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enginex-mthreads-vllm/vllm/lora/fully_sharded_layers.py
2026-01-09 13:34:11 +08:00

263 lines
10 KiB
Python

# pylint: disable=unused-argument
from typing import TYPE_CHECKING, List, Optional
import torch
import torch.nn as nn
from transformers import PretrainedConfig
from vllm.config import LoRAConfig
from vllm.distributed.communication_op import (
tensor_model_parallel_all_gather, tensor_model_parallel_all_reduce)
from vllm.distributed.parallel_state import get_tensor_model_parallel_rank
from vllm.lora.layers import (ColumnParallelLinearWithLoRA,
MergedColumnParallelLinearWithLoRA,
MergedQKVParallelLinearWithLora,
RowParallelLinearWithLoRA)
from vllm.lora.punica import bgmv, dispatch_bgmv_low_level
if TYPE_CHECKING:
pass
def _fully_sharded_can_replace(can_replace):
"""
decorator which adds the condition of fully sharded loras
intended to wrap can_replace_layer()
"""
def dec(*args, **kwargs):
return (can_replace(*args, **kwargs)
and kwargs['lora_config'].fully_sharded_loras)
return dec
# these layers are based on the tensor parallelism strategy given in
# Y. Sheng et al., S-LoRA: Serving Thousands of Concurrent LoRA Adapters. 2023,
# https://arxiv.org/abs/2311.03285.
class ColumnParallelLinearWithShardedLoRA(ColumnParallelLinearWithLoRA):
"""
Differs from ColumnParallelLinearWithLoRA by slicing LoRA A also.
Based on S-LoRA, slicing happens along the rank dim.
"""
def slice_lora_a(self, lora_a: torch.Tensor) -> torch.Tensor:
tp_rank = get_tensor_model_parallel_rank()
shard_size = self.lora_a_stacked.shape[2]
start_idx = tp_rank * shard_size
lora_a = lora_a[:, start_idx:start_idx + shard_size]
return lora_a
def apply_weights(self, x: torch.Tensor,
bias: Optional[torch.Tensor]) -> torch.Tensor:
output = self.base_layer.linear_method.apply_weights(
self.base_layer, x, bias)
x = x.view(-1, x.shape[-1])
output, out_orig_shape = output.view(-1,
output.shape[-1]), output.shape
buffer = torch.zeros((x.shape[0], self.lora_a_stacked.shape[2]),
dtype=torch.float32,
device=x.device)
bgmv(buffer, x, self.lora_a_stacked,
self.indices[:self.indices_len[0]], 0, 1.0)
buffer = tensor_model_parallel_all_gather(buffer)
bgmv(output, buffer, self.lora_b_stacked,
self.indices[:self.indices_len[0]], 0, 1.0)
# now have column partitioned output
output = output.view(*out_orig_shape)
return output
@classmethod
@_fully_sharded_can_replace
def can_replace_layer(cls, source_layer: nn.Module,
lora_config: LoRAConfig, packed_modules_list: List,
model_config: Optional[PretrainedConfig]) -> bool:
# specifying kwargs so they can be easily accessed in decorator
return super().can_replace_layer(
source_layer=source_layer,
lora_config=lora_config,
packed_modules_list=packed_modules_list,
model_config=model_config,
decorate=False,
)
def _mcp_apply_weights(x, bias, layer):
"""
MergedColumnParallelLinearWithShardedLoRA and
QKVParallelLinearWithShardedLora share the same
LoRa weight application method.
The main difference is the step by shard_size for lora_b which can
vary for QKVParallelLinearWithShardedLora but is constant for
MergedColumnParallelLinearWithShardedLoRA.
"""
# expecting 2 for column parallel and 3 for qkv
n = len(layer.lora_a_stacked)
output = layer.base_layer.linear_method.apply_weights(
layer.base_layer, x, bias)
x = x.view(-1, x.shape[-1])
output, out_orig_shape = output.view(-1, output.shape[-1]), output.shape
buffers = torch.zeros((n, x.shape[0], layer.lora_a_stacked[0].shape[2]),
dtype=torch.float32,
device=x.device)
for idx in range(n):
bgmv(buffers[idx], x, layer.lora_a_stacked[idx],
layer.indices[:layer.indices_len[0]], 0, 1.0)
buffers = tensor_model_parallel_all_gather(buffers)
left_offset = 0
for idx in range(n):
shard_size = layer.lora_b_stacked[idx].shape[2]
dispatch_bgmv_low_level(output, buffers[idx],
layer.lora_b_stacked[idx],
layer.indices[:layer.indices_len[0]], 0, 1.0,
left_offset, shard_size)
left_offset += shard_size
output = output.view(*out_orig_shape)
# now have column partitioned and packed output
return output
class MergedColumnParallelLinearWithShardedLoRA(
MergedColumnParallelLinearWithLoRA):
"""
Differs from MergedColumnParallelLinearWithLoRA by slicing the
LoRA A's also.
Based on S-LoRA, slicing happens along the rank dim.
"""
def slice_lora_a(self, lora_a: List[torch.Tensor]) -> List[torch.Tensor]:
output_shard_size = self.lora_a_stacked[0].shape[2]
output_start_idx = self.tp_rank * output_shard_size
lora_a = [
lora_a[i][:, output_start_idx:output_start_idx + output_shard_size]
for i in range(2)
]
return lora_a
def apply_weights(self, x: torch.Tensor,
bias: Optional[torch.Tensor]) -> torch.Tensor:
return _mcp_apply_weights(x, bias, self)
@classmethod
@_fully_sharded_can_replace
def can_replace_layer(cls, source_layer: nn.Module,
lora_config: LoRAConfig, packed_modules_list: List,
model_config: Optional[PretrainedConfig]) -> bool:
# specifying kwargs so they can be easily accessed in decorator
return super().can_replace_layer(
source_layer=source_layer,
lora_config=lora_config,
packed_modules_list=packed_modules_list,
model_config=model_config,
decorate=False,
)
class MergedQKVParallelLinearWithShardedLora(MergedQKVParallelLinearWithLora):
"""
Differs from QKVParallelLinearWithLora by slicing the
LoRA A's also.
Based on S-LoRA, slicing happens along the rank dim.
"""
def slice_lora_a(self, lora_a: List[torch.Tensor]) -> List[torch.Tensor]:
shard_size = [self.lora_a_stacked[i].shape[2] for i in range(3)]
start_idx = [self.tp_rank * shard_size[i] for i in range(3)]
lora_a = [
lora_a[i][:, start_idx[i]:start_idx[i] +
shard_size[i]] if lora_a[i] is not None else None
for i in range(3)
]
return lora_a
def apply_weights(self, x: torch.Tensor,
bias: Optional[torch.Tensor]) -> torch.Tensor:
return _mcp_apply_weights(x, bias, self)
@classmethod
@_fully_sharded_can_replace
def can_replace_layer(cls, source_layer: nn.Module,
lora_config: LoRAConfig, packed_modules_list: List,
model_config: Optional[PretrainedConfig]) -> bool:
# specifying kwargs so they can be easily accessed in decorator
return super().can_replace_layer(
source_layer=source_layer,
lora_config=lora_config,
packed_modules_list=packed_modules_list,
model_config=model_config,
decorate=False,
)
class RowParallelLinearWithShardedLoRA(RowParallelLinearWithLoRA):
"""
Differs from RowParallelLinearWithLoRA by slicing the
LoRA B's also.
Based on S-LoRA, slicing happens along the output dim.
This yields a combined partial sum from the row parallel base
layer and column partitioned output from the LoRA.
"""
def slice_lora_b(self, lora_b: torch.Tensor) -> torch.Tensor:
shard_size = self.lora_b_stacked.shape[2]
start_idx = self.tp_rank * shard_size
end_idx = (self.tp_rank + 1) * shard_size
lora_b = lora_b[:, start_idx:end_idx]
return lora_b
def apply_weights(self, x: torch.Tensor) -> torch.Tensor:
output = self.base_layer.linear_method.apply_weights(
self.base_layer, x)
x = x.view(-1, x.shape[-1])
output, out_orig_shape = output.view(-1,
output.shape[-1]), output.shape
buffer = torch.zeros((x.shape[0], self.lora_a_stacked.shape[2]),
dtype=torch.float32,
device=x.device)
bgmv(buffer, x, self.lora_a_stacked,
self.indices[:self.indices_len[0]], 0, 1.0)
buffer = tensor_model_parallel_all_reduce(buffer)
# following S-LoRA, allows the fusing of all_gather and all_reduce
# by adding the column partitioned lora output to a slice of output
# tensor, which is a partial sum due to row parallel. All that
# remains is a standard all_reduce. User should be aware though that
# the output is not the same as a normal row_parallel, it should be
# reduced before being used
shard_size = self.lora_b_stacked.shape[2]
start_idx = self.tp_rank * shard_size
dispatch_bgmv_low_level(output, buffer, self.lora_b_stacked,
self.indices[:self.indices_len[0]], 0, 1.0,
start_idx, shard_size)
output = output.view(*out_orig_shape)
return output
@classmethod
@_fully_sharded_can_replace
def can_replace_layer(cls, source_layer: nn.Module,
lora_config: LoRAConfig, packed_modules_list: List,
model_config: Optional[PretrainedConfig]) -> bool:
# specifying kwargs so they can be easily accessed in decorator
return super().can_replace_layer(
source_layer=source_layer,
lora_config=lora_config,
packed_modules_list=packed_modules_list,
model_config=model_config,
decorate=False,
)