Cohere 新论文发现投机解码在细粒度 MoE 模型上即使 batch size 为 1 也能带来明显收益,而此前研究预测低 batch 下增益有限。论文指出 MoE 中相邻 token 共享 20% 到 45% 的专家,远高于独立路由预期的 4% 到 12%,因此验证额外 token 的代价更低。
New @cohere paper finds that speculative decoding works well on fine-grained MoE models even at batch size 1, where prior work predicted small gains.
Finds that in mixture-of-experts models, neighboring tokens share 20% to 45% of their experts, against 4% to 12% expected, which makes speculative decoding cheaper than predicted.
Speculative decoding lets a small drafter propose tokens that the big model checks in 1 pass. For MoE models, prior work said checking several tokens loads many extra experts, limiting gains at low batch sizes.
They tested 10 MoE models from 30B to 1T parameters and profiled them on H100 GPUs. Consecutive tokens reuse many experts, and small experts use GPU bandwidth well, so checking extra tokens costs little.
Adjacent tokens shared 20% to 45% of their experts, against 4% to 12% expected from independent routing. For Qwen3-235B in FP8, the verification pass ran at 89% of a normal decoding step's speed, against 52% predicted.
For low-batch MoE serving, such as agent workloads, benchmark speculative decoding on your hardware instead of ruling it out.
来源:Rohan Paul · x.com