2 * sgen-cardtable.c: Card table implementation for sgen
5 * Rodrigo Kumpera (rkumpera@novell.com)
7 * SGen is licensed under the terms of the MIT X11 license
9 * Copyright 2001-2003 Ximian, Inc
10 * Copyright 2003-2010 Novell, Inc.
11 * Copyright 2011 Xamarin Inc (http://www.xamarin.com)
13 * Permission is hereby granted, free of charge, to any person obtaining
14 * a copy of this software and associated documentation files (the
15 * "Software"), to deal in the Software without restriction, including
16 * without limitation the rights to use, copy, modify, merge, publish,
17 * distribute, sublicense, and/or sell copies of the Software, and to
18 * permit persons to whom the Software is furnished to do so, subject to
19 * the following conditions:
21 * The above copyright notice and this permission notice shall be
22 * included in all copies or substantial portions of the Software.
24 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
25 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
26 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
27 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
28 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
29 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
30 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
36 #include "metadata/sgen-gc.h"
37 #include "metadata/sgen-cardtable.h"
38 #include "metadata/sgen-memory-governor.h"
39 #include "utils/mono-counters.h"
40 #include "utils/mono-time.h"
41 #include "utils/mono-memory-model.h"
43 #ifdef SGEN_HAVE_CARDTABLE
45 //#define CARDTABLE_STATS
50 #ifdef HAVE_SYS_MMAN_H
53 #include <sys/types.h>
55 guint8 *sgen_cardtable;
58 #ifdef HEAVY_STATISTICS
59 long long marked_cards;
60 long long scanned_cards;
61 long long scanned_objects;
62 long long remarked_cards;
64 static long long los_marked_cards;
65 static long long large_objects;
66 static long long bloby_objects;
67 static long long los_array_cards;
68 static long long los_array_remsets;
71 static long long major_card_scan_time;
72 static long long los_card_scan_time;
74 static long long last_major_scan_time;
75 static long long last_los_scan_time;
77 static void sgen_card_tables_collect_stats (gboolean begin);
80 /*WARNING: This function returns the number of cards regardless of overflow in case of overlapping cards.*/
82 cards_in_range (mword address, mword size)
84 mword end = address + MAX (1, size) - 1;
85 return (end >> CARD_BITS) - (address >> CARD_BITS) + 1;
89 sgen_card_table_wbarrier_set_field (MonoObject *obj, gpointer field_ptr, MonoObject* value)
91 *(void**)field_ptr = value;
92 if (sgen_ptr_in_nursery (value))
93 sgen_card_table_mark_address ((mword)field_ptr);
94 sgen_dummy_use (value);
98 sgen_card_table_wbarrier_set_arrayref (MonoArray *arr, gpointer slot_ptr, MonoObject* value)
100 *(void**)slot_ptr = value;
101 if (sgen_ptr_in_nursery (value))
102 sgen_card_table_mark_address ((mword)slot_ptr);
103 sgen_dummy_use (value);
107 sgen_card_table_wbarrier_arrayref_copy (gpointer dest_ptr, gpointer src_ptr, int count)
109 gpointer *dest = dest_ptr;
110 gpointer *src = src_ptr;
112 /*overlapping that required backward copying*/
113 if (src < dest && (src + count) > dest) {
114 gpointer *start = dest;
118 for (; dest >= start; --src, --dest) {
119 gpointer value = *src;
121 if (sgen_ptr_in_nursery (value))
122 sgen_card_table_mark_address ((mword)dest);
123 sgen_dummy_use (value);
126 gpointer *end = dest + count;
127 for (; dest < end; ++src, ++dest) {
128 gpointer value = *src;
130 if (sgen_ptr_in_nursery (value))
131 sgen_card_table_mark_address ((mword)dest);
132 sgen_dummy_use (value);
138 sgen_card_table_wbarrier_value_copy (gpointer dest, gpointer src, int count, MonoClass *klass)
140 size_t element_size = mono_class_value_size (klass, NULL);
141 size_t size = count * element_size;
143 #ifdef DISABLE_CRITICAL_REGION
147 ENTER_CRITICAL_REGION;
149 mono_gc_memmove (dest, src, size);
150 sgen_card_table_mark_range ((mword)dest, size);
151 #ifdef DISABLE_CRITICAL_REGION
154 EXIT_CRITICAL_REGION;
159 sgen_card_table_wbarrier_object_copy (MonoObject* obj, MonoObject *src)
161 int size = mono_object_class (obj)->instance_size;
163 #ifdef DISABLE_CRITICAL_REGION
167 ENTER_CRITICAL_REGION;
169 mono_gc_memmove ((char*)obj + sizeof (MonoObject), (char*)src + sizeof (MonoObject),
170 size - sizeof (MonoObject));
171 sgen_card_table_mark_range ((mword)obj, size);
172 #ifdef DISABLE_CRITICAL_REGION
175 EXIT_CRITICAL_REGION;
180 sgen_card_table_wbarrier_generic_nostore (gpointer ptr)
182 sgen_card_table_mark_address ((mword)ptr);
185 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
187 guint8 *sgen_shadow_cardtable;
189 #define SGEN_SHADOW_CARDTABLE_END (sgen_shadow_cardtable + CARD_COUNT_IN_BYTES)
190 #define SGEN_CARDTABLE_END (sgen_cardtable + CARD_COUNT_IN_BYTES)
193 sgen_card_table_region_begin_scanning (mword start, mword end)
195 /*XXX this can be improved to work on words and have a single loop induction var */
196 while (start <= end) {
197 if (sgen_card_table_card_begin_scanning (start))
199 start += CARD_SIZE_IN_BYTES;
207 sgen_card_table_region_begin_scanning (mword start, mword size)
209 gboolean res = FALSE;
210 guint8 *card = sgen_card_table_get_card_address (start);
211 guint8 *end = card + cards_in_range (start, size);
213 /*XXX this can be improved to work on words and have a branchless body */
214 while (card != end) {
221 memset (sgen_card_table_get_card_address (start), 0, size >> CARD_BITS);
228 /*FIXME this assumes that major blocks are multiple of 4K which is pretty reasonable */
230 sgen_card_table_get_card_data (guint8 *data_dest, mword address, mword cards)
232 mword *start = (mword*)sgen_card_table_get_card_scan_address (address);
233 mword *dest = (mword*)data_dest;
234 mword *end = (mword*)(data_dest + cards);
237 for (; dest < end; ++dest, ++start) {
242 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
251 sgen_card_table_align_pointer (void *ptr)
253 return (void*)((mword)ptr & ~(CARD_SIZE_IN_BYTES - 1));
257 sgen_card_table_mark_range (mword address, mword size)
259 memset (sgen_card_table_get_card_address (address), 1, cards_in_range (address, size));
263 sgen_card_table_is_range_marked (guint8 *cards, mword address, mword size)
265 guint8 *end = cards + cards_in_range (address, size);
267 /*This is safe since this function is only called by code that only passes continuous card blocks*/
268 while (cards != end) {
277 sgen_card_table_record_pointer (gpointer address)
279 *sgen_card_table_get_card_address ((mword)address) = 1;
283 sgen_card_table_find_address (char *addr)
285 return sgen_card_table_address_is_marked ((mword)addr);
288 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
291 move_cards_to_shadow_table (mword start, mword size)
293 guint8 *from = sgen_card_table_get_card_address (start);
294 guint8 *to = sgen_card_table_get_shadow_card_address (start);
295 size_t bytes = cards_in_range (start, size);
297 if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
298 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
299 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
301 memcpy (to, from, first_chunk);
302 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
304 memcpy (to, from, bytes);
309 clear_cards (mword start, mword size)
311 guint8 *addr = sgen_card_table_get_card_address (start);
312 size_t bytes = cards_in_range (start, size);
314 if (addr + bytes > SGEN_CARDTABLE_END) {
315 size_t first_chunk = SGEN_CARDTABLE_END - addr;
317 memset (addr, 0, first_chunk);
318 memset (sgen_cardtable, 0, bytes - first_chunk);
320 memset (addr, 0, bytes);
328 clear_cards (mword start, mword size)
330 memset (sgen_card_table_get_card_address (start), 0, cards_in_range (start, size));
337 sgen_card_table_prepare_for_major_collection (void)
339 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
340 sgen_major_collector_iterate_live_block_ranges (clear_cards);
341 sgen_los_iterate_live_block_ranges (clear_cards);
345 sgen_card_table_finish_minor_collection (void)
347 sgen_card_tables_collect_stats (FALSE);
351 sgen_card_table_finish_scan_remsets (void *start_nursery, void *end_nursery, SgenGrayQueue *queue)
353 SGEN_TV_DECLARE (atv);
354 SGEN_TV_DECLARE (btv);
356 sgen_card_tables_collect_stats (TRUE);
358 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
359 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
361 sgen_major_collector_iterate_live_block_ranges (move_cards_to_shadow_table);
362 sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
365 sgen_card_table_prepare_for_major_collection ();
367 SGEN_TV_GETTIME (atv);
368 sgen_major_collector_scan_card_table (queue);
369 SGEN_TV_GETTIME (btv);
370 last_major_scan_time = SGEN_TV_ELAPSED (atv, btv);
371 major_card_scan_time += last_major_scan_time;
372 sgen_los_scan_card_table (queue);
373 SGEN_TV_GETTIME (atv);
374 last_los_scan_time = SGEN_TV_ELAPSED (btv, atv);
375 los_card_scan_time += last_los_scan_time;
379 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
384 *shift_bits = CARD_BITS;
385 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
386 *mask = (gpointer)CARD_MASK;
391 return sgen_cardtable;
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 = (guint *) &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, SgenGrayQueue *queue)
490 MonoVTable *vt = (MonoVTable*)SGEN_LOAD_VTABLE (obj);
491 MonoClass *klass = vt->klass;
493 HEAVY_STAT (++large_objects);
495 if (!SGEN_VTABLE_HAS_REFERENCES (vt))
499 guint8 *card_data, *card_base;
500 guint8 *card_data_end;
501 char *obj_start = sgen_card_table_align_pointer (obj);
502 mword obj_size = sgen_par_object_get_size (vt, (MonoObject*)obj);
503 char *obj_end = obj + obj_size;
507 MonoArray *arr = (MonoArray*)obj;
508 mword desc = (mword)klass->element_class->gc_descr;
509 int elem_size = mono_array_element_size (klass);
511 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
512 guint8 *overflow_scan_end = NULL;
518 card_data = sgen_card_table_get_card_scan_address ((mword)obj);
520 card_base = card_data;
521 card_count = cards_in_range ((mword)obj, obj_size);
522 card_data_end = card_data + card_count;
525 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
526 /*Check for overflow and if so, setup to scan in two steps*/
527 if (!cards && card_data_end >= SGEN_SHADOW_CARDTABLE_END) {
528 overflow_scan_end = sgen_shadow_cardtable + (card_data_end - SGEN_SHADOW_CARDTABLE_END);
529 card_data_end = SGEN_SHADOW_CARDTABLE_END;
535 card_data = find_next_card (card_data, card_data_end);
536 for (; card_data < card_data_end; card_data = find_next_card (card_data + 1, card_data_end)) {
538 int idx = (card_data - card_base) + extra_idx;
539 char *start = (char*)(obj_start + idx * CARD_SIZE_IN_BYTES);
540 char *card_end = start + CARD_SIZE_IN_BYTES;
543 HEAVY_STAT (++los_marked_cards);
546 sgen_card_table_prepare_card_for_scanning (card_data);
548 card_end = MIN (card_end, obj_end);
550 if (start <= (char*)arr->vector)
553 index = ARRAY_OBJ_INDEX (start, obj, elem_size);
555 elem = (char*)mono_array_addr_with_size ((MonoArray*)obj, elem_size, index);
556 if (klass->element_class->valuetype) {
557 ScanVTypeFunc scan_vtype_func = sgen_get_current_object_ops ()->scan_vtype;
559 for (; elem < card_end; elem += elem_size)
560 scan_vtype_func (elem, desc, queue);
562 CopyOrMarkObjectFunc copy_func = sgen_get_current_object_ops ()->copy_or_mark_object;
564 HEAVY_STAT (++los_array_cards);
565 for (; elem < card_end; elem += SIZEOF_VOID_P) {
566 gpointer new, old = *(gpointer*)elem;
567 if (G_UNLIKELY (sgen_ptr_in_nursery (old))) {
568 HEAVY_STAT (++los_array_remsets);
569 copy_func ((void**)elem, queue);
570 new = *(gpointer*)elem;
571 if (G_UNLIKELY (sgen_ptr_in_nursery (new)))
572 sgen_add_to_global_remset (elem);
578 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
579 if (overflow_scan_end) {
580 extra_idx = card_data - card_base;
581 card_base = card_data = sgen_shadow_cardtable;
582 card_data_end = overflow_scan_end;
583 overflow_scan_end = NULL;
589 HEAVY_STAT (++bloby_objects);
591 if (sgen_card_table_is_range_marked (cards, (mword)obj, block_obj_size))
592 sgen_get_current_object_ops ()->scan_object (obj, queue);
593 } else if (sgen_card_table_region_begin_scanning ((mword)obj, block_obj_size)) {
594 sgen_get_current_object_ops ()->scan_object (obj, queue);
599 #ifdef CARDTABLE_STATS
602 int total, marked, remarked;
605 static card_stats major_stats, los_stats;
606 static card_stats *cur_stats;
609 count_marked_cards (mword start, mword size)
611 mword end = start + size;
612 while (start <= end) {
614 if (sgen_card_table_address_is_marked (start))
616 start += CARD_SIZE_IN_BYTES;
621 count_remarked_cards (mword start, mword size)
623 mword end = start + size;
624 while (start <= end) {
625 if (sgen_card_table_address_is_marked (start))
626 ++cur_stats->remarked;
627 start += CARD_SIZE_IN_BYTES;
634 sgen_card_tables_collect_stats (gboolean begin)
636 #ifdef CARDTABLE_STATS
638 memset (&major_stats, 0, sizeof (card_stats));
639 memset (&los_stats, 0, sizeof (card_stats));
640 cur_stats = &major_stats;
641 sgen_major_collector_iterate_live_block_ranges (count_marked_cards);
642 cur_stats = &los_stats;
643 sgen_los_iterate_live_block_ranges (count_marked_cards);
645 cur_stats = &major_stats;
646 sgen_major_collector_iterate_live_block_ranges (count_marked_cards);
647 cur_stats = &los_stats;
648 sgen_los_iterate_live_block_ranges (count_remarked_cards);
649 printf ("cards major (t %d m %d r %d) los (t %d m %d r %d) major_scan %.2fms los_scan %.2fms\n",
650 major_stats.total, major_stats.marked, major_stats.remarked,
651 los_stats.total, los_stats.marked, los_stats.remarked,
652 last_major_scan_time / 1000.0, last_los_scan_time / 1000.0);
658 sgen_card_table_init (SgenRemeberedSet *remset)
660 sgen_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "card table");
662 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
663 sgen_shadow_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "shadow card table");
666 #ifdef HEAVY_STATISTICS
667 mono_counters_register ("marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &marked_cards);
668 mono_counters_register ("scanned cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_cards);
669 mono_counters_register ("remarked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &remarked_cards);
671 mono_counters_register ("los marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_marked_cards);
672 mono_counters_register ("los array cards scanned ", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_cards);
673 mono_counters_register ("los array remsets", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_remsets);
674 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_objects);
675 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &large_objects);
676 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &bloby_objects);
678 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_TIME_INTERVAL, &major_card_scan_time);
679 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_TIME_INTERVAL, &los_card_scan_time);
682 remset->wbarrier_set_field = sgen_card_table_wbarrier_set_field;
683 remset->wbarrier_set_arrayref = sgen_card_table_wbarrier_set_arrayref;
684 remset->wbarrier_arrayref_copy = sgen_card_table_wbarrier_arrayref_copy;
685 remset->wbarrier_value_copy = sgen_card_table_wbarrier_value_copy;
686 remset->wbarrier_object_copy = sgen_card_table_wbarrier_object_copy;
687 remset->wbarrier_generic_nostore = sgen_card_table_wbarrier_generic_nostore;
688 remset->record_pointer = sgen_card_table_record_pointer;
690 remset->finish_scan_remsets = sgen_card_table_finish_scan_remsets;
692 remset->finish_minor_collection = sgen_card_table_finish_minor_collection;
693 remset->prepare_for_major_collection = sgen_card_table_prepare_for_major_collection;
695 remset->find_address = sgen_card_table_find_address;
701 sgen_card_table_mark_address (mword address)
703 g_assert_not_reached ();
707 sgen_card_table_mark_range (mword address, mword size)
709 g_assert_not_reached ();
713 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
720 #endif /*HAVE_SGEN_GC*/