etc/settings.* set a minimum MPI_BUFFER_SIZE, but retain larger values

etc/settings.csh

@@ -193,9 +193,17 @@ endsw
 _foamAddLib $FOAM_MPI_LIBBIN
 
 
-# Set the MPI buffer size (used by all platforms except SGI MPI)
-# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-setenv MPI_BUFFER_SIZE 20000000
+# Set the minimum MPI buffer size (used by all platforms except SGI MPI)
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+set minBufferSize=20000000
+
+if ( $?MPI_BUFFER_SIZE ) then
+    if ( $MPI_BUFFER_SIZE < $minBufferSize ) then
+        setenv MPI_BUFFER_SIZE $minBufferSize
+    endif
+else
+    setenv MPI_BUFFER_SIZE $minBufferSize
+endif
 
 
 # CGAL library if available
@@ -217,5 +225,6 @@ endif
 unalias _foamAddPath
 unalias _foamAddLib
 unalias _foamMkDir
+unset minBufferSize
 
 # -----------------------------------------------------------------------------

etc/settings.sh

@@ -223,9 +223,15 @@ esac
 _foamAddLib $FOAM_MPI_LIBBIN
 
 
-# Set the MPI buffer size (used by all platforms except SGI MPI)
-# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
-export MPI_BUFFER_SIZE=20000000
+# Set the minimum MPI buffer size (used by all platforms except SGI MPI)
+# ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+minBufferSize=20000000
+
+if [ "${MPI_BUFFER_SIZE:=$minBufferSize}" -lt $minBufferSize ]
+then
+    MPI_BUFFER_SIZE=$minBufferSize
+fi
+export MPI_BUFFER_SIZE
 
 
 # CGAL library if available
@@ -242,6 +248,6 @@ export MPI_BUFFER_SIZE=20000000
 
 # cleanup environment:
 # ~~~~~~~~~~~~~~~~~~~~
-unset _foamAddPath _foamAddLib _foamMkDir
+unset _foamAddPath _foamAddLib _foamMkDir minBufferSize
 
 # -----------------------------------------------------------------------------