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Main Authors: Guo, Han, Zhang, Jack, Menon, Arjun, Guessous, Driss, Thakkar, Vijay, Kim, Yoon, Dao, Tri
Format: Preprint
Published: 2026
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Online Access:https://arxiv.org/abs/2605.19269
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author Guo, Han
Zhang, Jack
Menon, Arjun
Guessous, Driss
Thakkar, Vijay
Kim, Yoon
Dao, Tri
author_facet Guo, Han
Zhang, Jack
Menon, Arjun
Guessous, Driss
Thakkar, Vijay
Kim, Yoon
Dao, Tri
contents Transformer training systems are built around dense linear algebra, yet a nontrivial fraction of end-to-end time is spent on surrounding memory-bound operators. Normalization, activations, residual updates, reductions, and related computations repeatedly move large intermediate tensors through global memory while performing little arithmetic, making data movement an increasingly important bottleneck in otherwise highly optimized training stacks. We introduce CODA, a GPU kernel abstraction that expresses these computations as GEMM-plus-epilogue programs. CODA is based on the observation that many Transformer operators exposed as separate framework kernels can be algebraically reparameterized to execute while a GEMM output tile remains on chip, before it is written to memory. The abstraction fixes the GEMM mainloop and exposes a small set of composable epilogue primitives for scaling, reductions, pairwise transformations, and accumulation. This constrained interface preserves the performance structure of expert-written GEMMs while remaining expressive enough to cover nearly all non-attention computation in the forward and backward pass of a standard Transformer block. Across representative Transformer workloads, both human- and LLM-authored CODA kernels achieve high performance, suggesting that GEMM-plus-epilogue programming offers a practical path toward combining framework-level productivity with hardware-level efficiency.
format Preprint
id arxiv_https___arxiv_org_abs_2605_19269
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle CODA: Rewriting Transformer Blocks as GEMM-Epilogue Programs
Guo, Han
Zhang, Jack
Menon, Arjun
Guessous, Driss
Thakkar, Vijay
Kim, Yoon
Dao, Tri
Machine Learning
Transformer training systems are built around dense linear algebra, yet a nontrivial fraction of end-to-end time is spent on surrounding memory-bound operators. Normalization, activations, residual updates, reductions, and related computations repeatedly move large intermediate tensors through global memory while performing little arithmetic, making data movement an increasingly important bottleneck in otherwise highly optimized training stacks. We introduce CODA, a GPU kernel abstraction that expresses these computations as GEMM-plus-epilogue programs. CODA is based on the observation that many Transformer operators exposed as separate framework kernels can be algebraically reparameterized to execute while a GEMM output tile remains on chip, before it is written to memory. The abstraction fixes the GEMM mainloop and exposes a small set of composable epilogue primitives for scaling, reductions, pairwise transformations, and accumulation. This constrained interface preserves the performance structure of expert-written GEMMs while remaining expressive enough to cover nearly all non-attention computation in the forward and backward pass of a standard Transformer block. Across representative Transformer workloads, both human- and LLM-authored CODA kernels achieve high performance, suggesting that GEMM-plus-epilogue programming offers a practical path toward combining framework-level productivity with hardware-level efficiency.
title CODA: Rewriting Transformer Blocks as GEMM-Epilogue Programs
topic Machine Learning
url https://arxiv.org/abs/2605.19269