---
id: pr-vllm-41745
repo: vllm-project/vllm
pr: 41745
title: '[Spec Decode] Add Gemma4 MTP speculative decoding support'
author: lucianommartins
date: '2026-05-06'
url: https://github.com/vllm-project/vllm/pull/41745
source_category: upstream-code
architectures:
- sm100
tags:
- Marlin
- attention_kv
- benchmark_test
- fp4
- gemm_quant
- nvfp4
- scheduler_autotune
techniques:
- autotuning
- fine-grained-quantization
- tile-scheduling
hardware_features:
- fp4
- nvfp4
kernel_types:
- attention
- decode
- gemm
- scheduler
languages: []
captured_at: '2026-05-16'
status: merged
merge_sha: 27e0057aeda6bc443069c20fdf2f3cc95ed892f3
inclusion_reason: Preserve page/KV/layout and plan-run contracts; profile memory traffic separately from math utilization.
changed_paths:
- tests/models/registry.py
- tests/v1/e2e/spec_decode/test_spec_decode.py
- vllm/config/speculative.py
- vllm/model_executor/models/gemma4_mtp.py
- vllm/model_executor/models/registry.py
- vllm/transformers_utils/model_arch_config_convertor.py
- vllm/v1/spec_decode/gemma4.py
- vllm/v1/spec_decode/llm_base_proposer.py
- vllm/v1/worker/gpu_model_runner.py
artifact_dir: evidence/pull-bundles/vllm/gh-41745
head_ref_oid: ce026b01c5f53770b526308b554ed8651857bcc3
---
# [Spec Decode] Add Gemma4 MTP speculative decoding support

- Repository: `vllm-project/vllm`
- PR: [41745](https://github.com/vllm-project/vllm/pull/41745)
- Decision: `Preserve page/KV/layout and plan-run contracts; profile memory traffic separately from math utilization.`
- Reason: Preserve page/KV/layout and plan-run contracts; profile memory traffic separately from math utilization.

## Changed Paths

- `tests/models/registry.py`
- `tests/v1/e2e/spec_decode/test_spec_decode.py`
- `vllm/config/speculative.py`
- `vllm/model_executor/models/gemma4_mtp.py`
- `vllm/model_executor/models/registry.py`
- `vllm/transformers_utils/model_arch_config_convertor.py`
- `vllm/v1/spec_decode/gemma4.py`
- `vllm/v1/spec_decode/llm_base_proposer.py`
- `vllm/v1/worker/gpu_model_runner.py`

## Evidence Bundle

`evidence/pull-bundles/vllm/gh-41745`
