VIA-SD: Verification via Intra-Model Routing for Speculative Decoding

Hugging Face Daily Papers Papers

Summary

VIA-SD introduces a multi-tier speculative decoding framework using intra-model routing to reduce verification costs, achieving significant speedups over traditional approaches.

Speculative decoding (SD) addresses the high inference costs of LLMs by having lightweight drafters generate candidates for large verifiers to validate in parallel. Existing draft-verify methods use binary decisions: accept or fully recompute. Yet we find that many rejected tokens can be verified correctly by a slim submodel derived from the full verifier via intra-model routing, instead of the full verifier. This motivates our slim-verifier to handle tokens requiring moderate verification resources, reducing expensive large-model calls. We propose Verification via Intra-Model Routing for Speculative Decoding (VIA-SD), a multi-tier framework using a routed slim-verifier. Draft tokens are processed hierarchically: direct acceptance for high-confidence cases, slim-verifier regeneration for medium-confidence cases, and full-model verification for uncertain cases. Across four representative tasks and multiple model families, VIA-SD reduces rejection rates by 0.10-0.22 and delivers 10-20% speedups over strong SD baselines, while achieving 2.5-3x acceleration over non-drafting decoding. Moreover, VIA-SD is compatible with existing SD frameworks without modifying their training procedures. Our results suggest multi-tier SD as a general paradigm for scalable and efficient LLM inference. Project page: https://zju-xyc.github.io/VIA-SD-Project-Page/
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Cached at: 06/12/26, 10:52 AM

Paper page - VIA-SD: Verification via Intra-Model Routing for Speculative Decoding

Source: https://huggingface.co/papers/2606.12243

Abstract

VIA-SD introduces a multi-tier speculative decoding framework that uses intra-model routing to reduce verification costs by employing slim submodels for medium-confidence token validation, achieving significant speedups over traditional approaches.

Speculative decoding(SD) addresses the high inference costs of LLMs by having lightweightdraftersgenerate candidates for largeverifiersto validate in parallel. Existing draft-verify methods use binary decisions: accept or fully recompute. Yet we find that many rejected tokens can be verified correctly by a slim submodel derived from the full verifier viaintra-model routing, instead of the full verifier. This motivates ourslim-verifierto handle tokens requiring moderate verification resources, reducing expensive large-model calls. We propose Verification viaIntra-Model RoutingforSpeculative Decoding(VIA-SD), amulti-tier frameworkusing a routedslim-verifier. Draft tokens are processed hierarchically: direct acceptance for high-confidence cases,slim-verifierregeneration for medium-confidence cases, and full-model verification for uncertain cases. Across four representative tasks and multiple model families, VIA-SD reduces rejection rates by 0.10-0.22 and delivers 10-20%speedups over strong SD baselines, while achieving 2.5-3x acceleration over non-drafting decoding. Moreover, VIA-SD is compatible with existing SD frameworks without modifying their training procedures. Our results suggest multi-tier SD as a general paradigm for scalable and efficient LLM inference. Project page: https://zju-xyc.github.io/VIA-SD-Project-Page/

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What is Speculative Decoding? (trending on paperswithco.de) [R]

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Speculative decoding is an inference optimization technique that uses a fast draft model to propose future tokens verified in parallel by a larger model, improving LLM generation speed. The article highlights its trending status on Papers with Code and a recent SGLang blog post about state-of-the-art latencies using DFlash models.