From 579be3aa9d0e196fc9cc91f6e1f2372e87638f78 Mon Sep 17 00:00:00 2001
From: Martin Kroeker <martin@ruby.chemie.uni-freiburg.de>
Date: Sun, 9 Feb 2020 23:28:04 +0100
Subject: [PATCH 1/3] Add configuration option for BUFFER_SIZE

---
 Makefile.rule | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/Makefile.rule b/Makefile.rule
index 21b7e138a..724a60ec4 100644
--- a/Makefile.rule
+++ b/Makefile.rule
@@ -97,6 +97,15 @@ VERSION = 0.3.9.dev
 # they need to wait for the preceding API calls to finish or risk data corruption.
 # NUM_PARALLEL = 2
 
+# When multithreading, OpenBLAS needs to use a memory buffer for communicating
+# and collating results for individual subranges of the original matrix. Since
+# the original GotoBLAS of the early 2000s, the default size of this buffer has
+# been set at a value of 32<<20 (which is 32MB) on x86_64 , twice that on PPC.
+# If you expect to handle large problem sizes (beyond about 30000x30000) uncomment
+# this line and adjust the (32<<n) factor if necessary. Usually an insufficient value
+# manifests itself as a crash in the relevant scal kernel (sscal_k, dscal_k etc) 
+# BUFFERSIZE = 25
+
 # If you don't need to install the static library, please comment this in.
 # NO_STATIC = 1
 

From c353d8b106ebba6f7a7b6615bc88e6a1b165b60b Mon Sep 17 00:00:00 2001
From: Martin Kroeker <martin@ruby.chemie.uni-freiburg.de>
Date: Sun, 9 Feb 2020 23:30:22 +0100
Subject: [PATCH 2/3] Make BUFFER_SIZE configurable

---
 common_x86_64.h | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/common_x86_64.h b/common_x86_64.h
index c05998d58..fe5539abe 100644
--- a/common_x86_64.h
+++ b/common_x86_64.h
@@ -225,7 +225,11 @@ static __inline int blas_quickdivide(unsigned int x, unsigned int y){
 #endif
 #define HUGE_PAGESIZE	( 2 << 20)
 
+#ifndef BUFFERSIZE
 #define BUFFER_SIZE	(32 << 20)
+#else
+#define BUFFER_SIZE	(32 << BUFFERSIZE)
+#endif
 
 #define SEEK_ADDRESS
 

From 7f0d523b42feb70e7b8ad299d8005d73f620f219 Mon Sep 17 00:00:00 2001
From: Martin Kroeker <martin@ruby.chemie.uni-freiburg.de>
Date: Sun, 9 Feb 2020 23:32:57 +0100
Subject: [PATCH 3/3] Make BUFFER_SIZE configurable

---
 cmake/system.cmake | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/cmake/system.cmake b/cmake/system.cmake
index 4f8011603..ce980a7b9 100644
--- a/cmake/system.cmake
+++ b/cmake/system.cmake
@@ -289,6 +289,10 @@ set(CCOMMON_OPT "${CCOMMON_OPT} -DMAX_CPU_NUMBER=${NUM_THREADS}")
 
 set(CCOMMON_OPT "${CCOMMON_OPT} -DMAX_PARALLEL_NUMBER=${NUM_PARALLEL}")
 
+if (BUFFERSIZE)
+set(CCOMMON_OPT "${CCOMMON_OPT} -DBUFFERSIZE=${BUFFERSIZE}")
+endif ()
+
 if (USE_SIMPLE_THREADED_LEVEL3)
   set(CCOMMON_OPT "${CCOMMON_OPT} -DUSE_SIMPLE_THREADED_LEVEL3")
 endif ()