---
id: pr-cccl-cub-8421
repo: NVIDIA/cccl
pr: 8421
title: New tuning API for DeviceUniqueByKey
author: griwes
date: '2026-04-21'
url: https://github.com/NVIDIA/cccl/pull/8421
source_category: upstream-code
architectures:
- sm100
- sm90
tags:
- sm100
- sm90
techniques: []
hardware_features:
- blackwell
- hopper
kernel_types: []
languages: []
captured_at: '2026-05-16'
status: merged
merge_sha: 4b144a631eaf0bb6563c4b94664dae42fd27a2d7
inclusion_reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.
changed_paths:
- c/parallel/src/unique_by_key.cu
- cub/benchmarks/bench/select/unique_by_key.cu
- cub/cub/detail/arch_dispatch.cuh
- cub/cub/device/device_select.cuh
- cub/cub/device/dispatch/dispatch_unique_by_key.cuh
- cub/cub/device/dispatch/kernels/kernel_unique_by_key.cuh
- cub/cub/device/dispatch/tuning/tuning_unique_by_key.cuh
- cub/test/catch2_test_device_select_env.cu
artifact_dir: evidence/pull-bundles/cccl-cub/gh-8421
head_ref_oid: 5fb913dbab13a3b0200b07bef7341bc70fb920e1
---
# New tuning API for DeviceUniqueByKey

- Repository: `NVIDIA/cccl`
- PR: [8421](https://github.com/NVIDIA/cccl/pull/8421)
- Decision: `Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.`
- Reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.

## Changed Paths

- `c/parallel/src/unique_by_key.cu`
- `cub/benchmarks/bench/select/unique_by_key.cu`
- `cub/cub/detail/arch_dispatch.cuh`
- `cub/cub/device/device_select.cuh`
- `cub/cub/device/dispatch/dispatch_unique_by_key.cuh`
- `cub/cub/device/dispatch/kernels/kernel_unique_by_key.cuh`
- `cub/cub/device/dispatch/tuning/tuning_unique_by_key.cuh`
- `cub/test/catch2_test_device_select_env.cu`

## Evidence Bundle

`evidence/pull-bundles/cccl-cub/gh-8421`
