onnxruntime/docs/python/api_summary.rst
Du Li 063156d98d
IOBinding docs (#4432)
* Adding iobinding pathon docs.

* Adding iobinding pathon docs.

* Addressing PR comments.
2020-07-08 03:48:22 -07:00

121 lines
3.6 KiB
ReStructuredText
Raw Blame History

This file contains invisible Unicode characters

This file contains invisible Unicode characters that are indistinguishable to humans but may be processed differently by a computer. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

===========
API Summary
===========
Summary of public functions and classes exposed
in *ONNX Runtime*.
.. contents::
:local:
IOBinding
=========
By default, *ONNX Runtime* always places input(s) and output(s) on CPU, which
is not optimal if the input or output is consumed and produced on a device
other than CPU because it introduces data copy between CPU and the device.
*ONNX Runtime* provides a feature, *IO Binding*, which addresses this issue by
enabling users to specify which device to place input(s) and output(s) on.
Here are scenarios to use this feature.
(In the following code snippets, *model.onnx* is the model to execute,
*X* is the input data to feed, and *Y* is the output data.)
Scenario 1:
A graph is executed on a deivce other than CPU, for instance CUDA. Users can
use IOBinding to put input on CUDA as the follows.
.. code-block:: python
#X is numpy array on cpu
session = onnxruntime.InferenceSession('model.onnx')
io_binding = session.io_binding()
io_binding.bind_cpu_input('input', X)
io_binding.bind_output('output')
session.run_with_iobinding(io_binding)
Y = io_binding.copy_outputs_to_cpu()[0]
Scenario 2:
The input data is on a device, users direclty use the input. The output data is on CPU.
.. code-block:: python
session = onnxruntime.InferenceSession('model.onnx')
io_binding = session.io_binding()
io_binding.bind_input(name='input', device_type=X.device.type, device_id=0, element_type=np.float32, shape=list(X.size()), buffer_ptr=X.data_ptr())
io_binding.bind_output('output')
session.run_with_iobinding(io_binding)
Y = io_binding.copy_outputs_to_cpu()[0]
Scenario 3:
The input data on a dveice, users directly use the input and also place output on the device:
.. code-block:: python
session = onnxruntime.InferenceSession('model.onnx')
io_binding = session.io_binding()
io_binding.bind_input(name='input', device_type=X.device.type, device_id=0, element_type=np.float32, shape=list(X.size()), buffer_ptr=X.data_ptr())
io_binding.bind_output(name='output', device_type=Y.device.type, device_id=0, element_type=np.float32, shape=list(Y.size()), buffer_ptr=Y.data_ptr())
session.run_with_iobinding(io_binding)
Device
======
The package is compiled for a specific device, GPU or CPU.
The CPU implementation includes optimizations
such as MKL (Math Kernel Libary). The following function
indicates the chosen option:
.. autofunction:: onnxruntime.get_device
Examples and datasets
=====================
The package contains a few models stored in ONNX format
used in the documentation. These don't need to be downloaded
as they are installed with the package.
.. autofunction:: onnxruntime.datasets.get_example
Load and run a model
====================
*ONNX Runtime* reads a model saved in ONNX format.
The main class *InferenceSession* wraps these functionalities
in a single place.
.. autoclass:: onnxruntime.ModelMetadata
:members:
.. autoclass:: onnxruntime.InferenceSession
:members:
.. autoclass:: onnxruntime.NodeArg
:members:
.. autoclass:: onnxruntime.RunOptions
:members:
.. autoclass:: onnxruntime.SessionOptions
:members:
Backend
=======
In addition to the regular API which is optimized for performance and usability, 
*ONNX Runtime* also implements the
`ONNX backend API <https://github.com/onnx/onnx/blob/master/docs/ImplementingAnOnnxBackend.md>`_
for verification of *ONNX* specification conformance.
The following functions are supported:
.. autofunction:: onnxruntime.backend.is_compatible
.. autofunction:: onnxruntime.backend.prepare
.. autofunction:: onnxruntime.backend.run
.. autofunction:: onnxruntime.backend.supports_device