AWS details fused MoE kernel engineering on Hopper, yielding 2-4% throughput gains

AWS ML Blog · rss · 2026-10-13

An AWS ML Blog post breaks down kernel optimizations for MoE models on SageMaker. First, a Swap-AB matrix transpose works around Hopper's WGMMA M=64 operand layout constraint (decode-phase batches are often M=1), filling Tensor Cores and enabling async prefetching—delivering 2-4% end-to-end throughput gains on H200, upstreamed to vLLM 0.24.0+. Second, profiling shows the Triton backend consistently beats the default FLASHINFERCUTLASS path for FP8 tensor-quantized MoE at low concurrency, thanks to single-pass register-level fusion that reads HBM once.

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