SparseGPT

PALS: Percentile-aware per-layer sparsity improves LLM pruning on LLaMA-2 but not universally

PALS (Percentile-Aware Layerwise Sparsity) is a one-shot pruning method that assigns per-layer sparsity ratios based on the 99th percentile of activation magnitudes, bounded within ±5% of a target ratio. On LLaMA-2-7B at 50% sparsity, PALS achieves perplexity of 10.96 vs. 12.92 for uniform Wanda, a statistically significant improvement requiring no fine-tuning. However, gains are architecture-dependent: LLaMA-3-8B shows marginal improvement and Mistral-7B shows none. A notable negative finding is that gradient-based allocation performs worse than random, suggesting gradient magnitude is a poor proxy for the impact of discrete weight removal.