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
48 #ifdef HAVE_SYS_MMAN_H
51 #include <sys/types.h>
53 guint8 *sgen_cardtable;
56 #ifdef HEAVY_STATISTICS
57 long long marked_cards;
58 long long scanned_cards;
59 long long scanned_objects;
60 long long remarked_cards;
62 static long long los_marked_cards;
63 static long long large_objects;
64 static long long bloby_objects;
65 static long long los_array_cards;
66 static long long los_array_remsets;
69 static long long major_card_scan_time;
70 static long long los_card_scan_time;
72 static long long last_major_scan_time;
73 static long long last_los_scan_time;
75 static void sgen_card_tables_collect_stats (gboolean begin);
78 /*WARNING: This function returns the number of cards regardless of overflow in case of overlapping cards.*/
80 cards_in_range (mword address, mword size)
82 mword end = address + MAX (1, size) - 1;
83 return (end >> CARD_BITS) - (address >> CARD_BITS) + 1;
87 sgen_card_table_wbarrier_set_field (MonoObject *obj, gpointer field_ptr, MonoObject* value)
89 *(void**)field_ptr = value;
90 if (sgen_ptr_in_nursery (value))
91 sgen_card_table_mark_address ((mword)field_ptr);
92 sgen_dummy_use (value);
96 sgen_card_table_wbarrier_set_arrayref (MonoArray *arr, gpointer slot_ptr, MonoObject* value)
98 *(void**)slot_ptr = value;
99 if (sgen_ptr_in_nursery (value))
100 sgen_card_table_mark_address ((mword)slot_ptr);
101 sgen_dummy_use (value);
105 sgen_card_table_wbarrier_arrayref_copy (gpointer dest_ptr, gpointer src_ptr, int count)
107 gpointer *dest = dest_ptr;
108 gpointer *src = src_ptr;
110 /*overlapping that required backward copying*/
111 if (src < dest && (src + count) > dest) {
112 gpointer *start = dest;
116 for (; dest >= start; --src, --dest) {
117 gpointer value = *src;
119 if (sgen_ptr_in_nursery (value))
120 sgen_card_table_mark_address ((mword)dest);
121 sgen_dummy_use (value);
124 gpointer *end = dest + count;
125 for (; dest < end; ++src, ++dest) {
126 gpointer value = *src;
128 if (sgen_ptr_in_nursery (value))
129 sgen_card_table_mark_address ((mword)dest);
130 sgen_dummy_use (value);
136 sgen_card_table_wbarrier_value_copy (gpointer dest, gpointer src, int count, MonoClass *klass)
138 size_t element_size = mono_class_value_size (klass, NULL);
139 size_t size = count * element_size;
141 #ifdef DISABLE_CRITICAL_REGION
145 ENTER_CRITICAL_REGION;
147 mono_gc_memmove (dest, src, size);
148 sgen_card_table_mark_range ((mword)dest, size);
149 #ifdef DISABLE_CRITICAL_REGION
152 EXIT_CRITICAL_REGION;
157 sgen_card_table_wbarrier_object_copy (MonoObject* obj, MonoObject *src)
159 int size = mono_object_class (obj)->instance_size;
161 #ifdef DISABLE_CRITICAL_REGION
165 ENTER_CRITICAL_REGION;
167 mono_gc_memmove ((char*)obj + sizeof (MonoObject), (char*)src + sizeof (MonoObject),
168 size - sizeof (MonoObject));
169 sgen_card_table_mark_range ((mword)obj, size);
170 #ifdef DISABLE_CRITICAL_REGION
173 EXIT_CRITICAL_REGION;
178 sgen_card_table_wbarrier_generic_nostore (gpointer ptr)
180 sgen_card_table_mark_address ((mword)ptr);
183 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
185 guint8 *sgen_shadow_cardtable;
187 #define SGEN_SHADOW_CARDTABLE_END (sgen_shadow_cardtable + CARD_COUNT_IN_BYTES)
188 #define SGEN_CARDTABLE_END (sgen_cardtable + CARD_COUNT_IN_BYTES)
191 sgen_card_table_region_begin_scanning (mword start, mword end)
193 /*XXX this can be improved to work on words and have a single loop induction var */
194 while (start <= end) {
195 if (sgen_card_table_card_begin_scanning (start))
197 start += CARD_SIZE_IN_BYTES;
205 sgen_card_table_region_begin_scanning (mword start, mword size)
207 gboolean res = FALSE;
208 guint8 *card = sgen_card_table_get_card_address (start);
209 guint8 *end = card + cards_in_range (start, size);
211 /*XXX this can be improved to work on words and have a branchless body */
212 while (card != end) {
219 memset (sgen_card_table_get_card_address (start), 0, size >> CARD_BITS);
226 /*FIXME this assumes that major blocks are multiple of 4K which is pretty reasonable */
228 sgen_card_table_get_card_data (guint8 *data_dest, mword address, mword cards)
230 mword *start = (mword*)sgen_card_table_get_card_scan_address (address);
231 mword *dest = (mword*)data_dest;
232 mword *end = (mword*)(data_dest + cards);
235 for (; dest < end; ++dest, ++start) {
240 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
249 sgen_card_table_align_pointer (void *ptr)
251 return (void*)((mword)ptr & ~(CARD_SIZE_IN_BYTES - 1));
255 sgen_card_table_mark_range (mword address, mword size)
257 memset (sgen_card_table_get_card_address (address), 1, cards_in_range (address, size));
261 sgen_card_table_is_range_marked (guint8 *cards, mword address, mword size)
263 guint8 *end = cards + cards_in_range (address, size);
265 /*This is safe since this function is only called by code that only passes continuous card blocks*/
266 while (cards != end) {
275 sgen_card_table_record_pointer (gpointer address)
277 *sgen_card_table_get_card_address ((mword)address) = 1;
281 sgen_card_table_find_address (char *addr)
283 return sgen_card_table_address_is_marked ((mword)addr);
286 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
289 move_cards_to_shadow_table (mword start, mword size)
291 guint8 *from = sgen_card_table_get_card_address (start);
292 guint8 *to = sgen_card_table_get_shadow_card_address (start);
293 size_t bytes = cards_in_range (start, size);
295 if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
296 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
297 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
299 memcpy (to, from, first_chunk);
300 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
302 memcpy (to, from, bytes);
307 clear_cards (mword start, mword size)
309 guint8 *addr = sgen_card_table_get_card_address (start);
310 size_t bytes = cards_in_range (start, size);
312 if (addr + bytes > SGEN_CARDTABLE_END) {
313 size_t first_chunk = SGEN_CARDTABLE_END - addr;
315 memset (addr, 0, first_chunk);
316 memset (sgen_cardtable, 0, bytes - first_chunk);
318 memset (addr, 0, bytes);
326 clear_cards (mword start, mword size)
328 memset (sgen_card_table_get_card_address (start), 0, cards_in_range (start, size));
335 sgen_card_table_prepare_for_major_collection (void)
337 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
338 sgen_major_collector_iterate_live_block_ranges (clear_cards);
339 sgen_los_iterate_live_block_ranges (clear_cards);
343 sgen_card_table_finish_minor_collection (void)
345 sgen_card_tables_collect_stats (FALSE);
349 sgen_card_table_finish_scan_remsets (void *start_nursery, void *end_nursery, SgenGrayQueue *queue)
351 SGEN_TV_DECLARE (atv);
352 SGEN_TV_DECLARE (btv);
354 sgen_card_tables_collect_stats (TRUE);
356 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
357 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
359 sgen_major_collector_iterate_live_block_ranges (move_cards_to_shadow_table);
360 sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
363 sgen_card_table_prepare_for_major_collection ();
365 SGEN_TV_GETTIME (atv);
366 sgen_major_collector_scan_card_table (queue);
367 SGEN_TV_GETTIME (btv);
368 last_major_scan_time = SGEN_TV_ELAPSED (atv, btv);
369 major_card_scan_time += last_major_scan_time;
370 sgen_los_scan_card_table (queue);
371 SGEN_TV_GETTIME (atv);
372 last_los_scan_time = SGEN_TV_ELAPSED (btv, atv);
373 los_card_scan_time += last_los_scan_time;
377 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
382 *shift_bits = CARD_BITS;
383 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
384 *mask = (gpointer)CARD_MASK;
389 return sgen_cardtable;
394 collect_faulted_cards (void)
396 #define CARD_PAGES (CARD_COUNT_IN_BYTES / 4096)
398 unsigned char faulted [CARD_PAGES] = { 0 };
399 mincore (sgen_cardtable, CARD_COUNT_IN_BYTES, faulted);
401 for (i = 0; i < CARD_PAGES; ++i) {
406 printf ("TOTAL card pages %d faulted %d\n", CARD_PAGES, count);
410 sgen_card_table_dump_obj_card (char *object, size_t size, void *dummy)
412 guint8 *start = sgen_card_table_get_card_scan_address (object);
413 guint8 *end = start + cards_in_range (object, size);
415 printf ("--obj %p %d cards [%p %p]--", object, size, start, end);
416 for (; start < end; ++start) {
418 printf ("\n\t[%p] ", start);
419 printf ("%x ", *start);
428 #define MWORD_MASK (sizeof (mword) - 1)
431 find_card_offset (mword card)
433 /*XXX Use assembly as this generates some pretty bad code */
434 #if defined(__i386__) && defined(__GNUC__)
435 return (__builtin_ffs (card) - 1) / 8;
436 #elif defined(__x86_64__) && defined(__GNUC__)
437 return (__builtin_ffsll (card) - 1) / 8;
438 #elif defined(__s390x__)
439 return (__builtin_ffsll (GUINT64_TO_LE(card)) - 1) / 8;
442 guint8 *ptr = (guint *) &card;
443 for (i = 0; i < sizeof (mword); ++i) {
452 find_next_card (guint8 *card_data, guint8 *end)
454 mword *cards, *cards_end;
457 while ((((mword)card_data) & MWORD_MASK) && card_data < end) {
463 if (card_data == end)
466 cards = (mword*)card_data;
467 cards_end = (mword*)((mword)end & ~MWORD_MASK);
468 while (cards < cards_end) {
471 return (guint8*)cards + find_card_offset (card);
475 card_data = (guint8*)cards_end;
476 while (card_data < end) {
486 sgen_cardtable_scan_object (char *obj, mword block_obj_size, guint8 *cards, SgenGrayQueue *queue)
488 MonoVTable *vt = (MonoVTable*)SGEN_LOAD_VTABLE (obj);
489 MonoClass *klass = vt->klass;
491 HEAVY_STAT (++large_objects);
493 if (!SGEN_VTABLE_HAS_REFERENCES (vt))
497 guint8 *card_data, *card_base;
498 guint8 *card_data_end;
499 char *obj_start = sgen_card_table_align_pointer (obj);
500 mword obj_size = sgen_par_object_get_size (vt, (MonoObject*)obj);
501 char *obj_end = obj + obj_size;
505 MonoArray *arr = (MonoArray*)obj;
506 mword desc = (mword)klass->element_class->gc_descr;
507 int elem_size = mono_array_element_size (klass);
509 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
510 guint8 *overflow_scan_end = NULL;
516 card_data = sgen_card_table_get_card_scan_address ((mword)obj);
518 card_base = card_data;
519 card_count = cards_in_range ((mword)obj, obj_size);
520 card_data_end = card_data + card_count;
523 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
524 /*Check for overflow and if so, setup to scan in two steps*/
525 if (!cards && card_data_end >= SGEN_SHADOW_CARDTABLE_END) {
526 overflow_scan_end = sgen_shadow_cardtable + (card_data_end - SGEN_SHADOW_CARDTABLE_END);
527 card_data_end = SGEN_SHADOW_CARDTABLE_END;
533 card_data = find_next_card (card_data, card_data_end);
534 for (; card_data < card_data_end; card_data = find_next_card (card_data + 1, card_data_end)) {
536 int idx = (card_data - card_base) + extra_idx;
537 char *start = (char*)(obj_start + idx * CARD_SIZE_IN_BYTES);
538 char *card_end = start + CARD_SIZE_IN_BYTES;
541 HEAVY_STAT (++los_marked_cards);
544 sgen_card_table_prepare_card_for_scanning (card_data);
546 card_end = MIN (card_end, obj_end);
548 if (start <= (char*)arr->vector)
551 index = ARRAY_OBJ_INDEX (start, obj, elem_size);
553 elem = (char*)mono_array_addr_with_size ((MonoArray*)obj, elem_size, index);
554 if (klass->element_class->valuetype) {
555 ScanVTypeFunc scan_vtype_func = sgen_get_current_object_ops ()->scan_vtype;
557 for (; elem < card_end; elem += elem_size)
558 scan_vtype_func (elem, desc, queue);
560 CopyOrMarkObjectFunc copy_func = sgen_get_current_object_ops ()->copy_or_mark_object;
562 HEAVY_STAT (++los_array_cards);
563 for (; elem < card_end; elem += SIZEOF_VOID_P) {
564 gpointer new, old = *(gpointer*)elem;
565 if (G_UNLIKELY (sgen_ptr_in_nursery (old))) {
566 HEAVY_STAT (++los_array_remsets);
567 copy_func ((void**)elem, queue);
568 new = *(gpointer*)elem;
569 if (G_UNLIKELY (sgen_ptr_in_nursery (new)))
570 sgen_add_to_global_remset (elem);
576 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
577 if (overflow_scan_end) {
578 extra_idx = card_data - card_base;
579 card_base = card_data = sgen_shadow_cardtable;
580 card_data_end = overflow_scan_end;
581 overflow_scan_end = NULL;
587 HEAVY_STAT (++bloby_objects);
589 if (sgen_card_table_is_range_marked (cards, (mword)obj, block_obj_size))
590 sgen_get_current_object_ops ()->scan_object (obj, queue);
591 } else if (sgen_card_table_region_begin_scanning ((mword)obj, block_obj_size)) {
592 sgen_get_current_object_ops ()->scan_object (obj, queue);
597 #ifdef CARDTABLE_STATS
600 int total, marked, remarked;
603 static card_stats major_stats, los_stats;
604 static card_stats *cur_stats;
607 count_marked_cards (mword start, mword size)
609 mword end = start + size;
610 while (start <= end) {
612 if (sgen_card_table_address_is_marked (start))
614 start += CARD_SIZE_IN_BYTES;
619 count_remarked_cards (mword start, mword size)
621 mword end = start + size;
622 while (start <= end) {
623 if (sgen_card_table_address_is_marked (start))
624 ++cur_stats->remarked;
625 start += CARD_SIZE_IN_BYTES;
632 sgen_card_tables_collect_stats (gboolean begin)
634 #ifdef CARDTABLE_STATS
636 memset (&major_stats, 0, sizeof (card_stats));
637 memset (&los_stats, 0, sizeof (card_stats));
638 cur_stats = &major_stats;
639 sgen_major_collector_iterate_live_block_ranges (count_marked_cards);
640 cur_stats = &los_stats;
641 sgen_los_iterate_live_block_ranges (count_marked_cards);
643 cur_stats = &major_stats;
644 sgen_major_collector_iterate_live_block_ranges (count_marked_cards);
645 cur_stats = &los_stats;
646 sgen_los_iterate_live_block_ranges (count_remarked_cards);
647 printf ("cards major (t %d m %d r %d) los (t %d m %d r %d) major_scan %.2fms los_scan %.2fms\n",
648 major_stats.total, major_stats.marked, major_stats.remarked,
649 los_stats.total, los_stats.marked, los_stats.remarked,
650 last_major_scan_time / 1000.0, last_los_scan_time / 1000.0);
656 sgen_card_table_init (SgenRemeberedSet *remset)
658 sgen_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "card table");
660 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
661 sgen_shadow_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "shadow card table");
664 #ifdef HEAVY_STATISTICS
665 mono_counters_register ("marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &marked_cards);
666 mono_counters_register ("scanned cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_cards);
667 mono_counters_register ("remarked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &remarked_cards);
669 mono_counters_register ("los marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_marked_cards);
670 mono_counters_register ("los array cards scanned ", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_cards);
671 mono_counters_register ("los array remsets", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_remsets);
672 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_objects);
673 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &large_objects);
674 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &bloby_objects);
676 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_TIME_INTERVAL, &major_card_scan_time);
677 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_TIME_INTERVAL, &los_card_scan_time);
680 remset->wbarrier_set_field = sgen_card_table_wbarrier_set_field;
681 remset->wbarrier_set_arrayref = sgen_card_table_wbarrier_set_arrayref;
682 remset->wbarrier_arrayref_copy = sgen_card_table_wbarrier_arrayref_copy;
683 remset->wbarrier_value_copy = sgen_card_table_wbarrier_value_copy;
684 remset->wbarrier_object_copy = sgen_card_table_wbarrier_object_copy;
685 remset->wbarrier_generic_nostore = sgen_card_table_wbarrier_generic_nostore;
686 remset->record_pointer = sgen_card_table_record_pointer;
688 remset->finish_scan_remsets = sgen_card_table_finish_scan_remsets;
690 remset->finish_minor_collection = sgen_card_table_finish_minor_collection;
691 remset->prepare_for_major_collection = sgen_card_table_prepare_for_major_collection;
693 remset->find_address = sgen_card_table_find_address;
699 sgen_card_table_mark_address (mword address)
701 g_assert_not_reached ();
705 sgen_card_table_mark_range (mword address, mword size)
707 g_assert_not_reached ();
711 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
718 #endif /*HAVE_SGEN_GC*/