Skip to content

[Feature]: AutoScheme: recommended bit options for mixed-precision at an average of 4/5 bits? #2118

Description

@HsuWanTing

Feature Description

Are there recommended bit options for mixed-precision quantization at an average of 4 or 5 bits? For instance, is it better to supply only two options (e.g., 4 bits and 8 bits for average 5 bits), as in your 3.5-bit experiments, rather than a wider set (e.g., 2~8 bits)? Or, at higher bit-widths, is it better not to use mixed precision at all?

I ask because in SignRoundV2 Table 2, the uniform W3G128/W4G128 rows (gray) beat mixed-precision "Ours" on all four models at an average of 3 bits, and on three of the four at an average of 4 bits. For example, on Qwen3-8B the uniform baseline scores 73.24 vs 72.21 at 3 bits and 74.11 vs 73.76 at 4 bits. Is that expected?

Motivation and Use Case

Choosing options is currently guesswork: the docs give no guidance for weight-only 4/5-bit budgets. A poor option set can make AutoScheme worse than plain uniform quantization, so users burn GPU hours discovering this themselves. Documented recommendations per average bit-width would let us pick a recipe once and trust it.

Alternatives Considered

No response

Definition of Done

No response

Additional Context

No response

Metadata

Metadata

Assignees

No one assigned

    Labels

    enhancementNew feature or request

    Type

    No type

    Projects

    No projects

    Milestone

    No milestone

    Relationships

    None yet

    Development

    No branches or pull requests

    Issue actions