---
id: pr-vllm-41428
repo: vllm-project/vllm
pr: 41428
title: '[DSv4] Improved fused Indexer Q quant kernel'
author: gau-nernst
date: '2026-05-09'
url: https://github.com/vllm-project/vllm/pull/41428
source_category: upstream-code
architectures:
- sm100
tags:
- CUDA kernel
- attention_kv
- benchmark kernel
- benchmark_test
- compiler_runtime
- cutlass
- fp4
- gemm_quant
- quantization kernel
- sm100
- topk
techniques:
- fine-grained-quantization
- kernel-fusion
hardware_features:
- blackwell
- fp4
- mxfp4
kernel_types:
- attention
- compiler
- gemm
languages:
- cuda-cpp
- cute-dsl
- triton
captured_at: '2026-05-16'
status: merged
merge_sha: 530d37130278d38b07b089f936850537aa1ea5e6
inclusion_reason: Inspect scale layout, accumulator type, tile/schedule choice, epilogue fusion, and partial-tile guards before deriving a candidate.
changed_paths:
- tests/kernels/test_fused_indexer_q_rope_quant.py
- vllm/utils/import_utils.py
- vllm/v1/attention/ops/deepseek_v4_ops/fused_indexer_q.py
- vllm/v1/attention/ops/deepseek_v4_ops/fused_indexer_q_cutedsl.py
artifact_dir: evidence/pull-bundles/vllm/gh-41428
head_ref_oid: 9d469b8c12b132d96559872bea3be462f5e7ded4
---
# [DSv4] Improved fused Indexer Q quant kernel

- Repository: `vllm-project/vllm`
- PR: [41428](https://github.com/vllm-project/vllm/pull/41428)
- Decision: `Inspect scale layout, accumulator type, tile/schedule choice, epilogue fusion, and partial-tile guards before deriving a candidate.`
- Reason: Inspect scale layout, accumulator type, tile/schedule choice, epilogue fusion, and partial-tile guards before deriving a candidate.

## Changed Paths

- `tests/kernels/test_fused_indexer_q_rope_quant.py`
- `vllm/utils/import_utils.py`
- `vllm/v1/attention/ops/deepseek_v4_ops/fused_indexer_q.py`
- `vllm/v1/attention/ops/deepseek_v4_ops/fused_indexer_q_cutedsl.py`

## Evidence Bundle

`evidence/pull-bundles/vllm/gh-41428`
