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Main Authors: He, Zhitao, Yang, Haolin, Min, Rui, Qin, Zeyu, Fung, Yi R.
Format: Preprint
Published: 2026
Subjects:
Online Access:https://arxiv.org/abs/2605.01357
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author He, Zhitao
Yang, Haolin
Min, Rui
Qin, Zeyu
Fung, Yi R.
author_facet He, Zhitao
Yang, Haolin
Min, Rui
Qin, Zeyu
Fung, Yi R.
contents Large Language Models (LLMs) excel at long-context understanding but exhibit significant limitations in long-form generation. Existing studies primarily focus on single-generation quality, generally overlooking the volatility of the output. This volatility not only leads to significant computational costs but also severely impacts the models' reliable application. To address this gap, our work unfolds in three stages: benchmarking, probing, and mitigation. We first propose the VOlatility in Long-form Text Benchmark (VOLTBench), a novel heterogeneous-task benchmark designed to systematically quantify the length volatility of long-form generation. Subsequently, by analyzing attention traces, we conduct an in-depth probe to identify several common internal patterns that cause this volatility. Finally, to mitigate long-form output volatility, we propose Stable Generation via Logits Boosting (GLoBo), a lightweight decoding-stage optimization strategy, designed to significantly enhance both the length accuracy and stability of long-form generation without additional training. Extensive experiments on VOLTBench provide the first systematic confirmation of severe long-form output instability in mainstream models and validate that our proposed method successfully improves the mean output length of the base model by 148% and reduces the length volatility by 69%, while maintaining high generation quality.
format Preprint
id arxiv_https___arxiv_org_abs_2605_01357
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle On Stable Long-Form Generation: Benchmarking and Mitigating Length Volatility
He, Zhitao
Yang, Haolin
Min, Rui
Qin, Zeyu
Fung, Yi R.
Computation and Language
Large Language Models (LLMs) excel at long-context understanding but exhibit significant limitations in long-form generation. Existing studies primarily focus on single-generation quality, generally overlooking the volatility of the output. This volatility not only leads to significant computational costs but also severely impacts the models' reliable application. To address this gap, our work unfolds in three stages: benchmarking, probing, and mitigation. We first propose the VOlatility in Long-form Text Benchmark (VOLTBench), a novel heterogeneous-task benchmark designed to systematically quantify the length volatility of long-form generation. Subsequently, by analyzing attention traces, we conduct an in-depth probe to identify several common internal patterns that cause this volatility. Finally, to mitigate long-form output volatility, we propose Stable Generation via Logits Boosting (GLoBo), a lightweight decoding-stage optimization strategy, designed to significantly enhance both the length accuracy and stability of long-form generation without additional training. Extensive experiments on VOLTBench provide the first systematic confirmation of severe long-form output instability in mainstream models and validate that our proposed method successfully improves the mean output length of the base model by 148% and reduces the length volatility by 69%, while maintaining high generation quality.
title On Stable Long-Form Generation: Benchmarking and Mitigating Length Volatility
topic Computation and Language
url https://arxiv.org/abs/2605.01357