From 8a93e9db8e8bf0ff0569d1cbefeb38a2c18bd2b1 Mon Sep 17 00:00:00 2001
From: Matthieu Schaller <schaller@strw.leidenuniv.nl>
Date: Sat, 12 Dec 2020 17:21:49 +0100
Subject: [PATCH] Describe the specifics of the OpenMPI 4.0.5 module used on
 cosma7 as it may be more generally useful.

---
 README-mpi-hints.md | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/README-mpi-hints.md b/README-mpi-hints.md
index dd21fa3870..b55d27390e 100644
--- a/README-mpi-hints.md
+++ b/README-mpi-hints.md
@@ -48,3 +48,13 @@ UCX_TLS=ud_x,shm,self
 UCX_RC_MLX5_TM_ENABLE=n
 UCX_DC_MLX5_TM_ENABLE=n
 ```
+
+These environment variables (set on the Mellanox-base cosma system in Durham)
+for version 4.0.5 with the UCX backend can also be useful:
+
+```
+OMPI_MCA_btl                    ^openib
+OMPI_MCA_btl_openib_flags       1
+OMPI_MCA_plm_rsh_num_concurrent 768
+OMPI_MCA_mpool_rdma_rcache_size_limit   209715200
+```
\ No newline at end of file
-- 
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