Move log_normal to Aten(CPU) (#31854)
Summary:
Fix https://github.com/pytorch/pytorch/issues/24723.
Benchmark script :
```
import torch
import torch.nn as nn
import time
torch.manual_seed(0)
def _time():
return time.time()
device = "cpu"
#warm up
for n in [10, 100, 1000]:
input = torch.randn(128, n, requires_grad=False, device=device)
for i in range(1000):
input.log_normal_()
for n in [1, 10, 100, 1000]:
fwd_t = 0
input = torch.randn(128, n, requires_grad=False, device=device)
for i in range(10000):
t1 = _time()
input.log_normal_()
t2 = _time()
fwd_t = fwd_t + (t2 -t1)
fwd_avg = fwd_t / 10000 * 1000
print("input size(128, %d) forward time is %.4f (ms)." % (n, fwd_avg))
```
Test Device: skx-8180.
Before:
```
input size(128, 1) forward time is 0.0114 (ms).
input size(128, 10) forward time is 0.1021 (ms).
input size(128, 100) forward time is 1.0081 (ms).
input size(128, 1000) forward time is 10.1831 (ms).
```
After:
```
input size(128, 1) forward time is 0.0108 (ms).
input size(128, 10) forward time is 0.0969 (ms).
input size(128, 100) forward time is 0.9804 (ms).
input size(128, 1000) forward time is 9.6131 (ms).
```
Pull Request resolved: https://github.com/pytorch/pytorch/pull/31854
Differential Revision: D19314586
Pulled By: pbelevich
fbshipit-source-id: 2ea1d9a2c505e36aca9e609b52ccb3e8caf2ba8f
