Patch to account for rlimits in GC heuristics

["Kaveh R. Ghazi" <ghazi at caip dot rutgers dot edu>]

As noted elsewhere, rlimits need to be accounted for in the GC
heuristics.  The patch below does this by taking the lesser of actual
RAM, RLIMIT_RSS and RLIMIT_DATA as input into the algorithm.

I tested it by setting RLIMIT_DATA to 64Mb and bootstrapping C-only on
sparc-sun-solaris2.7.  Without the patch it crashes with an out of
memory error in stage2.  With the patch it succeeds.

With a restricted 64Mb RLIMIT_DATA, the heuristics show:

> GGC heuristics: --param ggc-min-expand=34 --param ggc-min-heapsize=8192

which by my manual calcuation is correct:
(30% + 70%*(64M/1G) == 34% and 64M/8 == 8M.)

Solaris2 doesn't have RLIMIT_RSS, so I'd like to install it for wider
testing of that bit.

Ok for trunk and 3.3?

		Thanks,
		--Kaveh


2003-02-22  Kaveh R. Ghazi  <ghazi at caip dot rutgers dot edu>

	* doc/invoke.texi (ggc-min-expand, ggc-min-heapsize): Document
	new default behavior.
	* ggc-common.c: Include sys/resource.h.
	(ggc_min_expand_heuristic, ggc_min_heapsize_heuristic): Update
	defaults to account for rlimits.

diff -rup orig/egcc-CVS20030222/gcc/doc/invoke.texi egcc-CVS20030222/gcc/doc/invoke.texi
--- orig/egcc-CVS20030222/gcc/doc/invoke.texi	2003-02-21 22:04:45.000000000 -0500
+++ egcc-CVS20030222/gcc/doc/invoke.texi	2003-02-22 13:27:54.360348000 -0500
@@ -4474,11 +4474,12 @@ Tuning this may improve compilation spee
 generation.
 
 The default is 30% + 70% * (RAM/1GB) with an upper bound of 100% when
-RAM >= 1GB.  If GCC is not able to calculate RAM on a particular
-platform, the lower bound of 30% is used.  Setting this parameter and
- at option{ggc-min-heapsize} to zero causes a full collection to occur at
-every opportunity.  This is extremely slow, but can be useful for
-debugging.
+RAM >= 1GB.  If @code{getrlimit} is available, the notion of "RAM" is
+the lesser of actual RAM, RLIMIT_RSS and RLIMIT_DATA.  If GCC is not
+able to calculate RAM on a particular platform, the lower bound of 30%
+is used.  Setting this parameter and @option{ggc-min-heapsize} to zero
+causes a full collection to occur at every opportunity.  This is
+extremely slow, but can be useful for debugging.
 
 @item ggc-min-heapsize
 
@@ -4489,11 +4490,13 @@ tuning this may improve compilation spee
 generation.
 
 The default is RAM/8, with a lower bound of 4096 (four megabytes) and an
-upper bound of 131072 (128 megabytes).  If GCC is not able to calculate
-RAM on a particular platform, the lower bound is used.  Setting this
-parameter very large effectively disables garbage collection.  Setting
-this parameter and @option{ggc-min-expand} to zero causes a full
-collection to occur at every opportunity.
+upper bound of 131072 (128 megabytes).  If @code{getrlimit} is
+available, the notion of "RAM" is the lesser of actual RAM, RLIMIT_RSS
+and RLIMIT_DATA.  If GCC is not able to calculate RAM on a particular
+platform, the lower bound is used.  Setting this parameter very large
+effectively disables garbage collection.  Setting this parameter and
+ at option{ggc-min-expand} to zero causes a full collection to occur at
+every opportunity.
 
 @end table
 @end table
diff -rup orig/egcc-CVS20030222/gcc/ggc-common.c egcc-CVS20030222/gcc/ggc-common.c
--- orig/egcc-CVS20030222/gcc/ggc-common.c	2003-02-21 22:05:53.000000000 -0500
+++ egcc-CVS20030222/gcc/ggc-common.c	2003-02-22 13:27:02.022855000 -0500
@@ -29,6 +29,10 @@ Software Foundation, 59 Temple Place - S
 #include "toplev.h"
 #include "params.h"
 
+#ifdef HAVE_SYS_RESOURCE_H
+# include <sys/resource.h>
+#endif
+
 #ifdef HAVE_MMAP_FILE
 # include <sys/mman.h>
 #endif
@@ -631,6 +635,18 @@ int
 ggc_min_expand_heuristic()
 {
   double min_expand = physmem_total();
+
+#if defined(HAVE_GETRLIMIT)
+  struct rlimit rlim;
+# ifdef RLIMIT_RSS
+  if (getrlimit (RLIMIT_RSS, &rlim) == 0 && rlim.rlim_cur < min_expand)
+    min_expand = rlim.rlim_cur;
+# endif
+# ifdef RLIMIT_DATA
+  if (getrlimit (RLIMIT_DATA, &rlim) == 0 && rlim.rlim_cur < min_expand)
+    min_expand = rlim.rlim_cur;
+# endif
+#endif /* HAVE_GETRLIMIT */
   
   /* The heuristic is a percentage equal to 30% + 70%*(RAM/1GB), yielding
      a lower bound of 30% and an upper bound of 100% (when RAM >= 1GB).  */
@@ -646,7 +662,21 @@ ggc_min_expand_heuristic()
 int
 ggc_min_heapsize_heuristic()
 {
-  double min_heap_kbytes = physmem_total() / 1024;
+  double min_heap_kbytes = physmem_total();
+
+#if defined(HAVE_GETRLIMIT)
+  struct rlimit rlim;
+# ifdef RLIMIT_RSS
+  if (getrlimit (RLIMIT_RSS, &rlim) == 0 && rlim.rlim_cur < min_heap_kbytes)
+    min_heap_kbytes = rlim.rlim_cur;
+# endif
+# ifdef RLIMIT_DATA
+  if (getrlimit (RLIMIT_DATA, &rlim) == 0 && rlim.rlim_cur < min_heap_kbytes)
+    min_heap_kbytes = rlim.rlim_cur;
+# endif
+#endif /* HAVE_GETRLIMIT */
+
+  min_heap_kbytes /= 1024; /* convert to Kbytes. */
   
   /* The heuristic is RAM/8, with a lower bound of 4M and an upper
      bound of 128M (when RAM >= 1GB).  */