[sgen] Preclean mod union entries before the finishing pause

[mono.git] / mono / sgen / sgen-cardtable.c

diff --git a/mono/sgen/sgen-cardtable.c b/mono/sgen/sgen-cardtable.c
index f88b933a68e49f9d3e9fc3f81cda93d1f9e2d51a..16f4ea6a7d9ae8c7066d33d793305b6e334d32af 100644 (file)
--- a/mono/sgen/sgen-cardtable.c
+++ b/mono/sgen/sgen-cardtable.c
@@ -342,6 +342,29 @@ sgen_card_table_update_mod_union (guint8 *dest, char *obj, mword obj_size, size_
                *out_num_cards = num_cards;
 }
 
+/* Preclean cards and saves the cards that need to be scanned afterwards in cards_preclean */
+void
+sgen_card_table_preclean_mod_union (guint8 *cards, guint8 *cards_preclean, size_t num_cards)
+{
+       size_t i;
+
+       memcpy (cards_preclean, cards, num_cards);
+       for (i = 0; i < num_cards; i++) {
+               if (cards_preclean [i]) {
+                       cards [i] = 0;
+               }
+       }
+       /*
+        * When precleaning we need to make sure the card cleaning
+        * takes place before the object is scanned. If we don't
+        * do this we could finish scanning the object and, before
+        * the cleaning of the card takes place, another thread
+        * could dirty the object, mark the mod_union card only for
+        * us to clean it back, without scanning the object again.
+        */
+       mono_memory_barrier ();
+}
+
 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
 
 static void
@@ -426,11 +449,11 @@ sgen_card_table_scan_remsets (ScanCopyContext ctx)
        sgen_card_table_clear_cards ();
 #endif
        SGEN_TV_GETTIME (atv);
-       sgen_get_major_collector ()->scan_card_table (FALSE, ctx);
+       sgen_get_major_collector ()->scan_card_table (CARDTABLE_SCAN_GLOBAL, ctx);
        SGEN_TV_GETTIME (btv);
        last_major_scan_time = SGEN_TV_ELAPSED (atv, btv); 
        major_card_scan_time += last_major_scan_time;
-       sgen_los_scan_card_table (FALSE, ctx);
+       sgen_los_scan_card_table (CARDTABLE_SCAN_GLOBAL, ctx);
        SGEN_TV_GETTIME (atv);
        last_los_scan_time = SGEN_TV_ELAPSED (btv, atv);
        los_card_scan_time += last_los_scan_time;
@@ -477,11 +500,11 @@ sgen_card_table_dump_obj_card (GCObject *object, size_t size, void *dummy)
 #endif
 
 void
-sgen_cardtable_scan_object (GCObject *obj, mword block_obj_size, guint8 *cards, gboolean mod_union, ScanCopyContext ctx)
+sgen_cardtable_scan_object (GCObject *obj, mword block_obj_size, guint8 *cards, ScanCopyContext ctx)
 {
        HEAVY_STAT (++large_objects);
 
-       if (sgen_client_cardtable_scan_object (obj, block_obj_size, cards, mod_union, ctx))
+       if (sgen_client_cardtable_scan_object (obj, block_obj_size, cards, ctx))
                return;
 
        HEAVY_STAT (++bloby_objects);