BURST: Seeking High-performance, Interoperability and Scalability in Soft-RDMA#

Huijun Shen (Hunan University), Zelong Yue, Jian Yang, et al. (ByteDance), Xijin Yin, et al. (Hunan University)

• Why: Heterogeneous pods — commercial RNICs, plain Ethernet NICs, in-house hardware — are now the norm, and non-RNIC↔RNIC traffic keeps falling back to TCP. ByteDance attacks exactly the interoperability wall that limits RDMA estate scaling during LLM-infra buildouts.
• What: A user-space software RDMA stack that runs unmodified Verbs applications on ordinary Ethernet NICs at 400G: 98.7% line-rate bandwidth, 3.2–6.3x kernel RXE throughput, LLM inference latency at 25.2% of TCP, and 12x faster connection setup than native RDMA CM.
• How: Runs as an independent user-space process with full Verbs API compatibility; lock-free DPDK data plane for line-rate packet processing; Intel DSA offload to cut CPU cost; kernel-bypass connection manager.
• Where applicable: Data centers with mixed NIC estates, especially where RNIC hardware can't be everywhere (storage-attached hosts, upgraded clusters). x86-specific today (DPDK + Intel DSA); ByteDance production-workload validation, academic authors.