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.. * you may not use this file except in compliance with the License.
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.. highlight:: cpp
.. default-domain:: cpp

.. _api_spmd:

======================
Distributed SPMD model
======================

Refer to :ref:`Developer Guide: SPMD <dg_spmd>`.

---------------------
Programming interface
---------------------

All types and functions in this section are declared in the
``oneapi::dal::spmd::preview`` namespace and are available via inclusion of the
header file from specified backend.

:term:`SPMD` distributed model consists of the following components:

1. Additional ``train``, ``infer``, and ``compute`` methods that accept ``communicator`` object
   as the first parameter. Those methods are expected to be called on all ranks to start
   distributed simulations.

2. The :term:`communicator` class that contains methods to perform collective operations among all ranks.

3. Free functions to create a :term:`communicator` using a specified :term:`communicator backend`. Available backends are ``ccl``
   and ``mpi``.

-------------
Usage Example
-------------

The following listings provide a brief introduction on how to create a particular communicator.

.. rubric:: MPI backend

.. include:: ../../includes/spmd/mpi-comm-usage-example.rst

.. rubric:: CCL backend

.. include:: ../../includes/spmd/ccl-comm-usage-example.rst