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from typing import Any, Dict, List, Optional
import torch
from torch.nn import Module
from torch.nn.parameter import Parameter
from vllm.logger import init_logger
from vllm.model_executor.layers.linear import (LinearBase, LinearMethodBase,
UnquantizedLinearMethod)
from vllm.model_executor.layers.quantization.base_config import (
QuantizationConfig, QuantizeMethodBase)
from vllm.model_executor.layers.quantization.fp8 import cutlass_fp8_supported
from vllm.model_executor.layers.quantization.utils.marlin_utils_fp8 import (
apply_fp8_marlin_linear, prepare_fp8_layer_for_marlin)
from vllm.model_executor.layers.quantization.utils.quant_utils import (
is_layer_skipped)
from vllm.model_executor.layers.quantization.utils.w8a8_utils import (
apply_fp8_linear, normalize_e4m3fn_to_e4m3fnuz)
from vllm.model_executor.parameter import (ChannelQuantScaleParameter,
ModelWeightParameter)
from vllm.platforms import current_platform
from vllm.utils import is_hip
logger = init_logger(__name__)
class FBGEMMFp8Config(QuantizationConfig):
"""Config class for FBGEMM Fp8."""
def __init__(self, ignore_list: List[str], input_scale_ub: float):
self.ignore_list = ignore_list if ignore_list else []
self.input_scale_ub = input_scale_ub
# For GPUs that lack FP8 hardware support, we can leverage the Marlin
# kernel for fast weight-only FP8 quantization
self.use_marlin = not current_platform.has_device_capability(89)
@classmethod
def get_name(cls) -> str:
return "fbgemm_fp8"
@classmethod
def get_supported_act_dtypes(cls) -> List[torch.dtype]:
return [torch.bfloat16, torch.float16]
@classmethod
def get_min_capability(cls) -> int:
return 80
@classmethod
def get_config_filenames(cls) -> List[str]:
return []
@classmethod
def from_config(cls, config: Dict[str, Any]) -> "FBGEMMFp8Config":
ignore_list = cls.get_from_keys(config, ["modules_to_not_convert"])
input_scale_ub = cls.get_from_keys(config, ["activation_scale_ub"])
return cls(ignore_list=ignore_list, input_scale_ub=input_scale_ub)
def get_quant_method(self, layer: torch.nn.Module,
prefix: str) -> Optional["QuantizeMethodBase"]:
if isinstance(layer, LinearBase):
if is_layer_skipped(prefix, self.ignore_list):
return UnquantizedLinearMethod()
return FBGEMMFp8LinearMethod(self)
return None
def get_scaled_act_names(self) -> List[str]:
return []
class FBGEMMFp8LinearMethod(LinearMethodBase):
def __init__(self, quant_config: FBGEMMFp8Config):
self.quant_config = quant_config
self.cutlass_fp8_supported = cutlass_fp8_supported()
def create_weights(
self,
layer: torch.nn.Module,
input_size_per_partition: int,
output_partition_sizes: List[int],
input_size: int,
output_size: int,
params_dtype: torch.dtype,
**extra_weight_attrs,
):
weight_loader = extra_weight_attrs.get("weight_loader")
del input_size, output_size
output_size_per_partition = sum(output_partition_sizes)
layer.logical_widths = output_partition_sizes
layer.input_size_per_partition = input_size_per_partition
layer.output_size_per_partition = output_size_per_partition
layer.orig_dtype = params_dtype
# WEIGHT
weight = ModelWeightParameter(data=torch.empty(
output_size_per_partition,
input_size_per_partition,
dtype=torch.float8_e4m3fn),
input_dim=1,
output_dim=0,
weight_loader=weight_loader)
layer.register_parameter("weight", weight)
# WEIGHT SCALE
weight_scale = ChannelQuantScaleParameter(data=torch.empty(
(sum(output_partition_sizes), 1), dtype=torch.float32),
output_dim=0,
weight_loader=weight_loader)
weight_scale[:] = torch.finfo(torch.float32).min
layer.register_parameter("weight_scale", weight_scale)
# INPUT SCALE UPPER BOUND
input_scale_ub = torch.nn.Parameter(torch.tensor(
(self.quant_config.input_scale_ub), dtype=torch.float32),
requires_grad=False)
layer.input_scale_ub = input_scale_ub
def process_weights_after_loading(self, layer: Module) -> None:
# required by torch.compile
layer.weight_scale = Parameter(layer.weight_scale.data,
requires_grad=False)
layer.weight = Parameter(layer.weight.data, requires_grad=False)
weight = layer.weight
if is_hip():
weight, weight_scale, input_scale = \
normalize_e4m3fn_to_e4m3fnuz(
weight=weight,
weight_scale=layer.weight_scale,
input_scale=None)
if input_scale is not None:
layer.input_scale = Parameter(input_scale, requires_grad=False)
layer.weight_scale = Parameter(weight_scale, requires_grad=False)
layer.weight = Parameter(weight.t(), requires_grad=False)
if self.quant_config.use_marlin:
prepare_fp8_layer_for_marlin(layer)
# Activations not quantized for marlin.
del layer.input_scale_ub
def apply(self,
layer: torch.nn.Module,
x: torch.Tensor,
bias: Optional[torch.Tensor] = None) -> torch.Tensor:
if self.quant_config.use_marlin:
return apply_fp8_marlin_linear(
input=x,
weight=layer.weight,
weight_scale=layer.weight_scale,
workspace=layer.workspace,
size_n=layer.output_size_per_partition,
size_k=layer.input_size_per_partition,
bias=bias)
return apply_fp8_linear(
input=x,
weight=layer.weight,
weight_scale=layer.weight_scale,
input_scale=None,
input_scale_ub=layer.input_scale_ub,
bias=bias,
cutlass_fp8_supported=self.cutlass_fp8_supported,
use_per_token_if_dynamic=True)