WIP: Iterative Post-training Pruning with Weighted Importance Estimation for Large Language Models
摘要
Modern large language models (LLMs) achieve impressive accuracy but are difficult to deploy due to their enormous size and computational demands. Post-training pruning—removing redundant weights from a pre-trained model without retraining—promises to mitigate these issues but often risks channel collapse, where entire neurons are inadvertently zeroed out, especially at higher sparsity levels. We introduce a new Weighted-Iterative Pruning (WIP) approach that tackles these challenges through two key innovations. First, our weighted importance metric strikes a tunable balance between row-wise and column-wise contributions of the weight matrix, preventing over-pruning of entire channels. Second, we adopt an iterative multi-stage pruning strategy that recalculates importance scores after each partial prune, mitigating the greedy errors seen in one-shot methods. Experiments across multiple LLMs and benchmarks show that WIP preserves perplexity and zero-shot accuracy better than existing techniques, especially at high sparsities. Additionally, our 2:4 semi-structured pruned models achieve real-world inference speedups of up to 1.88 \(\times \) on GPUs, underscoring WIP’s practicality for resource-constrained environments. Our code is publicly available at https://github.com/truongdo619/WIP .