Accelerating Packet Processing in Container Overlay Networks via Packet-level Parallelism.

Overlay networks serve as the de facto network virtualization technique for providing connectivity among distributed containers. Despite the flexibility in building customized private container networks, overlay networks incur significant performance loss compared to physical networks (i.e., the native). The culprit lies in the inclusion of multiple network processing stages in overlay networks, which prolongs the network processing path and overloads CPU cores. In this paper, we propose MFLOW, a novel packet steering approach to parallelize the in-kernel data path of network flows. MFLOW exploits packet-level parallelism in the kernel network stack by splitting the packets of the same flow into multiple micro-flows, which can be processed in parallel on multiple cores. MFLOW devises new, generic mechanisms for flow splitting while preserving in-order packet delivery with little overhead. Our evaluation with both micro-benchmarks and real-world applications demonstrates the effectiveness of MFLOW, with significantly improved performance - e.g., by 81% in TCP throughput and 139% in UDP compared to vanilla overlay networks. MFLOW even achieved higher TCP throughput than the native (e.g., 29.8 vs. 26.6 Gbps).