模型合并

Search documents
字节Seed新作:模型合并如何改变大模型预训练范式
机器之心· 2025-06-06 09:12AI Processing
LoRA中到底有多少参数冗余?新研究:砍掉95%都能保持高性能
机器之心· 2025-05-02 04:39
Core Viewpoint - The article introduces the LoRI technology, which demonstrates that significantly reducing the trainable parameters of LoRA can still maintain strong model performance, achieving comparable or superior results to full fine-tuning and other methods while using only 5% of LoRA's parameters [1][9]. Summary by Sections LoRA and Its Limitations - LoRA is widely adopted for parameter-efficient fine-tuning (PEFT) but still incurs significant memory overhead, especially in large models [3][4]. - Recent research indicates substantial redundancy in incremental parameters, prompting the development of LoRI, which reduces the number of trainable parameters while preserving model knowledge [4]. LoRI Methodology - LoRI keeps the low-rank matrix A fixed as a random projection and uses a task-specific sparse mask to train matrix B, allowing for significant parameter reduction [4][13]. - Even with 90% sparsity in B, LoRI maintains good performance, indicating that the adaptation process does not require updating A [4][17]. Multi-Task Learning and Adapter Merging - Multi-task learning is essential for creating versatile models, but training on mixed datasets is costly. LoRI allows for the merging of existing models without retraining, effectively combining LoRA adapters for multi-task capabilities [7]. - Directly merging heterogeneous LoRA can lead to parameter interference, but LoRI mitigates this by mapping task-specific adapters to nearly orthogonal subspaces [7][20]. Continuous Learning and Safety - LoRI provides a lightweight continuous learning method that maintains safety while adapting to new tasks, addressing the challenge of catastrophic forgetting [8][22]. - The two-phase training process for safety adapters shows that LoRI-S outperforms other methods in retaining safety alignment, even under aggressive sparsity [22][23]. Performance Evaluation - Extensive experiments on various benchmarks show that LoRI achieves or exceeds the performance of full fine-tuning and other PEFT methods while using 95% fewer trainable parameters [9][19]. - In single-task performance, LoRI variants demonstrate competitive results across natural language understanding, mathematics, programming, and safety tasks [19][20]. Conclusion - Overall, LoRI presents an effective and lightweight approach to building safe adapters that support downstream task adaptation while maintaining alignment [23].