Title: StatsMerging: Statistics-Guided Model Merging via Task-Specific Teacher Distillation
Primary area: other topics in machine learning (i.e., none of the above)
Keywords: Model merging, efficient neural network, SVD, single value decomposition, statistics-guided, knowledge distillation

Abstract: As large models are increasingly deployed across various tasks, the limited GPU memory available for storing and executing task-specific models presents a growing bottleneck. Model merging has emerged as a promising solution to accommodate multiple large models within constrained memory budgets. While traditional multi-task learning methods attempt to merge common layers, they require labor-intensive annotated labels and incur significant computational overhead. Recent merging techniques aim to address this issue by combining models at inference time; however, these approaches often rely on simplistic heuristics, ignore weight distribution characteristics, assume architectural identity, or require access to test samples to infer merging coefficients, thereby limiting generalization and scalability. We present StatsMerging, a novel lightweight learning-based model merging method guided by weight distribution statistics without requiring ground truth labels or test samples. StatsMerging offers three key advantages: (1) It uniquely leverages singular values from singular value decomposition (SVD) to capture task-specific weight distributions, serving as a proxy for task importance to guide task coefficient learning; (2) It employs a lightweight learner StatsMergeLearner to model the weight distributions of task-specific pre-trained models, improving generalization and enhancing adaptation to unseen samples; (3) It introduces Task-Specific Teacher Distillation for merging vision models with heterogeneous architectures, a merging training paradigm that avoids costly ground-truth labels by task-specific teacher distillation. Notably, we present two types of knowledge distillation, (a) distilling knowledge from task-specific models to train StatsMergeLearner; and (b) for the first time, distilling knowledge from models with different architectures prior to merging, following a distill-then-merge paradigm. Extensive experiments across eight tasks demonstrate the effectiveness of StatsMerging. Our results show that StatsMerging outperforms state-of-the-art techniques, achieving overall accuracies of 94.5% for Vision and 77.6% for NLP, while further exhibiting strong generalization to unseen tasks, and robustness to image quality variations.

TL;DR: We present a novel lightweight learning-based model merging method guided by weight distribution statistics without requiring ground truth labels.