instead. We propose a prototype implementation on NVIDIA BlueField-3 SoC. Evaluated in multiple NFV scenarios, it manages to serve 2.2x more traffic under the same loss ratio constraints than state-of-the-art solutions.