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 guint8 *sgen_cardtable;
50 static gboolean need_mod_union;
52 #ifdef HEAVY_STATISTICS
53 long long marked_cards;
54 long long scanned_cards;
55 long long scanned_objects;
56 long long remarked_cards;
58 static long long los_marked_cards;
59 static long long large_objects;
60 static long long bloby_objects;
61 static long long los_array_cards;
62 static long long los_array_remsets;
65 static long long major_card_scan_time;
66 static long long los_card_scan_time;
68 static long long last_major_scan_time;
69 static long long last_los_scan_time;
71 static void sgen_card_tables_collect_stats (gboolean begin);
74 /*WARNING: This function returns the number of cards regardless of overflow in case of overlapping cards.*/
76 cards_in_range (mword address, mword size)
78 mword end = address + MAX (1, size) - 1;
79 return (end >> CARD_BITS) - (address >> CARD_BITS) + 1;
83 sgen_card_table_wbarrier_set_field (MonoObject *obj, gpointer field_ptr, MonoObject* value)
85 *(void**)field_ptr = value;
86 if (need_mod_union || sgen_ptr_in_nursery (value))
87 sgen_card_table_mark_address ((mword)field_ptr);
88 sgen_dummy_use (value);
92 sgen_card_table_wbarrier_set_arrayref (MonoArray *arr, gpointer slot_ptr, MonoObject* value)
94 *(void**)slot_ptr = value;
95 if (need_mod_union || sgen_ptr_in_nursery (value))
96 sgen_card_table_mark_address ((mword)slot_ptr);
97 sgen_dummy_use (value);
101 sgen_card_table_wbarrier_arrayref_copy (gpointer dest_ptr, gpointer src_ptr, int count)
103 gpointer *dest = dest_ptr;
104 gpointer *src = src_ptr;
106 /*overlapping that required backward copying*/
107 if (src < dest && (src + count) > dest) {
108 gpointer *start = dest;
112 for (; dest >= start; --src, --dest) {
113 gpointer value = *src;
115 if (need_mod_union || sgen_ptr_in_nursery (value))
116 sgen_card_table_mark_address ((mword)dest);
117 sgen_dummy_use (value);
120 gpointer *end = dest + count;
121 for (; dest < end; ++src, ++dest) {
122 gpointer value = *src;
124 if (need_mod_union || sgen_ptr_in_nursery (value))
125 sgen_card_table_mark_address ((mword)dest);
126 sgen_dummy_use (value);
132 sgen_card_table_wbarrier_value_copy (gpointer dest, gpointer src, int count, MonoClass *klass)
134 size_t element_size = mono_class_value_size (klass, NULL);
135 size_t size = count * element_size;
137 #ifdef DISABLE_CRITICAL_REGION
141 ENTER_CRITICAL_REGION;
143 mono_gc_memmove_atomic (dest, src, size);
144 sgen_card_table_mark_range ((mword)dest, size);
145 #ifdef DISABLE_CRITICAL_REGION
148 EXIT_CRITICAL_REGION;
153 sgen_card_table_wbarrier_object_copy (MonoObject* obj, MonoObject *src)
155 int size = mono_object_class (obj)->instance_size;
157 #ifdef DISABLE_CRITICAL_REGION
161 ENTER_CRITICAL_REGION;
163 mono_gc_memmove_aligned ((char*)obj + sizeof (MonoObject), (char*)src + sizeof (MonoObject),
164 size - sizeof (MonoObject));
165 sgen_card_table_mark_range ((mword)obj, size);
166 #ifdef DISABLE_CRITICAL_REGION
169 EXIT_CRITICAL_REGION;
174 sgen_card_table_wbarrier_generic_nostore (gpointer ptr)
176 sgen_card_table_mark_address ((mword)ptr);
179 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
181 guint8 *sgen_shadow_cardtable;
183 #define SGEN_SHADOW_CARDTABLE_END (sgen_shadow_cardtable + CARD_COUNT_IN_BYTES)
184 #define SGEN_CARDTABLE_END (sgen_cardtable + CARD_COUNT_IN_BYTES)
187 sgen_card_table_region_begin_scanning (mword start, mword end)
189 /*XXX this can be improved to work on words and have a single loop induction var */
190 while (start <= end) {
191 if (sgen_card_table_card_begin_scanning (start))
193 start += CARD_SIZE_IN_BYTES;
201 sgen_card_table_region_begin_scanning (mword start, mword size)
203 gboolean res = FALSE;
204 guint8 *card = sgen_card_table_get_card_address (start);
205 guint8 *end = card + cards_in_range (start, size);
207 /*XXX this can be improved to work on words and have a branchless body */
208 while (card != end) {
215 memset (sgen_card_table_get_card_address (start), 0, size >> CARD_BITS);
222 /*FIXME this assumes that major blocks are multiple of 4K which is pretty reasonable */
224 sgen_card_table_get_card_data (guint8 *data_dest, mword address, mword cards)
226 mword *start = (mword*)sgen_card_table_get_card_scan_address (address);
227 mword *dest = (mword*)data_dest;
228 mword *end = (mword*)(data_dest + cards);
231 for (; dest < end; ++dest, ++start) {
236 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
245 sgen_card_table_align_pointer (void *ptr)
247 return (void*)((mword)ptr & ~(CARD_SIZE_IN_BYTES - 1));
251 sgen_card_table_mark_range (mword address, mword size)
253 memset (sgen_card_table_get_card_address (address), 1, cards_in_range (address, size));
257 sgen_card_table_is_range_marked (guint8 *cards, mword address, mword size)
259 guint8 *end = cards + cards_in_range (address, size);
261 /*This is safe since this function is only called by code that only passes continuous card blocks*/
262 while (cards != end) {
271 sgen_card_table_record_pointer (gpointer address)
273 *sgen_card_table_get_card_address ((mword)address) = 1;
277 sgen_card_table_find_address (char *addr)
279 return sgen_card_table_address_is_marked ((mword)addr);
283 sgen_card_table_find_address_with_cards (char *cards_start, guint8 *cards, char *addr)
285 cards_start = sgen_card_table_align_pointer (cards_start);
286 return cards [(addr - cards_start) >> CARD_BITS];
290 update_mod_union (guint8 *dest, gboolean init, guint8 *start_card, size_t num_cards)
293 memcpy (dest, start_card, num_cards);
296 for (i = 0; i < num_cards; ++i)
297 dest [i] |= start_card [i];
302 alloc_mod_union (size_t num_cards)
304 return sgen_alloc_internal_dynamic (num_cards, INTERNAL_MEM_CARDTABLE_MOD_UNION, TRUE);
308 sgen_card_table_update_mod_union_from_cards (guint8 *dest, guint8 *start_card, size_t num_cards)
310 gboolean init = dest == NULL;
313 dest = alloc_mod_union (num_cards);
315 update_mod_union (dest, init, start_card, num_cards);
321 sgen_card_table_update_mod_union (guint8 *dest, char *obj, mword obj_size, size_t *out_num_cards)
323 guint8 *start_card = sgen_card_table_get_card_address ((mword)obj);
324 guint8 *end_card = sgen_card_table_get_card_address ((mword)obj + obj_size - 1) + 1;
325 size_t num_cards, rest_num_cards;
326 guint8 *result = NULL;
328 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
331 rest = num_cards = cards_in_range ((mword) obj, obj_size);
333 while (start_card + rest > SGEN_CARDTABLE_END) {
334 size_t count = SGEN_CARDTABLE_END - start_card;
335 dest = sgen_card_table_update_mod_union_from_cards (dest, start_card, count);
340 start_card = sgen_cardtable;
344 num_cards = end_card - start_card;
347 dest = sgen_card_table_update_mod_union_from_cards (dest, start_card, num_cards);
352 *out_num_cards = num_cards;
357 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
360 move_cards_to_shadow_table (mword start, mword size)
362 guint8 *from = sgen_card_table_get_card_address (start);
363 guint8 *to = sgen_card_table_get_shadow_card_address (start);
364 size_t bytes = cards_in_range (start, size);
366 if (bytes >= CARD_COUNT_IN_BYTES) {
367 memcpy (sgen_shadow_cardtable, sgen_cardtable, CARD_COUNT_IN_BYTES);
368 } else if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
369 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
370 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
372 memcpy (to, from, first_chunk);
373 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
375 memcpy (to, from, bytes);
380 clear_cards (mword start, mword size)
382 guint8 *addr = sgen_card_table_get_card_address (start);
383 size_t bytes = cards_in_range (start, size);
385 if (bytes >= CARD_COUNT_IN_BYTES) {
386 memset (sgen_cardtable, 0, CARD_COUNT_IN_BYTES);
387 } else if (addr + bytes > SGEN_CARDTABLE_END) {
388 size_t first_chunk = SGEN_CARDTABLE_END - addr;
390 memset (addr, 0, first_chunk);
391 memset (sgen_cardtable, 0, bytes - first_chunk);
393 memset (addr, 0, bytes);
401 clear_cards (mword start, mword size)
403 memset (sgen_card_table_get_card_address (start), 0, cards_in_range (start, size));
410 sgen_card_table_prepare_for_major_collection (void)
412 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
413 sgen_major_collector_iterate_live_block_ranges (clear_cards);
414 sgen_los_iterate_live_block_ranges (clear_cards);
418 sgen_card_table_finish_minor_collection (void)
420 sgen_card_tables_collect_stats (FALSE);
424 sgen_card_table_finish_scan_remsets (void *start_nursery, void *end_nursery, SgenGrayQueue *queue)
426 SGEN_TV_DECLARE (atv);
427 SGEN_TV_DECLARE (btv);
429 sgen_card_tables_collect_stats (TRUE);
431 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
432 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
434 sgen_major_collector_iterate_live_block_ranges (move_cards_to_shadow_table);
435 sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
438 sgen_card_table_prepare_for_major_collection ();
440 SGEN_TV_GETTIME (atv);
441 sgen_major_collector_scan_card_table (queue);
442 SGEN_TV_GETTIME (btv);
443 last_major_scan_time = SGEN_TV_ELAPSED (atv, btv);
444 major_card_scan_time += last_major_scan_time;
445 sgen_los_scan_card_table (FALSE, queue);
446 SGEN_TV_GETTIME (atv);
447 last_los_scan_time = SGEN_TV_ELAPSED (btv, atv);
448 los_card_scan_time += last_los_scan_time;
452 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
457 *shift_bits = CARD_BITS;
458 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
459 *mask = (gpointer)CARD_MASK;
464 return sgen_cardtable;
468 mono_gc_card_table_nursery_check (void)
470 return !major_collector.is_concurrent;
475 collect_faulted_cards (void)
477 #define CARD_PAGES (CARD_COUNT_IN_BYTES / 4096)
479 unsigned char faulted [CARD_PAGES] = { 0 };
480 mincore (sgen_cardtable, CARD_COUNT_IN_BYTES, faulted);
482 for (i = 0; i < CARD_PAGES; ++i) {
487 printf ("TOTAL card pages %d faulted %d\n", CARD_PAGES, count);
491 sgen_card_table_dump_obj_card (char *object, size_t size, void *dummy)
493 guint8 *start = sgen_card_table_get_card_scan_address (object);
494 guint8 *end = start + cards_in_range (object, size);
496 printf ("--obj %p %d cards [%p %p]--", object, size, start, end);
497 for (; start < end; ++start) {
499 printf ("\n\t[%p] ", start);
500 printf ("%x ", *start);
509 #define MWORD_MASK (sizeof (mword) - 1)
512 find_card_offset (mword card)
514 /*XXX Use assembly as this generates some pretty bad code */
515 #if defined(__i386__) && defined(__GNUC__)
516 return (__builtin_ffs (card) - 1) / 8;
517 #elif defined(__x86_64__) && defined(__GNUC__)
518 return (__builtin_ffsll (card) - 1) / 8;
519 #elif defined(__s390x__)
520 return (__builtin_ffsll (GUINT64_TO_LE(card)) - 1) / 8;
523 guint8 *ptr = (guint8 *) &card;
524 for (i = 0; i < sizeof (mword); ++i) {
533 find_next_card (guint8 *card_data, guint8 *end)
535 mword *cards, *cards_end;
538 while ((((mword)card_data) & MWORD_MASK) && card_data < end) {
544 if (card_data == end)
547 cards = (mword*)card_data;
548 cards_end = (mword*)((mword)end & ~MWORD_MASK);
549 while (cards < cards_end) {
552 return (guint8*)cards + find_card_offset (card);
556 card_data = (guint8*)cards_end;
557 while (card_data < end) {
567 sgen_cardtable_scan_object (char *obj, mword block_obj_size, guint8 *cards, gboolean mod_union, SgenGrayQueue *queue)
569 MonoVTable *vt = (MonoVTable*)SGEN_LOAD_VTABLE (obj);
570 MonoClass *klass = vt->klass;
572 HEAVY_STAT (++large_objects);
574 if (!SGEN_VTABLE_HAS_REFERENCES (vt)) {
575 sgen_object_layout_scanned_bitmap (0);
580 guint8 *card_data, *card_base;
581 guint8 *card_data_end;
582 char *obj_start = sgen_card_table_align_pointer (obj);
583 mword obj_size = sgen_par_object_get_size (vt, (MonoObject*)obj);
584 char *obj_end = obj + obj_size;
588 MonoArray *arr = (MonoArray*)obj;
589 mword desc = (mword)klass->element_class->gc_descr;
590 int elem_size = mono_array_element_size (klass);
592 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
593 guint8 *overflow_scan_end = NULL;
596 #ifdef SGEN_OBJECT_LAYOUT_STATISTICS
597 if (klass->element_class->valuetype)
598 sgen_object_layout_scanned_vtype_array ();
600 sgen_object_layout_scanned_ref_array ();
606 card_data = sgen_card_table_get_card_scan_address ((mword)obj);
608 card_base = card_data;
609 card_count = cards_in_range ((mword)obj, obj_size);
610 card_data_end = card_data + card_count;
613 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
614 /*Check for overflow and if so, setup to scan in two steps*/
615 if (!cards && card_data_end >= SGEN_SHADOW_CARDTABLE_END) {
616 overflow_scan_end = sgen_shadow_cardtable + (card_data_end - SGEN_SHADOW_CARDTABLE_END);
617 card_data_end = SGEN_SHADOW_CARDTABLE_END;
623 card_data = find_next_card (card_data, card_data_end);
624 for (; card_data < card_data_end; card_data = find_next_card (card_data + 1, card_data_end)) {
626 int idx = (card_data - card_base) + extra_idx;
627 char *start = (char*)(obj_start + idx * CARD_SIZE_IN_BYTES);
628 char *card_end = start + CARD_SIZE_IN_BYTES;
629 char *first_elem, *elem;
631 HEAVY_STAT (++los_marked_cards);
634 sgen_card_table_prepare_card_for_scanning (card_data);
636 card_end = MIN (card_end, obj_end);
638 if (start <= (char*)arr->vector)
641 index = ARRAY_OBJ_INDEX (start, obj, elem_size);
643 elem = first_elem = (char*)mono_array_addr_with_size_fast ((MonoArray*)obj, elem_size, index);
644 if (klass->element_class->valuetype) {
645 ScanVTypeFunc scan_vtype_func = sgen_get_current_object_ops ()->scan_vtype;
647 for (; elem < card_end; elem += elem_size)
648 scan_vtype_func (elem, desc, queue BINARY_PROTOCOL_ARG (elem_size));
650 CopyOrMarkObjectFunc copy_func = sgen_get_current_object_ops ()->copy_or_mark_object;
652 HEAVY_STAT (++los_array_cards);
653 for (; elem < card_end; elem += SIZEOF_VOID_P) {
654 gpointer new, old = *(gpointer*)elem;
655 if ((mod_union && old) || G_UNLIKELY (sgen_ptr_in_nursery (old))) {
656 HEAVY_STAT (++los_array_remsets);
657 copy_func ((void**)elem, queue);
658 new = *(gpointer*)elem;
659 if (G_UNLIKELY (sgen_ptr_in_nursery (new)))
660 sgen_add_to_global_remset (elem, new);
665 binary_protocol_card_scan (first_elem, elem - first_elem);
668 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
669 if (overflow_scan_end) {
670 extra_idx = card_data - card_base;
671 card_base = card_data = sgen_shadow_cardtable;
672 card_data_end = overflow_scan_end;
673 overflow_scan_end = NULL;
679 HEAVY_STAT (++bloby_objects);
681 if (sgen_card_table_is_range_marked (cards, (mword)obj, block_obj_size))
682 sgen_get_current_object_ops ()->scan_object (obj, queue);
683 } else if (sgen_card_table_region_begin_scanning ((mword)obj, block_obj_size)) {
684 sgen_get_current_object_ops ()->scan_object (obj, queue);
687 binary_protocol_card_scan (obj, sgen_safe_object_get_size ((MonoObject*)obj));
691 #ifdef CARDTABLE_STATS
694 int total, marked, remarked, gc_marked;
697 static card_stats major_stats, los_stats;
698 static card_stats *cur_stats;
701 count_marked_cards (mword start, mword size)
703 mword end = start + size;
704 while (start <= end) {
705 guint8 card = *sgen_card_table_get_card_address (start);
710 ++cur_stats->gc_marked;
711 start += CARD_SIZE_IN_BYTES;
716 count_remarked_cards (mword start, mword size)
718 mword end = start + size;
719 while (start <= end) {
720 if (sgen_card_table_address_is_marked (start)) {
721 ++cur_stats->remarked;
722 *sgen_card_table_get_card_address (start) = 2;
724 start += CARD_SIZE_IN_BYTES;
731 sgen_card_tables_collect_stats (gboolean begin)
733 #ifdef CARDTABLE_STATS
735 memset (&major_stats, 0, sizeof (card_stats));
736 memset (&los_stats, 0, sizeof (card_stats));
737 cur_stats = &major_stats;
738 sgen_major_collector_iterate_live_block_ranges (count_marked_cards);
739 cur_stats = &los_stats;
740 sgen_los_iterate_live_block_ranges (count_marked_cards);
742 cur_stats = &major_stats;
743 sgen_major_collector_iterate_live_block_ranges (count_remarked_cards);
744 cur_stats = &los_stats;
745 sgen_los_iterate_live_block_ranges (count_remarked_cards);
746 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",
747 major_stats.total, major_stats.marked, major_stats.gc_marked, major_stats.remarked,
748 los_stats.total, los_stats.marked, los_stats.gc_marked, los_stats.remarked,
749 last_major_scan_time / 1000.0, last_los_scan_time / 1000.0);
755 sgen_card_table_init (SgenRemeberedSet *remset)
757 sgen_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "card table");
759 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
760 sgen_shadow_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "shadow card table");
763 #ifdef HEAVY_STATISTICS
764 mono_counters_register ("marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &marked_cards);
765 mono_counters_register ("scanned cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_cards);
766 mono_counters_register ("remarked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &remarked_cards);
768 mono_counters_register ("los marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_marked_cards);
769 mono_counters_register ("los array cards scanned ", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_cards);
770 mono_counters_register ("los array remsets", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_remsets);
771 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_objects);
772 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &large_objects);
773 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &bloby_objects);
775 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_TIME_INTERVAL, &major_card_scan_time);
776 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_TIME_INTERVAL, &los_card_scan_time);
779 remset->wbarrier_set_field = sgen_card_table_wbarrier_set_field;
780 remset->wbarrier_set_arrayref = sgen_card_table_wbarrier_set_arrayref;
781 remset->wbarrier_arrayref_copy = sgen_card_table_wbarrier_arrayref_copy;
782 remset->wbarrier_value_copy = sgen_card_table_wbarrier_value_copy;
783 remset->wbarrier_object_copy = sgen_card_table_wbarrier_object_copy;
784 remset->wbarrier_generic_nostore = sgen_card_table_wbarrier_generic_nostore;
785 remset->record_pointer = sgen_card_table_record_pointer;
787 remset->finish_scan_remsets = sgen_card_table_finish_scan_remsets;
789 remset->finish_minor_collection = sgen_card_table_finish_minor_collection;
790 remset->prepare_for_major_collection = sgen_card_table_prepare_for_major_collection;
792 remset->find_address = sgen_card_table_find_address;
793 remset->find_address_with_cards = sgen_card_table_find_address_with_cards;
795 need_mod_union = sgen_get_major_collector ()->is_concurrent;
798 #endif /*HAVE_SGEN_GC*/