tensorpack benchmarks

We use TensorFlow in the efficient way. Tensorpack is:

• As fast as tensorflow/benchmarks in multi-GPU ResNet training
• 1.2x~5x faster than Keras & tflearn in common CNNs
• Able to reproduce "ImageNet in one hour" with 256 GPUs
• Able to train Cifar10 to 94% accuracy within a minute
• 5x faster than matterport/Mask_RCNN
• 2.8x faster than DCGAN-tensorflow

All above claims can be reproduced with the corresponding code.