321 lines
11 KiB
Python
321 lines
11 KiB
Python
# SPDX-License-Identifier: Apache-2.0
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# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
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# Adapted from https://github.com/vllm-project/vllm/blob/main/vllm/model_executor/layers/quantization/modelopt.py
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from typing import Any, Optional
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import regex as re
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import torch
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from torch.nn.parameter import Parameter
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from vllm.logger import init_logger
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from vllm.model_executor.layers.linear import (
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LinearBase,
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LinearMethodBase,
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UnquantizedLinearMethod,
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)
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from vllm.model_executor.layers.quantization import QuantizationMethods
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from vllm.model_executor.layers.quantization.base_config import (
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QuantizationConfig,
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QuantizeMethodBase,
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)
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from vllm.model_executor.layers.quantization.kv_cache import BaseKVCacheMethod
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from vllm.model_executor.layers.quantization.utils.petit_utils import (
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apply_petit_nvfp4_linear,
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prepare_nvfp4_layer_for_petit,
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verify_petit_nvfp4_supported,
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)
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from vllm.model_executor.layers.quantization.utils.quant_utils import is_layer_skipped
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from vllm.model_executor.parameter import ModelWeightParameter, PerTensorScaleParameter
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from vllm.platforms import current_platform
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# Initialize logger for the module
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logger = init_logger(__name__)
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# Configuration class to support the NVFP4 quantized model
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# generated by the ModelOpt quantization tool
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class PetitNvFp4Config(QuantizationConfig):
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"""Config class for Petit FP4."""
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def __init__(
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self,
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is_checkpoint_nvfp4_serialized: bool = False,
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kv_cache_quant_algo: str | None = None,
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group_size: int | None = None,
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exclude_modules: list[str] | None = None,
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) -> None:
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self._check_hardware_support()
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self.is_checkpoint_nvfp4_serialized = is_checkpoint_nvfp4_serialized
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if is_checkpoint_nvfp4_serialized:
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logger.warning(
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"Detected nvfp4 checkpoint. Please note that the "
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"format is experimental and subject to change."
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)
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self.group_size = group_size
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self.kv_cache_quant_algo = kv_cache_quant_algo
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self.exclude_modules = exclude_modules
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def _check_hardware_support(self) -> None:
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"""
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Verifies that the current hardware is supported by the Petit backend.
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This backend is specifically designed for AMD GPUs and is not
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supported on the CUDA platform.
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"""
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# This check ensures the code is NOT running on an NVIDIA GPU.
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if current_platform.is_cuda():
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raise ValueError(
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"The 'petit' quantization backend is designed for AMD GPUs "
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"and is not supported on the CUDA platform. For NVIDIA GPUs, "
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"please use a different quantization method such as FP8, AWQ, "
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"or GPTQ."
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)
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@classmethod
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def get_name(cls) -> QuantizationMethods:
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return "petit_nvfp4"
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@classmethod
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def get_supported_act_dtypes(cls) -> list[torch.dtype]:
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return [torch.bfloat16, torch.half]
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@classmethod
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def get_min_capability(cls) -> int:
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# Petit supports the gfx90a and gfx942 GPUs
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return 90
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@classmethod
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def get_config_filenames(cls) -> list[str]:
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return ["hf_quant_config.json"]
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@classmethod
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def from_config(cls, config: dict[str, Any]) -> "PetitNvFp4Config":
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qc = cls.get_from_keys(config, ["quantization"])
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quant_method_raw = qc.get("quant_algo")
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if not isinstance(quant_method_raw, str) or not quant_method_raw:
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raise ValueError("Missing or invalid 'quant_algo' in quantization config.")
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quant_method = quant_method_raw.upper()
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group_size_raw = qc.get("group_size")
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if not isinstance(group_size_raw, int):
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raise ValueError(
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"Missing or invalid 'group_size' (int) in hf_quant_config.json."
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)
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group_size = group_size_raw
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verify_petit_nvfp4_supported(quant_method, group_size)
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kv_cache_quant_algo_raw = qc.get("kv_cache_quant_algo") or "auto"
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if not isinstance(kv_cache_quant_algo_raw, str):
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raise ValueError("'kv_cache_quant_algo' must be a string if provided.")
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kv_cache_quant_algo = kv_cache_quant_algo_raw
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exclude_raw = qc.get("exclude_modules", [])
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if exclude_raw is None:
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exclude_modules: list[str] = []
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elif isinstance(exclude_raw, list) and all(
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isinstance(x, str) for x in exclude_raw
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):
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exclude_modules = exclude_raw
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else:
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raise ValueError("'exclude_modules' must be a list[str] (or omitted).")
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is_checkpoint_nvfp4_serialized = "NVFP4" in quant_method
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return cls(
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is_checkpoint_nvfp4_serialized=is_checkpoint_nvfp4_serialized,
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kv_cache_quant_algo=kv_cache_quant_algo,
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group_size=group_size,
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exclude_modules=exclude_modules,
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)
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@classmethod
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def override_quantization_method(
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cls, hf_quant_cfg, user_quant
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) -> QuantizationMethods | None:
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if not current_platform.is_rocm():
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return None
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qc = hf_quant_cfg.get("quantization", hf_quant_cfg)
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algo = (qc.get("quant_algo") or qc.get("quant_method") or "").upper()
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if algo in ("NVFP4", "MODELOPT_FP4", "MODELOPT"):
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return cls.get_name() # "petit_nvfp4"
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return None
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@classmethod
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def is_petit_nvfp4_compatible(cls, quant_config: dict[str, Any]) -> bool:
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qc = quant_config.get("quantization", quant_config)
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algo = (qc.get("quant_algo") or qc.get("quant_method") or "").upper()
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return algo == "NVFP4"
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def is_layer_excluded(self, prefix: str, exclude_modules: list[str]) -> bool:
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for pattern in exclude_modules:
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regex_str = pattern.replace(".", r"\.").replace("*", r".*")
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if re.fullmatch(regex_str, prefix):
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return True
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return False
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def get_quant_method(
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self, layer: torch.nn.Module, prefix: str
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) -> Optional["QuantizeMethodBase"]:
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from vllm.attention.layer import Attention # Avoid circular import
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exclude = self.require_exclude_modules()
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if isinstance(layer, LinearBase):
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if is_layer_skipped(prefix, exclude) or self.is_layer_excluded(
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prefix, exclude
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):
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return UnquantizedLinearMethod()
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return PetitNvFp4LinearMethod(self)
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elif isinstance(layer, Attention):
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return PetitFp8KVCacheMethod(self)
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return None
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def get_scaled_act_names(self) -> list[str]:
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return []
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def require_group_size(self) -> int:
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if self.group_size is None:
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logger.warning("group_size not set; defaulting to 16 for NVFP4.")
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return 16
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return self.group_size
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def require_kv_cache_quant_algo(self) -> str:
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return self.kv_cache_quant_algo or "auto"
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def require_exclude_modules(self) -> list[str]:
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return list(self.exclude_modules or [])
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class PetitFp8KVCacheMethod(BaseKVCacheMethod):
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"""
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Supports loading kv-cache scaling factors from FP8 checkpoints.
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"""
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def __init__(self, quant_config: PetitNvFp4Config):
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super().__init__(quant_config)
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class PetitNvFp4LinearMethod(LinearMethodBase):
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"""Linear method for NVFP4.
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Supports loading NVFP4 checkpoints with the following structure:
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|Tensor Name | datatype | shape |
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|----------------------------------------------------|
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|input_scale | torch.float32 | scalar |
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|weight | NVFP4(SE2M1) | [1, X, y/2] |
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|weight_scale | FP8-E4M3 | [X, Y] |
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|weight_scale_2 | torch.float32 | scalar |
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The weights are quantized per block of 16 elements.
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Args: quant_config: The ModelOpt quantization config.
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"""
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def __init__(self, quant_config: PetitNvFp4Config):
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self.quant_config = quant_config
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def create_weights(
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self,
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layer: torch.nn.Module,
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input_size_per_partition: int,
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output_partition_sizes: list[int],
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input_size: int,
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output_size: int,
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params_dtype: torch.dtype,
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**extra_weight_attrs,
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):
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del input_size, output_size
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if not self.quant_config.is_checkpoint_nvfp4_serialized:
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raise ValueError(
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"NVFP4 quantization was selected, "
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" dynamic quantization is not supported."
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)
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output_size_per_partition = sum(output_partition_sizes)
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weight_loader = extra_weight_attrs.get("weight_loader")
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layer.logical_widths = output_partition_sizes
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layer.input_size_per_partition = input_size_per_partition
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layer.output_size_per_partition = output_size_per_partition
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if input_size_per_partition % 16 != 0:
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raise ValueError(
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"Unsupported model when in features size is not multiple of 16"
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)
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weight_dtype = (
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torch.float8_e4m3fn
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if self.quant_config.is_checkpoint_nvfp4_serialized
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else params_dtype
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)
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weight = ModelWeightParameter(
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data=torch.empty(
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# 2 fp4 data is packed in one uint8 in the input dimension
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output_size_per_partition,
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input_size_per_partition // 2,
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dtype=torch.uint8,
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),
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input_dim=1,
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output_dim=0,
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weight_loader=weight_loader,
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)
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layer.register_parameter("weight", weight)
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input_scale = PerTensorScaleParameter(
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data=torch.empty(len(output_partition_sizes), dtype=torch.float32),
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weight_loader=weight_loader,
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)
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layer.register_parameter("input_scale", input_scale)
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weight_scale_2 = PerTensorScaleParameter(
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data=torch.empty(len(output_partition_sizes), dtype=torch.float32),
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weight_loader=weight_loader,
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)
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layer.register_parameter("weight_scale_2", weight_scale_2)
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group_size = self.quant_config.require_group_size()
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weight_scale = ModelWeightParameter(
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data=torch.empty(
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output_size_per_partition,
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input_size_per_partition // group_size,
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dtype=weight_dtype,
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),
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input_dim=1,
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output_dim=0,
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weight_loader=weight_loader,
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)
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layer.register_parameter("weight_scale", weight_scale)
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def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
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input_scale_2 = layer.input_scale.max().to(torch.float32)
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weight_scale_2 = layer.weight_scale_2.max().to(torch.float32)
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layer.input_scale = Parameter(input_scale_2, requires_grad=False)
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layer.weight_scale_2 = Parameter(weight_scale_2, requires_grad=False)
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layer.alpha = Parameter(
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layer.input_scale * layer.weight_scale_2, requires_grad=False
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)
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prepare_nvfp4_layer_for_petit(layer)
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del layer.input_scale
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def apply(
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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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return apply_petit_nvfp4_linear(
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input=x,
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weight=layer.weight,
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weight_scale=layer.weight_scale,
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weight_scale_2=layer.weight_scale_2,
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size_n=layer.output_size_per_partition,
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size_k=layer.input_size_per_partition,
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bias=bias,
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)
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