Where Does Warm-Up Come From? Adaptive Scheduling for Norm-Constrained Optimizers

Fuente: arXiv
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Main Authors: Riabinin, Artem, Veprikov, Andrey, Bolatov, Arman, Takáč, Martin, Beznosikov, Aleksandr
Format: Preprint
Published: 2026
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author Riabinin, Artem
Veprikov, Andrey
Bolatov, Arman
Takáč, Martin
Beznosikov, Aleksandr
author_facet Riabinin, Artem
Veprikov, Andrey
Bolatov, Arman
Takáč, Martin
Beznosikov, Aleksandr
contents We study adaptive learning rate scheduling for norm-constrained optimizers (e.g., Muon and Lion). We introduce a generalized smoothness assumption under which local curvature decreases with the suboptimality gap and empirically verify that this behavior holds along optimization trajectories. Under this assumption, we establish convergence guarantees under an appropriate choice of learning rate, for which warm-up followed by decay arises naturally from the proof rather than being imposed heuristically. Building on this theory, we develop a practical learning rate scheduler that relies only on standard hyperparameters and adapts the warm-up duration automatically at the beginning of training. We evaluate this method on large language model pretraining with LLaMA architectures and show that our adaptive warm-up selection consistently outperforms or at least matches the best manually tuned warm-up schedules across all considered setups, without additional hyperparameter search. Our source code is available at https://github.com/brain-lab-research/llm-baselines/tree/warmup
format Preprint
id arxiv_https___arxiv_org_abs_2602_05813
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Where Does Warm-Up Come From? Adaptive Scheduling for Norm-Constrained Optimizers
Riabinin, Artem
Veprikov, Andrey
Bolatov, Arman
Takáč, Martin
Beznosikov, Aleksandr
Machine Learning
Optimization and Control
We study adaptive learning rate scheduling for norm-constrained optimizers (e.g., Muon and Lion). We introduce a generalized smoothness assumption under which local curvature decreases with the suboptimality gap and empirically verify that this behavior holds along optimization trajectories. Under this assumption, we establish convergence guarantees under an appropriate choice of learning rate, for which warm-up followed by decay arises naturally from the proof rather than being imposed heuristically. Building on this theory, we develop a practical learning rate scheduler that relies only on standard hyperparameters and adapts the warm-up duration automatically at the beginning of training. We evaluate this method on large language model pretraining with LLaMA architectures and show that our adaptive warm-up selection consistently outperforms or at least matches the best manually tuned warm-up schedules across all considered setups, without additional hyperparameter search. Our source code is available at https://github.com/brain-lab-research/llm-baselines/tree/warmup
title Where Does Warm-Up Come From? Adaptive Scheduling for Norm-Constrained Optimizers
topic Machine Learning
Optimization and Control
url https://arxiv.org/abs/2602.05813