PTPP-Aware Adaptation Scaling Laws: Predicting Domain-Adaptation Performance at Unseen Pre-Training Budgets
Etienne Goffinet, Shane Bergsma, Avraham Sheinin, Natalia Vassilieva, Shaheer Muhammad, Preslav Nakov, Gurpreet Gosal
TL;DR
The paper introduces Ptpp-aware adaptation scaling laws that explicitly model the pre-training budget $P_{\mathrm{tpp}}$ as a driver of domain-adaptation performance. By proposing three formulations that combine a loss floor and data-exponent gating, the authors demonstrate accurate prediction of target-domain loss at unseen budgets, notably $P_{\mathrm{tpp}}=279$, in a multilingual English/Arabic to French setting and with various model sizes. A small set of 241M-scale anchors further improves calibration, and a practical use-case shows how the fitted laws enable optimized replay ratios and adaptation budgets under compute constraints. This work clarifies how pre-training compute modulates both the loss floor and adaptation efficiency, offering a scalable tool for budgeting, scheduling, and planning in continual pre-training and domain adaptation tasks.
Abstract
Continual pre-training (CPT) for domain adaptation must balance target-domain gains with stability on the base domain. Existing CPT scaling laws typically assume a fixed pre-training budget, which limits their ability to forecast adaptation outcomes for models trained at different tokens-per-parameter (PTPP). We present \emph{PTPP-aware} adaptation scaling laws that make the pre-training budget an explicit variable, enabling accurate \emph{prediction} of adaptation loss at unseen \ptpp. On a multilingual setup (English/Arabic $\rightarrow$ French), PTPP-aware formulations trained on early stages (\ptpp{}=\{15,31\}) predict target loss at \ptpp{}=279 and outperform a PTPP-agnostic \dcpt{} transfer baseline on metrics (Huber-on-log, MAE$_\mathrm{rel}$, calibration slope); full diagnostics (RMSE, MAPE) are in the appendix. Beyond forecasting, we show a practical use case: planning replay ratios and adaptation token budgets that satisfy target and forgetting constraints under compute limits.
