From dc8e4e1959855ca24af7e2d675f2be33087ff96c Mon Sep 17 00:00:00 2001
From: Martin Kroeker <martin@ruby.chemie.uni-freiburg.de>
Date: Sun, 4 Oct 2020 22:59:24 +0200
Subject: [PATCH 1/2] Reduce the BLAS3 heap allocation threshold to 32 and mark
 it as configurable

---
 Makefile.rule | 17 ++++++++++++++++-
 common.h      |  2 +-
 2 files changed, 17 insertions(+), 2 deletions(-)

diff --git a/Makefile.rule b/Makefile.rule
index 4d6f2d313..635e02c02 100644
--- a/Makefile.rule
+++ b/Makefile.rule
@@ -279,7 +279,22 @@ COMMON_PROF = -pg
 
 # If you want to enable the experimental BFLOAT16 support
 # BUILD_HALF = 1
-#
+
+
+# Set the thread number threshold beyond which the job array for the threaded level3 BLAS
+# will be allocated on the heap rather than the stack. (This array alone requires 
+# NUM_THREADS*NUM_THREADS*128 bytes of memory so should not pose a problem at low cpu
+# counts, but obviously it is not the only item that ends up on the stack.
+# The default value of 32 ensures that the overall requirement is compatible
+# with the default 1MB stacksize imposed by having the Java VM loaded without use
+# of its -Xss parameter.
+# The value of 160 formerly used from about version 0.2.7 until 0.3.10 is easily compatible
+# with the common Linux stacksize of 8MB but will cause crashes with unwary use of the java
+# VM e.g. in Octave or with the java-based libhdfs in numpy or scipy code
+# BLAS3_MEM_ALLOC_THRESHOLD = 160
+
+
+
 # the below is not yet configurable, use cmake if you need to build only select types
 BUILD_SINGLE = 1
 BUILD_DOUBLE = 1
diff --git a/common.h b/common.h
index ac12dd6d8..ab287262c 100644
--- a/common.h
+++ b/common.h
@@ -402,7 +402,7 @@ please https://github.com/xianyi/OpenBLAS/issues/246
 #endif
 
 #ifndef BLAS3_MEM_ALLOC_THRESHOLD
-#define BLAS3_MEM_ALLOC_THRESHOLD 160
+#define BLAS3_MEM_ALLOC_THRESHOLD 32 
 #endif
 
 #ifdef QUAD_PRECISION

From a5feea6611f49e875de83282c061843e18050af6 Mon Sep 17 00:00:00 2001
From: Martin Kroeker <martin@ruby.chemie.uni-freiburg.de>
Date: Sun, 4 Oct 2020 23:01:06 +0200
Subject: [PATCH 2/2] make BLAS3_MEM_ALLOC_THRESHOLD configurable on
 non-Windows

---
 cmake/system.cmake | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/cmake/system.cmake b/cmake/system.cmake
index 8908a1890..0734065df 100644
--- a/cmake/system.cmake
+++ b/cmake/system.cmake
@@ -323,7 +323,13 @@ else ()
 set(CCOMMON_OPT "${CCOMMON_OPT} -DMAX_STACK_ALLOC=2048")
 endif ()
 endif ()
-
+if (NOT ${CMAKE_SYSTEM_NAME} STREQUAL "Windows")
+if (DEFINED BLAS3_MEM_ALLOC_THRESHOLD)
+if (NOT ${BLAS3_MEM_ALLOC_THRESHOLD} EQUAL 32)
+set(CCOMMON_OPT "${CCOMMON_OPT} -DBLAS3_MEM_ALLOC_THRESHOLD=${BLAS3_MEM_ALLOC_THRESHOLD}")
+endif()
+endif()
+endif()
 if (DEFINED LIBNAMESUFFIX)
   set(LIBPREFIX "libopenblas_${LIBNAMESUFFIX}")
 else ()