From 7f20eaed93d1844f76a68898143a496e5d11b070 Mon Sep 17 00:00:00 2001
From: Jiaming Yuan <jm.yuan@outlook.com>
Date: Wed, 31 May 2023 05:00:02 +0800
Subject: [PATCH] [doc] Troubleshoot nccl shared memory. [skip ci] (#9206)

---
 doc/tutorials/dask.rst | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/doc/tutorials/dask.rst b/doc/tutorials/dask.rst
index 888683975..3562015e2 100644
--- a/doc/tutorials/dask.rst
+++ b/doc/tutorials/dask.rst
@@ -519,6 +519,9 @@ Troubleshooting
   the ``NCCL_SOCKET_IFNAME``. In addition, you can use ``NCCL_DEBUG`` to obtain debug
   logs.
 
+- If NCCL fails to initialize in a container environment, it might be caused by limited
+  system shared memory. With docker, one can try the flag: `--shm-size=4g`.
+
 - MIG (Multi-Instance GPU) is not yet supported by NCCL. You will receive an error message
   that includes `Multiple processes within a communication group ...` upon initialization.