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Apply x row scaling with grad

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This commit is contained in:
Daniel Povey 2022-06-10 16:42:52 +08:00
parent 86c2d0fcc0
commit cecd52155c
1 changed files with 11 additions and 38 deletions
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49
egs/librispeech/ASR/pruned_transducer_stateless2/scaling.py
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@ -713,25 +713,6 @@ class GaussProjDrop(torch.nn.Module):
x = (x_next * self.rand_scale + x_bypass)
return x
class PseudoNormalizeFunction(torch.autograd.Function):
"""
Function object that is the identity function in the forward pass; and, in the
backward pass, removes the component of the derivative in the direction of x itself
(as if it had gone through some kind of normalization layer
"""
@staticmethod
def forward(ctx, x: Tensor) -> Tensor:
ctx.save_for_backward(x)
return x
@staticmethod
def backward(ctx, x_grad: Tensor) -> Tensor:
x, = ctx.saved_tensors
eps = 1.0e-20
x_sumsq = (x**2).sum() + eps
grad_x_sum = (x_grad * x).sum()
return x_grad - x * (grad_x_sum / x_sumsq)
def _compute_correlation_loss(cov: Tensor,
eps: float) -> Tensor:
@ -759,7 +740,6 @@ def _update_cov_stats(cov: Tensor,
x: Tensor of features/activations, of shape (num_frames, num_channels)
beta: The decay constant for the stats, e.g. 0.8.
"""
x = PseudoNormalizeFunction.apply(x)
new_cov = torch.matmul(x.t(), x)
return cov * beta + new_cov * (1-beta)
@ -818,18 +798,19 @@ class DecorrelateFunction(torch.autograd.Function):
# the computation.
x_grad_old_sqnorm = (x_grad ** 2).sum(dim=1)
x_sqnorm = (x.detach() ** 2).sum(dim=1)
x_desired_sqscale = x_grad_old_sqnorm ** 0.5 # desired scale of x*x in sum for cov
x_desired_sqscale /= (x_desired_sqscale.sum() + 1.0e-20) # sum-to-one scales
x_desired_sqscale_is_inf = (x_desired_sqscale - x_desired_sqscale != 0)
# if grads are inf, use equal scales for frames (can happen due to GradScaler, in half
# precision)
x_desired_sqscale.masked_fill_(x_desired_sqscale_is_inf, 1.0 / x_desired_sqscale.numel())
x_factor = (x_desired_sqscale * num_channels / (x_sqnorm + ctx.eps)) ** 0.5
with torch.enable_grad():
x_sqnorm = (x ** 2).sum(dim=1)
x_desired_sqscale = x_grad_old_sqnorm ** 0.5 # desired scale of x*x in sum for cov
x_desired_sqscale /= (x_desired_sqscale.sum() + 1.0e-20) # sum-to-one scales
x_desired_sqscale_is_inf = (x_desired_sqscale - x_desired_sqscale != 0)
# if grads are inf, use equal scales for frames (can happen due to GradScaler, in half
# precision)
x_desired_sqscale.masked_fill_(x_desired_sqscale_is_inf, 1.0 / x_desired_sqscale.numel())
x_factor = (x_desired_sqscale * num_channels / (x_sqnorm + ctx.eps)) ** 0.5
scaled_x = x * x_factor.unsqueeze(-1)
cov = _update_cov_stats(old_cov, scaled_x, ctx.beta)
assert old_cov.dtype != torch.float16
@ -1014,13 +995,6 @@ def _test_gauss_proj_drop():
m1.eval()
m2.eval()
def _test_pseudo_normalize():
x = torch.randn(3, 4)
x.requires_grad = True
y = PseudoNormalizeFunction.apply(x)
l = (y**2).sum()
l.backward()
assert (x.grad * x).sum().abs() < 0.1
def _test_decorrelate():
D = 384
@ -1049,7 +1023,6 @@ if __name__ == "__main__":
logging.getLogger().setLevel(logging.INFO)
torch.set_num_threads(1)
torch.set_num_interop_threads(1)
_test_pseudo_normalize()
_test_decorrelate()
_test_gauss_proj_drop()
_test_activation_balancer_sign()