From: Vlad Brezae <brezaevlad@gmail.com>
Date: Thu, 21 Apr 2016 13:53:02 +0000 (+0300)
Subject: Merge pull request #2869 from BrzVlad/feature-mod-union-opt
X-Git-Url: http://wien.tomnetworks.com/gitweb/?p=mono.git;a=commitdiff_plain;h=a4a3aea41e3dcf845181c2a86f468fca22d18e4f;hp=ed9211bae9cb010426d9a3796722ac5dfd9772cd

Merge pull request #2869 from BrzVlad/feature-mod-union-opt

[sgen] Optimize mod union usage
---

diff --git a/mono/sgen/sgen-los.c b/mono/sgen/sgen-los.c
index 5cb3c71253d..c22afd22f21 100644
--- a/mono/sgen/sgen-los.c
+++ b/mono/sgen/sgen-los.c
@@ -307,7 +307,8 @@ free_los_section_memory (LOSObject *obj, size_t size)
 void
 sgen_los_free_object (LOSObject *obj)
 {
-	SGEN_ASSERT (0, !obj->cardtable_mod_union, "We should never free a LOS object with a mod-union table.");
+	if (obj->cardtable_mod_union)
+		sgen_card_table_free_mod_union (obj->cardtable_mod_union, (char*)obj->data, sgen_los_object_size (obj));
 
 #ifndef LOS_DUMMY
 	mword size = sgen_los_object_size (obj);
@@ -433,12 +434,13 @@ sgen_los_sweep (void)
 	for (bigobj = los_object_list; bigobj;) {
 		SGEN_ASSERT (0, !SGEN_OBJECT_IS_PINNED (bigobj->data), "Who pinned a LOS object?");
 
-		if (bigobj->cardtable_mod_union) {
-			sgen_card_table_free_mod_union (bigobj->cardtable_mod_union, (char*)bigobj->data, sgen_los_object_size (bigobj));
-			bigobj->cardtable_mod_union = NULL;
-		}
-
 		if (sgen_los_object_is_pinned (bigobj->data)) {
+			if (bigobj->cardtable_mod_union) {
+				mword obj_size = sgen_los_object_size (bigobj);
+				mword num_cards = sgen_card_table_number_of_cards_in_range ((mword) bigobj->data, obj_size);
+				memset (bigobj->cardtable_mod_union, 0, num_cards);
+			}
+
 			sgen_los_unpin_object (bigobj->data);
 			sgen_update_heap_boundaries ((mword)bigobj->data, (mword)bigobj->data + sgen_los_object_size (bigobj));
 		} else {
diff --git a/mono/sgen/sgen-marksweep.c b/mono/sgen/sgen-marksweep.c
index d2e3ccdd009..4c63191ad44 100644
--- a/mono/sgen/sgen-marksweep.c
+++ b/mono/sgen/sgen-marksweep.c
@@ -375,11 +375,14 @@ ms_get_empty_block (void)
  * list, where it will either be freed later on, or reused in nursery collections.
  */
 static void
-ms_free_block (void *block)
+ms_free_block (MSBlockInfo *info)
 {
 	void *empty;
+	char *block = MS_BLOCK_FOR_BLOCK_INFO (info);
 
 	sgen_memgov_release_space (MS_BLOCK_SIZE, SPACE_MAJOR);
+	if (info->cardtable_mod_union)
+		sgen_card_table_free_mod_union (info->cardtable_mod_union, block, MS_BLOCK_SIZE);
 	memset (block, 0, MS_BLOCK_SIZE);
 
 	do {
@@ -1507,10 +1510,8 @@ ensure_block_is_checked_for_sweeping (guint32 block_index, gboolean wait, gboole
 
 	count = MS_BLOCK_FREE / block->obj_size;
 
-	if (block->cardtable_mod_union) {
-		sgen_card_table_free_mod_union (block->cardtable_mod_union, MS_BLOCK_FOR_BLOCK_INFO (block), MS_BLOCK_SIZE);
-		block->cardtable_mod_union = NULL;
-	}
+	if (block->cardtable_mod_union)
+		memset (block->cardtable_mod_union, 0, CARDS_PER_BLOCK);
 
 	/* Count marked objects in the block */
 	for (i = 0; i < MS_NUM_MARK_WORDS; ++i)
@@ -2484,10 +2485,21 @@ update_cardtable_mod_union (void)
 	MSBlockInfo *block;
 
 	FOREACH_BLOCK_NO_LOCK (block) {
-		size_t num_cards;
-		guint8 *mod_union = get_cardtable_mod_union_for_block (block, TRUE);
-		sgen_card_table_update_mod_union (mod_union, MS_BLOCK_FOR_BLOCK_INFO (block), MS_BLOCK_SIZE, &num_cards);
-		SGEN_ASSERT (6, num_cards == CARDS_PER_BLOCK, "Number of cards calculation is wrong");
+		gpointer *card_start = (gpointer*) sgen_card_table_get_card_address ((mword)MS_BLOCK_FOR_BLOCK_INFO (block));
+		gboolean has_dirty_cards = FALSE;
+		int i;
+		for (i = 0; i < CARDS_PER_BLOCK / sizeof(gpointer); i++) {
+			if (card_start [i]) {
+				has_dirty_cards = TRUE;
+				break;
+			}
+		}
+		if (has_dirty_cards) {
+			size_t num_cards;
+			guint8 *mod_union = get_cardtable_mod_union_for_block (block, TRUE);
+			sgen_card_table_update_mod_union (mod_union, MS_BLOCK_FOR_BLOCK_INFO (block), MS_BLOCK_SIZE, &num_cards);
+			SGEN_ASSERT (6, num_cards == CARDS_PER_BLOCK, "Number of cards calculation is wrong");
+		}
 	} END_FOREACH_BLOCK_NO_LOCK;
 }