SafeStart: Mitigating the Overlooked Safety Cost of Active Expert Reduction in MoE LLM Serving
This paper reveals that expert-reduction methods for MoE LLM serving, which speed up inference by running fewer experts per token, can weaken refusal of harmful requests. The authors introduce SafeStart, which runs all experts for the prompt and first eight generated tokens, then reduces experts afterward, preserving most speedup while restoring safety. In vLLM on an RTX A6000, SafeStart keeps at least 85% of the offline decode speedup at batch sizes 8 and 32 and reduces harmful compliance increases to near baseline levels across three models.
Why it matters: Provides a concrete, recent finding that expert reduction in MoE serving has safety costs and offers a practical mitigation, valuable for AI serving systems and safety research.