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GPT_SoVITS/AR/modules/scaling.py
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319
GPT_SoVITS/AR/modules/scaling.py
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# Copyright 2022 Xiaomi Corp. (authors: Daniel Povey)
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#
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# See ../../../../LICENSE for clarification regarding multiple authors
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#
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# Licensed under the Apache License, Version 2.0 (the "License");
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# you may not use this file except in compliance with the License.
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# You may obtain a copy of the License at
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#
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# http://www.apache.org/licenses/LICENSE-2.0
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#
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# Unless required by applicable law or agreed to in writing, software
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# distributed under the License is distributed on an "AS IS" BASIS,
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# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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# See the License for the specific language governing permissions and
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# limitations under the License.
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import logging
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import math
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import random
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from typing import Optional
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from typing import Tuple
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from typing import Union
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import torch
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import torch.nn as nn
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from torch import Tensor
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class DoubleSwishFunction(torch.autograd.Function):
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"""
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double_swish(x) = x * torch.sigmoid(x-1)
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This is a definition, originally motivated by its close numerical
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similarity to swish(swish(x)), where swish(x) = x * sigmoid(x).
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Memory-efficient derivative computation:
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double_swish(x) = x * s, where s(x) = torch.sigmoid(x-1)
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double_swish'(x) = d/dx double_swish(x) = x * s'(x) + x' * s(x) = x * s'(x) + s(x).
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Now, s'(x) = s(x) * (1-s(x)).
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double_swish'(x) = x * s'(x) + s(x).
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= x * s(x) * (1-s(x)) + s(x).
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= double_swish(x) * (1-s(x)) + s(x)
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... so we just need to remember s(x) but not x itself.
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"""
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@staticmethod
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def forward(ctx, x: Tensor) -> Tensor:
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requires_grad = x.requires_grad
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x_dtype = x.dtype
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if x.dtype == torch.float16:
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x = x.to(torch.float32)
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s = torch.sigmoid(x - 1.0)
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y = x * s
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if requires_grad:
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deriv = y * (1 - s) + s
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# notes on derivative of x * sigmoid(x - 1):
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# https://www.wolframalpha.com/input?i=d%2Fdx+%28x+*+sigmoid%28x-1%29%29
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# min \simeq -0.043638. Take floor as -0.043637 so it's a lower bund
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# max \simeq 1.1990. Take ceil to be 1.2 so it's an upper bound.
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# the combination of "+ torch.rand_like(deriv)" and casting to torch.uint8 (which
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# floors), should be expectation-preserving.
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floor = -0.043637
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ceil = 1.2
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d_scaled = (deriv - floor) * (255.0 / (ceil - floor)
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) + torch.rand_like(deriv)
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if __name__ == "__main__":
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# for self-testing only.
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assert d_scaled.min() >= 0.0
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assert d_scaled.max() < 256.0
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d_int = d_scaled.to(torch.uint8)
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ctx.save_for_backward(d_int)
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if x.dtype == torch.float16 or torch.is_autocast_enabled():
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y = y.to(torch.float16)
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return y
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@staticmethod
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def backward(ctx, y_grad: Tensor) -> Tensor:
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(d, ) = ctx.saved_tensors
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# the same constants as used in forward pass.
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floor = -0.043637
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ceil = 1.2
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d = d * ((ceil - floor) / 255.0) + floor
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return y_grad * d
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class DoubleSwish(torch.nn.Module):
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def forward(self, x: Tensor) -> Tensor:
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"""Return double-swish activation function which is an approximation to Swish(Swish(x)),
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that we approximate closely with x * sigmoid(x-1).
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"""
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if torch.jit.is_scripting() or torch.jit.is_tracing():
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return x * torch.sigmoid(x - 1.0)
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return DoubleSwishFunction.apply(x)
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class ActivationBalancerFunction(torch.autograd.Function):
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@staticmethod
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def forward(
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ctx,
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x: Tensor,
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scale_factor: Tensor,
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sign_factor: Optional[Tensor],
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channel_dim: int, ) -> Tensor:
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if channel_dim < 0:
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channel_dim += x.ndim
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ctx.channel_dim = channel_dim
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xgt0 = x > 0
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if sign_factor is None:
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ctx.save_for_backward(xgt0, scale_factor)
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else:
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ctx.save_for_backward(xgt0, scale_factor, sign_factor)
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return x
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@staticmethod
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def backward(ctx, x_grad: Tensor) -> Tuple[Tensor, None, None, None]:
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if len(ctx.saved_tensors) == 3:
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xgt0, scale_factor, sign_factor = ctx.saved_tensors
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for _ in range(ctx.channel_dim, x_grad.ndim - 1):
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scale_factor = scale_factor.unsqueeze(-1)
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sign_factor = sign_factor.unsqueeze(-1)
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factor = sign_factor + scale_factor * (xgt0.to(x_grad.dtype) - 0.5)
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else:
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xgt0, scale_factor = ctx.saved_tensors
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for _ in range(ctx.channel_dim, x_grad.ndim - 1):
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scale_factor = scale_factor.unsqueeze(-1)
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factor = scale_factor * (xgt0.to(x_grad.dtype) - 0.5)
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neg_delta_grad = x_grad.abs() * factor
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return (x_grad - neg_delta_grad, None, None, None, )
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def _compute_scale_factor(
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x: Tensor,
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channel_dim: int,
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min_abs: float,
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max_abs: float,
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gain_factor: float,
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max_factor: float, ) -> Tensor:
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if channel_dim < 0:
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channel_dim += x.ndim
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sum_dims = [d for d in range(x.ndim) if d != channel_dim]
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x_abs_mean = torch.mean(x.abs(), dim=sum_dims).to(torch.float32)
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if min_abs == 0.0:
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below_threshold = 0.0
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else:
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# below_threshold is 0 if x_abs_mean > min_abs, can be at most max_factor if
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# x_abs)_mean , min_abs.
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below_threshold = (
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(min_abs - x_abs_mean) * (gain_factor / min_abs)).clamp(
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min=0, max=max_factor)
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above_threshold = ((x_abs_mean - max_abs) * (gain_factor / max_abs)).clamp(
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min=0, max=max_factor)
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return below_threshold - above_threshold
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def _compute_sign_factor(
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x: Tensor,
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channel_dim: int,
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min_positive: float,
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max_positive: float,
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gain_factor: float,
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max_factor: float, ) -> Tensor:
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if channel_dim < 0:
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channel_dim += x.ndim
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sum_dims = [d for d in range(x.ndim) if d != channel_dim]
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proportion_positive = torch.mean((x > 0).to(torch.float32), dim=sum_dims)
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if min_positive == 0.0:
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factor1 = 0.0
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else:
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# 0 if proportion_positive >= min_positive, else can be
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# as large as max_factor.
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factor1 = ((min_positive - proportion_positive) *
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(gain_factor / min_positive)).clamp_(
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min=0, max=max_factor)
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if max_positive == 1.0:
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factor2 = 0.0
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else:
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# 0 if self.proportion_positive <= max_positive, else can be
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# as large as -max_factor.
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factor2 = ((proportion_positive - max_positive) *
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(gain_factor / (1.0 - max_positive))).clamp_(
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min=0, max=max_factor)
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sign_factor = factor1 - factor2
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# require min_positive != 0 or max_positive != 1:
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assert not isinstance(sign_factor, float)
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return sign_factor
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class ActivationBalancer(torch.nn.Module):
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"""
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Modifies the backpropped derivatives of a function to try to encourage, for
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each channel, that it is positive at least a proportion `threshold` of the
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time. It does this by multiplying negative derivative values by up to
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(1+max_factor), and positive derivative values by up to (1-max_factor),
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interpolated from 1 at the threshold to those extremal values when none
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of the inputs are positive.
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Args:
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num_channels: the number of channels
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channel_dim: the dimension/axis corresponding to the channel, e.g.
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-1, 0, 1, 2; will be interpreted as an offset from x.ndim if negative.
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min_positive: the minimum, per channel, of the proportion of the time
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that (x > 0), below which we start to modify the derivatives.
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max_positive: the maximum, per channel, of the proportion of the time
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that (x > 0), above which we start to modify the derivatives.
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max_factor: the maximum factor by which we modify the derivatives for
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either the sign constraint or the magnitude constraint;
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e.g. with max_factor=0.02, the the derivatives would be multiplied by
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values in the range [0.98..1.02].
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sign_gain_factor: determines the 'gain' with which we increase the
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change in gradient once the constraints on min_positive and max_positive
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are violated.
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scale_gain_factor: determines the 'gain' with which we increase the
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change in gradient once the constraints on min_abs and max_abs
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are violated.
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min_abs: the minimum average-absolute-value difference from the mean
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value per channel, which we allow, before we start to modify
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the derivatives to prevent this.
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max_abs: the maximum average-absolute-value difference from the mean
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value per channel, which we allow, before we start to modify
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the derivatives to prevent this.
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min_prob: determines the minimum probability with which we modify the
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gradients for the {min,max}_positive and {min,max}_abs constraints,
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on each forward(). This is done randomly to prevent all layers
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from doing it at the same time. Early in training we may use
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higher probabilities than this; it will decay to this value.
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"""
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def __init__(
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self,
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num_channels: int,
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channel_dim: int,
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min_positive: float=0.05,
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max_positive: float=0.95,
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max_factor: float=0.04,
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sign_gain_factor: float=0.01,
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scale_gain_factor: float=0.02,
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min_abs: float=0.2,
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max_abs: float=100.0,
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min_prob: float=0.1, ):
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super(ActivationBalancer, self).__init__()
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self.num_channels = num_channels
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self.channel_dim = channel_dim
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self.min_positive = min_positive
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self.max_positive = max_positive
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self.max_factor = max_factor
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self.min_abs = min_abs
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self.max_abs = max_abs
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self.min_prob = min_prob
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self.sign_gain_factor = sign_gain_factor
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self.scale_gain_factor = scale_gain_factor
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# count measures how many times the forward() function has been called.
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# We occasionally sync this to a tensor called `count`, that exists to
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# make sure it is synced to disk when we load and save the model.
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self.cpu_count = 0
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self.register_buffer("count", torch.tensor(0, dtype=torch.int64))
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def forward(self, x: Tensor) -> Tensor:
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if (torch.jit.is_scripting() or not x.requires_grad or
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torch.jit.is_tracing()):
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return _no_op(x)
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count = self.cpu_count
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self.cpu_count += 1
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if random.random() < 0.01:
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# Occasionally sync self.cpu_count with self.count.
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# count affects the decay of 'prob'. don't do this on every iter,
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# because syncing with the GPU is slow.
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self.cpu_count = max(self.cpu_count, self.count.item())
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self.count.fill_(self.cpu_count)
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# the prob of doing some work exponentially decreases from 0.5 till it hits
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# a floor at min_prob (==0.1, by default)
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prob = max(self.min_prob, 0.5**(1 + (count / 4000.0)))
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if random.random() < prob:
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sign_gain_factor = 0.5
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if self.min_positive != 0.0 or self.max_positive != 1.0:
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sign_factor = _compute_sign_factor(
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x,
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self.channel_dim,
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self.min_positive,
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self.max_positive,
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gain_factor=self.sign_gain_factor / prob,
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max_factor=self.max_factor, )
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else:
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sign_factor = None
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scale_factor = _compute_scale_factor(
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x.detach(),
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self.channel_dim,
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min_abs=self.min_abs,
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max_abs=self.max_abs,
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gain_factor=self.scale_gain_factor / prob,
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max_factor=self.max_factor, )
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return ActivationBalancerFunction.apply(
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x,
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scale_factor,
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sign_factor,
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self.channel_dim, )
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else:
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return _no_op(x)
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def BalancedDoubleSwish(d_model, channel_dim=-1, max_abs=10.0,
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min_prob=0.25) -> nn.Sequential:
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"""
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ActivationBalancer -> DoubleSwish
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"""
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balancer = ActivationBalancer(
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d_model, channel_dim=channel_dim, max_abs=max_abs, min_prob=min_prob)
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return nn.Sequential(
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balancer,
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DoubleSwish(), )
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