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 "utils/mono-counters.h"
33 #include "utils/mono-time.h"
34 #include "utils/mono-memory-model.h"
36 #ifdef SGEN_HAVE_CARDTABLE
38 //#define CARDTABLE_STATS
43 #ifdef HAVE_SYS_MMAN_H
46 #include <sys/types.h>
48 guint8 *sgen_cardtable;
51 #ifdef HEAVY_STATISTICS
52 long long marked_cards;
53 long long scanned_cards;
54 long long scanned_objects;
55 long long remarked_cards;
57 static long long los_marked_cards;
58 static long long large_objects;
59 static long long bloby_objects;
60 static long long los_array_cards;
61 static long long los_array_remsets;
64 static long long major_card_scan_time;
65 static long long los_card_scan_time;
67 static long long last_major_scan_time;
68 static long long last_los_scan_time;
70 static void sgen_card_tables_collect_stats (gboolean begin);
73 /*WARNING: This function returns the number of cards regardless of overflow in case of overlapping cards.*/
75 cards_in_range (mword address, mword size)
77 mword end = address + MAX (1, size) - 1;
78 return (end >> CARD_BITS) - (address >> CARD_BITS) + 1;
82 sgen_card_table_wbarrier_set_field (MonoObject *obj, gpointer field_ptr, MonoObject* value)
84 *(void**)field_ptr = value;
85 if (sgen_ptr_in_nursery (value))
86 sgen_card_table_mark_address ((mword)field_ptr);
87 sgen_dummy_use (value);
91 sgen_card_table_wbarrier_set_arrayref (MonoArray *arr, gpointer slot_ptr, MonoObject* value)
93 *(void**)slot_ptr = value;
94 if (sgen_ptr_in_nursery (value))
95 sgen_card_table_mark_address ((mword)slot_ptr);
96 sgen_dummy_use (value);
100 sgen_card_table_wbarrier_arrayref_copy (gpointer dest_ptr, gpointer src_ptr, int count)
102 gpointer *dest = dest_ptr;
103 gpointer *src = src_ptr;
105 /*overlapping that required backward copying*/
106 if (src < dest && (src + count) > dest) {
107 gpointer *start = dest;
111 for (; dest >= start; --src, --dest) {
112 gpointer value = *src;
114 if (sgen_ptr_in_nursery (value))
115 sgen_card_table_mark_address ((mword)dest);
116 sgen_dummy_use (value);
119 gpointer *end = dest + count;
120 for (; dest < end; ++src, ++dest) {
121 gpointer value = *src;
123 if (sgen_ptr_in_nursery (value))
124 sgen_card_table_mark_address ((mword)dest);
125 sgen_dummy_use (value);
131 sgen_card_table_wbarrier_value_copy (gpointer dest, gpointer src, int count, MonoClass *klass)
133 size_t element_size = mono_class_value_size (klass, NULL);
134 size_t size = count * element_size;
136 #ifdef DISABLE_CRITICAL_REGION
140 ENTER_CRITICAL_REGION;
142 mono_gc_memmove (dest, src, size);
143 sgen_card_table_mark_range ((mword)dest, size);
144 #ifdef DISABLE_CRITICAL_REGION
147 EXIT_CRITICAL_REGION;
152 sgen_card_table_wbarrier_object_copy (MonoObject* obj, MonoObject *src)
154 int size = mono_object_class (obj)->instance_size;
156 #ifdef DISABLE_CRITICAL_REGION
160 ENTER_CRITICAL_REGION;
162 mono_gc_memmove ((char*)obj + sizeof (MonoObject), (char*)src + sizeof (MonoObject),
163 size - sizeof (MonoObject));
164 sgen_card_table_mark_range ((mword)obj, size);
165 #ifdef DISABLE_CRITICAL_REGION
168 EXIT_CRITICAL_REGION;
173 sgen_card_table_wbarrier_generic_nostore (gpointer ptr)
175 sgen_card_table_mark_address ((mword)ptr);
178 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
180 guint8 *sgen_shadow_cardtable;
182 #define SGEN_SHADOW_CARDTABLE_END (sgen_shadow_cardtable + CARD_COUNT_IN_BYTES)
183 #define SGEN_CARDTABLE_END (sgen_cardtable + CARD_COUNT_IN_BYTES)
186 sgen_card_table_region_begin_scanning (mword start, mword end)
188 /*XXX this can be improved to work on words and have a single loop induction var */
189 while (start <= end) {
190 if (sgen_card_table_card_begin_scanning (start))
192 start += CARD_SIZE_IN_BYTES;
200 sgen_card_table_region_begin_scanning (mword start, mword size)
202 gboolean res = FALSE;
203 guint8 *card = sgen_card_table_get_card_address (start);
204 guint8 *end = card + cards_in_range (start, size);
206 /*XXX this can be improved to work on words and have a branchless body */
207 while (card != end) {
214 memset (sgen_card_table_get_card_address (start), 0, size >> CARD_BITS);
221 /*FIXME this assumes that major blocks are multiple of 4K which is pretty reasonable */
223 sgen_card_table_get_card_data (guint8 *data_dest, mword address, mword cards)
225 mword *start = (mword*)sgen_card_table_get_card_scan_address (address);
226 mword *dest = (mword*)data_dest;
227 mword *end = (mword*)(data_dest + cards);
230 for (; dest < end; ++dest, ++start) {
235 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
244 sgen_card_table_align_pointer (void *ptr)
246 return (void*)((mword)ptr & ~(CARD_SIZE_IN_BYTES - 1));
250 sgen_card_table_mark_range (mword address, mword size)
252 memset (sgen_card_table_get_card_address (address), 1, cards_in_range (address, size));
256 sgen_card_table_is_range_marked (guint8 *cards, mword address, mword size)
258 guint8 *end = cards + cards_in_range (address, size);
260 /*This is safe since this function is only called by code that only passes continuous card blocks*/
261 while (cards != end) {
270 sgen_card_table_record_pointer (gpointer address)
272 *sgen_card_table_get_card_address ((mword)address) = 1;
276 sgen_card_table_find_address (char *addr)
278 return sgen_card_table_address_is_marked ((mword)addr);
281 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
284 move_cards_to_shadow_table (mword start, mword size)
286 guint8 *from = sgen_card_table_get_card_address (start);
287 guint8 *to = sgen_card_table_get_shadow_card_address (start);
288 size_t bytes = cards_in_range (start, size);
290 if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
291 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
292 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
294 memcpy (to, from, first_chunk);
295 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
297 memcpy (to, from, bytes);
302 clear_cards (mword start, mword size)
304 guint8 *addr = sgen_card_table_get_card_address (start);
305 size_t bytes = cards_in_range (start, size);
307 if (addr + bytes > SGEN_CARDTABLE_END) {
308 size_t first_chunk = SGEN_CARDTABLE_END - addr;
310 memset (addr, 0, first_chunk);
311 memset (sgen_cardtable, 0, bytes - first_chunk);
313 memset (addr, 0, bytes);
321 clear_cards (mword start, mword size)
323 memset (sgen_card_table_get_card_address (start), 0, cards_in_range (start, size));
330 sgen_card_table_prepare_for_major_collection (void)
332 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
333 sgen_major_collector_iterate_live_block_ranges (clear_cards);
334 sgen_los_iterate_live_block_ranges (clear_cards);
338 sgen_card_table_finish_minor_collection (void)
340 sgen_card_tables_collect_stats (FALSE);
344 sgen_card_table_finish_scan_remsets (void *start_nursery, void *end_nursery, SgenGrayQueue *queue)
346 SGEN_TV_DECLARE (atv);
347 SGEN_TV_DECLARE (btv);
349 sgen_card_tables_collect_stats (TRUE);
351 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
352 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
354 sgen_major_collector_iterate_live_block_ranges (move_cards_to_shadow_table);
355 sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
358 sgen_card_table_prepare_for_major_collection ();
360 SGEN_TV_GETTIME (atv);
361 sgen_major_collector_scan_card_table (queue);
362 SGEN_TV_GETTIME (btv);
363 last_major_scan_time = SGEN_TV_ELAPSED (atv, btv);
364 major_card_scan_time += last_major_scan_time;
365 sgen_los_scan_card_table (FALSE, queue);
366 SGEN_TV_GETTIME (atv);
367 last_los_scan_time = SGEN_TV_ELAPSED (btv, atv);
368 los_card_scan_time += last_los_scan_time;
372 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
377 *shift_bits = CARD_BITS;
378 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
379 *mask = (gpointer)CARD_MASK;
384 return sgen_cardtable;
388 mono_gc_card_table_nursery_check (void)
390 return !major_collector.is_concurrent;
395 collect_faulted_cards (void)
397 #define CARD_PAGES (CARD_COUNT_IN_BYTES / 4096)
399 unsigned char faulted [CARD_PAGES] = { 0 };
400 mincore (sgen_cardtable, CARD_COUNT_IN_BYTES, faulted);
402 for (i = 0; i < CARD_PAGES; ++i) {
407 printf ("TOTAL card pages %d faulted %d\n", CARD_PAGES, count);
411 sgen_card_table_dump_obj_card (char *object, size_t size, void *dummy)
413 guint8 *start = sgen_card_table_get_card_scan_address (object);
414 guint8 *end = start + cards_in_range (object, size);
416 printf ("--obj %p %d cards [%p %p]--", object, size, start, end);
417 for (; start < end; ++start) {
419 printf ("\n\t[%p] ", start);
420 printf ("%x ", *start);
429 #define MWORD_MASK (sizeof (mword) - 1)
432 find_card_offset (mword card)
434 /*XXX Use assembly as this generates some pretty bad code */
435 #if defined(__i386__) && defined(__GNUC__)
436 return (__builtin_ffs (card) - 1) / 8;
437 #elif defined(__x86_64__) && defined(__GNUC__)
438 return (__builtin_ffsll (card) - 1) / 8;
439 #elif defined(__s390x__)
440 return (__builtin_ffsll (GUINT64_TO_LE(card)) - 1) / 8;
443 guint8 *ptr = (guint *) &card;
444 for (i = 0; i < sizeof (mword); ++i) {
453 find_next_card (guint8 *card_data, guint8 *end)
455 mword *cards, *cards_end;
458 while ((((mword)card_data) & MWORD_MASK) && card_data < end) {
464 if (card_data == end)
467 cards = (mword*)card_data;
468 cards_end = (mword*)((mword)end & ~MWORD_MASK);
469 while (cards < cards_end) {
472 return (guint8*)cards + find_card_offset (card);
476 card_data = (guint8*)cards_end;
477 while (card_data < end) {
487 sgen_cardtable_scan_object (char *obj, mword block_obj_size, guint8 *cards, SgenGrayQueue *queue)
489 MonoVTable *vt = (MonoVTable*)SGEN_LOAD_VTABLE (obj);
490 MonoClass *klass = vt->klass;
492 HEAVY_STAT (++large_objects);
494 if (!SGEN_VTABLE_HAS_REFERENCES (vt))
498 guint8 *card_data, *card_base;
499 guint8 *card_data_end;
500 char *obj_start = sgen_card_table_align_pointer (obj);
501 mword obj_size = sgen_par_object_get_size (vt, (MonoObject*)obj);
502 char *obj_end = obj + obj_size;
506 MonoArray *arr = (MonoArray*)obj;
507 mword desc = (mword)klass->element_class->gc_descr;
508 int elem_size = mono_array_element_size (klass);
510 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
511 guint8 *overflow_scan_end = NULL;
517 card_data = sgen_card_table_get_card_scan_address ((mword)obj);
519 card_base = card_data;
520 card_count = cards_in_range ((mword)obj, obj_size);
521 card_data_end = card_data + card_count;
524 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
525 /*Check for overflow and if so, setup to scan in two steps*/
526 if (!cards && card_data_end >= SGEN_SHADOW_CARDTABLE_END) {
527 overflow_scan_end = sgen_shadow_cardtable + (card_data_end - SGEN_SHADOW_CARDTABLE_END);
528 card_data_end = SGEN_SHADOW_CARDTABLE_END;
534 card_data = find_next_card (card_data, card_data_end);
535 for (; card_data < card_data_end; card_data = find_next_card (card_data + 1, card_data_end)) {
537 int idx = (card_data - card_base) + extra_idx;
538 char *start = (char*)(obj_start + idx * CARD_SIZE_IN_BYTES);
539 char *card_end = start + CARD_SIZE_IN_BYTES;
542 HEAVY_STAT (++los_marked_cards);
545 sgen_card_table_prepare_card_for_scanning (card_data);
547 card_end = MIN (card_end, obj_end);
549 if (start <= (char*)arr->vector)
552 index = ARRAY_OBJ_INDEX (start, obj, elem_size);
554 elem = (char*)mono_array_addr_with_size ((MonoArray*)obj, elem_size, index);
555 if (klass->element_class->valuetype) {
556 ScanVTypeFunc scan_vtype_func = sgen_get_current_object_ops ()->scan_vtype;
558 for (; elem < card_end; elem += elem_size)
559 scan_vtype_func (elem, desc, queue);
561 CopyOrMarkObjectFunc copy_func = sgen_get_current_object_ops ()->copy_or_mark_object;
563 HEAVY_STAT (++los_array_cards);
564 for (; elem < card_end; elem += SIZEOF_VOID_P) {
565 gpointer new, old = *(gpointer*)elem;
566 if (G_UNLIKELY (sgen_ptr_in_nursery (old))) {
567 HEAVY_STAT (++los_array_remsets);
568 copy_func ((void**)elem, queue);
569 new = *(gpointer*)elem;
570 if (G_UNLIKELY (sgen_ptr_in_nursery (new)))
571 sgen_add_to_global_remset (elem, new);
577 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
578 if (overflow_scan_end) {
579 extra_idx = card_data - card_base;
580 card_base = card_data = sgen_shadow_cardtable;
581 card_data_end = overflow_scan_end;
582 overflow_scan_end = NULL;
588 HEAVY_STAT (++bloby_objects);
590 if (sgen_card_table_is_range_marked (cards, (mword)obj, block_obj_size))
591 sgen_get_current_object_ops ()->scan_object (obj, queue);
592 } else if (sgen_card_table_region_begin_scanning ((mword)obj, block_obj_size)) {
593 sgen_get_current_object_ops ()->scan_object (obj, queue);
598 #ifdef CARDTABLE_STATS
601 int total, marked, remarked, gc_marked;
604 static card_stats major_stats, los_stats;
605 static card_stats *cur_stats;
608 count_marked_cards (mword start, mword size)
610 mword end = start + size;
611 while (start <= end) {
612 guint8 card = *sgen_card_table_get_card_address (start);
617 ++cur_stats->gc_marked;
618 start += CARD_SIZE_IN_BYTES;
623 count_remarked_cards (mword start, mword size)
625 mword end = start + size;
626 while (start <= end) {
627 if (sgen_card_table_address_is_marked (start)) {
628 ++cur_stats->remarked;
629 *sgen_card_table_get_card_address (start) = 2;
631 start += CARD_SIZE_IN_BYTES;
638 sgen_card_tables_collect_stats (gboolean begin)
640 #ifdef CARDTABLE_STATS
642 memset (&major_stats, 0, sizeof (card_stats));
643 memset (&los_stats, 0, sizeof (card_stats));
644 cur_stats = &major_stats;
645 sgen_major_collector_iterate_live_block_ranges (count_marked_cards);
646 cur_stats = &los_stats;
647 sgen_los_iterate_live_block_ranges (count_marked_cards);
649 cur_stats = &major_stats;
650 sgen_major_collector_iterate_live_block_ranges (count_remarked_cards);
651 cur_stats = &los_stats;
652 sgen_los_iterate_live_block_ranges (count_remarked_cards);
653 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",
654 major_stats.total, major_stats.marked, major_stats.gc_marked, major_stats.remarked,
655 los_stats.total, los_stats.marked, los_stats.gc_marked, los_stats.remarked,
656 last_major_scan_time / 1000.0, last_los_scan_time / 1000.0);
662 sgen_card_table_init (SgenRemeberedSet *remset)
664 sgen_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "card table");
666 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
667 sgen_shadow_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "shadow card table");
670 #ifdef HEAVY_STATISTICS
671 mono_counters_register ("marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &marked_cards);
672 mono_counters_register ("scanned cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_cards);
673 mono_counters_register ("remarked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &remarked_cards);
675 mono_counters_register ("los marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_marked_cards);
676 mono_counters_register ("los array cards scanned ", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_cards);
677 mono_counters_register ("los array remsets", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_remsets);
678 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_objects);
679 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &large_objects);
680 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &bloby_objects);
682 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_TIME_INTERVAL, &major_card_scan_time);
683 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_TIME_INTERVAL, &los_card_scan_time);
686 remset->wbarrier_set_field = sgen_card_table_wbarrier_set_field;
687 remset->wbarrier_set_arrayref = sgen_card_table_wbarrier_set_arrayref;
688 remset->wbarrier_arrayref_copy = sgen_card_table_wbarrier_arrayref_copy;
689 remset->wbarrier_value_copy = sgen_card_table_wbarrier_value_copy;
690 remset->wbarrier_object_copy = sgen_card_table_wbarrier_object_copy;
691 remset->wbarrier_generic_nostore = sgen_card_table_wbarrier_generic_nostore;
692 remset->record_pointer = sgen_card_table_record_pointer;
694 remset->finish_scan_remsets = sgen_card_table_finish_scan_remsets;
696 remset->finish_minor_collection = sgen_card_table_finish_minor_collection;
697 remset->prepare_for_major_collection = sgen_card_table_prepare_for_major_collection;
699 remset->find_address = sgen_card_table_find_address;
705 sgen_card_table_mark_address (mword address)
707 g_assert_not_reached ();
711 sgen_card_table_mark_range (mword address, mword size)
713 g_assert_not_reached ();
717 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
724 #endif /*HAVE_SGEN_GC*/