Dataflow Is All You Need

Darshan Gandhi, Pushkar Nandkar, David Koeplinger, Nasim Farahini, Romy Tsoupidi, Samuel Rydh, Matheen Musaddiq, Tuowen Zhao, Reid Goodbar, Nathan Sheeley, Leon Zhang, Matthew Shaffer, John Long, Han Wang, Angela Wang, Arjun Sabnis, Joshua Brot, Yun Du, Hakan Zeffer, Mingran Wang, Raghu Prabhakar

Proceedings of Machine Learning and Systems 8 (MLSys 2026) Conference

The autoregressive decode phase of token generation is often a major performance bottleneck in modern AI workflows due to its memory-bandwidth-bound characteristics, which are amplified by powerful open-source models with large context windows and techniques such as chain-of-thought reasoning. Popular GPU architectures extract as little as 21\% of the available memory bandwidth from loading weights and KV caches, as the scope of asynchronous execution is limited by CPU scheduling overheads, kernel synchronization overheads, and inadequate compute-communication overlap. While prior work attempts to address these overheads with kernel fusion and asynchronous execution on GPUs, they mostly focus on a single GPU and do not generalize across different model architectures. We argue that to truly mitigate these overheads, $\textit{Dataflow Is All You Need}$. In this paper, we chronicle a co-design approach to achieve peak decoding performance on a dataflow architecture -- the SambaNova SN40 Reconfigurable Dataflow Unit (RDU), substantiated by three key dataflow enabled optimizations -- $\textit{KernelLooping}$, $\textit{BatchStreaming}$, and $\textit{ScheduleOffloading}$ -- that generalize to models that are small, large, dense, MoEs, or hybrids, and that use different attention mechanisms. Collectively, these optimizations deliver more than $\textbf{75}$\% of the theoretical peak roofline performance for a wide range of popular open-source models and demonstrate a speedup of more than $\textbf{6$\times$}$ when using popular speculative decoding techniques. Finally, we show that speculative decoding is $\textbf{1.7$\times$}$ faster on 16 SN40 ~chips than on a DGX H100 despite both systems having comparable HBM bandwidth. The techniques described in this paper and the models used in the evaluation are deployed in a production AI inference cloud at $\href{}{cloud.sambanova.ai}$.