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enginex-ascend-910-vllm/vllm_ascend/quantization/methods/w4a4_mxfp4_flatquant.py
Sun Ruoxi 7f8a1b1f7a init v0.23.0
Signed-off-by: Sun Ruoxi <sunruoxi@4paradigm.com>
2026-08-27 15:11:51 +08:00

181 lines
7.4 KiB
Python

#
# Copyright (c) 2025 Huawei Technologies Co., Ltd. All Rights Reserved.
# This file is a part of the vllm-ascend project.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#
import math
from typing import Any
import torch
import torch_npu
from vllm.config import get_current_vllm_config
from vllm.distributed import get_tensor_model_parallel_world_size
from vllm.model_executor.layers.linear import RowParallelLinear
from vllm_ascend.device.mxfp_compat import ensure_mxfp4_flatquant_linear_available
from .base import AscendLinearScheme
from .registry import register_scheme
# Maximum supported dimension for Kronecker quantization left_trans_dim and right_trans_dim
MAX_SUPPORT_DIM = 256
def get_decompose_dim(n: int, m: int) -> tuple[int, int]:
"""Get decomposed dimensions for Kronecker quantization.
Args:
n: Dimension to decompose
m: Tensor parallelism size
Returns:
tuple[int, int]: Left decomposed dim, right decomposed dim
Raises:
ValueError: If decomposed dimension exceeds MAX_SUPPORT_DIM
"""
a = int(math.sqrt(n))
if a * a < n:
a += 1
while True:
tmp = a * a - n
b = int(math.sqrt(tmp))
if b * b == tmp:
break
a += 1
if (a + b) > MAX_SUPPORT_DIM:
raise ValueError(
f"Kronecker quantization left_trans_dim and right_trans_dim should be less than {MAX_SUPPORT_DIM}"
)
if (a - b) * m > MAX_SUPPORT_DIM:
return MAX_SUPPORT_DIM, m * n // MAX_SUPPORT_DIM
return a - b, a + b
@register_scheme("W4A4_MXFP4_FLATQUANT", "linear")
class AscendW4A4MXFP4FlatQuantDynamicLinearMethod(AscendLinearScheme):
"""Linear method for Ascend W4A4_MXFP4_FLATQUANT_DYNAMIC."""
def __init__(self):
ensure_mxfp4_flatquant_linear_available("W4A4_MXFP4_FLATQUANT linear quantization")
vllm_config = get_current_vllm_config()
self.group_size = vllm_config.quant_config.quant_description.get("group_size", 32)
self.max_supported_tp = vllm_config.quant_config.quant_description.get("max_supported_tp", 4)
self.tp_size = get_tensor_model_parallel_world_size()
if self.tp_size > self.max_supported_tp:
raise ValueError(
f"For W4A4_MXFP4_FLATQUANT, TP size ({self.tp_size}) is not supported. "
f"Max supported TP size is {self.max_supported_tp}, "
f"according to the max_supported_tp parameter in quant_description."
)
def get_weight(self, input_size: int, output_size: int, params_dtype: torch.dtype) -> dict[str, Any]:
if input_size % 2 != 0:
raise ValueError(f"input_size ({input_size}) must be divisible by 2 for fp4 packing")
self.input_size = input_size
params_dict = {"weight": torch.empty(output_size, input_size // 2, dtype=torch.uint8)}
return params_dict
def get_pertensor_param(self, params_dtype: torch.dtype, **kwargs: Any) -> dict[str, Any]:
params_dict = {}
layer_type = kwargs.get("layer_type")
if layer_type == "row":
origin_size = self.input_size * self.tp_size
_, right_trans_dim = get_decompose_dim(origin_size // self.max_supported_tp, self.max_supported_tp)
left_trans_dim = origin_size // right_trans_dim
else:
left_trans_dim, right_trans_dim = get_decompose_dim(self.input_size, 1)
params_dict["left_trans"] = torch.empty(left_trans_dim, left_trans_dim, dtype=params_dtype)
params_dict["right_trans"] = torch.empty(right_trans_dim, right_trans_dim, dtype=params_dtype)
params_dict["clip_ratio"] = torch.empty(1, dtype=torch.float32)
return params_dict
def get_pergroup_param(
self, input_size: int, output_size: int, params_dtype: torch.dtype, layer_type: str | None = None
) -> dict[str, Any]:
params_dict = {}
params_dict["weight_scale"] = torch.empty(output_size, input_size // self.group_size, dtype=torch.uint8)
return params_dict
def apply(
self,
layer: torch.nn.Module,
x: torch.Tensor,
bias: torch.Tensor | None = None,
tp_rank: int | None = 0,
) -> torch.Tensor:
original_dtype = x.dtype
input_shape = x.shape
in_features = input_shape[-1]
left_dim = layer.left_trans.shape[0]
right_dim = layer.right_trans.shape[0]
if left_dim * right_dim != in_features:
raise ValueError(
f"FlatQuant transform matrices dimension mismatch: "
f"left_dim({left_dim}) * right_dim({right_dim}) != in_features({in_features})"
)
x_reshaped = x.view(-1, left_dim, right_dim)
x_quantized_fp4, pertoken_scale = torch_npu.npu_kronecker_quant(
x_reshaped,
layer.left_trans,
layer.right_trans,
layer.aclnn_clip_ratio,
dst_dtype=torch_npu.float4_e2m1fn_x2,
)
output = torch_npu.npu_quant_matmul(
x_quantized_fp4,
layer.weight,
layer.weight_scale,
scale_dtype=torch_npu.float8_e8m0fnu,
pertoken_scale=pertoken_scale,
pertoken_scale_dtype=torch_npu.float8_e8m0fnu,
bias=bias,
output_dtype=original_dtype,
x1_dtype=torch_npu.float4_e2m1fn_x2,
x2_dtype=torch_npu.float4_e2m1fn_x2,
group_sizes=[1, 1, self.group_size],
)
output = output.view(*input_shape[:-1], -1)
return output
def process_weights_after_loading(self, layer):
if isinstance(layer, RowParallelLinear):
"""
Process weights after loading with TP diagonal block extraction.
This is the special weight loading logic for FlatQuant row parallelism.
"""
left_dim = layer.left_trans.data.shape[0]
# Calculate block sizes
left_block_size = left_dim // layer.tp_size
# Extract diagonal block for current rank
layer.left_trans.data = layer.left_trans.data[
layer.tp_rank * left_block_size : (layer.tp_rank + 1) * left_block_size,
layer.tp_rank * left_block_size : (layer.tp_rank + 1) * left_block_size,
]
layer.weight_scale.data = layer.weight_scale.data.view(-1, layer.weight_scale.shape[-1] // 2, 2)
layer.weight.data = layer.weight.data.transpose(0, 1)
layer.weight_scale.data = layer.weight_scale.data.transpose(0, 1)
layer.left_trans = torch.nn.Parameter(layer.left_trans.data.t().contiguous())
layer.right_trans = torch.nn.Parameter(layer.right_trans.data)
layer.clip_ratio = torch.nn.Parameter(layer.clip_ratio.data.to(torch.float32))
layer.aclnn_clip_ratio = layer.clip_ratio.item()