SageBwd: A Trainable Low-bit Attention

Fuente: arXiv
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Hauptverfasser: Zhang, Jintao, Chen, Marco, Wang, Haoxu, Jiang, Kai, Stoica, Ion, Gonzalez, Joseph E., Chen, Jianfei, Zhu, Jun
Format: Preprint
Veröffentlicht: 2026
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author Zhang, Jintao
Chen, Marco
Wang, Haoxu
Jiang, Kai
Stoica, Ion
Gonzalez, Joseph E.
Chen, Jianfei
Zhu, Jun
author_facet Zhang, Jintao
Chen, Marco
Wang, Haoxu
Jiang, Kai
Stoica, Ion
Gonzalez, Joseph E.
Chen, Jianfei
Zhu, Jun
contents Low-bit attention, such as SageAttention, has emerged as an effective approach for accelerating model inference, but its applicability to training remains poorly understood. In prior work, we introduced SageBwd, a trainable INT8 attention that quantizes six of seven attention matrix multiplications while preserving fine-tuning performance. However, SageBwd exhibited a persistent performance gap to full-precision attention (FPA) during pre-training. In this work, we investigate why this gap occurs and demonstrate that SageBwd matches full-precision attention during pretraining. Through experiments and theoretical analysis, we reach a few important insights and conclusions: (i) QK-norm is necessary for stable training at large tokens per step, (ii) quantization errors primarily arise from the backward-pass score gradient dS, (iii) reducing tokens per step enables SageBwd to match FPA performance in pre-training, and (iv) K-smoothing remains essential for training stability, while Q-smoothing provides limited benefit during pre-training.
format Preprint
id arxiv_https___arxiv_org_abs_2603_02170
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle SageBwd: A Trainable Low-bit Attention
Zhang, Jintao
Chen, Marco
Wang, Haoxu
Jiang, Kai
Stoica, Ion
Gonzalez, Joseph E.
Chen, Jianfei
Zhu, Jun
Machine Learning
Artificial Intelligence
Low-bit attention, such as SageAttention, has emerged as an effective approach for accelerating model inference, but its applicability to training remains poorly understood. In prior work, we introduced SageBwd, a trainable INT8 attention that quantizes six of seven attention matrix multiplications while preserving fine-tuning performance. However, SageBwd exhibited a persistent performance gap to full-precision attention (FPA) during pre-training. In this work, we investigate why this gap occurs and demonstrate that SageBwd matches full-precision attention during pretraining. Through experiments and theoretical analysis, we reach a few important insights and conclusions: (i) QK-norm is necessary for stable training at large tokens per step, (ii) quantization errors primarily arise from the backward-pass score gradient dS, (iii) reducing tokens per step enables SageBwd to match FPA performance in pre-training, and (iv) K-smoothing remains essential for training stability, while Q-smoothing provides limited benefit during pre-training.
title SageBwd: A Trainable Low-bit Attention
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2603.02170