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.
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32 #ifdef SGEN_HAVE_CARDTABLE
34 //#define CARDTABLE_STATS
37 #ifdef HAVE_SYS_MMAN_H
40 #include <sys/types.h>
42 guint8 *sgen_cardtable;
45 #ifdef HEAVY_STATISTICS
46 long long marked_cards;
47 long long scanned_cards;
48 long long scanned_objects;
50 static long long los_marked_cards;
51 static long long large_objects;
52 static long long bloby_objects;
53 static long long los_array_cards;
54 static long long los_array_remsets;
57 static long long major_card_scan_time;
58 static long long los_card_scan_time;
60 static long long last_major_scan_time;
61 static long long last_los_scan_time;
62 /*WARNING: This function returns the number of cards regardless of overflow in case of overlapping cards.*/
64 cards_in_range (mword address, mword size)
66 mword end = address + MAX (1, size) - 1;
67 return (end >> CARD_BITS) - (address >> CARD_BITS) + 1;
70 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
72 guint8 *sgen_shadow_cardtable;
74 #define SGEN_SHADOW_CARDTABLE_END (sgen_shadow_cardtable + CARD_COUNT_IN_BYTES)
75 #define SGEN_CARDTABLE_END (sgen_cardtable + CARD_COUNT_IN_BYTES)
78 sgen_card_table_region_begin_scanning (mword start, mword end)
80 /*XXX this can be improved to work on words and have a single loop induction var */
81 while (start <= end) {
82 if (sgen_card_table_card_begin_scanning (start))
84 start += CARD_SIZE_IN_BYTES;
92 sgen_card_table_region_begin_scanning (mword start, mword size)
95 guint8 *card = sgen_card_table_get_card_address (start);
96 guint8 *end = card + cards_in_range (start, size);
98 /*XXX this can be improved to work on words and have a branchless body */
106 memset (sgen_card_table_get_card_address (start), 0, size >> CARD_BITS);
113 /*FIXME this assumes that major blocks are multiple of 4K which is pretty reasonable */
115 sgen_card_table_get_card_data (guint8 *data_dest, mword address, mword cards)
117 mword *start = (mword*)sgen_card_table_get_card_scan_address (address);
118 mword *dest = (mword*)data_dest;
119 mword *end = (mword*)(data_dest + cards);
122 for (; dest < end; ++dest, ++start) {
127 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
136 sgen_card_table_address_is_marked (mword address)
138 return *sgen_card_table_get_card_address (address) != 0;
142 sgen_card_table_mark_address (mword address)
144 *sgen_card_table_get_card_address (address) = 1;
148 sgen_card_table_align_pointer (void *ptr)
150 return (void*)((mword)ptr & ~(CARD_SIZE_IN_BYTES - 1));
154 sgen_card_table_mark_range (mword address, mword size)
156 mword end = address + size;
158 sgen_card_table_mark_address (address);
159 address += CARD_SIZE_IN_BYTES;
160 } while (address < end);
164 sgen_card_table_is_range_marked (guint8 *cards, mword address, mword size)
166 guint8 *end = cards + cards_in_range (address, size);
168 /*This is safe since this function is only called by code that only passes continuous card blocks*/
169 while (cards != end) {
178 card_table_init (void)
180 sgen_cardtable = mono_sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, TRUE);
182 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
183 sgen_shadow_cardtable = mono_sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, TRUE);
186 #ifdef HEAVY_STATISTICS
187 mono_counters_register ("marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &marked_cards);
188 mono_counters_register ("scanned cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_cards);
189 mono_counters_register ("los marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_marked_cards);
190 mono_counters_register ("los array cards scanned ", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_cards);
191 mono_counters_register ("los array remsets", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_remsets);
192 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_objects);
193 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &large_objects);
194 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &bloby_objects);
196 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_LONG, &major_card_scan_time);
197 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_card_scan_time);
200 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
203 move_cards_to_shadow_table (mword start, mword size)
205 guint8 *from = sgen_card_table_get_card_address (start);
206 guint8 *to = sgen_card_table_get_shadow_card_address (start);
207 size_t bytes = cards_in_range (start, size);
209 if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
210 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
211 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
213 memcpy (to, from, first_chunk);
214 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
216 memcpy (to, from, bytes);
221 clear_cards (mword start, mword size)
223 guint8 *addr = sgen_card_table_get_card_address (start);
224 size_t bytes = cards_in_range (start, size);
226 if (addr + bytes > SGEN_CARDTABLE_END) {
227 size_t first_chunk = SGEN_CARDTABLE_END - addr;
229 memset (addr, 0, first_chunk);
230 memset (sgen_cardtable, 0, bytes - first_chunk);
232 memset (addr, 0, bytes);
240 clear_cards (mword start, mword size)
242 memset (sgen_card_table_get_card_address (start), 0, cards_in_range (start, size));
249 card_table_clear (void)
251 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
253 major_collector.iterate_live_block_ranges (clear_cards);
254 mono_sgen_los_iterate_live_block_ranges (clear_cards);
258 scan_from_card_tables (void *start_nursery, void *end_nursery, GrayQueue *queue)
264 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
265 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
267 major_collector.iterate_live_block_ranges (move_cards_to_shadow_table);
268 mono_sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
274 major_collector.scan_card_table (queue);
276 last_major_scan_time = TV_ELAPSED_MS (atv, btv);
277 major_card_scan_time += last_major_scan_time;
278 mono_sgen_los_scan_card_table (queue);
280 last_los_scan_time = TV_ELAPSED_MS (btv, atv);
281 los_card_scan_time += last_los_scan_time;
286 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
291 g_assert (sgen_cardtable);
292 *shift_bits = CARD_BITS;
293 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
294 *mask = (gpointer)CARD_MASK;
299 return sgen_cardtable;
304 collect_faulted_cards (void)
306 #define CARD_PAGES (CARD_COUNT_IN_BYTES / 4096)
308 unsigned char faulted [CARD_PAGES] = { 0 };
309 mincore (sgen_cardtable, CARD_COUNT_IN_BYTES, faulted);
311 for (i = 0; i < CARD_PAGES; ++i) {
316 printf ("TOTAL card pages %d faulted %d\n", CARD_PAGES, count);
320 #define MWORD_MASK (sizeof (mword) - 1)
323 find_card_offset (mword card)
325 /*XXX Use assembly as this generates some pretty bad code */
326 #if defined(__i386__) && defined(__GNUC__)
327 return (__builtin_ffs (card) - 1) / 8;
328 #elif defined(__x86_64__) && defined(__GNUC__)
329 return (__builtin_ffsll (card) - 1) / 8;
330 #elif defined(__s390x__)
331 return (__builtin_ffsll (GUINT64_TO_LE(card)) - 1) / 8;
334 g_assert_not_reached ();
337 guint8 *ptr = (guint *) &card;
338 for (i = 0; i < sizeof (mword); ++i) {
348 find_next_card (guint8 *card_data, guint8 *end)
350 mword *cards, *cards_end;
353 while ((((mword)card_data) & MWORD_MASK) && card_data < end) {
359 if (card_data == end)
362 cards = (mword*)card_data;
363 cards_end = (mword*)((mword)end & ~MWORD_MASK);
364 while (cards < cards_end) {
367 return (guint8*)cards + find_card_offset (card);
371 card_data = (guint8*)cards_end;
372 while (card_data < end) {
382 sgen_cardtable_scan_object (char *obj, mword block_obj_size, guint8 *cards, SgenGrayQueue *queue)
384 MonoVTable *vt = (MonoVTable*)LOAD_VTABLE (obj);
385 MonoClass *klass = vt->klass;
386 CopyOrMarkObjectFunc copy_func = mono_sgen_get_copy_object ();
387 ScanObjectFunc scan_object_func = mono_sgen_get_minor_scan_object ();
388 ScanVTypeFunc scan_vtype_func = mono_sgen_get_minor_scan_vtype ();
390 HEAVY_STAT (++large_objects);
392 if (!SGEN_VTABLE_HAS_REFERENCES (vt))
396 guint8 *card_data, *card_base;
397 guint8 *card_data_end;
398 char *obj_start = sgen_card_table_align_pointer (obj);
399 mword obj_size = mono_sgen_par_object_get_size (vt, (MonoObject*)obj);
400 char *obj_end = obj + obj_size;
404 MonoArray *arr = (MonoArray*)obj;
405 mword desc = (mword)klass->element_class->gc_descr;
406 int elem_size = mono_array_element_size (klass);
408 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
409 guint8 *overflow_scan_end = NULL;
415 card_data = sgen_card_table_get_card_scan_address ((mword)obj);
417 card_base = card_data;
418 card_count = cards_in_range ((mword)obj, obj_size);
419 card_data_end = card_data + card_count;
422 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
423 /*Check for overflow and if so, setup to scan in two steps*/
424 if (!cards && card_data_end >= SGEN_SHADOW_CARDTABLE_END) {
425 overflow_scan_end = sgen_shadow_cardtable + (card_data_end - SGEN_SHADOW_CARDTABLE_END);
426 card_data_end = SGEN_SHADOW_CARDTABLE_END;
432 card_data = find_next_card (card_data, card_data_end);
433 for (; card_data < card_data_end; card_data = find_next_card (card_data + 1, card_data_end)) {
435 int idx = (card_data - card_base) + extra_idx;
436 char *start = (char*)(obj_start + idx * CARD_SIZE_IN_BYTES);
437 char *card_end = start + CARD_SIZE_IN_BYTES;
440 HEAVY_STAT (++los_marked_cards);
443 sgen_card_table_prepare_card_for_scanning (card_data);
445 card_end = MIN (card_end, obj_end);
447 if (start <= (char*)arr->vector)
450 index = ARRAY_OBJ_INDEX (start, obj, elem_size);
452 elem = (char*)mono_array_addr_with_size ((MonoArray*)obj, elem_size, index);
453 if (klass->element_class->valuetype) {
454 for (; elem < card_end; elem += elem_size)
455 scan_vtype_func (elem, desc, queue);
457 HEAVY_STAT (++los_array_cards);
458 for (; elem < card_end; elem += SIZEOF_VOID_P) {
459 gpointer new, old = *(gpointer*)elem;
460 if (G_UNLIKELY (ptr_in_nursery (old))) {
461 HEAVY_STAT (++los_array_remsets);
462 copy_func ((void**)elem, queue);
463 new = *(gpointer*)elem;
464 if (G_UNLIKELY (ptr_in_nursery (new)))
465 mono_sgen_add_to_global_remset (elem);
471 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
472 if (overflow_scan_end) {
473 extra_idx = card_data - card_base;
474 card_base = card_data = sgen_shadow_cardtable;
475 card_data_end = overflow_scan_end;
476 overflow_scan_end = NULL;
482 HEAVY_STAT (++bloby_objects);
484 if (sgen_card_table_is_range_marked (cards, (mword)obj, block_obj_size))
485 scan_object_func (obj, queue);
486 } else if (sgen_card_table_region_begin_scanning ((mword)obj, block_obj_size)) {
487 scan_object_func (obj, queue);
492 #ifdef CARDTABLE_STATS
495 int total, marked, remarked;
498 static card_stats major_stats, los_stats;
499 static card_stats *cur_stats;
502 count_marked_cards (mword start, mword size)
504 mword end = start + size;
505 while (start <= end) {
507 if (sgen_card_table_address_is_marked (start))
509 start += CARD_SIZE_IN_BYTES;
514 count_remarked_cards (mword start, mword size)
516 mword end = start + size;
517 while (start <= end) {
518 if (sgen_card_table_address_is_marked (start))
519 ++cur_stats->remarked;
520 start += CARD_SIZE_IN_BYTES;
527 card_tables_collect_stats (gboolean begin)
529 #ifdef CARDTABLE_STATS
531 memset (&major_stats, 0, sizeof (card_stats));
532 memset (&los_stats, 0, sizeof (card_stats));
533 cur_stats = &major_stats;
534 major_collector.iterate_live_block_ranges (count_marked_cards);
535 cur_stats = &los_stats;
536 mono_sgen_los_iterate_live_block_ranges (count_marked_cards);
538 cur_stats = &major_stats;
539 major_collector.iterate_live_block_ranges (count_marked_cards);
540 cur_stats = &los_stats;
541 mono_sgen_los_iterate_live_block_ranges (count_remarked_cards);
542 printf ("cards major (t %d m %d r %d) los (t %d m %d r %d) major_scan %lld los_scan %lld\n",
543 major_stats.total, major_stats.marked, major_stats.remarked,
544 los_stats.total, los_stats.marked, los_stats.remarked,
545 last_major_scan_time, last_los_scan_time);
553 sgen_card_table_mark_address (mword address)
555 g_assert_not_reached ();
559 sgen_card_table_mark_range (mword address, mword size)
561 g_assert_not_reached ();
564 #define sgen_card_table_address_is_marked(p) FALSE
565 #define scan_from_card_tables(start,end,queue)
566 #define card_table_clear()
567 #define card_table_init()
568 #define card_tables_collect_stats(begin)
571 mono_gc_get_card_table (int *shift_bits, gpointer *mask)