f8d03d21f1
### What this PR does / why we need it?
`vllm_ascend` already supports several speculative decoding strategies
such as MTP, EAGLE, N-gram, and suffix decoding. However, Medusa is not
yet supported. Medusa is an efficient speculative decoding framework
that leverages a lightweight draft model to propose multiple tokens in a
single step, which can significantly improve decoding throughput and
reduce latency.
To enable Medusa-based speculative decoding on Ascend hardware and
provide more decoding options for users, this PR adds Medusa support
into the `vllm_ascend` speculative decoding pipeline.
### Does this PR introduce _any_ user-facing change?
This PR introduces Medusa speculative decoding as an additional
speculative decoding method:
✔ Adds `MedusaProposer` and integrates it into the speculative decoding
registry
✔ Extends `SpecDcodeType` with a `MEDUSA` enum entry
✔ Updates `NPUModelRunner` to recognize and invoke Medusa during
decoding
✔ Adds Medusa-specific handling in the draft token generation logic
✔ Ensures backward compatibility — Medusa is only used when explicitly
enabled
Key code changes include:
* New file: `vllm_ascend/spec_decode/medusa_proposer.py`
* Register Medusa in `get_spec_decode_method`
* Extend proposer type hints to include `MedusaProposer`
* Add a Medusa-specific branch in `generate_draft_token_ids`
* Pass `sample_hidden_states` required by Medusa
### How was this patch tested?
Medusa is implemented as a new proposer class (`MedusaProposer`)
following the existing speculative decoding interface. The integration
works as follows:
1. Users enable Medusa via the speculative decoding configuration.
2. `get_spec_decode_method()` returns a `MedusaProposer` instance when
`method="medusa"`.
3. During decoding, `NPUModelRunner` detects that the active drafter is
a `MedusaProposer`.
4. Instead of the generic speculative decoding path, the Medusa-specific
`generate_token_ids()` method is invoked, which consumes:
* `valid_sampled_token_ids`
* `sampling_metadata`
* `spec_decode_metadata`
* `sample_hidden_states`
5. The proposed tokens are validated by the target model as usual.
When Medusa is not enabled, the decoding pipeline behaves exactly as
before, ensuring full backward compatibility.
- vLLM version: v0.13.0
- vLLM main:
2f4e6548ef
Signed-off-by: simplzyu <191163281@qq.com>
Signed-off-by: simplzyu <zhenyuguo@cmbchina.com>
vLLM Ascend Plugin
| About Ascend | Documentation | #sig-ascend | Users Forum | Weekly Meeting |
English | 中文
Latest News 🔥
- [2025/12] We released the new official version v0.11.0! Please follow the official guide to start using vLLM Ascend Plugin on Ascend.
- [2025/09] We released the new official version v0.9.1! Please follow the official guide to start deploy large scale Expert Parallelism (EP) on Ascend.
- [2025/08] We hosted the vLLM Beijing Meetup with vLLM and Tencent! Please find the meetup slides here.
- [2025/06] User stories page is now live! It kicks off with LLaMA-Factory/verl//TRL/GPUStack to demonstrate how vLLM Ascend assists Ascend users in enhancing their experience across fine-tuning, evaluation, reinforcement learning (RL), and deployment scenarios.
- [2025/06] Contributors page is now live! All contributions deserve to be recorded, thanks for all contributors.
- [2025/05] We've released first official version v0.7.3! We collaborated with the vLLM community to publish a blog post sharing our practice: Introducing vLLM Hardware Plugin, Best Practice from Ascend NPU.
- [2025/03] We hosted the vLLM Beijing Meetup with vLLM team! Please find the meetup slides here.
- [2025/02] vLLM community officially created vllm-project/vllm-ascend repo for running vLLM seamlessly on the Ascend NPU.
- [2024/12] We are working with the vLLM community to support [RFC]: Hardware pluggable.
Overview
vLLM Ascend (vllm-ascend) is a community maintained hardware plugin for running vLLM seamlessly on the Ascend NPU.
It is the recommended approach for supporting the Ascend backend within the vLLM community. It adheres to the principles outlined in the [RFC]: Hardware pluggable, providing a hardware-pluggable interface that decouples the integration of the Ascend NPU with vLLM.
By using vLLM Ascend plugin, popular open-source models, including Transformer-like, Mixture-of-Expert, Embedding, Multi-modal LLMs can run seamlessly on the Ascend NPU.
Prerequisites
- Hardware: Atlas 800I A2 Inference series, Atlas A2 Training series, Atlas 800I A3 Inference series, Atlas A3 Training series, Atlas 300I Duo (Experimental)
- OS: Linux
- Software:
- Python >= 3.10, < 3.12
- CANN == 8.5.0 (Ascend HDK version refers to here)
- PyTorch == 2.9.0, torch-npu == 2.9.0
- vLLM (the same version as vllm-ascend)
Getting Started
Please use the following recommended versions to get started quickly:
| Version | Release type | Doc |
|---|---|---|
| v0.13.0rc1 | Latest release candidate | QuickStart and Installation for more details |
| v0.11.0 | Latest stable version | QuickStart and Installation for more details |
Contributing
See CONTRIBUTING for more details, which is a step-by-step guide to help you set up development environment, build and test.
We welcome and value any contributions and collaborations:
- Please let us know if you encounter a bug by filing an issue
- Please use User forum for usage questions and help.
Branch
vllm-ascend has main branch and dev branch.
- main: main branch，corresponds to the vLLM main branch, and is continuously monitored for quality through Ascend CI.
- releases/vX.Y.Z: development branch, created with part of new releases of vLLM. For example,
releases/v0.13.0is the dev branch for vLLMv0.13.0version.
Below is maintained branches:
| Branch | Status | Note |
|---|---|---|
| main | Maintained | CI commitment for vLLM main branch and vLLM v0.13.0 tag |
| v0.7.1-dev | Unmaintained | Only doc fixed is allowed |
| v0.7.3-dev | Maintained | CI commitment for vLLM 0.7.3 version, only bug fix is allowed and no new release tag any more. |
| v0.9.1-dev | Maintained | CI commitment for vLLM 0.9.1 version |
| v0.11.0-dev | Maintained | CI commitment for vLLM 0.11.0 version |
| releases/v0.13.0 | Maintained | CI commitment for vLLM 0.13.0 version |
| rfc/feature-name | Maintained | Feature branches for collaboration |
Please refer to Versioning policy for more details.
Weekly Meeting
- vLLM Ascend Weekly Meeting: https://tinyurl.com/vllm-ascend-meeting
- Wednesday, 15:00 - 16:00 (UTC+8, Convert to your timezone)
License
Apache License 2.0, as found in the LICENSE file.