2 * sgen-cardtable.c: Card table implementation for sgen
5 * Rodrigo Kumpera (rkumpera@novell.com)
7 * Copyright 2001-2003 Ximian, Inc
8 * Copyright 2003-2010 Novell, Inc.
9 * Copyright 2011 Xamarin Inc (http://www.xamarin.com)
10 * Copyright (C) 2012 Xamarin Inc
12 * This library is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU Library General Public
14 * License 2.0 as published by the Free Software Foundation;
16 * This library is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Library General Public License for more details.
21 * You should have received a copy of the GNU Library General Public
22 * License 2.0 along with this library; if not, write to the Free
23 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
29 #include "metadata/sgen-gc.h"
30 #include "metadata/sgen-cardtable.h"
31 #include "metadata/sgen-memory-governor.h"
32 #include "metadata/sgen-protocol.h"
33 #include "metadata/sgen-layout-stats.h"
34 #include "utils/mono-counters.h"
35 #include "utils/mono-time.h"
36 #include "utils/mono-memory-model.h"
38 //#define CARDTABLE_STATS
43 #ifdef HAVE_SYS_MMAN_H
46 #include <sys/types.h>
48 #define ARRAY_OBJ_INDEX(ptr,array,elem_size) (((char*)(ptr) - ((char*)(array) + G_STRUCT_OFFSET (MonoArray, vector))) / (elem_size))
50 guint8 *sgen_cardtable;
52 static gboolean need_mod_union;
54 #ifdef HEAVY_STATISTICS
56 guint64 scanned_cards;
57 guint64 scanned_objects;
58 guint64 remarked_cards;
60 static guint64 los_marked_cards;
61 static guint64 large_objects;
62 static guint64 bloby_objects;
63 static guint64 los_array_cards;
64 static guint64 los_array_remsets;
67 static guint64 major_card_scan_time;
68 static guint64 los_card_scan_time;
70 static guint64 last_major_scan_time;
71 static guint64 last_los_scan_time;
73 static void sgen_card_tables_collect_stats (gboolean begin);
76 /*WARNING: This function returns the number of cards regardless of overflow in case of overlapping cards.*/
78 cards_in_range (mword address, mword size)
80 mword end = address + MAX (1, size) - 1;
81 return (end >> CARD_BITS) - (address >> CARD_BITS) + 1;
85 sgen_card_table_wbarrier_set_field (MonoObject *obj, gpointer field_ptr, MonoObject* value)
87 *(void**)field_ptr = value;
88 if (need_mod_union || sgen_ptr_in_nursery (value))
89 sgen_card_table_mark_address ((mword)field_ptr);
90 sgen_dummy_use (value);
94 sgen_card_table_wbarrier_set_arrayref (MonoArray *arr, gpointer slot_ptr, MonoObject* value)
96 *(void**)slot_ptr = value;
97 if (need_mod_union || sgen_ptr_in_nursery (value))
98 sgen_card_table_mark_address ((mword)slot_ptr);
99 sgen_dummy_use (value);
103 sgen_card_table_wbarrier_arrayref_copy (gpointer dest_ptr, gpointer src_ptr, int count)
105 gpointer *dest = dest_ptr;
106 gpointer *src = src_ptr;
108 /*overlapping that required backward copying*/
109 if (src < dest && (src + count) > dest) {
110 gpointer *start = dest;
114 for (; dest >= start; --src, --dest) {
115 gpointer value = *src;
116 SGEN_UPDATE_REFERENCE_ALLOW_NULL (dest, value);
117 if (need_mod_union || sgen_ptr_in_nursery (value))
118 sgen_card_table_mark_address ((mword)dest);
119 sgen_dummy_use (value);
122 gpointer *end = dest + count;
123 for (; dest < end; ++src, ++dest) {
124 gpointer value = *src;
125 SGEN_UPDATE_REFERENCE_ALLOW_NULL (dest, value);
126 if (need_mod_union || sgen_ptr_in_nursery (value))
127 sgen_card_table_mark_address ((mword)dest);
128 sgen_dummy_use (value);
134 sgen_card_table_wbarrier_value_copy (gpointer dest, gpointer src, int count, MonoClass *klass)
136 size_t element_size = mono_class_value_size (klass, NULL);
137 size_t size = count * element_size;
139 #ifdef DISABLE_CRITICAL_REGION
143 ENTER_CRITICAL_REGION;
145 mono_gc_memmove_atomic (dest, src, size);
146 sgen_card_table_mark_range ((mword)dest, size);
147 #ifdef DISABLE_CRITICAL_REGION
150 EXIT_CRITICAL_REGION;
155 sgen_card_table_wbarrier_object_copy (MonoObject* obj, MonoObject *src)
157 int size = mono_object_class (obj)->instance_size;
159 #ifdef DISABLE_CRITICAL_REGION
163 ENTER_CRITICAL_REGION;
165 mono_gc_memmove_aligned ((char*)obj + sizeof (MonoObject), (char*)src + sizeof (MonoObject),
166 size - sizeof (MonoObject));
167 sgen_card_table_mark_range ((mword)obj, size);
168 #ifdef DISABLE_CRITICAL_REGION
171 EXIT_CRITICAL_REGION;
176 sgen_card_table_wbarrier_generic_nostore (gpointer ptr)
178 sgen_card_table_mark_address ((mword)ptr);
181 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
183 guint8 *sgen_shadow_cardtable;
185 #define SGEN_SHADOW_CARDTABLE_END (sgen_shadow_cardtable + CARD_COUNT_IN_BYTES)
186 #define SGEN_CARDTABLE_END (sgen_cardtable + CARD_COUNT_IN_BYTES)
189 sgen_card_table_region_begin_scanning (mword start, mword size)
191 mword end = start + size;
192 /*XXX this can be improved to work on words and have a single loop induction var */
193 while (start < end) {
194 if (sgen_card_table_card_begin_scanning (start))
196 start += CARD_SIZE_IN_BYTES;
204 sgen_card_table_region_begin_scanning (mword start, mword size)
206 gboolean res = FALSE;
207 guint8 *card = sgen_card_table_get_card_address (start);
208 guint8 *end = card + cards_in_range (start, size);
210 /*XXX this can be improved to work on words and have a branchless body */
211 while (card != end) {
218 memset (sgen_card_table_get_card_address (start), 0, size >> CARD_BITS);
225 /*FIXME this assumes that major blocks are multiple of 4K which is pretty reasonable */
227 sgen_card_table_get_card_data (guint8 *data_dest, mword address, mword cards)
229 mword *start = (mword*)sgen_card_table_get_card_scan_address (address);
230 mword *dest = (mword*)data_dest;
231 mword *end = (mword*)(data_dest + cards);
234 for (; dest < end; ++dest, ++start) {
239 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
248 sgen_card_table_align_pointer (void *ptr)
250 return (void*)((mword)ptr & ~(CARD_SIZE_IN_BYTES - 1));
254 sgen_card_table_mark_range (mword address, mword size)
256 memset (sgen_card_table_get_card_address (address), 1, cards_in_range (address, size));
260 sgen_card_table_is_range_marked (guint8 *cards, mword address, mword size)
262 guint8 *end = cards + cards_in_range (address, size);
264 /*This is safe since this function is only called by code that only passes continuous card blocks*/
265 while (cards != end) {
274 sgen_card_table_record_pointer (gpointer address)
276 *sgen_card_table_get_card_address ((mword)address) = 1;
280 sgen_card_table_find_address (char *addr)
282 return sgen_card_table_address_is_marked ((mword)addr);
286 sgen_card_table_find_address_with_cards (char *cards_start, guint8 *cards, char *addr)
288 cards_start = sgen_card_table_align_pointer (cards_start);
289 return cards [(addr - cards_start) >> CARD_BITS];
293 update_mod_union (guint8 *dest, gboolean init, guint8 *start_card, size_t num_cards)
296 memcpy (dest, start_card, num_cards);
299 for (i = 0; i < num_cards; ++i)
300 dest [i] |= start_card [i];
305 alloc_mod_union (size_t num_cards)
307 return sgen_alloc_internal_dynamic (num_cards, INTERNAL_MEM_CARDTABLE_MOD_UNION, TRUE);
311 sgen_card_table_update_mod_union_from_cards (guint8 *dest, guint8 *start_card, size_t num_cards)
313 gboolean init = dest == NULL;
316 dest = alloc_mod_union (num_cards);
318 update_mod_union (dest, init, start_card, num_cards);
324 sgen_card_table_update_mod_union (guint8 *dest, char *obj, mword obj_size, size_t *out_num_cards)
326 guint8 *start_card = sgen_card_table_get_card_address ((mword)obj);
327 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
328 guint8 *end_card = sgen_card_table_get_card_address ((mword)obj + obj_size - 1) + 1;
331 guint8 *result = NULL;
333 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
336 rest = num_cards = cards_in_range ((mword) obj, obj_size);
338 while (start_card + rest > SGEN_CARDTABLE_END) {
339 size_t count = SGEN_CARDTABLE_END - start_card;
340 dest = sgen_card_table_update_mod_union_from_cards (dest, start_card, count);
345 start_card = sgen_cardtable;
349 num_cards = end_card - start_card;
352 dest = sgen_card_table_update_mod_union_from_cards (dest, start_card, num_cards);
357 *out_num_cards = num_cards;
362 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
365 move_cards_to_shadow_table (mword start, mword size)
367 guint8 *from = sgen_card_table_get_card_address (start);
368 guint8 *to = sgen_card_table_get_shadow_card_address (start);
369 size_t bytes = cards_in_range (start, size);
371 if (bytes >= CARD_COUNT_IN_BYTES) {
372 memcpy (sgen_shadow_cardtable, sgen_cardtable, CARD_COUNT_IN_BYTES);
373 } else if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
374 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
375 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
377 memcpy (to, from, first_chunk);
378 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
380 memcpy (to, from, bytes);
385 clear_cards (mword start, mword size)
387 guint8 *addr = sgen_card_table_get_card_address (start);
388 size_t bytes = cards_in_range (start, size);
390 if (bytes >= CARD_COUNT_IN_BYTES) {
391 memset (sgen_cardtable, 0, CARD_COUNT_IN_BYTES);
392 } else if (addr + bytes > SGEN_CARDTABLE_END) {
393 size_t first_chunk = SGEN_CARDTABLE_END - addr;
395 memset (addr, 0, first_chunk);
396 memset (sgen_cardtable, 0, bytes - first_chunk);
398 memset (addr, 0, bytes);
406 clear_cards (mword start, mword size)
408 memset (sgen_card_table_get_card_address (start), 0, cards_in_range (start, size));
415 sgen_card_table_clear_cards (void)
417 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
418 sgen_major_collector_iterate_live_block_ranges (clear_cards);
419 sgen_los_iterate_live_block_ranges (clear_cards);
423 sgen_card_table_finish_minor_collection (void)
425 sgen_card_tables_collect_stats (FALSE);
429 sgen_card_table_scan_remsets (SgenGrayQueue *queue)
431 SGEN_TV_DECLARE (atv);
432 SGEN_TV_DECLARE (btv);
434 sgen_card_tables_collect_stats (TRUE);
436 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
437 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
439 sgen_major_collector_iterate_live_block_ranges (move_cards_to_shadow_table);
440 sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
443 sgen_card_table_clear_cards ();
445 SGEN_TV_GETTIME (atv);
446 sgen_major_collector_scan_card_table (queue);
447 SGEN_TV_GETTIME (btv);
448 last_major_scan_time = SGEN_TV_ELAPSED (atv, btv);
449 major_card_scan_time += last_major_scan_time;
450 sgen_los_scan_card_table (FALSE, queue);
451 SGEN_TV_GETTIME (atv);
452 last_los_scan_time = SGEN_TV_ELAPSED (btv, atv);
453 los_card_scan_time += last_los_scan_time;
457 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
459 #ifndef MANAGED_WBARRIER
465 *shift_bits = CARD_BITS;
466 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
467 *mask = (gpointer)CARD_MASK;
472 return sgen_cardtable;
477 mono_gc_card_table_nursery_check (void)
479 return !major_collector.is_concurrent;
484 sgen_card_table_dump_obj_card (char *object, size_t size, void *dummy)
486 guint8 *start = sgen_card_table_get_card_scan_address (object);
487 guint8 *end = start + cards_in_range (object, size);
489 printf ("--obj %p %d cards [%p %p]--", object, size, start, end);
490 for (; start < end; ++start) {
492 printf ("\n\t[%p] ", start);
493 printf ("%x ", *start);
502 #define MWORD_MASK (sizeof (mword) - 1)
505 find_card_offset (mword card)
507 /*XXX Use assembly as this generates some pretty bad code */
508 #if defined(__i386__) && defined(__GNUC__)
509 return (__builtin_ffs (card) - 1) / 8;
510 #elif defined(__x86_64__) && defined(__GNUC__)
511 return (__builtin_ffsll (card) - 1) / 8;
512 #elif defined(__s390x__)
513 return (__builtin_ffsll (GUINT64_TO_LE(card)) - 1) / 8;
516 guint8 *ptr = (guint8 *) &card;
517 for (i = 0; i < sizeof (mword); ++i) {
526 find_next_card (guint8 *card_data, guint8 *end)
528 mword *cards, *cards_end;
531 while ((((mword)card_data) & MWORD_MASK) && card_data < end) {
537 if (card_data == end)
540 cards = (mword*)card_data;
541 cards_end = (mword*)((mword)end & ~MWORD_MASK);
542 while (cards < cards_end) {
545 return (guint8*)cards + find_card_offset (card);
549 card_data = (guint8*)cards_end;
550 while (card_data < end) {
560 sgen_cardtable_scan_object (char *obj, mword block_obj_size, guint8 *cards, gboolean mod_union, SgenGrayQueue *queue)
562 MonoVTable *vt = (MonoVTable*)SGEN_LOAD_VTABLE (obj);
563 MonoClass *klass = vt->klass;
565 HEAVY_STAT (++large_objects);
567 if (!SGEN_VTABLE_HAS_REFERENCES (vt)) {
568 sgen_object_layout_scanned_bitmap (0);
573 guint8 *card_data, *card_base;
574 guint8 *card_data_end;
575 char *obj_start = sgen_card_table_align_pointer (obj);
576 mword obj_size = sgen_par_object_get_size (vt, (MonoObject*)obj);
577 char *obj_end = obj + obj_size;
579 size_t extra_idx = 0;
581 MonoArray *arr = (MonoArray*)obj;
582 mword desc = (mword)klass->element_class->gc_descr;
583 int elem_size = mono_array_element_size (klass);
585 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
586 guint8 *overflow_scan_end = NULL;
589 #ifdef SGEN_OBJECT_LAYOUT_STATISTICS
590 if (klass->element_class->valuetype)
591 sgen_object_layout_scanned_vtype_array ();
593 sgen_object_layout_scanned_ref_array ();
599 card_data = sgen_card_table_get_card_scan_address ((mword)obj);
601 card_base = card_data;
602 card_count = cards_in_range ((mword)obj, obj_size);
603 card_data_end = card_data + card_count;
606 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
607 /*Check for overflow and if so, setup to scan in two steps*/
608 if (!cards && card_data_end >= SGEN_SHADOW_CARDTABLE_END) {
609 overflow_scan_end = sgen_shadow_cardtable + (card_data_end - SGEN_SHADOW_CARDTABLE_END);
610 card_data_end = SGEN_SHADOW_CARDTABLE_END;
616 card_data = find_next_card (card_data, card_data_end);
617 for (; card_data < card_data_end; card_data = find_next_card (card_data + 1, card_data_end)) {
619 size_t idx = (card_data - card_base) + extra_idx;
620 char *start = (char*)(obj_start + idx * CARD_SIZE_IN_BYTES);
621 char *card_end = start + CARD_SIZE_IN_BYTES;
622 char *first_elem, *elem;
624 HEAVY_STAT (++los_marked_cards);
627 sgen_card_table_prepare_card_for_scanning (card_data);
629 card_end = MIN (card_end, obj_end);
631 if (start <= (char*)arr->vector)
634 index = ARRAY_OBJ_INDEX (start, obj, elem_size);
636 elem = first_elem = (char*)mono_array_addr_with_size_fast ((MonoArray*)obj, elem_size, index);
637 if (klass->element_class->valuetype) {
638 ScanVTypeFunc scan_vtype_func = sgen_get_current_object_ops ()->scan_vtype;
640 for (; elem < card_end; elem += elem_size)
641 scan_vtype_func (elem, desc, queue BINARY_PROTOCOL_ARG (elem_size));
643 CopyOrMarkObjectFunc copy_func = sgen_get_current_object_ops ()->copy_or_mark_object;
645 HEAVY_STAT (++los_array_cards);
646 for (; elem < card_end; elem += SIZEOF_VOID_P) {
647 gpointer new, old = *(gpointer*)elem;
648 if ((mod_union && old) || G_UNLIKELY (sgen_ptr_in_nursery (old))) {
649 HEAVY_STAT (++los_array_remsets);
650 copy_func ((void**)elem, queue);
651 new = *(gpointer*)elem;
652 if (G_UNLIKELY (sgen_ptr_in_nursery (new)))
653 sgen_add_to_global_remset (elem, new);
658 binary_protocol_card_scan (first_elem, elem - first_elem);
661 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
662 if (overflow_scan_end) {
663 extra_idx = card_data - card_base;
664 card_base = card_data = sgen_shadow_cardtable;
665 card_data_end = overflow_scan_end;
666 overflow_scan_end = NULL;
672 HEAVY_STAT (++bloby_objects);
674 if (sgen_card_table_is_range_marked (cards, (mword)obj, block_obj_size))
675 sgen_get_current_object_ops ()->scan_object (obj, sgen_obj_get_descriptor (obj), queue);
676 } else if (sgen_card_table_region_begin_scanning ((mword)obj, block_obj_size)) {
677 sgen_get_current_object_ops ()->scan_object (obj, sgen_obj_get_descriptor (obj), queue);
680 binary_protocol_card_scan (obj, sgen_safe_object_get_size ((MonoObject*)obj));
684 #ifdef CARDTABLE_STATS
687 int total, marked, remarked, gc_marked;
690 static card_stats major_stats, los_stats;
691 static card_stats *cur_stats;
694 count_marked_cards (mword start, mword size)
696 mword end = start + size;
697 while (start <= end) {
698 guint8 card = *sgen_card_table_get_card_address (start);
703 ++cur_stats->gc_marked;
704 start += CARD_SIZE_IN_BYTES;
709 count_remarked_cards (mword start, mword size)
711 mword end = start + size;
712 while (start <= end) {
713 if (sgen_card_table_address_is_marked (start)) {
714 ++cur_stats->remarked;
715 *sgen_card_table_get_card_address (start) = 2;
717 start += CARD_SIZE_IN_BYTES;
724 sgen_card_tables_collect_stats (gboolean begin)
726 #ifdef CARDTABLE_STATS
728 memset (&major_stats, 0, sizeof (card_stats));
729 memset (&los_stats, 0, sizeof (card_stats));
730 cur_stats = &major_stats;
731 sgen_major_collector_iterate_live_block_ranges (count_marked_cards);
732 cur_stats = &los_stats;
733 sgen_los_iterate_live_block_ranges (count_marked_cards);
735 cur_stats = &major_stats;
736 sgen_major_collector_iterate_live_block_ranges (count_remarked_cards);
737 cur_stats = &los_stats;
738 sgen_los_iterate_live_block_ranges (count_remarked_cards);
739 printf ("cards major (t %d m %d g %d r %d) los (t %d m %d g %d r %d) major_scan %.2fms los_scan %.2fms\n",
740 major_stats.total, major_stats.marked, major_stats.gc_marked, major_stats.remarked,
741 los_stats.total, los_stats.marked, los_stats.gc_marked, los_stats.remarked,
742 last_major_scan_time / 10000.0f, last_los_scan_time / 10000.0f);
748 sgen_card_table_init (SgenRememberedSet *remset)
750 sgen_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "card table");
752 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
753 sgen_shadow_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "shadow card table");
756 #ifdef HEAVY_STATISTICS
757 mono_counters_register ("marked cards", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &marked_cards);
758 mono_counters_register ("scanned cards", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &scanned_cards);
759 mono_counters_register ("remarked cards", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &remarked_cards);
761 mono_counters_register ("los marked cards", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &los_marked_cards);
762 mono_counters_register ("los array cards scanned ", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &los_array_cards);
763 mono_counters_register ("los array remsets", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &los_array_remsets);
764 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &scanned_objects);
765 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &large_objects);
766 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &bloby_objects);
768 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &major_card_scan_time);
769 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &los_card_scan_time);
772 remset->wbarrier_set_field = sgen_card_table_wbarrier_set_field;
773 remset->wbarrier_set_arrayref = sgen_card_table_wbarrier_set_arrayref;
774 remset->wbarrier_arrayref_copy = sgen_card_table_wbarrier_arrayref_copy;
775 remset->wbarrier_value_copy = sgen_card_table_wbarrier_value_copy;
776 remset->wbarrier_object_copy = sgen_card_table_wbarrier_object_copy;
777 remset->wbarrier_generic_nostore = sgen_card_table_wbarrier_generic_nostore;
778 remset->record_pointer = sgen_card_table_record_pointer;
780 remset->scan_remsets = sgen_card_table_scan_remsets;
782 remset->finish_minor_collection = sgen_card_table_finish_minor_collection;
783 remset->clear_cards = sgen_card_table_clear_cards;
785 remset->find_address = sgen_card_table_find_address;
786 remset->find_address_with_cards = sgen_card_table_find_address_with_cards;
788 need_mod_union = sgen_get_major_collector ()->is_concurrent;
791 #endif /*HAVE_SGEN_GC*/