add OpenBlas multi-threading introduction

apache · Jul 6, 2017 · a4d4f50 · a4d4f50
1 parent 7ef8b80
commit a4d4f50
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Showing 2 changed files with 5 additions and 3 deletions.
diff --git a/conf/spark-env.sh.template b/conf/spark-env.sh.template
@@ -62,6 +62,6 @@
 # - SPARK_NICENESS      The scheduling priority for daemons. (Default: 0)
 # - SPARK_NO_DAEMONIZE  Run the proposed command in the foreground. It will not output a PID file.
 # Options for native BLAS, like Intel MKL, OpenBLAS, and so on.
-# You shoud enable these options if use native BLAS (SPARK-21305).
+# You shoud enable these options if using native BLAS (see SPARK-21305).
 # - MKL_NUM_THREADS=1        Disable multi-threading of Intel MKL
 # - OPENBLAS_NUM_THREADS=1   Disable multi-threading of OpenBLAS
diff --git a/docs/ml-guide.md b/docs/ml-guide.md
@@ -61,8 +61,10 @@ 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, are based on multi-threading, which will conflict with Spark.
-To use multi-threading based native BLAS, you must set it to use single thread first (SPARK-21305).
+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. 
+For example, when OpenBLAS is loaded, it will create a thread pool with `MAX_CPU_NUMBER` threads, and the threads are using spinlock by default, which will conflict with Spark.
+
+If using a native BLAS based on multi-threading, for the best performance you must set it to use single thread first ([SPARK-21305](https://issues.apache.org/jira/browse/SPARK-21305)).
 
 To use MLlib in Python, you will need [NumPy](http://www.numpy.org) version 1.4 or newer.