Linear Model Merging Unlocks Simple and Scalable Multimodal Data Mixture Optimization

Fuente: arXiv
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Autori principali: Berasi, Davide, Farina, Matteo, Mancini, Massimiliano, Ricci, Elisa
Natura: Preprint
Pubblicazione: 2026
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author Berasi, Davide
Farina, Matteo
Mancini, Massimiliano
Ricci, Elisa
author_facet Berasi, Davide
Farina, Matteo
Mancini, Massimiliano
Ricci, Elisa
contents Selecting the best data mixture is critical for successful Supervised Fine-Tuning (SFT) of Multimodal Large Language Models. However, determining the optimal mixture weights across multiple domain-specific datasets remains a significant bottleneck due to the combinatorial search space and the high cost associated with even a single training run. This is the so-called Data Mixture Optimization (DMO) problem. On the other hand, model merging unifies domain-specific experts through parameter interpolation. This strategy is efficient, as it only requires a single training run per domain, yet oftentimes leads to suboptimal models. In this work, we take the best of both worlds, studying model merging as an efficient strategy for estimating the performance of different data mixtures. We train domain-specific multimodal experts and evaluate their weighted parameter-space combinations to estimate the efficacy of corresponding data mixtures. We conduct extensive experiments on 14 multimodal benchmarks, and empirically demonstrate that the merged proxy models exhibit a high rank correlation with models trained on actual data mixtures. This decouples the search for optimal mixtures from the resource-intensive training process, thereby providing a scalable and efficient strategy for navigating the complex landscape of mixture weights. Code is publicly available at https://github.com/BerasiDavide/mLLMs_merging_4_DMO.
format Preprint
id arxiv_https___arxiv_org_abs_2602_04937
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Linear Model Merging Unlocks Simple and Scalable Multimodal Data Mixture Optimization
Berasi, Davide
Farina, Matteo
Mancini, Massimiliano
Ricci, Elisa
Machine Learning
Artificial Intelligence
Computation and Language
Selecting the best data mixture is critical for successful Supervised Fine-Tuning (SFT) of Multimodal Large Language Models. However, determining the optimal mixture weights across multiple domain-specific datasets remains a significant bottleneck due to the combinatorial search space and the high cost associated with even a single training run. This is the so-called Data Mixture Optimization (DMO) problem. On the other hand, model merging unifies domain-specific experts through parameter interpolation. This strategy is efficient, as it only requires a single training run per domain, yet oftentimes leads to suboptimal models. In this work, we take the best of both worlds, studying model merging as an efficient strategy for estimating the performance of different data mixtures. We train domain-specific multimodal experts and evaluate their weighted parameter-space combinations to estimate the efficacy of corresponding data mixtures. We conduct extensive experiments on 14 multimodal benchmarks, and empirically demonstrate that the merged proxy models exhibit a high rank correlation with models trained on actual data mixtures. This decouples the search for optimal mixtures from the resource-intensive training process, thereby providing a scalable and efficient strategy for navigating the complex landscape of mixture weights. Code is publicly available at https://github.com/BerasiDavide/mLLMs_merging_4_DMO.
title Linear Model Merging Unlocks Simple and Scalable Multimodal Data Mixture Optimization
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2602.04937