microsoft / microsoft/BitNet

Drop-in replacement needed for f.linear?

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Description


class BitLinearInference(nn.Module):
    def __init__(self, 
        in_features: int,
        out_features: int,
    ):
        super().__init__()

        self.in_f = in_features
        self.out_f = out_features

        self.register_buffer("w", torch.empty((out_features, in_features)))
        self.register_buffer("w_scale", torch.empty((1,), dtype=torch.float32))

        self.norm = nn.RMSNorm(
            normalized_shape=in_features,
            eps=1e-5,
            elementwise_affine=True
        )

    def forward(self, x: Tensor) -> Tensor:
        x_norm = self.norm(x)
        x_int, x_scale = quantize_activation(x_norm)
        y_int = F.linear(x_int, self.w)
        y = y_int * (self.w_scale * x_scale)

May I know do we have a way to just drop-in replace the F.linear for the custom kernel? Current bitnet.cpp only support LLM but not just this simple drop-in replacement
Note that the activation is in 3d and weight is in 2d. but it seems like the kernel only support 2d matmul

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  3. Fork the repository and make your change on a branch.
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Research direction

Start by reading the BitNet.cpp kernel entry points and the F.linear call in the provided BitLinearInference example. Check how the kernel handles tensor dimensions, especially 3D activations with 2D weights. Done means a custom-kernel path can replace F.linear for this case and its supported shape behavior is documented or verified.

Written by the indexing model from the issue text.

Assessment

Tech stack
cpp, python, pytorch
Domain
machine-learning, performance
Issue type
Feature
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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