Scaling Laws for Forgetting during Finetuning with Pretraining Data Injection

Fuente: arXiv
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Autores principales: Bethune, Louis, Grangier, David, Busbridge, Dan, Gualdoni, Eleonora, Cuturi, Marco, Ablin, Pierre
Formato: Preprint
Publicado: 2025
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author Bethune, Louis
Grangier, David
Busbridge, Dan
Gualdoni, Eleonora
Cuturi, Marco
Ablin, Pierre
author_facet Bethune, Louis
Grangier, David
Busbridge, Dan
Gualdoni, Eleonora
Cuturi, Marco
Ablin, Pierre
contents A widespread strategy to obtain a language model that performs well on a target domain is to finetune a pretrained model to perform unsupervised next-token prediction on data from that target domain. Finetuning presents two challenges: (i) if the amount of target data is limited, as in most practical applications, the model will quickly overfit, and (ii) the model will drift away from the original model, forgetting the pretraining data and the generic knowledge that comes with it. We aim to derive scaling laws that quantify these two phenomena for various target domains, amounts of available target data, and model scales. We measure the efficiency of injecting pretraining data into the finetuning data mixture to avoid forgetting and mitigate overfitting. A key practical takeaway from our study is that injecting as little as 1% of pretraining data in the finetuning data mixture prevents the model from forgetting the pretraining set.
format Preprint
id arxiv_https___arxiv_org_abs_2502_06042
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Scaling Laws for Forgetting during Finetuning with Pretraining Data Injection
Bethune, Louis
Grangier, David
Busbridge, Dan
Gualdoni, Eleonora
Cuturi, Marco
Ablin, Pierre
Machine Learning
Computation and Language
A widespread strategy to obtain a language model that performs well on a target domain is to finetune a pretrained model to perform unsupervised next-token prediction on data from that target domain. Finetuning presents two challenges: (i) if the amount of target data is limited, as in most practical applications, the model will quickly overfit, and (ii) the model will drift away from the original model, forgetting the pretraining data and the generic knowledge that comes with it. We aim to derive scaling laws that quantify these two phenomena for various target domains, amounts of available target data, and model scales. We measure the efficiency of injecting pretraining data into the finetuning data mixture to avoid forgetting and mitigate overfitting. A key practical takeaway from our study is that injecting as little as 1% of pretraining data in the finetuning data mixture prevents the model from forgetting the pretraining set.
title Scaling Laws for Forgetting during Finetuning with Pretraining Data Injection
topic Machine Learning
Computation and Language
url https://arxiv.org/abs/2502.06042