CSV-Decode: Certifiable Sub-Vocabulary Decoding for Efficient Large Language Model Inference

Fuente: arXiv
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Auteurs principaux: Liu, Dong, Yu, Yanxuan, Lengerich, Ben
Format: Preprint
Publié: 2025
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author Liu, Dong
Yu, Yanxuan
Lengerich, Ben
author_facet Liu, Dong
Yu, Yanxuan
Lengerich, Ben
contents Large language models face significant computational bottlenecks during inference due to the expensive output layer computation over large vocabularies. We present CSV-Decode, a novel approach that uses geometric upper bounds to construct small sub-vocabularies for each decoding step, enabling efficient sparse computation while maintaining dual correctness guarantees: exact top-$k$ certification and $\varepsilon$-certified softmax approximations. Our method clusters vocabulary embeddings offline and uses centroid-plus-radius bounds to identify which tokens can be safely omitted from computation. We provide a complete system implementation with sparse GEMV kernels, multi-GPU sharding, and CUDA Graph optimization. Experimental results demonstrate significant speedup over full vocabulary decoding while maintaining distributional guarantees and low fallback rates. Our code implementation available at \href{https://github.com/FastLM/CSV-Decode}{https://github.com/FastLM/CSV-Decode}.
format Preprint
id arxiv_https___arxiv_org_abs_2511_21702
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle CSV-Decode: Certifiable Sub-Vocabulary Decoding for Efficient Large Language Model Inference
Liu, Dong
Yu, Yanxuan
Lengerich, Ben
Computation and Language
Artificial Intelligence
Large language models face significant computational bottlenecks during inference due to the expensive output layer computation over large vocabularies. We present CSV-Decode, a novel approach that uses geometric upper bounds to construct small sub-vocabularies for each decoding step, enabling efficient sparse computation while maintaining dual correctness guarantees: exact top-$k$ certification and $\varepsilon$-certified softmax approximations. Our method clusters vocabulary embeddings offline and uses centroid-plus-radius bounds to identify which tokens can be safely omitted from computation. We provide a complete system implementation with sparse GEMV kernels, multi-GPU sharding, and CUDA Graph optimization. Experimental results demonstrate significant speedup over full vocabulary decoding while maintaining distributional guarantees and low fallback rates. Our code implementation available at \href{https://github.com/FastLM/CSV-Decode}{https://github.com/FastLM/CSV-Decode}.
title CSV-Decode: Certifiable Sub-Vocabulary Decoding for Efficient Large Language Model Inference
topic Computation and Language
Artificial Intelligence
url https://arxiv.org/abs/2511.21702