Github user srowen commented on a diff in the pull request:
https://github.com/apache/spark/pull/18551#discussion_r126657737
--- Diff: docs/ml-guide.md ---
@@ -61,6 +61,12 @@ To configure `netlib-java` / Breeze to use system
optimised binaries, include
project and read the [netlib-java](https://github.com/fommil/netlib-java)
documentation for your
platform's additional installation instructions.
+The most popular native BLAS such as [Intel
MKL](https://software.intel.com/en-us/mkl),
[OpenBLAS](http://www.openblas.net), are based on multi-threading, which will
conflict with Spark.
+
+If using a native BLAS based on multi-threading, you might get better
performance to set it to use single thread first
([SPARK-21305](https://issues.apache.org/jira/browse/SPARK-21305)).
+
+Please reference the recommended settings for [Intel
MKL](https://software.intel.com/en-us/articles/recommended-settings-for-calling-intel-mkl-routines-from-multi-threaded-applications)
and [OpenBLAS](https://github.com/xianyi/OpenBLAS/wiki/faq#multi-threaded).
--- End diff --
Maybe: "Please refer to resources like the following to understand how to
configure the number of threads these BLAS implementations use: ..."
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