Environment Variables

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.

General

Note

Please see C++ API documentation for additional variables used to tune oneCCL’s behavior here.

CCL_PLUGIN

Syntax

Select plugin by name or by path to binary implementing oneCCL’s plugin interface:

CCL_PLUGIN="<plugin_name>"
CCL_PLUGIN="<plugin_path>"

Where:

• <plugin_name> is selected from the list of available plugins.

• <plugin_path> is absolute path to .so/.dll implementing oneCCL plugins interface.

Example

CCL_PLUGIN="ONECCL_LEGACY"
CCL_PLUGIN="/home/user/oneCCL/build/plugins/legacy/libccl_legacy.so"

Arguments

<plugin_name>	Description
ONECCL_LEGACY	Legacy oneCCL implementation based on SYCL for CPU and GPU workloads
ONECCL_LEGACY_CPU	Legacy oneCCL implementation for CPU only workloads
ONECCL_NULL	Empty implementation of oneCCL plugin, will always return ONECCL_SUCCESS

Description

Use this environment variable to specify underlying implementation of all oneCCL functions.