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Adding usage tip for ignore cpu affinity (#1948)

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* Adding usage tip for ignore cpu affinity

* Update docs/how-to/rccl-usage-tips.rst

Co-authored-by: Jeffrey Novotny <jnovotny@amd.com>

* Update docs/how-to/rccl-usage-tips.rst

Co-authored-by: Jeffrey Novotny <jnovotny@amd.com>

---------

Co-authored-by: Jeffrey Novotny <jnovotny@amd.com>
This commit is contained in:
David DeBonis
2025-09-29 10:11:21 -06:00
committed by GitHub
parent 65b69bf318
commit d23d18f423
1 changed files with 15 additions and 1 deletions
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docs/how-to/rccl-usage-tips.rst
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@@ -82,6 +82,20 @@ set the HSA environment variable as follows:
This feature requires GPUs that support peer-to-peer access along with
proper large BAR addressing support.
Ignoring CPU affinity with multi-node
=====================================
Depending on the job launcher and the requirements of your workload, performance as the communication workload scales
can be improved by setting ``NCCL_IGNORE_CPU_AFFINITY``. This allows the RCCL communication library to
ignore the job's supplied CPU affinity and use the GPU affinity only.
.. code-block:: shell
NCCL_IGNORE_CPU_AFFINITY=1
For general usage, this environment variable is not set so it doesn't interfere with the user or launcher
supplied preferences.
Improving performance on the MI300X
===================================
@@ -262,4 +276,4 @@ To disable context tracking for Radeon GPUs, set the following environment varia
.. code-block:: shell
export RCCL_DISABLE_CONTEXT_TRACKING=1
export RCCL_DISABLE_CONTEXT_TRACKING=1