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

# Copyright 2023-2024 SGLang Team
# 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.
# ==============================================================================
"""Fused operators for normalization layers."""
import logging
from typing import Optional, Tuple, Union
import torch
import torch.nn as nn
from sglang.srt.utils import is_flashinfer_available
if is_flashinfer_available():
from flashinfer.norm import (
fused_add_rmsnorm,
gemma_fused_add_rmsnorm,
gemma_rmsnorm,
rmsnorm,
)
from vllm.model_executor.custom_op import CustomOp
from sglang.srt.layers.custom_op_util import register_custom_op
logger = logging.getLogger(__name__)
@register_custom_op("sglang_rmsnorm")
class RMSNorm(CustomOp):
def __init__(
self,
hidden_size: int,
eps: float = 1e-6,
) -> None:
super().__init__()
self.weight = nn.Parameter(torch.ones(hidden_size))
self.variance_epsilon = eps
def forward_cuda(
self,
x: torch.Tensor,
residual: Optional[torch.Tensor] = None,
) -> Union[torch.Tensor, Tuple[torch.Tensor, torch.Tensor]]:
if residual is not None:
fused_add_rmsnorm(x, residual, self.weight.data, self.variance_epsilon)
return x, residual
out = rmsnorm(x, self.weight.data, self.variance_epsilon)
return out
def forward_native(
self,
x: torch.Tensor,
residual: Optional[torch.Tensor] = None,
) -> Union[torch.Tensor, Tuple[torch.Tensor, torch.Tensor]]:
orig_dtype = x.dtype
x = x.to(torch.float32)
if residual is not None:
x = x + residual.to(torch.float32)
residual = x.to(orig_dtype)
variance = x.pow(2).mean(dim=-1, keepdim=True)
x = x * torch.rsqrt(variance + self.variance_epsilon)
x = x.to(orig_dtype) * self.weight
if residual is None:
return x
else:
return x, residual
@register_custom_op("sglang_gemma_rmsnorm")
class GemmaRMSNorm(CustomOp):
def __init__(
self,
hidden_size: int,
eps: float = 1e-6,
) -> None:
super().__init__()
self.weight = nn.Parameter(torch.zeros(hidden_size))
self.variance_epsilon = eps
def forward_native(
self,
x: torch.Tensor,
residual: Optional[torch.Tensor] = None,
) -> Union[torch.Tensor, Tuple[torch.Tensor, torch.Tensor]]:
orig_dtype = x.dtype
if residual is not None:
x = x + residual
residual = x
x = x.float()
variance = x.pow(2).mean(dim=-1, keepdim=True)
x = x * torch.rsqrt(variance + self.variance_epsilon)
x = x * (1.0 + self.weight.float())
x = x.to(orig_dtype)
return x if residual is None else (x, residual)
def forward_cuda(
self,
x: torch.Tensor,
residual: Optional[torch.Tensor] = None,
) -> Union[torch.Tensor, Tuple[torch.Tensor, torch.Tensor]]:
if residual is not None:
gemma_fused_add_rmsnorm(
x, residual, self.weight.data, self.variance_epsilon
)
return x, residual
out = gemma_rmsnorm(x, self.weight.data, self.variance_epsilon)
return out
if not is_flashinfer_available():
logger.info(
"FlashInfer is not available on Non-NV platforms. Fallback to other kernel libraries."
)
from vllm.model_executor.layers.layernorm import GemmaRMSNorm, RMSNorm