vllm-project/vllm

[Feature]: Refactor Int8ScaledMMLinearLayerConfig to use QuantKey

Open

#32268 opened on Jan 13, 2026

View on GitHub
 (7 comments) (0 reactions) (1 assignee)Python (80,034 stars) (16,816 forks)batch import
feature requestgood first issuehelp wanted

Description

🚀 The feature, motivation and pitch

Replace boolean configuration fields in ScaledMMLinearLayerConfig with QuantKey objects to provide a more structured, type-safe quantization configuration API.

Ideally we should change this:

@dataclass
class ScaledMMLinearLayerConfig(ScaledMMLinearLayerConfig):
    is_static_input_scheme: bool
    is_channelwise: bool
    input_symmetric: bool

to this:

@dataclass
class ScaledMMLinearLayerConfig(ScaledMMLinearLayerConfig):
    weight_quant_key: QuantKey
    activation_quant_key: QuantKey
    input_symmetric: bool

A parallel work found here #27814 , has split the configuration into Int8 and Fp8 config classes and uses Quantkey for the FP8 config class.

Alternatives

No response

Additional context

No response

Before submitting a new issue...

  • Make sure you already searched for relevant issues, and asked the chatbot living at the bottom right corner of the documentation page, which can answer lots of frequently asked questions.

Contributor guide

Tech stack
pythonpytorch
Domain
machine learning
Issue type
refactor
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
3
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
half day
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
blocked
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
Python experienceFamiliarity with dataclassesUnderstanding of quantization concepts
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
45
Research direction
The main file to modify is vllm/model executor/layers/quantization/kernels/scaled mm/ScaledMMLinearKernel.py. Refer to parallel work in issue #27814 for context on using QuantKey with FP8 config. Ensure the refactor maintains backward compatibility and existing functionality.