[lmi-commits] [5562] Tune gcc

[Greg Chicares]

Revision: 5562
          http://svn.sv.gnu.org/viewvc/?view=rev&root=lmi&revision=5562
Author:   chicares
Date:     2012-09-03 14:07:14 +0000 (Mon, 03 Sep 2012)
Log Message:
-----------
Tune gcc

Modified Paths:
--------------
    lmi/trunk/ChangeLog
    lmi/trunk/workhorse.make

Modified: lmi/trunk/ChangeLog
===================================================================
--- lmi/trunk/ChangeLog 2012-09-03 09:54:26 UTC (rev 5561)
+++ lmi/trunk/ChangeLog 2012-09-03 14:07:14 UTC (rev 5562)
@@ -30710,3 +30710,13 @@
   multiple_cell_document.xsd
 Specify census defaults.
 
+20120903T0954Z <address@hidden> [567]
+
+  workhorse.make
+Guard against a perilous command-line override.
+
+20120903T1407Z <address@hidden> [567]
+
+  workhorse.make
+Tune gcc.
+

Modified: lmi/trunk/workhorse.make
===================================================================
--- lmi/trunk/workhorse.make    2012-09-03 09:54:26 UTC (rev 5561)
+++ lmi/trunk/workhorse.make    2012-09-03 14:07:14 UTC (rev 5562)
@@ -510,6 +510,19 @@
 
 
################################################################################
 
+# Flags for tuning gcc.
+
+# As this is written in 2012, lmi is often built on machines with less
+# RAM per core than gcc wants. Experiments show that these flags cut
+# gcc's RAM appetite by fifty percent, in return for a ten-percent
+# speed penalty that can be overcome by increasing parallelism.
+
+ifeq (gcc,$(toolset))
+  ggc_flags := --param ggc-min-expand=25 --param ggc-min-heapsize=32768
+endif
+
+################################################################################
+
 # Build type governs
 #  - optimization flags
 #  - mpatrol
@@ -622,10 +635,10 @@
 endif
 
 CFLAGS = \
-  $(debug_flag) $(optimization_flag) $(gprof_flag) \
+  $(ggc_flags) $(debug_flag) $(optimization_flag) $(gprof_flag) \
 
 CXXFLAGS = \
-  $(debug_flag) $(optimization_flag) $(gprof_flag) \
+  $(ggc_flags) $(debug_flag) $(optimization_flag) $(gprof_flag) \
 
 # Explicitly disable the infelicitous auto-import default. See:
 #   http://article.gmane.org/gmane.comp.gnu.mingw.user/19758