GRASPrune: Global Gating for Budgeted Structured Pruning of Large Language Models

Fuente: arXiv
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Main Authors: Wang, Ziyang, Xiao, Jiangfeng, Xiao, Chuan, Li, Ruoxiang, Mao, Rui, Qin, Jianbin
Format: Preprint
Published: 2026
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author Wang, Ziyang
Xiao, Jiangfeng
Xiao, Chuan
Li, Ruoxiang
Mao, Rui
Qin, Jianbin
author_facet Wang, Ziyang
Xiao, Jiangfeng
Xiao, Chuan
Li, Ruoxiang
Mao, Rui
Qin, Jianbin
contents Large language models (LLMs) are expensive to serve because model parameters, attention computation, and KV caches impose substantial memory and latency costs. We present GRASPrune, a structured pruning framework applied after pretraining that jointly prunes FFN channels and KV head groups under a single global budget. Instead of learning importance scores without constraints and applying the budget only after training, GRASPrune learns lightweight gate scores with a projected straight-through estimator that enforces a hard mask satisfying the budget at every step while keeping the backbone weights frozen. After the mask is fixed, we calibrate scaling factors on the retained units to mitigate scale mismatch caused by pruning, and fold these factors into the pruned weights to obtain a smaller dense checkpoint with no extra parameters at inference. On LLaMA-2-7B, GRASPrune removes 50% of parameters and achieves 12.18 perplexity on WikiText-2 while maintaining competitive average zero-shot accuracy on five benchmarks, using four epochs on 512 unlabeled calibration sequences on a single NVIDIA A100 80GB GPU without any full model fine-tuning.
format Preprint
id arxiv_https___arxiv_org_abs_2604_19398
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle GRASPrune: Global Gating for Budgeted Structured Pruning of Large Language Models
Wang, Ziyang
Xiao, Jiangfeng
Xiao, Chuan
Li, Ruoxiang
Mao, Rui
Qin, Jianbin
Artificial Intelligence
Large language models (LLMs) are expensive to serve because model parameters, attention computation, and KV caches impose substantial memory and latency costs. We present GRASPrune, a structured pruning framework applied after pretraining that jointly prunes FFN channels and KV head groups under a single global budget. Instead of learning importance scores without constraints and applying the budget only after training, GRASPrune learns lightweight gate scores with a projected straight-through estimator that enforces a hard mask satisfying the budget at every step while keeping the backbone weights frozen. After the mask is fixed, we calibrate scaling factors on the retained units to mitigate scale mismatch caused by pruning, and fold these factors into the pruned weights to obtain a smaller dense checkpoint with no extra parameters at inference. On LLaMA-2-7B, GRASPrune removes 50% of parameters and achieves 12.18 perplexity on WikiText-2 while maintaining competitive average zero-shot accuracy on five benchmarks, using four epochs on 512 unlabeled calibration sequences on a single NVIDIA A100 80GB GPU without any full model fine-tuning.
title GRASPrune: Global Gating for Budgeted Structured Pruning of Large Language Models
topic Artificial Intelligence
url https://arxiv.org/abs/2604.19398