---
id: pr-cccl-cub-7114
repo: NVIDIA/cccl
pr: 7114
title: Two-phase reduction for fixed size segmented reduction for very large segment sizes
author: srinivasyadav18
date: '2026-02-19'
url: https://github.com/NVIDIA/cccl/pull/7114
source_category: upstream-code
architectures:
- sm100
tags:
- benchmark_test
- block reduce
- memory_primitives
- segmented reduce
techniques: []
hardware_features: []
kernel_types:
- memory
- reduction
languages:
- cuda-cpp
captured_at: '2026-05-16'
status: merged
merge_sha: 788fe7cc59b9b2d56b75e463a8121bae4c4e0297
inclusion_reason: 'Transfer primitive policy carefully: coalescing, shared-memory staging, partial tiles, and determinism are part of the contract.'
changed_paths:
- cub/cub/device/dispatch/dispatch_fixed_size_segmented_reduce.cuh
- cub/cub/device/dispatch/kernels/kernel_segmented_reduce.cuh
- cub/test/catch2_test_device_segmented_reduce_large_offsets.cu
artifact_dir: evidence/pull-bundles/cccl-cub/gh-7114
head_ref_oid: 4f421ccaa771e67ef2b69dafba2f28b365c95a9c
---
# Two-phase reduction for fixed size segmented reduction for very large segment sizes

- Repository: `NVIDIA/cccl`
- PR: [7114](https://github.com/NVIDIA/cccl/pull/7114)
- 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

- `cub/cub/device/dispatch/dispatch_fixed_size_segmented_reduce.cuh`
- `cub/cub/device/dispatch/kernels/kernel_segmented_reduce.cuh`
- `cub/test/catch2_test_device_segmented_reduce_large_offsets.cu`

## Evidence Bundle

`evidence/pull-bundles/cccl-cub/gh-7114`
