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vllm-anthropic/vllm/model_executor/layers/layernorm.py
2025-10-16 21:40:25 +00:00

432 lines
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Python

# SPDX-License-Identifier: Apache-2.0
# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
"""Custom normalization layers."""
import torch
import torch.nn as nn
import torch.nn.functional as F
import vllm.envs as envs
from vllm.model_executor.custom_op import CustomOp
from vllm.model_executor.layers.batch_invariant import (
rms_norm_batch_invariant,
vllm_is_batch_invariant,
)
from vllm.platforms import current_platform
from vllm.utils import direct_register_custom_op
def is_rocm_aiter_rmsnorm_enabled() -> bool:
return envs.VLLM_ROCM_USE_AITER_RMSNORM and envs.VLLM_ROCM_USE_AITER
def rms_norm(
x: torch.Tensor, weight: torch.Tensor, variance_epsilon: float
) -> torch.Tensor:
from vllm import _custom_ops as ops
if vllm_is_batch_invariant():
return rms_norm_batch_invariant(x, weight, variance_epsilon)
out = torch.empty_like(x)
ops.rms_norm(
out,
x,
weight,
variance_epsilon,
)
return out
def fused_add_rms_norm(
x: torch.Tensor,
residual: torch.Tensor,
weight: torch.Tensor,
variance_epsilon: float,
) -> tuple[torch.Tensor, torch.Tensor]:
from vllm import _custom_ops as ops
if vllm_is_batch_invariant():
return rms_norm_batch_invariant(
x + residual, weight, variance_epsilon
), x + residual
ops.fused_add_rms_norm(
x,
residual,
weight,
variance_epsilon,
)
return x, residual
def poly_norm(
x: torch.Tensor, weight: torch.Tensor, bias: torch.Tensor, variance_epsilon: float
) -> torch.Tensor:
from vllm import _custom_ops as ops
out = torch.empty_like(x)
ops.poly_norm(
out,
x,
weight,
bias,
variance_epsilon,
)
return out
def rocm_aiter_rms_norm_impl(
x: torch.Tensor, weight: torch.Tensor, variance_epsilon: float
) -> torch.Tensor:
import aiter as rocm_aiter
if x.dim() > 2:
x_original_shape = x.shape
x = x.reshape(-1, x_original_shape[-1])
x = rocm_aiter.rms_norm(x, weight, variance_epsilon)
return x.reshape(x_original_shape)
return rocm_aiter.rms_norm(x, weight, variance_epsilon)
def rocm_aiter_rmsnorm2d_fwd_with_add_impl(
x: torch.Tensor,
residual: torch.Tensor,
weight: torch.Tensor,
variance_epsilon: float,
) -> tuple[torch.Tensor, torch.Tensor]:
import aiter as rocm_aiter
residual_out = torch.empty_like(residual)
output = torch.empty_like(x)
rocm_aiter.rmsnorm2d_fwd_with_add(
output, # output
x, # input
residual, # residual input
residual_out, # residual output
weight,
variance_epsilon,
)
return output, residual_out
def rocm_aiter_rms_norm_fake(
x: torch.Tensor, weight: torch.Tensor, variance_epsilon: float
) -> torch.Tensor:
return torch.empty_like(x)
def rocm_aiter_rmsnorm2d_fwd_with_add_fake(
x: torch.Tensor,
residual: torch.Tensor,
weight: torch.Tensor,
variance_epsilon: float,
) -> tuple[torch.Tensor, torch.Tensor]:
return torch.empty_like(x), torch.empty_like(residual)
if current_platform.is_rocm():
direct_register_custom_op(
op_name="rocm_aiter_rms_norm",
op_func=rocm_aiter_rms_norm_impl,
fake_impl=rocm_aiter_rms_norm_fake,
)
direct_register_custom_op(
op_name="rocm_aiter_rmsnorm2d_fwd_with_add",
op_func=rocm_aiter_rmsnorm2d_fwd_with_add_impl,
fake_impl=rocm_aiter_rmsnorm2d_fwd_with_add_fake,
)
def dispatch_rocm_rmsnorm_func(with_fused_add: bool, dtype: torch.dtype):
use_aiter = is_rocm_aiter_rmsnorm_enabled() and dtype in [
torch.float16,
torch.bfloat16,
]
if use_aiter and with_fused_add:
return torch.ops.vllm.rocm_aiter_rmsnorm2d_fwd_with_add
if use_aiter:
return torch.ops.vllm.rocm_aiter_rms_norm
# fall back to CUDA implementation
if with_fused_add:
return fused_add_rms_norm
return rms_norm
@CustomOp.register("rms_norm")
class RMSNorm(CustomOp):
"""Root mean square normalization.
Computes x -> w * x / sqrt(E[x^2] + eps) where w is the learned weight.
Refer to https://arxiv.org/abs/1910.07467
"""
def __init__(
self,
hidden_size: int,
eps: float = 1e-6,
var_hidden_size: int | None = None,
has_weight: bool = True,
dtype: torch.dtype | None = None,
) -> None:
super().__init__()
self.hidden_size = hidden_size
self.variance_epsilon = eps
self.variance_size_override = (
None if var_hidden_size == hidden_size else var_hidden_size
)
self.has_weight = has_weight
if dtype is not None:
self.weight = torch.ones(hidden_size, dtype=dtype)
else:
self.weight = torch.ones(hidden_size)
if self.has_weight:
self.weight = nn.Parameter(self.weight)
weight_dtype = self.weight.data.dtype
if current_platform.is_rocm():
self.rocm_norm_func = dispatch_rocm_rmsnorm_func(
with_fused_add=False, dtype=weight_dtype
)
self.rocm_norm_func_with_add = dispatch_rocm_rmsnorm_func(
with_fused_add=True, dtype=weight_dtype
)
def forward_native(
self,
x: torch.Tensor,
residual: torch.Tensor | None = None,
) -> torch.Tensor | tuple[torch.Tensor, torch.Tensor]:
"""PyTorch-native implementation equivalent to forward()."""
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)
hidden_size = x.shape[-1]
if hidden_size != self.hidden_size:
raise ValueError(
"Expected hidden_size to be "
f"{self.hidden_size}, but found: {hidden_size}"
)
if self.variance_size_override is None:
x_var = x
else:
if hidden_size < self.variance_size_override:
raise ValueError(
"Expected hidden_size to be at least "
f"{self.variance_size_override}, but found: {hidden_size}"
)
x_var = x[:, :, : self.variance_size_override]
variance = x_var.pow(2).mean(dim=-1, keepdim=True)
x = x * torch.rsqrt(variance + self.variance_epsilon)
x = x.to(orig_dtype)
if self.has_weight:
x = x * self.weight
if residual is None:
return x
else:
return x, residual
def forward_cuda(
self,
x: torch.Tensor,
residual: torch.Tensor | None = None,
) -> torch.Tensor | tuple[torch.Tensor, torch.Tensor]:
if self.variance_size_override is not None:
return self.forward_native(x, residual)
add_residual = residual is not None
if add_residual:
return fused_add_rms_norm(
x, residual, self.weight.data, self.variance_epsilon
)
else:
return rms_norm(x, self.weight.data, self.variance_epsilon)
def forward_hip(
self,
x: torch.Tensor,
residual: torch.Tensor | None = None,
) -> torch.Tensor | tuple[torch.Tensor, torch.Tensor]:
if self.variance_size_override is not None:
return self.forward_native(x, residual)
add_residual = residual is not None
if add_residual:
return self.rocm_norm_func_with_add(
x, residual, self.weight.data, self.variance_epsilon
)
else:
return self.rocm_norm_func(x, self.weight.data, self.variance_epsilon)
def forward_xpu(
self,
x: torch.Tensor,
residual: torch.Tensor | None = None,
) -> torch.Tensor | tuple[torch.Tensor, torch.Tensor]:
if self.variance_size_override is not None:
return self.forward_native(x, residual)
from vllm._ipex_ops import ipex_ops as ops
if residual is not None:
ops.fused_add_rms_norm(
x,
residual,
self.weight.data,
self.variance_epsilon,
)
return x, residual
return ops.rms_norm(
x,
self.weight.data,
self.variance_epsilon,
)
def extra_repr(self) -> str:
s = f"hidden_size={self.weight.data.size(0)}"
s += f", eps={self.variance_epsilon}"
return s
@CustomOp.register("gemma_rms_norm")
class GemmaRMSNorm(CustomOp):
"""RMS normalization for Gemma.
Two differences from the above RMSNorm:
1. x * (1 + w) instead of x * w.
2. (x * w).to(orig_dtype) instead of x.to(orig_dtype) * w.
"""
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
@staticmethod
def forward_static(
weight: torch.Tensor,
variance_epsilon: float,
x: torch.Tensor,
residual: torch.Tensor | None,
) -> torch.Tensor | tuple[torch.Tensor, torch.Tensor]:
"""PyTorch-native implementation equivalent to forward()."""
orig_dtype = x.dtype
if residual is not None:
x = (
x.float() + residual.float()
if orig_dtype == torch.float16
else x + residual
)
residual = x
x = x.float()
variance = x.pow(2).mean(dim=-1, keepdim=True)
x = x * torch.rsqrt(variance + variance_epsilon)
# Llama does x.to(float16) * w whilst Gemma is (x * w).to(float16)
# See https://github.com/huggingface/transformers/pull/29402
x = x * (1.0 + weight.float())
x = x.to(orig_dtype)
return x if residual is None else (x, residual)
def forward_native(
self,
x: torch.Tensor,
residual: torch.Tensor | None = None,
) -> torch.Tensor | tuple[torch.Tensor, torch.Tensor]:
"""PyTorch-native implementation equivalent to forward()."""
return self.forward_static(self.weight.data, self.variance_epsilon, x, residual)
def forward_cuda(
self,
x: torch.Tensor,
residual: torch.Tensor | None = None,
) -> torch.Tensor | tuple[torch.Tensor, torch.Tensor]:
if torch.compiler.is_compiling():
return self.forward_native(x, residual)
if not getattr(self, "_is_compiled", False):
self.forward_static = torch.compile( # type: ignore
self.forward_static
)
self._is_compiled = True
return self.forward_native(x, residual)
@CustomOp.register("poly_norm")
class PolyNorm(CustomOp):
"""Polynomial normalization.
Computes x -> w_0 * RMSNorm(x^3) + w_1 * RMSNorm(x^2) + w_2 * RMSNorm(x) + b
where w_n is the learned weight and b is the bias.
Refer to https://arxiv.org/html/2411.03884v1
"""
def __init__(
self,
eps: float = 1e-6,
) -> None:
super().__init__()
self.weight = torch.nn.Parameter(torch.ones(3) / 3)
self.bias = torch.nn.Parameter(torch.zeros(1))
self.variance_epsilon = eps
def _norm(self, x):
return x / torch.sqrt(x.pow(2).mean(-1, keepdim=True) + self.variance_epsilon)
def forward_native(
self,
x: torch.Tensor,
) -> torch.Tensor:
"""PyTorch-native implementation equivalent to forward().
Refer to https://github.com/BryceZhuo/PolyCom?tab=readme-ov-file/README.md
"""
orig_dtype = x.dtype
x_float = x.to(torch.float32)
output = (
self.weight[0] * self._norm(x_float**3)
+ self.weight[1] * self._norm(x_float**2)
+ self.weight[2] * self._norm(x_float)
+ self.bias
)
return output.to(orig_dtype)
def forward_cuda(
self,
x: torch.Tensor,
) -> torch.Tensor:
return poly_norm(x, self.weight, self.bias, self.variance_epsilon)
class LayerNorm(nn.Module):
"""
Layer Normalization.
"""
def __init__(self, dim: int, eps: float = 1e-6):
super().__init__()
self.dim = dim
self.eps = eps
self.weight = nn.Parameter(torch.ones(dim, dtype=torch.float32))
self.bias = nn.Parameter(torch.zeros(dim, dtype=torch.float32))
def forward(self, x: torch.Tensor):
return F.layer_norm(
x.float(), (self.dim,), self.weight, self.bias, self.eps
).type_as(x)