dParallel: Learnable Parallel Decoding for dLLMs

Fuente: arXiv
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Autores principales: Chen, Zigeng, Fang, Gongfan, Ma, Xinyin, Yu, Ruonan, Wang, Xinchao
Formato: Preprint
Publicado: 2025
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author Chen, Zigeng
Fang, Gongfan
Ma, Xinyin
Yu, Ruonan
Wang, Xinchao
author_facet Chen, Zigeng
Fang, Gongfan
Ma, Xinyin
Yu, Ruonan
Wang, Xinchao
contents Diffusion large language models (dLLMs) have recently drawn considerable attention within the research community as a promising alternative to autoregressive generation, offering parallel token prediction and lower inference latency. Yet, their parallel decoding potential remains largely underexplored, as existing open-source models still require nearly token-length decoding steps to ensure performance. To address this, we introduce dParallel, a simple and effective method that unlocks the inherent parallelism of dLLMs for fast sampling. We identify that the key bottleneck to parallel decoding arises from the sequential certainty convergence for masked tokens. Building on this insight, we introduce the core of our approach: certainty-forcing distillation, a novel training strategy that distills the model to follow its original sampling trajectories while enforcing it to achieve high certainty on masked tokens more rapidly and in parallel. Extensive experiments across various benchmarks demonstrate that our method can dramatically reduce the number of decoding steps while maintaining performance. When applied to the LLaDA-8B-Instruct model, dParallel reduces decoding steps from 256 to 30 on GSM8K, achieving an 8.5x speedup without performance degradation. On the MBPP benchmark, it cuts decoding steps from 256 to 24, resulting in a 10.5x speedup while maintaining accuracy. Our code is available at https://github.com/czg1225/dParallel
format Preprint
id arxiv_https___arxiv_org_abs_2509_26488
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle dParallel: Learnable Parallel Decoding for dLLMs
Chen, Zigeng
Fang, Gongfan
Ma, Xinyin
Yu, Ruonan
Wang, Xinchao
Computation and Language
Diffusion large language models (dLLMs) have recently drawn considerable attention within the research community as a promising alternative to autoregressive generation, offering parallel token prediction and lower inference latency. Yet, their parallel decoding potential remains largely underexplored, as existing open-source models still require nearly token-length decoding steps to ensure performance. To address this, we introduce dParallel, a simple and effective method that unlocks the inherent parallelism of dLLMs for fast sampling. We identify that the key bottleneck to parallel decoding arises from the sequential certainty convergence for masked tokens. Building on this insight, we introduce the core of our approach: certainty-forcing distillation, a novel training strategy that distills the model to follow its original sampling trajectories while enforcing it to achieve high certainty on masked tokens more rapidly and in parallel. Extensive experiments across various benchmarks demonstrate that our method can dramatically reduce the number of decoding steps while maintaining performance. When applied to the LLaDA-8B-Instruct model, dParallel reduces decoding steps from 256 to 30 on GSM8K, achieving an 8.5x speedup without performance degradation. On the MBPP benchmark, it cuts decoding steps from 256 to 24, resulting in a 10.5x speedup while maintaining accuracy. Our code is available at https://github.com/czg1225/dParallel
title dParallel: Learnable Parallel Decoding for dLLMs
topic Computation and Language
url https://arxiv.org/abs/2509.26488