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sglang/python/sglang/srt/layers/torchao_utils.py
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Python

"""
Common utilities for torchao.
"""
from typing import Dict, Set
import torch
def torchao_quantize_param_data(param: torch.Tensor, torchao_config: str):
"""Quantize a Tensor with torchao quantization specified by torchao_config
Args:
`param`: weight parameter of the linear module
`torchao_config`: type of quantization and their arguments we want to use to
quantize the Tensor, e.g. int4wo-128 means int4 weight only quantization with group_size
128
"""
# Lazy import to suppress some warnings
from torchao.quantization import (
float8_dynamic_activation_float8_weight,
int4_weight_only,
int8_dynamic_activation_int8_weight,
int8_weight_only,
quantize_,
)
from torchao.quantization.observer import PerRow, PerTensor
dummy_linear = torch.nn.Linear(param.shape[1], param.shape[0], bias=False)
dummy_linear.weight = param
if "int8wo" in torchao_config:
quantize_(dummy_linear, int8_weight_only())
elif "int8dq" in torchao_config:
quantize_(dummy_linear, int8_dynamic_activation_int8_weight())
elif "int4wo" in torchao_config:
group_size = int(torchao_config.split("-")[-1])
assert group_size in [
32,
64,
128,
256,
], f"int4wo groupsize needs to be one of [32, 64, 128, 256] but got {group_size}"
quantize_(dummy_linear, int4_weight_only(group_size=group_size))
elif "fp8wo" in torchao_config:
from torchao.quantization import float8_weight_only
# this requires newer hardware
# [rank0]: AssertionError: fp8e4nv data type is not supported on CUDA arch < 89
quantize_(dummy_linear, float8_weight_only())
elif "fp8dq" in torchao_config:
granularity = torchao_config.split("-")[-1]
GRANULARITY_MAP = {
"per_row": PerRow(),
"per_tensor": PerTensor(),
}
assert (
granularity in GRANULARITY_MAP
), f"Supported granularity are: {GRANULARITY_MAP.keys()}, got {granularity}"
quantize_(
dummy_linear,
float8_dynamic_activation_float8_weight(
granularity=GRANULARITY_MAP[granularity]
),
)
else:
raise ValueError(f"Unexpected config: {torchao_config}")
return dummy_linear.weight
def apply_torchao_config_(
self: torch.nn.Module,
params_dict: Dict[str, torch.Tensor],
param_suffixes: Set[str],
) -> None:
"""A util function used for quantizing the weight parameters after they are loaded if
self.torchao_config is specified
Args:
`self`: the model we want to quantize
`params_dict`: dictionary mapping from param_name to the parameter Tensor
`param_suffixes`: a set of suffixes, we'll quantize the Tensor matching these suffixes
Returns:
None, the `params_dict` is modified inplace and the weights of `self` model are quantized
"""
if self.torchao_config:
for param_suffix in param_suffixes:
for name in params_dict:
param = params_dict[name]
if param_suffix in name and param.ndim == 2:
params_dict[name] = torchao_quantize_param_data(
param, self.torchao_config
)
self.load_state_dict(params_dict, assign=True)