Merge pull request #19 from github/2.1-gc-heap-growth

Backport 2.1 gc heap growth patch

gc.c

@@ -541,6 +541,9 @@ typedef struct rb_objspace {
 	int parent_object_is_old;
 
 	int need_major_gc;
+
+	size_t last_major_gc;
+
 	size_t remembered_shady_object_count;
 	size_t remembered_shady_object_limit;
 	size_t old_object_count;
@@ -1193,26 +1196,30 @@ heap_add_pages(rb_objspace_t *objspace, rb_heap_t *heap, size_t add)
     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;
     }
-    if (next_used_limit == heap_pages_used) next_used_limit++;
 
-    if (next_used_limit < minimum_limit) {
-	next_used_limit = minimum_limit;
+    return next_used_limit - used;
     }
 
+static void
+heap_set_increment(rb_objspace_t *objspace, size_t additional_pages)
+{
+    size_t used = heap_eden->page_length;
+    size_t next_used_limit = used + additional_pages;
+
+    if (next_used_limit == heap_pages_used) next_used_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
@@ -2855,7 +2862,7 @@ 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);
+	heap_set_increment(objspace, 1);
 	if (!heap_increment(objspace, heap)) { /* can't allocate additional free objects */
 	    during_gc = 0;
 	    rb_memerror();
@@ -2994,15 +3001,13 @@ gc_after_sweep(rb_objspace_t *objspace)
 		  (int)heap->total_slots, (int)heap_pages_swept_slots, (int)heap_pages_min_free_slots);
 
     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);
-
-#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;
+	if (objspace->rgengc.during_minor_gc && objspace->profile.count - objspace->rgengc.last_major_gc > 2 /* magic number */) {
+	    objspace->rgengc.need_major_gc = GPR_FLAG_MAJOR_BY_NOFREE;
+	}
+	else {
+	    heap_set_increment(objspace, heap_extend_pages(objspace));
+	    heap_increment(objspace, heap);
 	}
-#endif
     }
 
     gc_prof_set_heap_info(objspace);
@@ -4185,6 +4190,7 @@ gc_marks_body(rb_objspace_t *objspace, int full_mark)
     }
     else {
 	objspace->profile.major_gc_count++;
+	objspace->rgengc.last_major_gc = objspace->profile.count;
 	rgengc_mark_and_rememberset_clear(objspace, heap_eden);
     }
 #endif
@@ -5064,7 +5070,7 @@ heap_ready_to_gc(rb_objspace_t *objspace, rb_heap_t *heap)
     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);
             }
 	}