78 lines
2.3 KiB
Python
78 lines
2.3 KiB
Python
# SPDX-License-Identifier: Apache-2.0
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# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
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import torch
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from vllm._custom_ops import (
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cutlass_scaled_fp4_mm,
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scaled_fp4_quant,
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)
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from vllm.model_executor.layers.quantization.utils.nvfp4_utils import (
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cutlass_fp4_supported,
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pad_nvfp4_weight_for_cutlass,
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slice_nvfp4_output,
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swizzle_blockscale,
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)
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from .base import NvFp4LinearKernel, NvFp4LinearLayerConfig
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class CutlassNvFp4LinearKernel(NvFp4LinearKernel):
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"""NVFP4 GEMM via the vLLM CUTLASS kernel."""
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@classmethod
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def is_supported(
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cls, compute_capability: int | None = None
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) -> tuple[bool, str | None]:
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if cutlass_fp4_supported():
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return True, None
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return False, "CUTLASS FP4 kernels not available"
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@classmethod
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def can_implement(cls, config: NvFp4LinearLayerConfig) -> tuple[bool, str | None]:
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return True, None
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def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
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layer.weight_scale = torch.nn.Parameter(
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swizzle_blockscale(layer.weight_scale.data), requires_grad=False
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)
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padded_weight, weights_padding_cols = pad_nvfp4_weight_for_cutlass(
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layer.weight.data
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)
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layer.weight = torch.nn.Parameter(padded_weight, requires_grad=False)
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layer.weights_padding_cols = weights_padding_cols
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def apply_weights(
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self,
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layer: torch.nn.Module,
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x: torch.Tensor,
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bias: torch.Tensor | None = None,
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) -> torch.Tensor:
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output_size = layer.output_size_per_partition
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output_dtype = x.dtype
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output_shape = [*x.shape[:-1], output_size]
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weights_padding_bytes = getattr(layer, "weights_padding_cols", 0)
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x_fp4, x_blockscale = scaled_fp4_quant(
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x,
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layer.input_global_scale_inv,
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is_sf_swizzled_layout=True,
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backend="cutlass",
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padded_n=x.shape[-1] + weights_padding_bytes * 2,
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)
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out = cutlass_scaled_fp4_mm(
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x_fp4,
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layer.weight,
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x_blockscale,
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layer.weight_scale,
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layer.alpha,
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output_dtype,
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)
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out = slice_nvfp4_output(out, output_size)
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if bias is not None:
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out = out + bias
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return out.view(*output_shape)
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