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Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
import enum
from enum import Enum
from fractions import Fraction
from typing import Any, Optional, Union
import torch
from torch.nn.parameter import Parameter
from vllm import _custom_ops as ops
from vllm.model_executor.layers.linear import LinearMethodBase
from vllm.model_executor.layers.quantization import QuantizationMethods
from vllm.model_executor.layers.quantization.base_config import (
QuantizationConfig)
from vllm.model_executor.layers.quantization.utils.gptq_utils import (
get_linear_quant_method)
from vllm.model_executor.parameter import (ChannelQuantScaleParameter,
GroupQuantScaleParameter,
PackedColumnParameter,
PackedvLLMParameter,
RowvLLMParameter)
class GPTQConfig(QuantizationConfig):
"""Config class for GPTQ.
Reference: https://arxiv.org/abs/2210.17323
"""
def __init__(
self,
weight_bits: int,
group_size: int,
desc_act: bool,
lm_head_quantized: bool,
dynamic: dict[str, dict[str, Union[int, bool]]],
) -> None:
# GPTQModel use `dynamic` config property to allow per module
# quantization config so each module can be individually optimized.
# Format is dict[str, dict] where key is a regex string that can
# perform both positive ("+:" prefixed) or negative ("-:" prefixed)
# matching of a module.
# Default to positive match, override base quant config mode, if no
# prefix is used. Value is in dict format of field key and override
# value.
# Negative matching will skip quantization init for this module
# entirely:
# non-quantized inference. More details and quantization examples can be
# found at: https://github.com/ModelCloud/GPTQModel
# Example:
# # last 1/2 of the layers 10-21 has 8bit vs 4bit for 0-9
# # last 1/4 of the layers 16-21 has 8bit and group_size 64
# dynamic = {
# #`.*\.` matches the layers_node prefix
# # positive match layer 10-15
# r"+:.*\.(?:1[0-5])\..*": {"bits": 8,},
# # positive match layer 16-21
# r"+:.*\.(?:1[6-9]|20|21)\..*": {"bits": 8, "group_size": 64,},
# r"-:.*\.moe\..*": {}, # negative match (skip) all `moe` layers
# }
super().__init__()
self.dynamic = dynamic
self.weight_bits = weight_bits
self.group_size = group_size
self.desc_act = desc_act
self.lm_head_quantized = lm_head_quantized
self.pack_factor = Fraction(32, self.weight_bits)
if self.weight_bits not in [2, 3, 4, 8]:
raise ValueError(
"Currently, only 2/3/4/8-bit weight quantization is "
f"supported for GPTQ, but got {self.weight_bits} bits.")
def __repr__(self) -> str:
return (f"GPTQConfig(weight_bits={self.weight_bits}, "
f"group_size={self.group_size}, "
f"desc_act={self.desc_act}), "
f"lm_head_quantized={self.lm_head_quantized}), "
f"dynamic={self.dynamic}")
@classmethod
def get_name(cls) -> QuantizationMethods:
return "gptq"
@classmethod
def get_supported_act_dtypes(cls) -> list[torch.dtype]:
return [torch.half, torch.bfloat16]
@classmethod
# Need to figure it out
def get_min_capability(cls) -> int:
return 60
@classmethod
def get_config_filenames(cls) -> list[str]:
return ["quantize_config.json"]
@classmethod
def from_config(cls, config: dict[str, Any]) -> "GPTQConfig":
dynamic = cls.get_from_keys_or(config, ["dynamic"], default={})
dynamic = {} if dynamic is None else dynamic
weight_bits = cls.get_from_keys(config, ["bits"])
group_size = cls.get_from_keys(config, ["group_size"])
desc_act = cls.get_from_keys(config, ["desc_act"])
lm_head_quantized = cls.get_from_keys_or(config, ["lm_head"],
default=False)
return cls(weight_bits, group_size, desc_act, lm_head_quantized,
dynamic)
def get_quant_method(self, layer: torch.nn.Module,
prefix: str) -> Optional["GPTQLinearMethod"]:
return get_linear_quant_method(self, layer, prefix, GPTQLinearMethod)
class ExllamaState(Enum):
UNUSED = enum.auto()
UNINITIALIZED = enum.auto()
READY = enum.auto()
class GPTQLinearMethod(LinearMethodBase):
"""Linear method for GPTQ.
Args:
quant_config: The GPTQ quantization config.
"""
def __init__(self, quant_config: GPTQConfig):
self.quant_config = quant_config
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,
):
del output_size # Unused.
weight_loader = extra_weight_attrs.get("weight_loader")
if input_size_per_partition % self.quant_config.group_size != 0:
raise ValueError(
"The input size is not aligned with the quantized "
"weight shape. This can be caused by too large "
"tensor parallel size.")
output_size_per_partition = sum(output_partition_sizes)
if (output_size_per_partition % self.quant_config.pack_factor.numerator
!= 0):
raise ValueError(
"The output size is not aligned with the quantized "
"weight shape. This can be caused by too large "
"tensor parallel size.")
if self.quant_config.group_size != -1:
group_size = self.quant_config.group_size
else:
group_size = input_size
exllama_state = ExllamaState.UNINITIALIZED
scale_and_zero_size = input_size // group_size
scale_and_zero_input_dim = None
if (input_size != input_size_per_partition
and self.quant_config.group_size != -1):
# For act-order models, we cannot use Exllama for row parallel layer
if self.quant_config.desc_act:
exllama_state = ExllamaState.UNUSED
else:
# we need to partition qzeros and scales for exllama kernel
scale_and_zero_size = input_size_per_partition // group_size
scale_and_zero_input_dim = 0
qweight = PackedvLLMParameter(
data=torch.empty(
input_size_per_partition // self.quant_config.pack_factor,
output_size_per_partition,
dtype=torch.int32,
),
input_dim=0,
output_dim=1,
packed_dim=0,
packed_factor=self.quant_config.pack_factor,
weight_loader=weight_loader)
g_idx = RowvLLMParameter(data=torch.tensor(
[
i // self.quant_config.group_size
for i in range(input_size_per_partition)
],
dtype=torch.int32,
),
input_dim=0,
weight_loader=weight_loader)
qzeros_args = {
"data":
torch.empty(
scale_and_zero_size,
output_size_per_partition // self.quant_config.pack_factor,
dtype=torch.int32,
),
"weight_loader":
weight_loader
}
weight_scale_args = {
"data":
torch.empty(
scale_and_zero_size,
output_size_per_partition,
dtype=params_dtype,
),
"weight_loader":
weight_loader
}
if scale_and_zero_input_dim is None:
scales = ChannelQuantScaleParameter(output_dim=1,
**weight_scale_args)
qzeros = PackedColumnParameter(
output_dim=1,
packed_dim=1,
packed_factor=self.quant_config.pack_factor,
**qzeros_args)
else:
scales = GroupQuantScaleParameter(output_dim=1,
input_dim=0,
**weight_scale_args)
qzeros = PackedvLLMParameter(
input_dim=0,
output_dim=1,
packed_dim=1,
packed_factor=self.quant_config.pack_factor,
**qzeros_args)
layer.register_parameter("qweight", qweight)
layer.register_parameter("g_idx", g_idx)
layer.register_parameter("qzeros", qzeros)
layer.register_parameter("scales", scales)
layer.exllama_state = exllama_state
def process_weights_after_loading(self, layer: torch.nn.Module) -> None:
# for torch.compile
layer.qzeros = Parameter(layer.qzeros.data, requires_grad=False)
layer.qweight = Parameter(layer.qweight.data, requires_grad=False)
layer.g_idx = Parameter(layer.g_idx.data, requires_grad=False)
layer.scales = Parameter(layer.scales.data, requires_grad=False)
# exllama needs to shuffle the weight after the weight is loaded
# here we do the shuffle on first forward pass
if self.quant_config.group_size == 128 or self.quant_config.group_size == 64:
if self.quant_config.desc_act:
layer.g_idx.data = torch.argsort(layer.g_idx).to(torch.int)
else:
layer.g_idx.data = torch.empty((0, ),
dtype=torch.int,
device=layer.g_idx.device)
layer.exllama_state = ExllamaState.READY
ops.gptq_shuffle(layer.qweight, layer.g_idx,
self.quant_config.weight_bits)
if layer.scales.dtype != torch.bfloat16:
perm_space = torch.empty(0)
temp_space = torch.empty(0)
if self.quant_config.weight_bits == 4:
# warmup
reshaped_x = torch.randn(1, layer.qweight.shape[0]*8, dtype=layer.scales.dtype, device="cuda")
_ = ops.gptq_gemm(reshaped_x, layer.qweight, layer.qzeros,
layer.scales, layer.g_idx,
layer.exllama_state == ExllamaState.READY,
self.quant_config.weight_bits,
self.quant_config.group_size,
perm_space, temp_space,
False)
if self.quant_config.weight_bits == 8:
# warmup
reshaped_x = torch.randn(1, layer.qweight.shape[0]*4, dtype=layer.scales.dtype, device="cuda")
_ = ops.gptq_gemm(reshaped_x, layer.qweight, layer.qzeros,
layer.scales, layer.g_idx,
layer.exllama_state == ExllamaState.READY,
self.quant_config.weight_bits,
self.quant_config.group_size,
perm_space, temp_space,
False)
else:
if layer.exllama_state == ExllamaState.UNINITIALIZED:
if self.quant_config.desc_act:
layer.g_idx.data = torch.argsort(layer.g_idx).to(torch.int)
else:
layer.g_idx.data = torch.empty((0, ),
dtype=torch.int,
device=layer.g_idx.device)
layer.exllama_state = ExllamaState.READY
ops.gptq_shuffle(layer.qweight, layer.g_idx,
self.quant_config.weight_bits)
"""
perm_space = torch.empty(0)
if self.quant_config.weight_bits == 4:
# warmup
reshaped_x = torch.randn(1, layer.qweight.shape[0]*8, dtype=layer.scales.dtype, device="cuda")
_ = ops.gptq_gemm(reshaped_x, layer.qweight, layer.qzeros,
layer.scales, layer.g_idx,
layer.exllama_state == ExllamaState.READY,
self.quant_config.weight_bits,
self.quant_config.group_size,
perm_space)
if self.quant_config.weight_bits == 8:
# warmup
reshaped_x = torch.randn(1, layer.qweight.shape[0]*4, dtype=layer.scales.dtype, device="cuda")
_ = ops.gptq_gemm(reshaped_x, layer.qweight, layer.qzeros,
layer.scales, layer.g_idx,
layer.exllama_state == ExllamaState.READY,
self.quant_config.weight_bits,
self.quant_config.group_size,
perm_space)
"""
def apply(self,
layer: torch.nn.Module,
x: torch.Tensor,
bias: Optional[torch.Tensor] = None) -> torch.Tensor:
out_shape = x.shape[:-1] + (layer.qweight.shape[-1], )
reshaped_x = x.reshape(-1, x.shape[-1])
perm_space = torch.empty(0)
temp_space = torch.empty(0)
if self.quant_config.weight_bits == 4 or self.quant_config.weight_bits == 8:
if self.quant_config.group_size == 128 or self.quant_config.group_size == 64:
if self.quant_config.desc_act:
perm_space = torch.empty(reshaped_x.shape[0], reshaped_x.shape[1],
dtype=torch.float16, device="cuda")
if reshaped_x.dtype == torch.bfloat16:
temp_space = torch.zeros(reshaped_x.shape[0], layer.qweight.shape[1],
dtype=torch.float32, device="cuda")
output = ops.gptq_gemm(reshaped_x, layer.qweight, layer.qzeros,
layer.scales, layer.g_idx,
layer.exllama_state == ExllamaState.READY,
self.quant_config.weight_bits,
self.quant_config.group_size,
perm_space, temp_space,
True if reshaped_x.dtype == torch.bfloat16 else False)
if bias is not None:
output.add_(bias)
return output.reshape(out_shape)