不用跑一堆配置，用公式就能算清LLM服务的瓶颈在哪，还拿DeepSeek-V3.2在H20上做了实测，对推理优化的人很有参考价值。
该论文提出Floor-First残差驱动分流工作流，将解码步骤建模为HBM字节、FLOPs、网络字节、网络消息、KV容量五维资源向量，通过求和与最大值计算乐观下界和悲观上界，无需profiler即可判断重叠质量。基于DeepSeek-V3.2 671B MoE/MLA模型在16块NVIDIA H20 GPU上的案例显示，TP16解码受KV容量限制约70个并发8K请求；稀疏注意力可移除KV带宽项但容量墙不变；EP16+DP-attention布局将容量墙提升至约644，但单流延迟比TP布局慢2.4倍。该方法通过壁排序比较部署方案，替代点基准，并支持新注意力或状态空间模块的扩展。
Think Before You Grid-Search: Floor-First Triage for LLM Serving
LLM serving optimization typically benchmarks many configurations and reaches for heavy profilers when latency targets are missed. We argue for the reverse discipline: estimation is the analytical layer of profiling -- without it, optimization degenerates to grid search. Floor First is a residual-driven triage workflow. Each decode step is modeled as a five-dimensional resource vector (HBM bytes, FLOPs, network bytes, network messages, KV capacity); summing within a resource and maximizing across resources gives an optimistic floor, the plain sum a pessimistic one. Where a measurement lands inside this [max, sum] interval reads out overlap quality before any profiler is opened, and profilers escalate only on residuals above a stated threshold. Deployment alternatives are compared by wall ordering -- which resource wall binds first as load grows -- rather than by point benchmarks. The account is compositional: new attention or state-space variants enter by declaring one module, and the workflow ships as a zero-dependency calculator plus an agent skill that enforces the discipline in agentic optimization loops. As a case study we analyze a DeepSeek-V3.2-style 671B MoE/MLA model on 16 NVIDIA H20 GPUs, whose ridge point of ~74 FLOP/byte (vs ~590 for H100) makes it an extreme decode-oriented part. The floors show TP16 decoding is KV-capacity-limited to ~70 concurrent 8K requests; sparse attention removes the KV-bandwidth term but not the capacity wall; an EP16+DP-attention layout accepts slightly worse same-batch weight traffic for an order-of-magnitude higher capacity wall (~644) -- while single-stream latency favors TP by 2.4x. The layout judgment is thus a computable function of the operating point, explaining why production deployments on identical hardware have shipped opposite attention layouts.