2009-09-10 Ivan Maidanski <ivmai@mail.ru>

	(diff118_cvs - superseding diff53)

	* allchblk.c (MUNMAP_THRESHOLD): Move macro definition out of
	a function.
	* allchblk.c (GC_unmap_threshold): New global variable definition
	(initialized to MUNMAP_THRESHOLD).
	* allchblk.c (GC_unmap_old): Use GC_unmap_threshold instead of
	MUNMAP_THRESHOLD; skip unmapping if GC_unmap_threshold is 0.
	* doc/README.environment (GC_UNMAP_THRESHOLD): Add information.
	* misc.c (GC_unmap_threshold): New variable declaration.
	* misc.c (GC_init_inner): Recognize "GC_UNMAP_THRESHOLD"
	environment variable to set GC_unmap_threshold value (only if
	USE_MUNMAP).

diff --git a/ChangeLog b/ChangeLog
index 0ed06fe7ecc10e1293c94dd7438064d610890dce..3626918c415796b5a3e43bc28920ced0bde52cfa 100644 (file)
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,4 +1,19 @@
 
+2009-09-10  Ivan Maidanski <ivmai@mail.ru>
+       (diff118_cvs - superseding diff53)
+
+       * allchblk.c (MUNMAP_THRESHOLD): Move macro definition out of
+       a function.
+       * allchblk.c (GC_unmap_threshold): New global variable definition
+       (initialized to MUNMAP_THRESHOLD).
+       * allchblk.c (GC_unmap_old): Use GC_unmap_threshold instead of
+       MUNMAP_THRESHOLD; skip unmapping if GC_unmap_threshold is 0.
+       * doc/README.environment (GC_UNMAP_THRESHOLD): Add information.
+       * misc.c (GC_unmap_threshold): New variable declaration.
+       * misc.c (GC_init_inner): Recognize "GC_UNMAP_THRESHOLD"
+       environment variable to set GC_unmap_threshold value (only if
+       USE_MUNMAP).
+
 2009-09-10  Ivan Maidanski <ivmai@mail.ru>
        (diff117)
 
@@ -428,7 +443,8 @@
        GC_check_finalizer_nested): Ditto.
 
 2009-09-10  Ivan Maidanski <ivmai@mail.ru>
-       (diff103_cvs)
+       (diff103_cvs - resembling diff78, diff88_cvs, diff99_cvs,
+       diff100_cvs, diff101_cvs, diff102_cvs)
 
        * alloc.c (GC_stopped_mark): Remove GC_log_printf("") (not needed
        anymore and GCC produces a warning for it).

diff --git a/allchblk.c b/allchblk.c
index 627ef904a199e4ad4f08fb78dd4e4487fb474585..85cba94b3f84f3e71760a24346c51eae65c898e8 100644 (file)
--- a/allchblk.c
+++ b/allchblk.c
@@ -381,29 +381,31 @@ STATIC void GC_add_to_fl(struct hblk *h, hdr *hhdr)
 
 #ifdef USE_MUNMAP
 
+#   ifndef MUNMAP_THRESHOLD
+#     define MUNMAP_THRESHOLD 6
+#   endif
+
+int GC_unmap_threshold = MUNMAP_THRESHOLD;
+
 /* Unmap blocks that haven't been recently touched.  This is the only way */
 /* way blocks are ever unmapped.                                         */
 void GC_unmap_old(void)
 {
     struct hblk * h;
     hdr * hhdr;
-    word sz;
-    unsigned short last_rec, threshold;
     int i;
-#   ifndef MUNMAP_THRESHOLD
-#     define MUNMAP_THRESHOLD 6
-#   endif
+
+    if (GC_unmap_threshold == 0)
+      return; /* unmapping disabled */
     
     for (i = 0; i <= N_HBLK_FLS; ++i) {
       for (h = GC_hblkfreelist[i]; 0 != h; h = hhdr -> hb_next) {
         hhdr = HDR(h);
        if (!IS_MAPPED(hhdr)) continue;
-       threshold = (unsigned short)(GC_gc_no - MUNMAP_THRESHOLD);
-       last_rec = hhdr -> hb_last_reclaimed;
-       if ((last_rec > GC_gc_no || last_rec < threshold)
-           && threshold < GC_gc_no /* not recently wrapped */) {
-          sz = hhdr -> hb_sz;
-         GC_unmap((ptr_t)h, sz);
+
+       if ((unsigned short)GC_gc_no - hhdr -> hb_last_reclaimed >
+               (unsigned short)GC_unmap_threshold) {
+         GC_unmap((ptr_t)h, hhdr -> hb_sz);
          hhdr -> hb_flags |= WAS_UNMAPPED;
        }
       }

diff --git a/doc/README.environment b/doc/README.environment
index a5e110e36551ddb26440479a923f65b53b68a064..b6f6399d90709c93ffdcbfdf47f2bf23c5a4a63c 100644 (file)
--- a/doc/README.environment
+++ b/doc/README.environment
@@ -136,6 +136,11 @@ GC_FREE_SPACE_DIVISOR - Set GC_free_space_divisor to the indicated value.
                       Setting it to larger values decreases space consumption
                      and increases GC frequency.
 
+GC_UNMAP_THRESHOLD - Set the desired memory blocks unmapping threshold (the
+                  number of sequential garbage collections for which
+                  a candidate block for unmapping should remain free).  The
+                  special value "0" completely disables unmapping.
+
 GC_FIND_LEAK - Turns on GC_find_leak and thus leak detection.  Forces a
               collection at program termination to detect leaks that would
               otherwise occur after the last GC.

diff --git a/misc.c b/misc.c
index 60a0586c63aab38c1d5c4f83015a538c0c8b5219..e5e06c28077d3add947201c256bfa87bb605ed2a 100644 (file)
--- a/misc.c
+++ b/misc.c
@@ -498,6 +498,10 @@ static void maybe_install_looping_handler(void)
   void GC_thr_init(void);
 #endif
 
+#ifdef USE_MUNMAP
+  extern int GC_unmap_threshold;
+#endif
+
 void GC_init_inner(void)
 {
 #   if !defined(THREADS) && defined(GC_ASSERTIONS)
@@ -646,6 +650,21 @@ void GC_init_inner(void)
            GC_free_space_divisor = (GC_word)space_divisor;
        }
     }
+#   ifdef USE_MUNMAP
+      {
+       char * string = GETENV("GC_UNMAP_THRESHOLD");
+       if (string != NULL) {
+         if (*string == '0' && *(string + 1) == '\0') {
+           /* "0" is used to disable unmapping. */
+           GC_unmap_threshold = 0;
+         } else {
+           int unmap_threshold = atoi(string);
+           if (unmap_threshold > 0)
+             GC_unmap_threshold = unmap_threshold;
+         }
+       }
+      }
+#   endif
     maybe_install_looping_handler();
     /* Adjust normal object descriptor for extra allocation.   */
     if (ALIGNMENT > GC_DS_TAGS && EXTRA_BYTES != 0) {