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[NFC] polish colossalai/kernel/jit/bias_gelu.py code style (#946) 

Co-authored-by: jnbai <897086360@qq.com>
pull/997/head
luoling-LC 2022-05-13 18:03:11 +08:00 committed by binmakeswell
parent eb9a81d72a
commit 72c71b67ec
1 changed files with 8 additions and 4 deletions
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12
colossalai/kernel/jit/bias_gelu.py
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@ -1,6 +1,5 @@
import torch
###### BIAS GELU FUSION/ NO AUTOGRAD ################
# 1/sqrt(2*pi)-> 0.3989423
# 1/sqrt(2) -> 0.70710678
@ -9,10 +8,12 @@ import torch
# actual gelu is:
# x * 0.5 * (1.0 + torch.erf(x * 0.70710678))
@torch.jit.script
def bias_gelu(bias, y):
x = bias + y
return x * 0.5 * (1.0 + torch.tanh(0.79788456 * x * (1 + 0.044715 * x * x)))
return x * 0.5 * (1.0 + torch.tanh(0.79788456 * x * (1 + 0.044715 * x * x)))
# gradient of tanh approximation of gelu
# gradient of actual gelu is:
@ -23,9 +24,11 @@ def bias_gelu_back(g, bias, y):
tanh_out = torch.tanh(0.79788456 * x * (1 + 0.044715 * x * x))
# sqrt(2/pi) * 3 * 0.044715 -> 0.1070322243
ff = 0.5 * x * ((1 - tanh_out * tanh_out) * (0.79788456 + 0.1070322243 * x * x)) + 0.5 * (1 + tanh_out)
return ff*g
return ff * g
class GeLUFunction(torch.autograd.Function):
@staticmethod
# bias is an optional argument
def forward(ctx, input, bias):
@ -38,4 +41,5 @@ class GeLUFunction(torch.autograd.Function):
tmp = bias_gelu_back(grad_output, bias, input)
return tmp, tmp
bias_gelu_impl = GeLUFunction.apply
bias_gelu_impl = GeLUFunction.apply