Interleaved Function Stream Execution Model for Cache-Aware High-Speed Stateful Packet Processing

The evolving network infrastructure, particularly the 5G core network, is increasingly adopting cloud technologies. This shift brings to the forefront the challenge of meeting the demanding per-packet processing requirements posed by multi-hundred Gbps Ethernet NICs (network interface cards). While traditional NFV (network function virtualization) platforms are effective on older hardware, the per-packet run-to-completion (RTC) execution model for per-packet processing suffers from stalling on state access due to L1/L2 cache misses. Although previous work applying software prefetching can mitigate the issues, their applications are fundamentally limited by the nature of a single execution stream, hence limiting them to batch lookups, suffering from control-flow divergence, and requiring manual tuning. To address the limitations, we introduce a novel interleaved function stream execution model that exploits the function-level parallelism through memory-level parallelism, targeting feature-rich network functions such as 5G Core. To provide the visibility into network functions, we introduce a novel programming model based on the principle of Granular Decomposition, which provides deep visibility into the state access by decoupling the state in a more fine-grained manner compared to traditional modular approaches. We integrate these two innovative designs into a new open-source NF platform, which we refer to as GuNFu. We have tested GuNFu on widely deployed network functions such as 5G UPF (User Plane Function), 5G AMF (Access Management Function), NAT (Network Address Translator) and others. Extensive evaluations reveal that GuNFu can achieve throughput ranging from 1.5 to 6 times over the traditional modular approach.