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 /*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 mono_sgen_card_table_wbarrier_set_field (MonoObject *obj, gpointer field_ptr, MonoObject* value)
85 *(void**)field_ptr = value;
86 if (mono_sgen_ptr_in_nursery (value))
87 sgen_card_table_mark_address ((mword)field_ptr);
88 mono_sgen_dummy_use (value);
92 mono_sgen_card_table_wbarrier_set_arrayref (MonoArray *arr, gpointer slot_ptr, MonoObject* value)
94 *(void**)slot_ptr = value;
95 if (mono_sgen_ptr_in_nursery (value))
96 sgen_card_table_mark_address ((mword)slot_ptr);
97 mono_sgen_dummy_use (value);
101 mono_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 (mono_sgen_ptr_in_nursery (value))
116 sgen_card_table_mark_address ((mword)dest);
117 mono_sgen_dummy_use (value);
120 gpointer *end = dest + count;
121 for (; dest < end; ++src, ++dest) {
122 gpointer value = *src;
124 if (mono_sgen_ptr_in_nursery (value))
125 sgen_card_table_mark_address ((mword)dest);
126 mono_sgen_dummy_use (value);
132 mono_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 mono_sgen_card_table_wbarrier_object_copy (MonoObject* obj, MonoObject *src)
158 size = mono_object_class (obj)->instance_size;
160 #ifdef DISABLE_CRITICAL_REGION
163 ENTER_CRITICAL_REGION;
165 mono_gc_memmove ((char*)obj + sizeof (MonoObject), (char*)src + sizeof (MonoObject),
166 size - sizeof (MonoObject));
167 sgen_card_table_mark_range ((mword)obj, size);
168 #ifdef DISABLE_CRITICAL_REGION
171 EXIT_CRITICAL_REGION;
176 mono_sgen_card_table_wbarrier_generic_nostore (gpointer ptr)
178 sgen_card_table_mark_address ((mword)ptr);
181 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
183 guint8 *sgen_shadow_cardtable;
185 #define SGEN_SHADOW_CARDTABLE_END (sgen_shadow_cardtable + CARD_COUNT_IN_BYTES)
186 #define SGEN_CARDTABLE_END (sgen_cardtable + CARD_COUNT_IN_BYTES)
189 sgen_card_table_region_begin_scanning (mword start, mword end)
191 /*XXX this can be improved to work on words and have a single loop induction var */
192 while (start <= end) {
193 if (sgen_card_table_card_begin_scanning (start))
195 start += CARD_SIZE_IN_BYTES;
203 sgen_card_table_region_begin_scanning (mword start, mword size)
205 gboolean res = FALSE;
206 guint8 *card = sgen_card_table_get_card_address (start);
207 guint8 *end = card + cards_in_range (start, size);
209 /*XXX this can be improved to work on words and have a branchless body */
210 while (card != end) {
217 memset (sgen_card_table_get_card_address (start), 0, size >> CARD_BITS);
224 /*FIXME this assumes that major blocks are multiple of 4K which is pretty reasonable */
226 sgen_card_table_get_card_data (guint8 *data_dest, mword address, mword cards)
228 mword *start = (mword*)sgen_card_table_get_card_scan_address (address);
229 mword *dest = (mword*)data_dest;
230 mword *end = (mword*)(data_dest + cards);
233 for (; dest < end; ++dest, ++start) {
238 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
247 sgen_card_table_align_pointer (void *ptr)
249 return (void*)((mword)ptr & ~(CARD_SIZE_IN_BYTES - 1));
253 sgen_card_table_mark_range (mword address, mword size)
255 memset (sgen_card_table_get_card_address (address), 1, cards_in_range (address, size));
259 sgen_card_table_is_range_marked (guint8 *cards, mword address, mword size)
261 guint8 *end = cards + cards_in_range (address, size);
263 /*This is safe since this function is only called by code that only passes continuous card blocks*/
264 while (cards != end) {
273 sgen_card_table_init (void)
275 sgen_cardtable = mono_sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, TRUE);
277 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
278 sgen_shadow_cardtable = mono_sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, TRUE);
281 #ifdef HEAVY_STATISTICS
282 mono_counters_register ("marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &marked_cards);
283 mono_counters_register ("scanned cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_cards);
284 mono_counters_register ("remarked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &remarked_cards);
286 mono_counters_register ("los marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_marked_cards);
287 mono_counters_register ("los array cards scanned ", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_cards);
288 mono_counters_register ("los array remsets", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_remsets);
289 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_objects);
290 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &large_objects);
291 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &bloby_objects);
293 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_LONG, &major_card_scan_time);
294 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_card_scan_time);
297 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
300 move_cards_to_shadow_table (mword start, mword size)
302 guint8 *from = sgen_card_table_get_card_address (start);
303 guint8 *to = sgen_card_table_get_shadow_card_address (start);
304 size_t bytes = cards_in_range (start, size);
306 if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
307 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
308 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
310 memcpy (to, from, first_chunk);
311 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
313 memcpy (to, from, bytes);
318 clear_cards (mword start, mword size)
320 guint8 *addr = sgen_card_table_get_card_address (start);
321 size_t bytes = cards_in_range (start, size);
323 if (addr + bytes > SGEN_CARDTABLE_END) {
324 size_t first_chunk = SGEN_CARDTABLE_END - addr;
326 memset (addr, 0, first_chunk);
327 memset (sgen_cardtable, 0, bytes - first_chunk);
329 memset (addr, 0, bytes);
337 clear_cards (mword start, mword size)
339 memset (sgen_card_table_get_card_address (start), 0, cards_in_range (start, size));
346 sgen_card_table_clear (void)
348 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
349 sgen_major_collector_iterate_live_block_ranges (clear_cards);
350 mono_sgen_los_iterate_live_block_ranges (clear_cards);
354 sgen_scan_from_card_tables (void *start_nursery, void *end_nursery, SgenGrayQueue *queue)
356 SGEN_TV_DECLARE (atv);
357 SGEN_TV_DECLARE (btv);
359 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
360 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
362 sgen_major_collector_iterate_live_block_ranges (move_cards_to_shadow_table);
363 mono_sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
366 sgen_card_table_clear ();
368 SGEN_TV_GETTIME (atv);
369 sgen_major_collector_scan_card_table (queue);
370 SGEN_TV_GETTIME (btv);
371 last_major_scan_time = SGEN_TV_ELAPSED_MS (atv, btv);
372 major_card_scan_time += last_major_scan_time;
373 mono_sgen_los_scan_card_table (queue);
374 SGEN_TV_GETTIME (atv);
375 last_los_scan_time = SGEN_TV_ELAPSED_MS (btv, atv);
376 los_card_scan_time += last_los_scan_time;
380 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
385 *shift_bits = CARD_BITS;
386 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
387 *mask = (gpointer)CARD_MASK;
392 return sgen_cardtable;
397 collect_faulted_cards (void)
399 #define CARD_PAGES (CARD_COUNT_IN_BYTES / 4096)
401 unsigned char faulted [CARD_PAGES] = { 0 };
402 mincore (sgen_cardtable, CARD_COUNT_IN_BYTES, faulted);
404 for (i = 0; i < CARD_PAGES; ++i) {
409 printf ("TOTAL card pages %d faulted %d\n", CARD_PAGES, count);
413 sgen_card_table_dump_obj_card (char *object, size_t size, void *dummy)
415 guint8 *start = sgen_card_table_get_card_scan_address (object);
416 guint8 *end = start + cards_in_range (object, size);
418 printf ("--obj %p %d cards [%p %p]--", object, size, start, end);
419 for (; start < end; ++start) {
421 printf ("\n\t[%p] ", start);
422 printf ("%x ", *start);
431 #define MWORD_MASK (sizeof (mword) - 1)
434 find_card_offset (mword card)
436 /*XXX Use assembly as this generates some pretty bad code */
437 #if defined(__i386__) && defined(__GNUC__)
438 return (__builtin_ffs (card) - 1) / 8;
439 #elif defined(__x86_64__) && defined(__GNUC__)
440 return (__builtin_ffsll (card) - 1) / 8;
441 #elif defined(__s390x__)
442 return (__builtin_ffsll (GUINT64_TO_LE(card)) - 1) / 8;
445 guint8 *ptr = (guint *) &card;
446 for (i = 0; i < sizeof (mword); ++i) {
455 find_next_card (guint8 *card_data, guint8 *end)
457 mword *cards, *cards_end;
460 while ((((mword)card_data) & MWORD_MASK) && card_data < end) {
466 if (card_data == end)
469 cards = (mword*)card_data;
470 cards_end = (mword*)((mword)end & ~MWORD_MASK);
471 while (cards < cards_end) {
474 return (guint8*)cards + find_card_offset (card);
478 card_data = (guint8*)cards_end;
479 while (card_data < end) {
489 sgen_cardtable_scan_object (char *obj, mword block_obj_size, guint8 *cards, SgenGrayQueue *queue)
491 MonoVTable *vt = (MonoVTable*)SGEN_LOAD_VTABLE (obj);
492 MonoClass *klass = vt->klass;
493 CopyOrMarkObjectFunc copy_func = mono_sgen_get_copy_object ();
494 ScanObjectFunc scan_object_func = mono_sgen_get_minor_scan_object ();
495 ScanVTypeFunc scan_vtype_func = mono_sgen_get_minor_scan_vtype ();
497 HEAVY_STAT (++large_objects);
499 if (!SGEN_VTABLE_HAS_REFERENCES (vt))
503 guint8 *card_data, *card_base;
504 guint8 *card_data_end;
505 char *obj_start = sgen_card_table_align_pointer (obj);
506 mword obj_size = mono_sgen_par_object_get_size (vt, (MonoObject*)obj);
507 char *obj_end = obj + obj_size;
511 MonoArray *arr = (MonoArray*)obj;
512 mword desc = (mword)klass->element_class->gc_descr;
513 int elem_size = mono_array_element_size (klass);
515 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
516 guint8 *overflow_scan_end = NULL;
522 card_data = sgen_card_table_get_card_scan_address ((mword)obj);
524 card_base = card_data;
525 card_count = cards_in_range ((mword)obj, obj_size);
526 card_data_end = card_data + card_count;
529 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
530 /*Check for overflow and if so, setup to scan in two steps*/
531 if (!cards && card_data_end >= SGEN_SHADOW_CARDTABLE_END) {
532 overflow_scan_end = sgen_shadow_cardtable + (card_data_end - SGEN_SHADOW_CARDTABLE_END);
533 card_data_end = SGEN_SHADOW_CARDTABLE_END;
539 card_data = find_next_card (card_data, card_data_end);
540 for (; card_data < card_data_end; card_data = find_next_card (card_data + 1, card_data_end)) {
542 int idx = (card_data - card_base) + extra_idx;
543 char *start = (char*)(obj_start + idx * CARD_SIZE_IN_BYTES);
544 char *card_end = start + CARD_SIZE_IN_BYTES;
547 HEAVY_STAT (++los_marked_cards);
550 sgen_card_table_prepare_card_for_scanning (card_data);
552 card_end = MIN (card_end, obj_end);
554 if (start <= (char*)arr->vector)
557 index = ARRAY_OBJ_INDEX (start, obj, elem_size);
559 elem = (char*)mono_array_addr_with_size ((MonoArray*)obj, elem_size, index);
560 if (klass->element_class->valuetype) {
561 for (; elem < card_end; elem += elem_size)
562 scan_vtype_func (elem, desc, queue);
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 (mono_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 (mono_sgen_ptr_in_nursery (new)))
572 mono_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 scan_object_func (obj, queue);
593 } else if (sgen_card_table_region_begin_scanning ((mword)obj, block_obj_size)) {
594 scan_object_func (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 mono_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 mono_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 %lld los_scan %lld\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, last_los_scan_time);
660 sgen_card_table_mark_address (mword address)
662 g_assert_not_reached ();
666 sgen_card_table_mark_range (mword address, mword size)
668 g_assert_not_reached ();
672 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
679 #endif /*HAVE_SGEN_GC*/