GitLab

- Split a model's computation into multiple virtual stages as needed,
and schedule communication correctly between these virtual stages
- Move schedule code into `schedules.py` and communication code into
`p2p_communication.py`
- Use hyphens instead of spaces in all time logging for consistency
- Factor out code in megatron/training.py into helper functions
- Refactor evaluate() function: make it use forward_backward_schedule
functions

Also includes following changes for inter-layer model-parallel implementation:
- Refactoring of model implementations
- Training loop changes to support inter-layer communication using `ring_exchange`
- New groups for inter-layer communication
- Checkpoint changes
- Command line arguments

Signed-off-by: Boris Fomitchev <bfomitchev@nvidia.com>

Signed-off-by: Boris Fomitchev <bfomitchev@nvidia.com>

Signed-off-by: Boris Fomitchev <bfomitchev@nvidia.com>

Signed-off-by: Boris Fomitchev <bfomitchev@nvidia.com>

Signed-off-by: Boris Fomitchev <bfomitchev@nvidia.com>

Signed-off-by: Boris Fomitchev <bfomitchev@nvidia.com>

Signed-off-by: Boris Fomitchev <bfomitchev@nvidia.com>

Signed-off-by: Boris Fomitchev <bfomitchev@nvidia.com>

Added logic for initilialize_megatron to work with cpu only jobs. This is necessary for several evaluation and processing scripts in downstream repos.