tensorboard_profiling_keras.ipynb fails even in colab: logs -> $logs, No step marker found

[seanv507]

Environment information (required)

colab https://github.com/tensorflow/tensorboard/blob/master/docs/tensorboard_profiling_keras.ipynb

Issue description

tensorboard profiler will only find profile information if pointed to the exact subdirectory where log is written ( ie single run)

therefore code needs to be changed to %tensorboard --logdir=$logs from %tensorboard --logdir=logs (to include the timestamp ie logs/ )

when this is done, profile tab is visible (and can select profile in the dropdown inactive/...

profile information is now visible, but on the overview page it warns

No step marker observed and hence the step time is unknown. This may happen if (1) training steps are not instrumented (e.g., if you are not using Keras) or (2) the profiling duration is shorter than the step time. For (1), you need to add step instrumentation; for (2), you may try to profile longer.

all timings are reported as zero on overview page