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)
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33 #ifdef SGEN_HAVE_CARDTABLE
35 //#define CARDTABLE_STATS
38 #ifdef HAVE_SYS_MMAN_H
41 #include <sys/types.h>
43 guint8 *sgen_cardtable;
46 #ifdef HEAVY_STATISTICS
47 long long marked_cards;
48 long long scanned_cards;
49 long long scanned_objects;
51 static long long los_marked_cards;
52 static long long large_objects;
53 static long long bloby_objects;
54 static long long los_array_cards;
55 static long long los_array_remsets;
58 static long long major_card_scan_time;
59 static long long los_card_scan_time;
61 static long long last_major_scan_time;
62 static long long last_los_scan_time;
63 /*WARNING: This function returns the number of cards regardless of overflow in case of overlapping cards.*/
65 cards_in_range (mword address, mword size)
67 mword end = address + MAX (1, size) - 1;
68 return (end >> CARD_BITS) - (address >> CARD_BITS) + 1;
71 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
73 guint8 *sgen_shadow_cardtable;
75 #define SGEN_SHADOW_CARDTABLE_END (sgen_shadow_cardtable + CARD_COUNT_IN_BYTES)
76 #define SGEN_CARDTABLE_END (sgen_cardtable + CARD_COUNT_IN_BYTES)
79 sgen_card_table_region_begin_scanning (mword start, mword end)
81 /*XXX this can be improved to work on words and have a single loop induction var */
82 while (start <= end) {
83 if (sgen_card_table_card_begin_scanning (start))
85 start += CARD_SIZE_IN_BYTES;
93 sgen_card_table_region_begin_scanning (mword start, mword size)
96 guint8 *card = sgen_card_table_get_card_address (start);
97 guint8 *end = card + cards_in_range (start, size);
99 /*XXX this can be improved to work on words and have a branchless body */
100 while (card != end) {
107 memset (sgen_card_table_get_card_address (start), 0, size >> CARD_BITS);
114 /*FIXME this assumes that major blocks are multiple of 4K which is pretty reasonable */
116 sgen_card_table_get_card_data (guint8 *data_dest, mword address, mword cards)
118 mword *start = (mword*)sgen_card_table_get_card_scan_address (address);
119 mword *dest = (mword*)data_dest;
120 mword *end = (mword*)(data_dest + cards);
123 for (; dest < end; ++dest, ++start) {
128 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
137 sgen_card_table_address_is_marked (mword address)
139 return *sgen_card_table_get_card_address (address) != 0;
143 sgen_card_table_mark_address (mword address)
145 *sgen_card_table_get_card_address (address) = 1;
149 sgen_card_table_align_pointer (void *ptr)
151 return (void*)((mword)ptr & ~(CARD_SIZE_IN_BYTES - 1));
155 sgen_card_table_mark_range (mword address, mword size)
157 memset (sgen_card_table_get_card_address (address), 1, cards_in_range (address, size));
161 sgen_card_table_is_range_marked (guint8 *cards, mword address, mword size)
163 guint8 *end = cards + cards_in_range (address, size);
165 /*This is safe since this function is only called by code that only passes continuous card blocks*/
166 while (cards != end) {
175 card_table_init (void)
177 sgen_cardtable = mono_sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, TRUE);
179 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
180 sgen_shadow_cardtable = mono_sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, TRUE);
183 #ifdef HEAVY_STATISTICS
184 mono_counters_register ("marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &marked_cards);
185 mono_counters_register ("scanned cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_cards);
186 mono_counters_register ("los marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_marked_cards);
187 mono_counters_register ("los array cards scanned ", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_cards);
188 mono_counters_register ("los array remsets", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_remsets);
189 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_objects);
190 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &large_objects);
191 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &bloby_objects);
193 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_LONG, &major_card_scan_time);
194 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_card_scan_time);
197 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
200 move_cards_to_shadow_table (mword start, mword size)
202 guint8 *from = sgen_card_table_get_card_address (start);
203 guint8 *to = sgen_card_table_get_shadow_card_address (start);
204 size_t bytes = cards_in_range (start, size);
206 if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
207 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
208 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
210 memcpy (to, from, first_chunk);
211 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
213 memcpy (to, from, bytes);
218 clear_cards (mword start, mword size)
220 guint8 *addr = sgen_card_table_get_card_address (start);
221 size_t bytes = cards_in_range (start, size);
223 if (addr + bytes > SGEN_CARDTABLE_END) {
224 size_t first_chunk = SGEN_CARDTABLE_END - addr;
226 memset (addr, 0, first_chunk);
227 memset (sgen_cardtable, 0, bytes - first_chunk);
229 memset (addr, 0, bytes);
237 clear_cards (mword start, mword size)
239 memset (sgen_card_table_get_card_address (start), 0, cards_in_range (start, size));
246 card_table_clear (void)
248 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
250 major_collector.iterate_live_block_ranges (clear_cards);
251 mono_sgen_los_iterate_live_block_ranges (clear_cards);
255 scan_from_card_tables (void *start_nursery, void *end_nursery, GrayQueue *queue)
261 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
262 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
264 major_collector.iterate_live_block_ranges (move_cards_to_shadow_table);
265 mono_sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
271 major_collector.scan_card_table (queue);
273 last_major_scan_time = TV_ELAPSED_MS (atv, btv);
274 major_card_scan_time += last_major_scan_time;
275 mono_sgen_los_scan_card_table (queue);
277 last_los_scan_time = TV_ELAPSED_MS (btv, atv);
278 los_card_scan_time += last_los_scan_time;
283 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
288 g_assert (sgen_cardtable);
289 *shift_bits = CARD_BITS;
290 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
291 *mask = (gpointer)CARD_MASK;
296 return sgen_cardtable;
301 collect_faulted_cards (void)
303 #define CARD_PAGES (CARD_COUNT_IN_BYTES / 4096)
305 unsigned char faulted [CARD_PAGES] = { 0 };
306 mincore (sgen_cardtable, CARD_COUNT_IN_BYTES, faulted);
308 for (i = 0; i < CARD_PAGES; ++i) {
313 printf ("TOTAL card pages %d faulted %d\n", CARD_PAGES, count);
317 sgen_card_table_dump_obj_card (char *object, size_t size, void *dummy)
319 guint8 *start = sgen_card_table_get_card_scan_address (object);
320 guint8 *end = start + cards_in_range (object, size);
322 printf ("--obj %p %d cards [%p %p]--", object, size, start, end);
323 for (; start < end; ++start) {
325 printf ("\n\t[%p] ", start);
326 printf ("%x ", *start);
335 #define MWORD_MASK (sizeof (mword) - 1)
338 find_card_offset (mword card)
340 /*XXX Use assembly as this generates some pretty bad code */
341 #if defined(__i386__) && defined(__GNUC__)
342 return (__builtin_ffs (card) - 1) / 8;
343 #elif defined(__x86_64__) && defined(__GNUC__)
344 return (__builtin_ffsll (card) - 1) / 8;
345 #elif defined(__s390x__)
346 return (__builtin_ffsll (GUINT64_TO_LE(card)) - 1) / 8;
349 g_assert_not_reached ();
352 guint8 *ptr = (guint *) &card;
353 for (i = 0; i < sizeof (mword); ++i) {
363 find_next_card (guint8 *card_data, guint8 *end)
365 mword *cards, *cards_end;
368 while ((((mword)card_data) & MWORD_MASK) && card_data < end) {
374 if (card_data == end)
377 cards = (mword*)card_data;
378 cards_end = (mword*)((mword)end & ~MWORD_MASK);
379 while (cards < cards_end) {
382 return (guint8*)cards + find_card_offset (card);
386 card_data = (guint8*)cards_end;
387 while (card_data < end) {
397 sgen_cardtable_scan_object (char *obj, mword block_obj_size, guint8 *cards, SgenGrayQueue *queue)
399 MonoVTable *vt = (MonoVTable*)LOAD_VTABLE (obj);
400 MonoClass *klass = vt->klass;
401 CopyOrMarkObjectFunc copy_func = mono_sgen_get_copy_object ();
402 ScanObjectFunc scan_object_func = mono_sgen_get_minor_scan_object ();
403 ScanVTypeFunc scan_vtype_func = mono_sgen_get_minor_scan_vtype ();
405 HEAVY_STAT (++large_objects);
407 if (!SGEN_VTABLE_HAS_REFERENCES (vt))
411 guint8 *card_data, *card_base;
412 guint8 *card_data_end;
413 char *obj_start = sgen_card_table_align_pointer (obj);
414 mword obj_size = mono_sgen_par_object_get_size (vt, (MonoObject*)obj);
415 char *obj_end = obj + obj_size;
419 MonoArray *arr = (MonoArray*)obj;
420 mword desc = (mword)klass->element_class->gc_descr;
421 int elem_size = mono_array_element_size (klass);
423 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
424 guint8 *overflow_scan_end = NULL;
430 card_data = sgen_card_table_get_card_scan_address ((mword)obj);
432 card_base = card_data;
433 card_count = cards_in_range ((mword)obj, obj_size);
434 card_data_end = card_data + card_count;
437 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
438 /*Check for overflow and if so, setup to scan in two steps*/
439 if (!cards && card_data_end >= SGEN_SHADOW_CARDTABLE_END) {
440 overflow_scan_end = sgen_shadow_cardtable + (card_data_end - SGEN_SHADOW_CARDTABLE_END);
441 card_data_end = SGEN_SHADOW_CARDTABLE_END;
447 card_data = find_next_card (card_data, card_data_end);
448 for (; card_data < card_data_end; card_data = find_next_card (card_data + 1, card_data_end)) {
450 int idx = (card_data - card_base) + extra_idx;
451 char *start = (char*)(obj_start + idx * CARD_SIZE_IN_BYTES);
452 char *card_end = start + CARD_SIZE_IN_BYTES;
455 HEAVY_STAT (++los_marked_cards);
458 sgen_card_table_prepare_card_for_scanning (card_data);
460 card_end = MIN (card_end, obj_end);
462 if (start <= (char*)arr->vector)
465 index = ARRAY_OBJ_INDEX (start, obj, elem_size);
467 elem = (char*)mono_array_addr_with_size ((MonoArray*)obj, elem_size, index);
468 if (klass->element_class->valuetype) {
469 for (; elem < card_end; elem += elem_size)
470 scan_vtype_func (elem, desc, queue);
472 HEAVY_STAT (++los_array_cards);
473 for (; elem < card_end; elem += SIZEOF_VOID_P) {
474 gpointer new, old = *(gpointer*)elem;
475 if (G_UNLIKELY (ptr_in_nursery (old))) {
476 HEAVY_STAT (++los_array_remsets);
477 copy_func ((void**)elem, queue);
478 new = *(gpointer*)elem;
479 if (G_UNLIKELY (ptr_in_nursery (new)))
480 mono_sgen_add_to_global_remset (elem);
486 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
487 if (overflow_scan_end) {
488 extra_idx = card_data - card_base;
489 card_base = card_data = sgen_shadow_cardtable;
490 card_data_end = overflow_scan_end;
491 overflow_scan_end = NULL;
497 HEAVY_STAT (++bloby_objects);
499 if (sgen_card_table_is_range_marked (cards, (mword)obj, block_obj_size))
500 scan_object_func (obj, queue);
501 } else if (sgen_card_table_region_begin_scanning ((mword)obj, block_obj_size)) {
502 scan_object_func (obj, queue);
507 #ifdef CARDTABLE_STATS
510 int total, marked, remarked;
513 static card_stats major_stats, los_stats;
514 static card_stats *cur_stats;
517 count_marked_cards (mword start, mword size)
519 mword end = start + size;
520 while (start <= end) {
522 if (sgen_card_table_address_is_marked (start))
524 start += CARD_SIZE_IN_BYTES;
529 count_remarked_cards (mword start, mword size)
531 mword end = start + size;
532 while (start <= end) {
533 if (sgen_card_table_address_is_marked (start))
534 ++cur_stats->remarked;
535 start += CARD_SIZE_IN_BYTES;
542 card_tables_collect_stats (gboolean begin)
544 #ifdef CARDTABLE_STATS
546 memset (&major_stats, 0, sizeof (card_stats));
547 memset (&los_stats, 0, sizeof (card_stats));
548 cur_stats = &major_stats;
549 major_collector.iterate_live_block_ranges (count_marked_cards);
550 cur_stats = &los_stats;
551 mono_sgen_los_iterate_live_block_ranges (count_marked_cards);
553 cur_stats = &major_stats;
554 major_collector.iterate_live_block_ranges (count_marked_cards);
555 cur_stats = &los_stats;
556 mono_sgen_los_iterate_live_block_ranges (count_remarked_cards);
557 printf ("cards major (t %d m %d r %d) los (t %d m %d r %d) major_scan %lld los_scan %lld\n",
558 major_stats.total, major_stats.marked, major_stats.remarked,
559 los_stats.total, los_stats.marked, los_stats.remarked,
560 last_major_scan_time, last_los_scan_time);
568 sgen_card_table_mark_address (mword address)
570 g_assert_not_reached ();
574 sgen_card_table_mark_range (mword address, mword size)
576 g_assert_not_reached ();
579 #define sgen_card_table_address_is_marked(p) FALSE
580 #define scan_from_card_tables(start,end,queue)
581 #define card_table_clear()
582 #define card_table_init()
583 #define card_tables_collect_stats(begin)
586 mono_gc_get_card_table (int *shift_bits, gpointer *mask)