---
id: pr-cccl-cub-7384
repo: NVIDIA/cccl
pr: 7384
title: Radix-selection based `BlockTopK` specialization
author: elstehle
date: '2026-03-07'
url: https://github.com/NVIDIA/cccl/pull/7384
source_category: upstream-code
architectures:
- sm100
tags:
- DeviceTopK
- benchmark_test
- memory_primitives
- moe_routing
- topk
techniques: []
hardware_features: []
kernel_types:
- memory
- moe
languages:
- cuda-cpp
captured_at: '2026-05-16'
status: merged
merge_sha: 2c320152bd40ac1624f16210c5eb8d6a4d9a3eed
inclusion_reason: 'Transfer primitive policy carefully: coalescing, shared-memory staging, partial tiles, and determinism are part of the contract.'
changed_paths:
- cub/cub/agent/agent_batched_topk.cuh
- cub/cub/block/block_topk.cuh
- cub/cub/block/specializations/block_topk_air.cuh
- cub/test/catch2_test_device_segmented_topk_keys.cu
- cub/test/catch2_test_device_segmented_topk_pairs.cu
artifact_dir: evidence/pull-bundles/cccl-cub/gh-7384
head_ref_oid: 70acc7c6fbf925539632a9ea699e923b039bfda0
---
# Radix-selection based `BlockTopK` specialization

- Repository: `NVIDIA/cccl`
- PR: [7384](https://github.com/NVIDIA/cccl/pull/7384)
- 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/agent/agent_batched_topk.cuh`
- `cub/cub/block/block_topk.cuh`
- `cub/cub/block/specializations/block_topk_air.cuh`
- `cub/test/catch2_test_device_segmented_topk_keys.cu`
- `cub/test/catch2_test_device_segmented_topk_pairs.cu`

## Evidence Bundle

`evidence/pull-bundles/cccl-cub/gh-7384`
