---
id: pr-cccl-cub-6642
repo: NVIDIA/cccl
pr: 6642
title: Fea/6482 enable grid constant for all non-mutable CUB kernel parameters
author: toxicteddy00077
date: '2026-03-26'
url: https://github.com/NVIDIA/cccl/pull/6642
source_category: upstream-code
architectures:
- sm100
tags:
- benchmark kernel
techniques: []
hardware_features: []
kernel_types: []
languages:
- cuda-cpp
captured_at: '2026-05-16'
status: merged
merge_sha: 58b54a0d15158ef08ba386beb36441c1e647423d
inclusion_reason: Search-matched CUDA kernel optimization PR; materialize diff/source before synthesis.
changed_paths:
- cub/cub/agent/agent_histogram.cuh
- cub/cub/device/dispatch/dispatch_adjacent_difference.cuh
- cub/cub/device/dispatch/dispatch_batch_memcpy.cuh
- cub/cub/device/dispatch/dispatch_merge.cuh
- cub/cub/device/dispatch/dispatch_reduce_by_key.cuh
- cub/cub/device/dispatch/dispatch_rle.cuh
- cub/cub/device/dispatch/dispatch_scan_by_key.cuh
- cub/cub/device/dispatch/dispatch_segmented_sort.cuh
- cub/cub/device/dispatch/dispatch_select_if.cuh
- cub/cub/device/dispatch/dispatch_topk.cuh
- cub/cub/device/dispatch/kernels/kernel_for_each.cuh
- cub/cub/device/dispatch/kernels/kernel_histogram.cuh
- cub/cub/device/dispatch/kernels/kernel_merge_sort.cuh
- cub/cub/device/dispatch/kernels/kernel_radix_sort.cuh
- cub/cub/device/dispatch/kernels/kernel_reduce.cuh
- cub/cub/device/dispatch/kernels/kernel_scan.cuh
- cub/cub/device/dispatch/kernels/kernel_segmented_radix_sort.cuh
- cub/cub/device/dispatch/kernels/kernel_segmented_reduce.cuh
- cub/cub/device/dispatch/kernels/kernel_segmented_scan.cuh
- cub/cub/device/dispatch/kernels/kernel_segmented_sort.cuh
- cub/cub/device/dispatch/kernels/kernel_three_way_partition.cuh
- cub/cub/device/dispatch/kernels/kernel_transform.cuh
- cub/cub/device/dispatch/kernels/kernel_unique_by_key.cuh
- libcudacxx/include/cuda/std/__cccl/execution_space.h
artifact_dir: evidence/pull-bundles/cccl-cub/gh-6642
head_ref_oid: 965d3dc2fec26194ceb4b7b9451ffd7159046272
---
# Fea/6482 enable grid constant for all non-mutable CUB kernel parameters

- Repository: `NVIDIA/cccl`
- PR: [6642](https://github.com/NVIDIA/cccl/pull/6642)
- 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

- `cub/cub/agent/agent_histogram.cuh`
- `cub/cub/device/dispatch/dispatch_adjacent_difference.cuh`
- `cub/cub/device/dispatch/dispatch_batch_memcpy.cuh`
- `cub/cub/device/dispatch/dispatch_merge.cuh`
- `cub/cub/device/dispatch/dispatch_reduce_by_key.cuh`
- `cub/cub/device/dispatch/dispatch_rle.cuh`
- `cub/cub/device/dispatch/dispatch_scan_by_key.cuh`
- `cub/cub/device/dispatch/dispatch_segmented_sort.cuh`
- `cub/cub/device/dispatch/dispatch_select_if.cuh`
- `cub/cub/device/dispatch/dispatch_topk.cuh`
- `cub/cub/device/dispatch/kernels/kernel_for_each.cuh`
- `cub/cub/device/dispatch/kernels/kernel_histogram.cuh`
- `cub/cub/device/dispatch/kernels/kernel_merge_sort.cuh`
- `cub/cub/device/dispatch/kernels/kernel_radix_sort.cuh`
- `cub/cub/device/dispatch/kernels/kernel_reduce.cuh`
- `cub/cub/device/dispatch/kernels/kernel_scan.cuh`
- `cub/cub/device/dispatch/kernels/kernel_segmented_radix_sort.cuh`
- `cub/cub/device/dispatch/kernels/kernel_segmented_reduce.cuh`
- `cub/cub/device/dispatch/kernels/kernel_segmented_scan.cuh`
- `cub/cub/device/dispatch/kernels/kernel_segmented_sort.cuh`
- `cub/cub/device/dispatch/kernels/kernel_three_way_partition.cuh`
- `cub/cub/device/dispatch/kernels/kernel_transform.cuh`
- `cub/cub/device/dispatch/kernels/kernel_unique_by_key.cuh`
- `libcudacxx/include/cuda/std/__cccl/execution_space.h`

## Evidence Bundle

`evidence/pull-bundles/cccl-cub/gh-6642`
