Index: gc.c
===================================================================
--- gc.c	(revision 45277)
+++ gc.c	(working copy)
@@ -116,6 +116,13 @@
 #define GC_HEAP_OLDOBJECT_LIMIT_FACTOR 2.0
 #endif
 
+#ifndef GC_HEAP_FREE_SLOTS_MIN_RATIO
+#define GC_HEAP_FREE_SLOTS_MIN_RATIO 0.3
+#endif
+#ifndef GC_HEAP_FREE_SLOTS_MAX_RATIO
+#define GC_HEAP_FREE_SLOTS_MAX_RATIO 0.8
+#endif
+
 #ifndef GC_MALLOC_LIMIT_MIN
 #define GC_MALLOC_LIMIT_MIN (16 * 1024 * 1024 /* 16MB */)
 #endif
@@ -1161,26 +1168,30 @@
     heap_pages_increment = 0;
 }
 
-static void
-heap_set_increment(rb_objspace_t *objspace, size_t minimum_limit)
+static size_t
+heap_extend_pages(rb_objspace_t *objspace)
 {
     size_t used = heap_pages_used - heap_tomb->page_length;
     size_t next_used_limit = (size_t)(used * gc_params.growth_factor);
+
     if (gc_params.growth_max_slots > 0) {
 	size_t max_used_limit = (size_t)(used + gc_params.growth_max_slots/HEAP_OBJ_LIMIT);
 	if (next_used_limit > max_used_limit) next_used_limit = max_used_limit;
     }
+
+    return next_used_limit - used;
+}
+
+static void
+heap_set_increment(rb_objspace_t *objspace, size_t additional_pages)
+{
+    size_t used = heap_pages_used - heap_tomb->page_length;
+    size_t next_used_limit = used + additional_pages;
+
     if (next_used_limit == heap_pages_used) next_used_limit++;
 
-    if (next_used_limit < minimum_limit) {
-	next_used_limit = minimum_limit;
-    }
-
     heap_pages_increment = next_used_limit - used;
     heap_pages_expand_sorted(objspace);
-
-    if (0) fprintf(stderr, "heap_set_increment: heap_pages_length: %d, heap_pages_used: %d, heap_pages_increment: %d, next_used_limit: %d\n",
-		   (int)heap_pages_length, (int)heap_pages_used, (int)heap_pages_increment, (int)next_used_limit);
 }
 
 static int
@@ -2820,17 +2831,32 @@
     rgengc_report(1, objspace, "page_sweep: end.\n");
 }
 
-/* allocate additional minimum page to work */
+/* allocate minimum page to work */
 static void
+gc_heap_allocate_minimum_page(rb_objspace_t *objspace, rb_heap_t *heap)
+{
+    heap_set_increment(objspace, 1);
+    if (!heap_increment(objspace, heap)) { /* can't allocate additional free objects */
+	during_gc = 0;
+	rb_memerror();
+    }
+}
+
+static void
 gc_heap_prepare_minimum_pages(rb_objspace_t *objspace, rb_heap_t *heap)
 {
     if (!heap->free_pages) {
-	/* there is no free after page_sweep() */
-	heap_set_increment(objspace, 0);
-	if (!heap_increment(objspace, heap)) { /* can't allocate additional free objects */
-	    during_gc = 0;
-	    rb_memerror();
+#if USE_RGENGC
+	if (objspace->rgengc.during_minor_gc) {
+	    /* do full GC */
+	    garbage_collect(objspace, TRUE, TRUE, GPR_FLAG_NEWOBJ | GPR_FLAG_MAJOR_BY_NOFREE);
 	}
+	else {
+	    gc_heap_allocate_minimum_page(objspace, heap);
+	}
+#else
+	gc_heap_allocate_minimum_page(objspace, heap);
+#endif
     }
 }
 
@@ -2870,11 +2896,11 @@
     heap_pages_swept_slots = 0;
     total_limit_slot = objspace_total_slot(objspace);
 
-    heap_pages_min_free_slots = (size_t)(total_limit_slot * 0.30);
+    heap_pages_min_free_slots = (size_t)(total_limit_slot * GC_HEAP_FREE_SLOTS_MIN_RATIO);
     if (heap_pages_min_free_slots < gc_params.heap_free_slots) {
 	heap_pages_min_free_slots = gc_params.heap_free_slots;
     }
-    heap_pages_max_free_slots = (size_t)(total_limit_slot * 0.80);
+    heap_pages_max_free_slots = (size_t)(total_limit_slot * GC_HEAP_FREE_SLOTS_MAX_RATIO);
     if (heap_pages_max_free_slots < gc_params.heap_init_slots) {
 	heap_pages_max_free_slots = gc_params.heap_init_slots;
     }
@@ -2959,22 +2985,51 @@
 static void
 gc_after_sweep(rb_objspace_t *objspace)
 {
-    rb_heap_t *heap = heap_eden;
+    /* extend heap when space is not enough */
+#if USE_RGENGC
+    if (objspace->rgengc.during_minor_gc) {
+	if (heap_pages_swept_slots < heap_pages_min_free_slots) {
+	    objspace->rgengc.need_major_gc = GPR_FLAG_MAJOR_BY_RESCAN;
+	}
+    }
+    else {
+	/* check slots for newobj */
+	if (heap_pages_swept_slots < heap_pages_min_free_slots) {
+	    /* do not have enough slots for new objects */
+	    heap_set_increment(objspace, heap_extend_pages(objspace));
+	}
+	else if (gc_params.oldobject_limit_factor > 1) {
+	    size_t old_object_count = objspace->rgengc.old_object_count;
+	    size_t old_object_max = (size_t)(objspace->rgengc.old_object_limit * (1 - GC_HEAP_FREE_SLOTS_MIN_RATIO));
 
-    rgengc_report(1, objspace, "after_gc_sweep: heap->total_slots: %d, heap->swept_slots: %d, min_free_slots: %d\n",
-		  (int)heap->total_slots, (int)heap_pages_swept_slots, (int)heap_pages_min_free_slots);
+	    if (old_object_count > old_object_max) {
+		/* not enough old object space */
+		heap_set_increment(objspace, (old_object_count - old_object_max) / HEAP_OBJ_LIMIT + 1);
+	    }
+	}
 
-    if (heap_pages_swept_slots < heap_pages_min_free_slots) {
-	heap_set_increment(objspace, (heap_pages_min_free_slots - heap_pages_swept_slots) / HEAP_OBJ_LIMIT);
-	heap_increment(objspace, heap);
+	/* setup old_object_limit & remembered_shady_object_limit */
+	{
+	    /* See the comment about RUBY_GC_HEAP_OLDOBJECT_LIMIT_FACTOR */
+	    size_t old_object_count = objspace->rgengc.old_object_count;
+	    size_t old_limit_by_total_slots = (size_t)(objspace_total_slot(objspace) * (1 - GC_HEAP_FREE_SLOTS_MIN_RATIO));
+	    const double r = gc_params.oldobject_limit_factor;
+	    size_t old_limit_by_old_num = (size_t)(old_object_count * r);
 
-#if USE_RGENGC
-	if (objspace->rgengc.remembered_shady_object_count + objspace->rgengc.old_object_count > (heap_pages_length * HEAP_OBJ_LIMIT) / 2) {
-	    /* if [old]+[remembered shady] > [all object count]/2, then do major GC */
-	    objspace->rgengc.need_major_gc = GPR_FLAG_MAJOR_BY_RESCAN;
+	    objspace->rgengc.old_object_limit =
+	      old_limit_by_total_slots > old_limit_by_old_num ?
+	      old_limit_by_old_num : old_limit_by_total_slots;
+
+	    /* should we merge remembered shady object limit? */
+	    objspace->rgengc.remembered_shady_object_limit = (size_t)(objspace->rgengc.remembered_shady_object_count * r);
 	}
+    }
+#else
+    if (heap_pages_swept_slots < heap_pages_min_free_slots) {
+	/* do not have enough slots for new objects */
+	heap_set_increment(objspace, heap_extend_pages(objspace));
+    }
 #endif
-    }
 
     gc_prof_set_heap_info(objspace);
 
@@ -3082,8 +3137,6 @@
 	}
 	gc_heap_lazy_sweep(objspace, heap_eden);
     }
-
-    gc_heap_prepare_minimum_pages(objspace, heap_eden);
 }
 
 /* Marking - Marking stack */
@@ -4524,12 +4577,6 @@
 #endif
 
 	    gc_marks_body(objspace, TRUE);
-	    {
-		/* See the comment about RUBY_GC_HEAP_OLDOBJECT_LIMIT_FACTOR */
-		const double r = gc_params.oldobject_limit_factor;
-		objspace->rgengc.remembered_shady_object_limit = (size_t)(objspace->rgengc.remembered_shady_object_count * r);
-		objspace->rgengc.old_object_limit = (size_t)(objspace->rgengc.old_object_count * r);
-	    }
 	}
 	else { /* minor GC */
 	    gc_marks_body(objspace, FALSE);
@@ -5047,6 +5094,8 @@
     }
     gc_prof_timer_stop(objspace);
 
+    gc_heap_prepare_minimum_pages(objspace, heap_eden);
+
     if (GC_NOTIFY) fprintf(stderr, "end garbage_collect()\n");
     return TRUE;
 }
@@ -5057,7 +5106,7 @@
     if (dont_gc || during_gc) {
 	if (!heap->freelist && !heap->free_pages) {
 	    if (!heap_increment(objspace, heap)) {
-		heap_set_increment(objspace, 0);
+		heap_set_increment(objspace, 1);
                 heap_increment(objspace, heap);
             }
 	}