Files
2026-01-09 13:34:11 +08:00

228 lines
7.5 KiB
Python

from typing import Any, Dict, List, Optional
import torch
from torch.nn.parameter import Parameter
from vllm import _custom_ops as ops
from vllm.model_executor.layers.linear import LinearBase, LinearMethodBase
from vllm.model_executor.layers.quantization.base_config import (
QuantizationConfig)
from vllm.model_executor.utils import set_weight_attrs
class MarlinConfig(QuantizationConfig):
"""Config class for Marlin.
Reference: https://github.com/IST-DASLab/marlin/tree/master
"""
def __init__(
self,
group_size: int,
) -> None:
# Group size for the quantization.
self.group_size = group_size
if self.group_size != 128 and self.group_size != -1:
raise ValueError(
"Currently, only group size 128 and -1 (channelwise) "
"is supported for Marlin, but got group_size of "
f"{self.group_size}")
# 4 Bits packed into 32 bit datatype.
self.pack_factor = 32 // 4
# Tile size used by marlin kernels.
self.tile_size = 16
# Min out_features dim
self.min_n_threads = 64
# Min in_features dim
self.min_k_threads = 128
# Max parallel problems to solve at once (improves large
# batch performance)
self.max_parallel = 16
# Permutation length used by the marlin kernels.
self.perm_len = 1024
def __repr__(self) -> str:
return f"MarlinConfig(group_size={self.group_size})"
@classmethod
def get_name(cls) -> str:
return "marlin"
@classmethod
def get_supported_act_dtypes(cls) -> List[torch.dtype]:
return [torch.half]
@classmethod
# Need to figure it out
def get_min_capability(cls) -> int:
return 80
@classmethod
def get_config_filenames(cls) -> List[str]:
return ["quantize_config.json"]
@classmethod
def from_config(cls, config: Dict[str, Any]) -> "MarlinConfig":
group_size = cls.get_from_keys(config, ["group_size"])
return cls(group_size)
def get_quant_method(
self, layer: torch.nn.Module) -> Optional["MarlinLinearMethod"]:
if isinstance(layer, LinearBase):
return MarlinLinearMethod(self)
return None
def get_scaled_act_names(self) -> List[str]:
return []
class MarlinLinearMethod(LinearMethodBase):
"""Linear method for Marlin.
Args:
quant_config: The Marlin quantization config.
"""
def __init__(self, quant_config: MarlinConfig):
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.
if params_dtype != torch.float16:
raise ValueError(
f"The params dtype must be float16, but got {params_dtype}")
# Validate output_size_per_partition
output_size_per_partition = sum(output_partition_sizes)
if output_size_per_partition % self.quant_config.min_n_threads != 0:
raise ValueError(
f"Weight output_size_per_partition = "
f"{output_size_per_partition} is not divisible by "
f"min_n_threads = {self.quant_config.min_n_threads}.")
if output_size_per_partition % self.quant_config.pack_factor != 0:
raise ValueError(
f"Weight output_size_per_partition = "
f"{output_size_per_partition} is not divisible by "
f"pack_factor = {self.quant_config.pack_factor}.")
# Validate input_size_per_partition
if input_size_per_partition % self.quant_config.min_k_threads != 0:
raise ValueError(
f"Weight input_size_per_partition = "
f"{input_size_per_partition} is not divisible by "
f"min_k_threads = {self.quant_config.min_k_threads}.")
if (self.quant_config.group_size != -1 and
input_size_per_partition % self.quant_config.group_size != 0):
raise ValueError(f"Weight input_size_per_partition = "
f"{input_size_per_partition} is not divisible by "
f"group_size = {self.quant_config.group_size}.")
# Check that we have at least 4 tiles horizontally in the shard
num_tiles_per_perm = self.quant_config.perm_len // (
self.quant_config.tile_size**2)
if output_size_per_partition % num_tiles_per_perm != 0:
raise ValueError(
"Each permutation group must reside on the same gpu")
# Quantized 4Bit weights packed into Int32.
qweight = Parameter(
torch.empty(
input_size_per_partition // self.quant_config.tile_size,
output_size_per_partition * self.quant_config.tile_size //
self.quant_config.pack_factor,
device="cuda",
dtype=torch.int32,
),
requires_grad=False,
)
set_weight_attrs(
qweight,
{
"input_dim": 0,
"output_dim": 1,
"packed_dim": 1,
"pack_factor": self.quant_config.pack_factor,
"marlin_tile_size": self.quant_config.tile_size,
},
)
# Determine if channelwise or not
input_groups = (1 if self.quant_config.group_size == -1 else
input_size_per_partition //
self.quant_config.group_size)
scales = Parameter(
torch.empty(
input_groups,
output_size_per_partition,
device="cuda",
dtype=params_dtype,
),
requires_grad=False,
)
set_weight_attrs(
scales,
{
"input_dim": None if input_groups == 1 else 0,
"output_dim": 1,
},
)
# Allocate workspace (Used for internal locking mechanism)
max_workspace_size = (
output_size_per_partition //
self.quant_config.min_n_threads) * self.quant_config.max_parallel
workspace = Parameter(torch.zeros(max_workspace_size,
device="cuda",
dtype=torch.int),
requires_grad=False)
layer.register_parameter("B", qweight)
set_weight_attrs(qweight, extra_weight_attrs)
layer.register_parameter("s", scales)
set_weight_attrs(scales, extra_weight_attrs)
layer.register_parameter("workspace", workspace)
set_weight_attrs(workspace, extra_weight_attrs)
def apply(
self,
layer: torch.nn.Module,
x: torch.Tensor,
bias: Optional[torch.Tensor] = None,
) -> torch.Tensor:
qweight = layer.B
scales = layer.s
workspace = layer.workspace
x_2d = x.view(-1, x.shape[-1])
size_m = x_2d.shape[0]
size_k = x_2d.shape[1]
size_n = scales.shape[1]
output_2d = ops.marlin_gemm(x_2d, qweight, scales, workspace, size_m,
size_n, size_k)
output = output_2d.view(x.shape[:-1] + (output_2d.shape[1], ))
if bias is not None:
output.add_(bias) # In-place add
return output