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 "utils/mono-counters.h"
39 #include "utils/mono-time.h"
40 #include "utils/mono-memory-model.h"
42 #ifdef SGEN_HAVE_CARDTABLE
44 //#define CARDTABLE_STATS
47 #ifdef HAVE_SYS_MMAN_H
50 #include <sys/types.h>
52 guint8 *sgen_cardtable;
55 #ifdef HEAVY_STATISTICS
56 long long marked_cards;
57 long long scanned_cards;
58 long long scanned_objects;
59 long long remarked_cards;
61 static long long los_marked_cards;
62 static long long large_objects;
63 static long long bloby_objects;
64 static long long los_array_cards;
65 static long long los_array_remsets;
68 static long long major_card_scan_time;
69 static long long los_card_scan_time;
71 static long long last_major_scan_time;
72 static long long last_los_scan_time;
74 static void sgen_card_tables_collect_stats (gboolean begin);
77 /*WARNING: This function returns the number of cards regardless of overflow in case of overlapping cards.*/
79 cards_in_range (mword address, mword size)
81 mword end = address + MAX (1, size) - 1;
82 return (end >> CARD_BITS) - (address >> CARD_BITS) + 1;
86 sgen_card_table_wbarrier_set_field (MonoObject *obj, gpointer field_ptr, MonoObject* value)
88 *(void**)field_ptr = value;
89 if (sgen_ptr_in_nursery (value))
90 sgen_card_table_mark_address ((mword)field_ptr);
91 sgen_dummy_use (value);
95 sgen_card_table_wbarrier_set_arrayref (MonoArray *arr, gpointer slot_ptr, MonoObject* value)
97 *(void**)slot_ptr = value;
98 if (sgen_ptr_in_nursery (value))
99 sgen_card_table_mark_address ((mword)slot_ptr);
100 sgen_dummy_use (value);
104 sgen_card_table_wbarrier_arrayref_copy (gpointer dest_ptr, gpointer src_ptr, int count)
106 gpointer *dest = dest_ptr;
107 gpointer *src = src_ptr;
109 /*overlapping that required backward copying*/
110 if (src < dest && (src + count) > dest) {
111 gpointer *start = dest;
115 for (; dest >= start; --src, --dest) {
116 gpointer value = *src;
118 if (sgen_ptr_in_nursery (value))
119 sgen_card_table_mark_address ((mword)dest);
120 sgen_dummy_use (value);
123 gpointer *end = dest + count;
124 for (; dest < end; ++src, ++dest) {
125 gpointer value = *src;
127 if (sgen_ptr_in_nursery (value))
128 sgen_card_table_mark_address ((mword)dest);
129 sgen_dummy_use (value);
135 sgen_card_table_wbarrier_value_copy (gpointer dest, gpointer src, int count, MonoClass *klass)
137 size_t element_size = mono_class_value_size (klass, NULL);
138 size_t size = count * element_size;
140 #ifdef DISABLE_CRITICAL_REGION
144 ENTER_CRITICAL_REGION;
146 mono_gc_memmove (dest, src, size);
147 sgen_card_table_mark_range ((mword)dest, size);
148 #ifdef DISABLE_CRITICAL_REGION
151 EXIT_CRITICAL_REGION;
156 sgen_card_table_wbarrier_object_copy (MonoObject* obj, MonoObject *src)
161 size = mono_object_class (obj)->instance_size;
163 #ifdef DISABLE_CRITICAL_REGION
166 ENTER_CRITICAL_REGION;
168 mono_gc_memmove ((char*)obj + sizeof (MonoObject), (char*)src + sizeof (MonoObject),
169 size - sizeof (MonoObject));
170 sgen_card_table_mark_range ((mword)obj, size);
171 #ifdef DISABLE_CRITICAL_REGION
174 EXIT_CRITICAL_REGION;
179 sgen_card_table_wbarrier_generic_nostore (gpointer ptr)
181 sgen_card_table_mark_address ((mword)ptr);
184 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
186 guint8 *sgen_shadow_cardtable;
188 #define SGEN_SHADOW_CARDTABLE_END (sgen_shadow_cardtable + CARD_COUNT_IN_BYTES)
189 #define SGEN_CARDTABLE_END (sgen_cardtable + CARD_COUNT_IN_BYTES)
192 sgen_card_table_region_begin_scanning (mword start, mword end)
194 /*XXX this can be improved to work on words and have a single loop induction var */
195 while (start <= end) {
196 if (sgen_card_table_card_begin_scanning (start))
198 start += CARD_SIZE_IN_BYTES;
206 sgen_card_table_region_begin_scanning (mword start, mword size)
208 gboolean res = FALSE;
209 guint8 *card = sgen_card_table_get_card_address (start);
210 guint8 *end = card + cards_in_range (start, size);
212 /*XXX this can be improved to work on words and have a branchless body */
213 while (card != end) {
220 memset (sgen_card_table_get_card_address (start), 0, size >> CARD_BITS);
227 /*FIXME this assumes that major blocks are multiple of 4K which is pretty reasonable */
229 sgen_card_table_get_card_data (guint8 *data_dest, mword address, mword cards)
231 mword *start = (mword*)sgen_card_table_get_card_scan_address (address);
232 mword *dest = (mword*)data_dest;
233 mword *end = (mword*)(data_dest + cards);
236 for (; dest < end; ++dest, ++start) {
241 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
250 sgen_card_table_align_pointer (void *ptr)
252 return (void*)((mword)ptr & ~(CARD_SIZE_IN_BYTES - 1));
256 sgen_card_table_mark_range (mword address, mword size)
258 memset (sgen_card_table_get_card_address (address), 1, cards_in_range (address, size));
262 sgen_card_table_is_range_marked (guint8 *cards, mword address, mword size)
264 guint8 *end = cards + cards_in_range (address, size);
266 /*This is safe since this function is only called by code that only passes continuous card blocks*/
267 while (cards != end) {
276 sgen_card_table_record_pointer (gpointer address)
278 *sgen_card_table_get_card_address ((mword)address) = 1;
282 sgen_card_table_find_address (char *addr)
284 return sgen_card_table_address_is_marked ((mword)addr);
287 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
290 move_cards_to_shadow_table (mword start, mword size)
292 guint8 *from = sgen_card_table_get_card_address (start);
293 guint8 *to = sgen_card_table_get_shadow_card_address (start);
294 size_t bytes = cards_in_range (start, size);
296 if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
297 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
298 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
300 memcpy (to, from, first_chunk);
301 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
303 memcpy (to, from, bytes);
308 clear_cards (mword start, mword size)
310 guint8 *addr = sgen_card_table_get_card_address (start);
311 size_t bytes = cards_in_range (start, size);
313 if (addr + bytes > SGEN_CARDTABLE_END) {
314 size_t first_chunk = SGEN_CARDTABLE_END - addr;
316 memset (addr, 0, first_chunk);
317 memset (sgen_cardtable, 0, bytes - first_chunk);
319 memset (addr, 0, bytes);
327 clear_cards (mword start, mword size)
329 memset (sgen_card_table_get_card_address (start), 0, cards_in_range (start, size));
336 sgen_card_table_prepare_for_major_collection (void)
338 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
339 sgen_major_collector_iterate_live_block_ranges (clear_cards);
340 sgen_los_iterate_live_block_ranges (clear_cards);
344 sgen_card_table_finish_minor_collection (void)
346 sgen_card_tables_collect_stats (FALSE);
350 sgen_card_table_finish_scan_remsets (void *start_nursery, void *end_nursery, SgenGrayQueue *queue)
352 SGEN_TV_DECLARE (atv);
353 SGEN_TV_DECLARE (btv);
355 sgen_card_tables_collect_stats (TRUE);
357 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
358 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
360 sgen_major_collector_iterate_live_block_ranges (move_cards_to_shadow_table);
361 sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
364 sgen_card_table_prepare_for_major_collection ();
366 SGEN_TV_GETTIME (atv);
367 sgen_major_collector_scan_card_table (queue);
368 SGEN_TV_GETTIME (btv);
369 last_major_scan_time = SGEN_TV_ELAPSED (atv, btv);
370 major_card_scan_time += last_major_scan_time;
371 sgen_los_scan_card_table (queue);
372 SGEN_TV_GETTIME (atv);
373 last_los_scan_time = SGEN_TV_ELAPSED (btv, atv);
374 los_card_scan_time += last_los_scan_time;
378 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
383 *shift_bits = CARD_BITS;
384 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
385 *mask = (gpointer)CARD_MASK;
390 return sgen_cardtable;
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);
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;
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) {
613 if (sgen_card_table_address_is_marked (start))
615 start += CARD_SIZE_IN_BYTES;
620 count_remarked_cards (mword start, mword size)
622 mword end = start + size;
623 while (start <= end) {
624 if (sgen_card_table_address_is_marked (start))
625 ++cur_stats->remarked;
626 start += CARD_SIZE_IN_BYTES;
633 sgen_card_tables_collect_stats (gboolean begin)
635 #ifdef CARDTABLE_STATS
637 memset (&major_stats, 0, sizeof (card_stats));
638 memset (&los_stats, 0, sizeof (card_stats));
639 cur_stats = &major_stats;
640 sgen_major_collector_iterate_live_block_ranges (count_marked_cards);
641 cur_stats = &los_stats;
642 sgen_los_iterate_live_block_ranges (count_marked_cards);
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_remarked_cards);
648 printf ("cards major (t %d m %d r %d) los (t %d m %d r %d) major_scan %.2fms los_scan %.2fms\n",
649 major_stats.total, major_stats.marked, major_stats.remarked,
650 los_stats.total, los_stats.marked, los_stats.remarked,
651 last_major_scan_time / 1000.0, last_los_scan_time / 1000.0);
657 sgen_card_table_init (SgenRemeberedSet *remset)
659 sgen_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, TRUE);
661 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
662 sgen_shadow_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, TRUE);
665 #ifdef HEAVY_STATISTICS
666 mono_counters_register ("marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &marked_cards);
667 mono_counters_register ("scanned cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_cards);
668 mono_counters_register ("remarked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &remarked_cards);
670 mono_counters_register ("los marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_marked_cards);
671 mono_counters_register ("los array cards scanned ", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_cards);
672 mono_counters_register ("los array remsets", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_remsets);
673 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_objects);
674 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &large_objects);
675 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &bloby_objects);
677 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_TIME_INTERVAL, &major_card_scan_time);
678 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_TIME_INTERVAL, &los_card_scan_time);
681 remset->wbarrier_set_field = sgen_card_table_wbarrier_set_field;
682 remset->wbarrier_set_arrayref = sgen_card_table_wbarrier_set_arrayref;
683 remset->wbarrier_arrayref_copy = sgen_card_table_wbarrier_arrayref_copy;
684 remset->wbarrier_value_copy = sgen_card_table_wbarrier_value_copy;
685 remset->wbarrier_object_copy = sgen_card_table_wbarrier_object_copy;
686 remset->wbarrier_generic_nostore = sgen_card_table_wbarrier_generic_nostore;
687 remset->record_pointer = sgen_card_table_record_pointer;
689 remset->finish_scan_remsets = sgen_card_table_finish_scan_remsets;
691 remset->finish_minor_collection = sgen_card_table_finish_minor_collection;
692 remset->prepare_for_major_collection = sgen_card_table_prepare_for_major_collection;
694 remset->find_address = sgen_card_table_find_address;
700 sgen_card_table_mark_address (mword address)
702 g_assert_not_reached ();
706 sgen_card_table_mark_range (mword address, mword size)
708 g_assert_not_reached ();
712 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
719 #endif /*HAVE_SGEN_GC*/