SparseSSM: Efficient Selective Structured State Space Models Can Be Pruned in One-Shot

Fuente: arXiv
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Main Authors: Tuo, Kaiwen, Wang, Huan
Format: Preprint
Published: 2025
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author Tuo, Kaiwen
Wang, Huan
author_facet Tuo, Kaiwen
Wang, Huan
contents State-space language models such as Mamba match Transformer quality while permitting linear complexity inference, yet still comprise billions of parameters that hinder deployment. Existing one-shot pruning methods are tailored to attention blocks and fail to account for the time-shared and discretized state-transition matrix at the heart of the selective state-space module (SSM). In this paper, we introduce SparseSSM, the first training-free pruning framework that extends the classic optimal brain surgeon (OBS) framework to state space architectures. Our layer-wise algorithm (i) derives an approximate second-order saliency score that aggregates Hessian-trace information across time steps, (ii) incorporates a component sensitivity analysis to guide feed-forward network (FFN) pruning, which also sheds light on where redundancy resides in mamba architecture, (iii) can be easily extended to semi-structured and structured sparsity. Empirically, we prune 50% of SSM weights without fine-tuning and observe no zero-shot accuracy loss, achieving the current state-of-the-art pruning algorithm for Mamba-based LLMs.
format Preprint
id arxiv_https___arxiv_org_abs_2506_09613
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle SparseSSM: Efficient Selective Structured State Space Models Can Be Pruned in One-Shot
Tuo, Kaiwen
Wang, Huan
Machine Learning
State-space language models such as Mamba match Transformer quality while permitting linear complexity inference, yet still comprise billions of parameters that hinder deployment. Existing one-shot pruning methods are tailored to attention blocks and fail to account for the time-shared and discretized state-transition matrix at the heart of the selective state-space module (SSM). In this paper, we introduce SparseSSM, the first training-free pruning framework that extends the classic optimal brain surgeon (OBS) framework to state space architectures. Our layer-wise algorithm (i) derives an approximate second-order saliency score that aggregates Hessian-trace information across time steps, (ii) incorporates a component sensitivity analysis to guide feed-forward network (FFN) pruning, which also sheds light on where redundancy resides in mamba architecture, (iii) can be easily extended to semi-structured and structured sparsity. Empirically, we prune 50% of SSM weights without fine-tuning and observe no zero-shot accuracy loss, achieving the current state-of-the-art pruning algorithm for Mamba-based LLMs.
title SparseSSM: Efficient Selective Structured State Space Models Can Be Pruned in One-Shot
topic Machine Learning
url https://arxiv.org/abs/2506.09613