Created by: zhiqiu

Test for inplace addto strategy on ResNet-50 amp training. Related PR: https://github.com/PaddlePaddle/Paddle/pull/27112

Result

The performance of ResNet50 with amp enabled and batch_size=128 on V100 single card.

• before: 958.9 img/s
• after: 1016.5 img/s, 6% imporved.