vllm/vllm/model_executor/parameter.py
Robert Shaw 56fe4c297c
[TPU][Quantization] TPU W8A8 (#11785)
Co-authored-by: Woosuk Kwon <woosuk.kwon@berkeley.edu>
2025-01-08 19:33:29 +00:00

426 lines
15 KiB
Python

from fractions import Fraction
from typing import Callable, Optional, Union
import torch
from torch.nn import Parameter
from vllm.distributed import get_tensor_model_parallel_rank
from vllm.logger import init_logger
from vllm.model_executor.utils import _make_synced_weight_loader
__all__ = [
"BasevLLMParameter", "PackedvLLMParameter", "PerTensorScaleParameter",
"ModelWeightParameter", "ChannelQuantScaleParameter",
"GroupQuantScaleParameter", "PackedColumnParameter", "RowvLLMParameter"
]
logger = init_logger(__name__)
class BasevLLMParameter(Parameter):
"""
Base parameter for vLLM linear layers. Extends the torch.nn.parameter
by taking in a linear weight loader. Will copy the loaded weight
into the parameter when the provided weight loader is called.
"""
def __new__(cls, data: torch.Tensor, **kwargs):
return super().__new__(cls, data=data, requires_grad=False)
def __init__(self, data: torch.Tensor, weight_loader: Callable):
"""
Initialize the BasevLLMParameter
:param data: torch tensor with the parameter data
:param weight_loader: weight loader callable
:returns: a torch.nn.parameter
"""
# During weight loading, we often do something like:
# narrowed_tensor = param.data.narrow(0, offset, len)
# narrowed_tensor.copy_(real_weight)
# expecting narrowed_tensor and param.data to share the same storage.
# However, on TPUs, narrowed_tensor will lazily propagate to the base
# tensor, which is param.data, leading to the redundant memory usage.
# This sometimes causes OOM errors during model loading. To avoid this,
# we sync the param tensor after its weight loader is called.
from vllm.platforms import current_platform
if current_platform.is_tpu():
weight_loader = _make_synced_weight_loader(weight_loader)
self._weight_loader = weight_loader
@property
def weight_loader(self):
return self._weight_loader
def _assert_and_load(self, loaded_weight: torch.Tensor):
assert self.data.shape == loaded_weight.shape
self.data.copy_(loaded_weight)
def load_column_parallel_weight(self, loaded_weight: torch.Tensor):
self._assert_and_load(loaded_weight)
def load_row_parallel_weight(self, loaded_weight: torch.Tensor):
self._assert_and_load(loaded_weight)
def load_merged_column_weight(self, loaded_weight: torch.Tensor, **kwargs):
self._assert_and_load(loaded_weight)
def load_qkv_weight(self, loaded_weight: torch.Tensor, **kwargs):
self._assert_and_load(loaded_weight)
class _ColumnvLLMParameter(BasevLLMParameter):
"""
Private class defining weight loading functionality
(load_merged_column_weight, load_qkv_weight)
for parameters being loaded into linear layers with column
parallelism. This includes QKV and MLP layers which are
not already fused on disk. Requires an output dimension
to be defined. Called within the weight loader of
each of the column parallel linear layers.
"""
def __init__(self, output_dim: int, **kwargs):
self._output_dim = output_dim
super().__init__(**kwargs)
@property
def output_dim(self):
return self._output_dim
def load_column_parallel_weight(self, loaded_weight: torch.Tensor):
tp_rank = get_tensor_model_parallel_rank()
shard_size = self.data.shape[self.output_dim]
loaded_weight = loaded_weight.narrow(self.output_dim,
tp_rank * shard_size, shard_size)
assert self.data.shape == loaded_weight.shape
self.data.copy_(loaded_weight)
def load_merged_column_weight(self, loaded_weight: torch.Tensor, **kwargs):
shard_offset = kwargs.get("shard_offset")
shard_size = kwargs.get("shard_size")
if isinstance(
self,
(PackedColumnParameter,
PackedvLLMParameter)) and self.packed_dim == self.output_dim:
shard_size, shard_offset = self.adjust_shard_indexes_for_packing(
shard_offset=shard_offset, shard_size=shard_size)
param_data = self.data
tp_rank = get_tensor_model_parallel_rank()
param_data = param_data.narrow(self.output_dim, shard_offset,
shard_size)
loaded_weight = loaded_weight.narrow(self.output_dim,
tp_rank * shard_size, shard_size)
assert param_data.shape == loaded_weight.shape
param_data.copy_(loaded_weight)
def load_qkv_weight(self, loaded_weight: torch.Tensor, **kwargs):
shard_offset = kwargs.get("shard_offset")
shard_size = kwargs.get("shard_size")
shard_id = kwargs.get("shard_id")
num_heads = kwargs.get("num_heads")
if isinstance(
self,
(PackedColumnParameter,
PackedvLLMParameter)) and self.output_dim == self.packed_dim:
shard_size, shard_offset = self.adjust_shard_indexes_for_packing(
shard_offset=shard_offset, shard_size=shard_size)
param_data = self.data
tp_rank = get_tensor_model_parallel_rank()
shard_id = tp_rank if shard_id == "q" else tp_rank // num_heads
param_data = param_data.narrow(self.output_dim, shard_offset,
shard_size)
loaded_weight = loaded_weight.narrow(self.output_dim,
shard_id * shard_size, shard_size)
assert param_data.shape == loaded_weight.shape
param_data.copy_(loaded_weight)
class RowvLLMParameter(BasevLLMParameter):
"""
Parameter class defining weight_loading functionality
(load_row_parallel_weight) for parameters being loaded
into linear layers with row parallel functionality.
Requires an input_dim to be defined.
"""
def __init__(self, input_dim: int, **kwargs):
self._input_dim = input_dim
super().__init__(**kwargs)
@property
def input_dim(self):
return self._input_dim
def load_row_parallel_weight(self, loaded_weight: torch.Tensor):
tp_rank = get_tensor_model_parallel_rank()
shard_size = self.data.shape[self.input_dim]
loaded_weight = loaded_weight.narrow(self.input_dim,
tp_rank * shard_size, shard_size)
if len(loaded_weight.shape) == 0:
loaded_weight = loaded_weight.reshape(1)
assert self.data.shape == loaded_weight.shape
self.data.copy_(loaded_weight)
class ModelWeightParameter(_ColumnvLLMParameter, RowvLLMParameter):
"""
Parameter class for linear layer weights. Uses both column and
row parallelism.
"""
pass
class GroupQuantScaleParameter(_ColumnvLLMParameter, RowvLLMParameter):
"""
Parameter class for weight scales loaded for weights with
grouped quantization. Uses both column and row parallelism.
"""
pass
class ChannelQuantScaleParameter(_ColumnvLLMParameter):
"""
Parameter class for weight scales loaded for weights with
channel-wise quantization. Equivalent to _ColumnvLLMParameter.
"""
pass
class PerTensorScaleParameter(BasevLLMParameter):
"""
Parameter class for scales where the number of scales is
equivalent to the number of logical matrices in fused linear
layers (e.g. for QKV, there are 3 scales loaded from disk).
This is relevant to weights with per-tensor quantization.
Adds functionality to map the scalers to a shard during
weight loading.
Note: additional parameter manipulation may be handled
for each quantization config specifically, within
process_weights_after_loading
"""
def __init__(self, **kwargs):
self.qkv_idxs = {"q": 0, "k": 1, "v": 2}
super().__init__(**kwargs)
def _shard_id_as_int(self, shard_id: Union[str, int]) -> int:
if isinstance(shard_id, int):
return shard_id
# if not int, assume shard_id for qkv
# map to int and return
assert isinstance(shard_id, str)
assert shard_id in self.qkv_idxs
return self.qkv_idxs[shard_id]
# For row parallel layers, no sharding needed
# load weight into parameter as is
def load_row_parallel_weight(self, *args, **kwargs):
super().load_row_parallel_weight(*args, **kwargs)
def load_merged_column_weight(self, *args, **kwargs):
self._load_into_shard_id(*args, **kwargs)
def load_qkv_weight(self, *args, **kwargs):
self._load_into_shard_id(*args, **kwargs)
def load_column_parallel_weight(self, *args, **kwargs):
super().load_row_parallel_weight(*args, **kwargs)
def _load_into_shard_id(self, loaded_weight: torch.Tensor,
shard_id: Union[str, int], **kwargs):
"""
Slice the parameter data based on the shard id for
loading.
"""
param_data = self.data
shard_id = self._shard_id_as_int(shard_id)
# AutoFP8 scales do not have a shape
# compressed-tensors scales do have a shape
if len(loaded_weight.shape) != 0:
assert loaded_weight.shape[0] == 1
loaded_weight = loaded_weight[0]
param_data = param_data[shard_id]
assert param_data.shape == loaded_weight.shape
param_data.copy_(loaded_weight)
class PackedColumnParameter(_ColumnvLLMParameter):
"""
Parameter for model parameters which are packed on disk
and support column parallelism only. See PackedvLLMParameter
for more details on the packed properties.
"""
def __init__(self,
packed_factor: Union[int, Fraction],
packed_dim: int,
marlin_tile_size: Optional[int] = None,
**kwargs):
self._packed_factor = packed_factor
self._packed_dim = packed_dim
self._marlin_tile_size = marlin_tile_size
super().__init__(**kwargs)
@property
def packed_dim(self):
return self._packed_dim
@property
def packed_factor(self):
return self._packed_factor
@property
def marlin_tile_size(self):
return self._marlin_tile_size
def adjust_shard_indexes_for_packing(self, shard_size, shard_offset):
return _adjust_shard_indexes_for_packing(
shard_size=shard_size,
shard_offset=shard_offset,
packed_factor=self.packed_factor,
marlin_tile_size=self.marlin_tile_size)
class PackedvLLMParameter(ModelWeightParameter):
"""
Parameter for model weights which are packed on disk.
Example: GPTQ Marlin weights are int4 or int8, packed into int32.
Extends the ModelWeightParameter to take in the
packed factor, the packed dimension, and optionally, marlin
tile size for marlin kernels. Adjusts the shard_size and
shard_offset for fused linear layers model weight loading
by accounting for packing and optionally, marlin tile size.
"""
def __init__(self,
packed_factor: Union[int, Fraction],
packed_dim: int,
marlin_tile_size: Optional[int] = None,
**kwargs):
self._packed_factor = packed_factor
self._packed_dim = packed_dim
self._marlin_tile_size = marlin_tile_size
super().__init__(**kwargs)
@property
def packed_dim(self):
return self._packed_dim
@property
def packed_factor(self):
return self._packed_factor
@property
def marlin_tile_size(self):
return self._marlin_tile_size
def adjust_shard_indexes_for_packing(self, shard_size, shard_offset):
return _adjust_shard_indexes_for_packing(
shard_size=shard_size,
shard_offset=shard_offset,
packed_factor=self.packed_factor,
marlin_tile_size=self.marlin_tile_size)
class BlockQuantScaleParameter(_ColumnvLLMParameter, RowvLLMParameter):
"""
Parameter class for weight scales loaded for weights with
block-wise quantization. Uses both column and row parallelism.
"""
pass
def permute_param_layout_(param: BasevLLMParameter, input_dim: int,
output_dim: int, **kwargs) -> BasevLLMParameter:
"""
Permute a parameter's layout to the specified input and output dimensions,
useful for forcing the parameter into a known layout, for example, if I need
a packed (quantized) weight matrix to be in the layout
{input_dim = 0, output_dim = 1, packed_dim = 0}
then I can call:
permute_param_layout_(x, input_dim=0, output_dim=1, packed_dim=0)
to ensure x is in the correct layout (permuting it to the correct layout if
required, asserting if it cannot get it to the correct layout)
"""
curr_input_dim = getattr(param, "input_dim", None)
curr_output_dim = getattr(param, "output_dim", None)
if curr_input_dim is None or curr_output_dim is None:
assert param.data.dim() == 2,\
"permute_param_layout_ only supports 2D parameters when either "\
"input_dim or output_dim is not set"
# if one of the dimensions is not set, set it to the opposite of the other
# we can only do this since we asserted the parameter is 2D above
if curr_input_dim is None:
assert curr_output_dim is not None,\
"either input or output dim must be set"
curr_input_dim = (curr_output_dim + 1) % 2
if curr_output_dim is None:
assert curr_input_dim is not None,\
"either input or output dim must be set"
curr_output_dim = (curr_input_dim + 1) % 2
# create permutation from the current layout to the layout with
# self.input_dim at input_dim and self.output_dim at output_dim preserving
# other dimensions
perm = [
i for i in range(param.data.dim())
if i not in [curr_input_dim, curr_output_dim]
]
perm.insert(input_dim, curr_input_dim)
perm.insert(output_dim, curr_output_dim)
if "packed_dim" in kwargs:
assert hasattr(param, "packed_dim") and\
param.packed_dim == perm[kwargs["packed_dim"]],\
"permute_param_layout_ currently doesn't support repacking"
param.data = param.data.permute(*perm)
if hasattr(param, "_input_dim"):
param._input_dim = input_dim
if hasattr(param, "_output_dim"):
param._output_dim = output_dim
if "packed_dim" in kwargs and hasattr(param, "_packed_dim"):
param._packed_dim = kwargs["packed_dim"]
return param
def _adjust_shard_indexes_for_marlin(shard_size, shard_offset,
marlin_tile_size):
return shard_size * marlin_tile_size, shard_offset * marlin_tile_size
def _adjust_shard_indexes_for_packing(shard_size, shard_offset, packed_factor,
marlin_tile_size):
shard_size = shard_size // packed_factor
shard_offset = shard_offset // packed_factor
if marlin_tile_size is not None:
return _adjust_shard_indexes_for_marlin(
shard_size=shard_size,
shard_offset=shard_offset,
marlin_tile_size=marlin_tile_size)
return shard_size, shard_offset