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 "utils/mono-counters.h"
34 #include "utils/mono-time.h"
35 #include "utils/mono-memory-model.h"
37 #ifdef SGEN_HAVE_CARDTABLE
39 //#define CARDTABLE_STATS
44 #ifdef HAVE_SYS_MMAN_H
47 #include <sys/types.h>
49 guint8 *sgen_cardtable;
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 (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 (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 (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 (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 (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 ((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);
282 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
285 move_cards_to_shadow_table (mword start, mword size)
287 guint8 *from = sgen_card_table_get_card_address (start);
288 guint8 *to = sgen_card_table_get_shadow_card_address (start);
289 size_t bytes = cards_in_range (start, size);
291 if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
292 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
293 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
295 memcpy (to, from, first_chunk);
296 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
298 memcpy (to, from, bytes);
303 clear_cards (mword start, mword size)
305 guint8 *addr = sgen_card_table_get_card_address (start);
306 size_t bytes = cards_in_range (start, size);
308 if (addr + bytes > SGEN_CARDTABLE_END) {
309 size_t first_chunk = SGEN_CARDTABLE_END - addr;
311 memset (addr, 0, first_chunk);
312 memset (sgen_cardtable, 0, bytes - first_chunk);
314 memset (addr, 0, bytes);
322 clear_cards (mword start, mword size)
324 memset (sgen_card_table_get_card_address (start), 0, cards_in_range (start, size));
331 sgen_card_table_prepare_for_major_collection (void)
333 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
334 sgen_major_collector_iterate_live_block_ranges (clear_cards);
335 sgen_los_iterate_live_block_ranges (clear_cards);
339 sgen_card_table_finish_minor_collection (void)
341 sgen_card_tables_collect_stats (FALSE);
345 sgen_card_table_finish_scan_remsets (void *start_nursery, void *end_nursery, SgenGrayQueue *queue)
347 SGEN_TV_DECLARE (atv);
348 SGEN_TV_DECLARE (btv);
350 sgen_card_tables_collect_stats (TRUE);
352 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
353 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
355 sgen_major_collector_iterate_live_block_ranges (move_cards_to_shadow_table);
356 sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
359 sgen_card_table_prepare_for_major_collection ();
361 SGEN_TV_GETTIME (atv);
362 sgen_major_collector_scan_card_table (queue);
363 SGEN_TV_GETTIME (btv);
364 last_major_scan_time = SGEN_TV_ELAPSED (atv, btv);
365 major_card_scan_time += last_major_scan_time;
366 sgen_los_scan_card_table (FALSE, queue);
367 SGEN_TV_GETTIME (atv);
368 last_los_scan_time = SGEN_TV_ELAPSED (btv, atv);
369 los_card_scan_time += last_los_scan_time;
373 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
378 *shift_bits = CARD_BITS;
379 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
380 *mask = (gpointer)CARD_MASK;
385 return sgen_cardtable;
389 mono_gc_card_table_nursery_check (void)
391 return !major_collector.is_concurrent;
396 collect_faulted_cards (void)
398 #define CARD_PAGES (CARD_COUNT_IN_BYTES / 4096)
400 unsigned char faulted [CARD_PAGES] = { 0 };
401 mincore (sgen_cardtable, CARD_COUNT_IN_BYTES, faulted);
403 for (i = 0; i < CARD_PAGES; ++i) {
408 printf ("TOTAL card pages %d faulted %d\n", CARD_PAGES, count);
412 sgen_card_table_dump_obj_card (char *object, size_t size, void *dummy)
414 guint8 *start = sgen_card_table_get_card_scan_address (object);
415 guint8 *end = start + cards_in_range (object, size);
417 printf ("--obj %p %d cards [%p %p]--", object, size, start, end);
418 for (; start < end; ++start) {
420 printf ("\n\t[%p] ", start);
421 printf ("%x ", *start);
430 #define MWORD_MASK (sizeof (mword) - 1)
433 find_card_offset (mword card)
435 /*XXX Use assembly as this generates some pretty bad code */
436 #if defined(__i386__) && defined(__GNUC__)
437 return (__builtin_ffs (card) - 1) / 8;
438 #elif defined(__x86_64__) && defined(__GNUC__)
439 return (__builtin_ffsll (card) - 1) / 8;
440 #elif defined(__s390x__)
441 return (__builtin_ffsll (GUINT64_TO_LE(card)) - 1) / 8;
444 guint8 *ptr = (guint8 *) &card;
445 for (i = 0; i < sizeof (mword); ++i) {
454 find_next_card (guint8 *card_data, guint8 *end)
456 mword *cards, *cards_end;
459 while ((((mword)card_data) & MWORD_MASK) && card_data < end) {
465 if (card_data == end)
468 cards = (mword*)card_data;
469 cards_end = (mword*)((mword)end & ~MWORD_MASK);
470 while (cards < cards_end) {
473 return (guint8*)cards + find_card_offset (card);
477 card_data = (guint8*)cards_end;
478 while (card_data < end) {
488 sgen_cardtable_scan_object (char *obj, mword block_obj_size, guint8 *cards,
489 gboolean always_copy_or_mark, SgenGrayQueue *queue)
491 MonoVTable *vt = (MonoVTable*)SGEN_LOAD_VTABLE (obj);
492 MonoClass *klass = vt->klass;
494 HEAVY_STAT (++large_objects);
496 if (!SGEN_VTABLE_HAS_REFERENCES (vt))
500 guint8 *card_data, *card_base;
501 guint8 *card_data_end;
502 char *obj_start = sgen_card_table_align_pointer (obj);
503 mword obj_size = sgen_par_object_get_size (vt, (MonoObject*)obj);
504 char *obj_end = obj + obj_size;
508 MonoArray *arr = (MonoArray*)obj;
509 mword desc = (mword)klass->element_class->gc_descr;
510 int elem_size = mono_array_element_size (klass);
512 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
513 guint8 *overflow_scan_end = NULL;
519 card_data = sgen_card_table_get_card_scan_address ((mword)obj);
521 card_base = card_data;
522 card_count = cards_in_range ((mword)obj, obj_size);
523 card_data_end = card_data + card_count;
526 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
527 /*Check for overflow and if so, setup to scan in two steps*/
528 if (!cards && card_data_end >= SGEN_SHADOW_CARDTABLE_END) {
529 overflow_scan_end = sgen_shadow_cardtable + (card_data_end - SGEN_SHADOW_CARDTABLE_END);
530 card_data_end = SGEN_SHADOW_CARDTABLE_END;
536 card_data = find_next_card (card_data, card_data_end);
537 for (; card_data < card_data_end; card_data = find_next_card (card_data + 1, card_data_end)) {
539 int idx = (card_data - card_base) + extra_idx;
540 char *start = (char*)(obj_start + idx * CARD_SIZE_IN_BYTES);
541 char *card_end = start + CARD_SIZE_IN_BYTES;
542 char *first_elem, *elem;
544 HEAVY_STAT (++los_marked_cards);
547 sgen_card_table_prepare_card_for_scanning (card_data);
549 card_end = MIN (card_end, obj_end);
551 if (start <= (char*)arr->vector)
554 index = ARRAY_OBJ_INDEX (start, obj, elem_size);
556 elem = first_elem = (char*)mono_array_addr_with_size ((MonoArray*)obj, elem_size, index);
557 if (klass->element_class->valuetype) {
558 ScanVTypeFunc scan_vtype_func = sgen_get_current_object_ops ()->scan_vtype;
560 for (; elem < card_end; elem += elem_size)
561 scan_vtype_func (elem, desc, queue);
563 CopyOrMarkObjectFunc copy_func = sgen_get_current_object_ops ()->copy_or_mark_object;
565 HEAVY_STAT (++los_array_cards);
566 for (; elem < card_end; elem += SIZEOF_VOID_P) {
567 gpointer new, old = *(gpointer*)elem;
568 if ((always_copy_or_mark && old) || G_UNLIKELY (sgen_ptr_in_nursery (old))) {
569 HEAVY_STAT (++los_array_remsets);
570 copy_func ((void**)elem, queue);
571 new = *(gpointer*)elem;
572 if (G_UNLIKELY (sgen_ptr_in_nursery (new)))
573 sgen_add_to_global_remset (elem, new);
578 binary_protocol_card_scan (first_elem, elem - first_elem);
581 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
582 if (overflow_scan_end) {
583 extra_idx = card_data - card_base;
584 card_base = card_data = sgen_shadow_cardtable;
585 card_data_end = overflow_scan_end;
586 overflow_scan_end = NULL;
592 HEAVY_STAT (++bloby_objects);
594 if (sgen_card_table_is_range_marked (cards, (mword)obj, block_obj_size))
595 sgen_get_current_object_ops ()->scan_object (obj, queue);
596 } else if (sgen_card_table_region_begin_scanning ((mword)obj, block_obj_size)) {
597 sgen_get_current_object_ops ()->scan_object (obj, queue);
600 binary_protocol_card_scan (obj, sgen_safe_object_get_size ((MonoObject*)obj));
604 #ifdef CARDTABLE_STATS
607 int total, marked, remarked, gc_marked;
610 static card_stats major_stats, los_stats;
611 static card_stats *cur_stats;
614 count_marked_cards (mword start, mword size)
616 mword end = start + size;
617 while (start <= end) {
618 guint8 card = *sgen_card_table_get_card_address (start);
623 ++cur_stats->gc_marked;
624 start += CARD_SIZE_IN_BYTES;
629 count_remarked_cards (mword start, mword size)
631 mword end = start + size;
632 while (start <= end) {
633 if (sgen_card_table_address_is_marked (start)) {
634 ++cur_stats->remarked;
635 *sgen_card_table_get_card_address (start) = 2;
637 start += CARD_SIZE_IN_BYTES;
644 sgen_card_tables_collect_stats (gboolean begin)
646 #ifdef CARDTABLE_STATS
648 memset (&major_stats, 0, sizeof (card_stats));
649 memset (&los_stats, 0, sizeof (card_stats));
650 cur_stats = &major_stats;
651 sgen_major_collector_iterate_live_block_ranges (count_marked_cards);
652 cur_stats = &los_stats;
653 sgen_los_iterate_live_block_ranges (count_marked_cards);
655 cur_stats = &major_stats;
656 sgen_major_collector_iterate_live_block_ranges (count_remarked_cards);
657 cur_stats = &los_stats;
658 sgen_los_iterate_live_block_ranges (count_remarked_cards);
659 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",
660 major_stats.total, major_stats.marked, major_stats.gc_marked, major_stats.remarked,
661 los_stats.total, los_stats.marked, los_stats.gc_marked, los_stats.remarked,
662 last_major_scan_time / 1000.0, last_los_scan_time / 1000.0);
668 sgen_card_table_init (SgenRemeberedSet *remset)
670 sgen_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "card table");
672 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
673 sgen_shadow_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "shadow card table");
676 #ifdef HEAVY_STATISTICS
677 mono_counters_register ("marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &marked_cards);
678 mono_counters_register ("scanned cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_cards);
679 mono_counters_register ("remarked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &remarked_cards);
681 mono_counters_register ("los marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_marked_cards);
682 mono_counters_register ("los array cards scanned ", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_cards);
683 mono_counters_register ("los array remsets", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_remsets);
684 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_objects);
685 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &large_objects);
686 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &bloby_objects);
688 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_TIME_INTERVAL, &major_card_scan_time);
689 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_TIME_INTERVAL, &los_card_scan_time);
692 remset->wbarrier_set_field = sgen_card_table_wbarrier_set_field;
693 remset->wbarrier_set_arrayref = sgen_card_table_wbarrier_set_arrayref;
694 remset->wbarrier_arrayref_copy = sgen_card_table_wbarrier_arrayref_copy;
695 remset->wbarrier_value_copy = sgen_card_table_wbarrier_value_copy;
696 remset->wbarrier_object_copy = sgen_card_table_wbarrier_object_copy;
697 remset->wbarrier_generic_nostore = sgen_card_table_wbarrier_generic_nostore;
698 remset->record_pointer = sgen_card_table_record_pointer;
700 remset->finish_scan_remsets = sgen_card_table_finish_scan_remsets;
702 remset->finish_minor_collection = sgen_card_table_finish_minor_collection;
703 remset->prepare_for_major_collection = sgen_card_table_prepare_for_major_collection;
705 remset->find_address = sgen_card_table_find_address;
711 sgen_card_table_mark_address (mword address)
713 g_assert_not_reached ();
717 sgen_card_table_mark_range (mword address, mword size)
719 g_assert_not_reached ();
723 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
730 #endif /*HAVE_SGEN_GC*/