How to upgrade from C++ API

How to upgrade from C++ API#

Note

This document describes the new C API that closely follows the NVIDIA Collective Communications Library (NCCL)* API standard. Documentation for the legacy C++ API can be found here.

How to compile using oneCCL C API#

  • New C API is defined in oneapi/ccl.h header file.

  • The API is implemented in a new version of the library - libccl.so.2, but this new API is not yet the default. This new API shall become the default in our next major release.

  • Symbolic link libccl.so is still pointing to the C++ API.

  • To link with the C API use linker flag such as -l:libccl.so.2.

  • Sample cmake target: :

add_library(oneCCL INTERFACE)
target_include_directories(oneCCL INTERFACE $ENV{ONECCL_ROOT}/include)
target_link_libraries(oneCCL INTERFACE -l:libccl.so.2)

Key differences between the two APIs#

C++ API

C API

Header file

oneapi/ccl.hpp

oneapi/ccl.h

Shared object

libccl.so or libccl.so.1 or libccl.so.1.0

libccl.so.2 or libccl.so.2.0

APIs

C++ API

C API
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