50 lines
1.6 KiB
Python
50 lines
1.6 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.model_executor.layers.quantization.utils.nvfp4_emulation_utils import (
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kE2M1ToFloat_handle,
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run_nvfp4_emulations,
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)
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from .base import NvFp4LinearKernel, NvFp4LinearLayerConfig
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class EmulationNvFp4LinearKernel(NvFp4LinearKernel):
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"""Software emulation fallback for NVFP4 (dequant → BF16 matmul)."""
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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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# Always available as a last-resort fallback.
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return True, None
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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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# Move the E2M1 lookup table to the device now, because
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# `.to(device)` is not allowed during CUDA graph capture.
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kE2M1ToFloat_handle.val = kE2M1ToFloat_handle.val.to(layer.weight.device)
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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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out = run_nvfp4_emulations(
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x=x,
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input_global_scale=layer.input_global_scale_inv,
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weight=layer.weight,
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weight_scale_swizzled=layer.weight_scale,
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weight_global_scale=layer.weight_global_scale,
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swizzle=False,
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)
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if bias is not None:
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out = out + bias
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return out
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