Peri-LN: Revisiting Normalization Layer in the Transformer Architecture

Fuente: arXiv
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Autores principales: Kim, Jeonghoon, Lee, Byeongchan, Park, Cheonbok, Oh, Yeontaek, Kim, Beomjun, Yoo, Taehwan, Shin, Seongjin, Han, Dongyoon, Shin, Jinwoo, Yoo, Kang Min
Formato: Preprint
Publicado: 2025
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author Kim, Jeonghoon
Lee, Byeongchan
Park, Cheonbok
Oh, Yeontaek
Kim, Beomjun
Yoo, Taehwan
Shin, Seongjin
Han, Dongyoon
Shin, Jinwoo
Yoo, Kang Min
author_facet Kim, Jeonghoon
Lee, Byeongchan
Park, Cheonbok
Oh, Yeontaek
Kim, Beomjun
Yoo, Taehwan
Shin, Seongjin
Han, Dongyoon
Shin, Jinwoo
Yoo, Kang Min
contents Selecting a layer normalization (LN) strategy that stabilizes training and speeds convergence in Transformers remains difficult, even for today's large language models (LLM). We present a comprehensive analytical foundation for understanding how different LN strategies influence training dynamics in large-scale Transformers. Until recently, Pre-LN and Post-LN have long dominated practices despite their limitations in large-scale training. However, several open-source models have recently begun silently adopting a third strategy without much explanation. This strategy places normalization layer peripherally around sublayers, a design we term Peri-LN. While Peri-LN has demonstrated promising performance, its precise mechanisms and benefits remain almost unexplored. Our in-depth analysis delineates the distinct behaviors of LN strategies, showing how each placement shapes activation variance and gradient propagation. To validate our theoretical insight, we conduct extensive experiments on Transformers up to $3.2$B parameters, showing that Peri-LN consistently achieves more balanced variance growth, steadier gradient flow, and convergence stability. Our results suggest that Peri-LN warrants broader consideration for large-scale Transformer architectures, providing renewed insights into the optimal placement of LN.
format Preprint
id arxiv_https___arxiv_org_abs_2502_02732
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Peri-LN: Revisiting Normalization Layer in the Transformer Architecture
Kim, Jeonghoon
Lee, Byeongchan
Park, Cheonbok
Oh, Yeontaek
Kim, Beomjun
Yoo, Taehwan
Shin, Seongjin
Han, Dongyoon
Shin, Jinwoo
Yoo, Kang Min
Machine Learning
Artificial Intelligence
Computation and Language
Selecting a layer normalization (LN) strategy that stabilizes training and speeds convergence in Transformers remains difficult, even for today's large language models (LLM). We present a comprehensive analytical foundation for understanding how different LN strategies influence training dynamics in large-scale Transformers. Until recently, Pre-LN and Post-LN have long dominated practices despite their limitations in large-scale training. However, several open-source models have recently begun silently adopting a third strategy without much explanation. This strategy places normalization layer peripherally around sublayers, a design we term Peri-LN. While Peri-LN has demonstrated promising performance, its precise mechanisms and benefits remain almost unexplored. Our in-depth analysis delineates the distinct behaviors of LN strategies, showing how each placement shapes activation variance and gradient propagation. To validate our theoretical insight, we conduct extensive experiments on Transformers up to $3.2$B parameters, showing that Peri-LN consistently achieves more balanced variance growth, steadier gradient flow, and convergence stability. Our results suggest that Peri-LN warrants broader consideration for large-scale Transformer architectures, providing renewed insights into the optimal placement of LN.
title Peri-LN: Revisiting Normalization Layer in the Transformer Architecture
topic Machine Learning
Artificial Intelligence
Computation and Language
url https://arxiv.org/abs/2502.02732