---
id: pr-cccl-cub-7823
repo: NVIDIA/cccl
pr: 7823
title: Optimized Device-to-Device Tensor Copy (`cudax`)
author: fbusato
date: '2026-04-14'
url: https://github.com/NVIDIA/cccl/pull/7823
source_category: upstream-code
architectures:
- sm100
tags:
- benchmark_test
- mdspan copy
- memory_primitives
- transpose
techniques:
- vectorized-loads
hardware_features: []
kernel_types:
- memory
languages:
- cuda-cpp
- cute-dsl
captured_at: '2026-05-16'
status: merged
merge_sha: 26f74e101afe19f1670239aad8f3ddebc930cad3
inclusion_reason: 'Transfer primitive policy carefully: coalescing, shared-memory staging, partial tiles, and determinism are part of the contract.'
changed_paths:
- cudax/benchmarks/bench/copy/copy_bench.cu
- cudax/include/cuda/experimental/__copy/are_mdspan_byte_copyable.cuh
- cudax/include/cuda/experimental/__copy/copy_contiguous.cuh
- cudax/include/cuda/experimental/__copy/copy_optimized.cuh
- cudax/include/cuda/experimental/__copy/dispatch_by_vector.cuh
- cudax/include/cuda/experimental/__copy/mdspan_d2d.cuh
- cudax/include/cuda/experimental/__copy/tensor_copy_utils.cuh
- cudax/include/cuda/experimental/__copy/tensor_iterator.cuh
- cudax/include/cuda/experimental/__copy/vector_access.cuh
- cudax/include/cuda/experimental/__copy_bytes/simplify_paired.cuh
- cudax/include/cuda/experimental/copy.cuh
- cudax/test/CMakeLists.txt
- cudax/test/copy/copy.cu
- cudax/test/copy/copy_common.cuh
- cudax/test/copy/copy_edge_cases.cu
- cudax/test/copy/copy_llm.cu
- cudax/test/copy/copy_nvmath.cu
- cudax/test/copy/copy_nvmath_transpose.cu
- cudax/test/copy/copy_vectorize.cu
- cudax/test/copy/copy_vectorize_5d.cu
artifact_dir: evidence/pull-bundles/cccl-cub/gh-7823
head_ref_oid: 224c50c0b02e5cdb752a05c20cfd0457498f15e6
---
# Optimized Device-to-Device Tensor Copy (`cudax`)

- Repository: `NVIDIA/cccl`
- PR: [7823](https://github.com/NVIDIA/cccl/pull/7823)
- Decision: `Transfer primitive policy carefully: coalescing, shared-memory staging, partial tiles, and determinism are part of the contract.`
- Reason: Transfer primitive policy carefully: coalescing, shared-memory staging, partial tiles, and determinism are part of the contract.

## Changed Paths

- `cudax/benchmarks/bench/copy/copy_bench.cu`
- `cudax/include/cuda/experimental/__copy/are_mdspan_byte_copyable.cuh`
- `cudax/include/cuda/experimental/__copy/copy_contiguous.cuh`
- `cudax/include/cuda/experimental/__copy/copy_optimized.cuh`
- `cudax/include/cuda/experimental/__copy/dispatch_by_vector.cuh`
- `cudax/include/cuda/experimental/__copy/mdspan_d2d.cuh`
- `cudax/include/cuda/experimental/__copy/tensor_copy_utils.cuh`
- `cudax/include/cuda/experimental/__copy/tensor_iterator.cuh`
- `cudax/include/cuda/experimental/__copy/vector_access.cuh`
- `cudax/include/cuda/experimental/__copy_bytes/simplify_paired.cuh`
- `cudax/include/cuda/experimental/copy.cuh`
- `cudax/test/CMakeLists.txt`
- `cudax/test/copy/copy.cu`
- `cudax/test/copy/copy_common.cuh`
- `cudax/test/copy/copy_edge_cases.cu`
- `cudax/test/copy/copy_llm.cu`
- `cudax/test/copy/copy_nvmath.cu`
- `cudax/test/copy/copy_nvmath_transpose.cu`
- `cudax/test/copy/copy_vectorize.cu`
- `cudax/test/copy/copy_vectorize_5d.cu`

## Evidence Bundle

`evidence/pull-bundles/cccl-cub/gh-7823`
