---
id: pr-tensorrt-llm-12322
repo: NVIDIA/TensorRT-LLM
pr: 12322
title: '[https://nvbugs/5983390][perf] Kernel fusions in _gather_k_cache_for_chunk of Indexer in DSA'
author: hyukn
date: '2026-03-21'
url: https://github.com/NVIDIA/TensorRT-LLM/pull/12322
source_category: upstream-code
architectures:
- sm100
tags:
- DSA
- allreduce
- attention kernel
- attention_kv
- benchmark_test
- cuda kernel
- memory_primitives
techniques:
- cache-policy
- kernel-fusion
hardware_features:
- fp4
- nvfp4
kernel_types:
- attention
- memory
- moe
languages:
- cuda-cpp
- triton
captured_at: '2026-05-16'
status: merged
merge_sha: 6601758d3a8a313cde1e0f4f4ec5a38df8ca9d26
inclusion_reason: 'Transfer primitive policy carefully: coalescing, shared-memory staging, partial tiles, and determinism are part of the contract.'
changed_paths:
- tensorrt_llm/_torch/attention_backend/sparse/dsa.py
- tensorrt_llm/_torch/attention_backend/sparse/kernel.py
- tests/unittest/_torch/attention/sparse/test_triton_gather_k_cache.py
artifact_dir: evidence/pull-bundles/tensorrt-llm/gh-12322
head_ref_oid: 24242eef570007548348073c2003c969da8e64ab
---
# [https://nvbugs/5983390][perf] Kernel fusions in _gather_k_cache_for_chunk of Indexer in DSA

- Repository: `NVIDIA/TensorRT-LLM`
- PR: [12322](https://github.com/NVIDIA/TensorRT-LLM/pull/12322)
- 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

- `tensorrt_llm/_torch/attention_backend/sparse/dsa.py`
- `tensorrt_llm/_torch/attention_backend/sparse/kernel.py`
- `tests/unittest/_torch/attention/sparse/test_triton_gather_k_cache.py`

## Evidence Bundle

`evidence/pull-bundles/tensorrt-llm/gh-12322`
