SSD logging

[christ1ne]

Please review and see if the basics tags are in for ssd.

I know Taylor wants to update the logging code, I will update this branch once his fix is in.

[robieta]

I think some more detail would be useful. For instance:

1. A detailed logging of the topology. Both the backbone and the SSD specific feature extractors. Checking that topologies match layer-for-layer will be quite helpful for automatic checking. (It tripped us up a couple times when porting, particularly since TorchVision uses a non-standard ResNet.)

2. Tags outlining the data pipeline. SSD has a very elaborate input pipeline, with lots of opportunities for subtle mistakes. For instance when cropping there are aspect ratio thresholds, iou thresholds, criteria for accepting or rejecting a crop, etc.

[christ1ne]

I think some more detail would be useful. For instance:

1. A detailed logging of the topology. Both the backbone and the SSD specific feature extractors. Checking that topologies match layer-for-layer will be quite helpful for automatic checking. (It tripped us up a couple times when porting, particularly since TorchVision uses a non-standard ResNet.)
2. Tags outlining the data pipeline. SSD has a very elaborate input pipeline, with lots of opportunities for subtle mistakes. For instance when cropping there are aspect ratio thresholds, iou thresholds, criteria for accepting or rejecting a crop, etc.

@robieta I've added more tags on your second point. Can you suggest how I can log a topology? Logging layer by layer is very tedious. Any specific pointer will be appreciated.

[robieta]

When logging the topology I put logging statements in the layer definition helper functions. i.e. https://github.com/mlperf/training/blob/master/image_classification/tensorflow/official/resnet/resnet_model.py#L60

The other option would be to use a summary tool. When I was comparing SSD, I found https://github.com/sksq96/pytorch-summary to be quite nice. (It is based on pytorch/pytorch#2001, I believe.) I know it would be somewhat troublesome to try to reach into TorchVision, but once it is in summary form it should be rather straightforward to iterate and produce a topology summary.

[christ1ne]

This PR is replaced by #167