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.
12 * Permission is hereby granted, free of charge, to any person obtaining
13 * a copy of this software and associated documentation files (the
14 * "Software"), to deal in the Software without restriction, including
15 * without limitation the rights to use, copy, modify, merge, publish,
16 * distribute, sublicense, and/or sell copies of the Software, and to
17 * permit persons to whom the Software is furnished to do so, subject to
18 * the following conditions:
20 * The above copyright notice and this permission notice shall be
21 * included in all copies or substantial portions of the Software.
23 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
24 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
25 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
26 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
27 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
28 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
29 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
32 #ifdef SGEN_HAVE_CARDTABLE
34 //#define CARDTABLE_STATS
38 #include <sys/types.h>
40 guint8 *sgen_cardtable;
43 #ifdef HEAVY_STATISTICS
44 long long marked_cards;
45 long long scanned_cards;
46 long long scanned_objects;
48 static long long los_marked_cards;
49 static long long large_objects;
50 static long long bloby_objects;
51 static long long los_array_cards;
52 static long long los_array_remsets;
55 static long long major_card_scan_time;
56 static long long los_card_scan_time;
58 static long long last_major_scan_time;
59 static long long last_los_scan_time;
60 /*WARNING: This function returns the number of cards regardless of overflow in case of overlapping cards.*/
62 cards_in_range (mword address, mword size)
64 mword end = address + MAX (1, size) - 1;
65 return (end >> CARD_BITS) - (address >> CARD_BITS) + 1;
68 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
70 guint8 *sgen_shadow_cardtable;
72 #define SGEN_SHADOW_CARDTABLE_END (sgen_shadow_cardtable + CARD_COUNT_IN_BYTES)
73 #define SGEN_CARDTABLE_END (sgen_cardtable + CARD_COUNT_IN_BYTES)
76 sgen_card_table_region_begin_scanning (mword start, mword end)
78 /*XXX this can be improved to work on words and have a single loop induction var */
79 while (start <= end) {
80 if (sgen_card_table_card_begin_scanning (start))
82 start += CARD_SIZE_IN_BYTES;
90 sgen_card_table_region_begin_scanning (mword start, mword size)
93 guint8 *card = sgen_card_table_get_card_address (start);
94 guint8 *end = card + cards_in_range (start, size);
96 /*XXX this can be improved to work on words and have a branchless body */
104 memset (sgen_card_table_get_card_address (start), 0, size >> CARD_BITS);
111 /*FIXME this assumes that major blocks are multiple of 4K which is pretty reasonable */
113 sgen_card_table_get_card_data (guint8 *data_dest, mword address, mword cards)
115 mword *start = (mword*)sgen_card_table_get_card_scan_address (address);
116 mword *dest = (mword*)data_dest;
117 mword *end = (mword*)(data_dest + cards);
120 for (; dest < end; ++dest, ++start) {
125 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
134 sgen_card_table_address_is_marked (mword address)
136 return *sgen_card_table_get_card_address (address) != 0;
140 sgen_card_table_mark_address (mword address)
142 *sgen_card_table_get_card_address (address) = 1;
146 sgen_card_table_align_pointer (void *ptr)
148 return (void*)((mword)ptr & ~(CARD_SIZE_IN_BYTES - 1));
152 sgen_card_table_mark_range (mword address, mword size)
154 mword end = address + size;
156 sgen_card_table_mark_address (address);
157 address += CARD_SIZE_IN_BYTES;
158 } while (address < end);
162 sgen_card_table_is_range_marked (guint8 *cards, mword address, mword size)
164 guint8 *end = cards + cards_in_range (address, size);
166 /*This is safe since this function is only called by code that only passes continuous card blocks*/
167 while (cards != end) {
176 card_table_init (void)
178 sgen_cardtable = mono_sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, TRUE);
180 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
181 sgen_shadow_cardtable = mono_sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, TRUE);
184 #ifdef HEAVY_STATISTICS
185 mono_counters_register ("marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &marked_cards);
186 mono_counters_register ("scanned cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_cards);
187 mono_counters_register ("los marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_marked_cards);
188 mono_counters_register ("los array cards scanned ", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_cards);
189 mono_counters_register ("los array remsets", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_remsets);
190 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_objects);
191 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &large_objects);
192 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &bloby_objects);
194 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_LONG, &major_card_scan_time);
195 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_card_scan_time);
198 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
201 move_cards_to_shadow_table (mword start, mword size)
203 guint8 *from = sgen_card_table_get_card_address (start);
204 guint8 *to = sgen_card_table_get_shadow_card_address (start);
205 size_t bytes = cards_in_range (start, size);
207 if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
208 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
209 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
211 memcpy (to, from, first_chunk);
212 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
214 memcpy (to, from, bytes);
219 clear_cards (mword start, mword size)
221 guint8 *addr = sgen_card_table_get_card_address (start);
222 size_t bytes = cards_in_range (start, size);
224 if (addr + bytes > SGEN_CARDTABLE_END) {
225 size_t first_chunk = SGEN_CARDTABLE_END - addr;
227 memset (addr, 0, first_chunk);
228 memset (sgen_cardtable, 0, bytes - first_chunk);
230 memset (addr, 0, bytes);
238 clear_cards (mword start, mword size)
240 memset (sgen_card_table_get_card_address (start), 0, cards_in_range (start, size));
247 card_table_clear (void)
249 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
251 major_collector.iterate_live_block_ranges (clear_cards);
252 mono_sgen_los_iterate_live_block_ranges (clear_cards);
256 scan_from_card_tables (void *start_nursery, void *end_nursery, GrayQueue *queue)
262 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
263 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
265 major_collector.iterate_live_block_ranges (move_cards_to_shadow_table);
266 mono_sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
272 major_collector.scan_card_table (queue);
274 last_major_scan_time = TV_ELAPSED_MS (atv, btv);
275 major_card_scan_time += last_major_scan_time;
276 mono_sgen_los_scan_card_table (queue);
278 last_los_scan_time = TV_ELAPSED_MS (btv, atv);
279 los_card_scan_time += last_los_scan_time;
284 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
289 g_assert (sgen_cardtable);
290 *shift_bits = CARD_BITS;
291 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
292 *mask = (gpointer)CARD_MASK;
297 return sgen_cardtable;
302 collect_faulted_cards (void)
304 #define CARD_PAGES (CARD_COUNT_IN_BYTES / 4096)
306 unsigned char faulted [CARD_PAGES] = { 0 };
307 mincore (sgen_cardtable, CARD_COUNT_IN_BYTES, faulted);
309 for (i = 0; i < CARD_PAGES; ++i) {
314 printf ("TOTAL card pages %d faulted %d\n", CARD_PAGES, count);
318 #define MWORD_MASK (sizeof (mword) - 1)
321 find_card_offset (mword card)
323 /*XXX Use assembly as this generates some pretty bad code */
324 #if defined(__i386__) && defined(__GNUC__)
325 return (__builtin_ffs (card) - 1) / 8;
326 #elif defined(__x86_64__) && defined(__GNUC__)
327 return (__builtin_ffsll (card) - 1) / 8;
328 #elif defined(__s390x__)
329 return (__builtin_ffsll (GUINT64_TO_LE(card)) - 1) / 8;
332 g_assert_not_reached ();
335 guint8 *ptr = (guint *) &card;
336 for (i = 0; i < sizeof (mword); ++i) {
346 find_next_card (guint8 *card_data, guint8 *end)
348 mword *cards, *cards_end;
351 while ((((mword)card_data) & MWORD_MASK) && card_data < end) {
357 if (card_data == end)
360 cards = (mword*)card_data;
361 cards_end = (mword*)((mword)end & ~MWORD_MASK);
362 while (cards < cards_end) {
365 return (guint8*)cards + find_card_offset (card);
369 card_data = (guint8*)cards_end;
370 while (card_data < end) {
380 sgen_cardtable_scan_object (char *obj, mword block_obj_size, guint8 *cards, SgenGrayQueue *queue)
382 MonoVTable *vt = (MonoVTable*)LOAD_VTABLE (obj);
383 MonoClass *klass = vt->klass;
384 CopyOrMarkObjectFunc copy_func = mono_sgen_get_copy_object ();
385 ScanObjectFunc scan_object_func = mono_sgen_get_minor_scan_object ();
386 ScanVTypeFunc scan_vtype_func = mono_sgen_get_minor_scan_vtype ();
388 HEAVY_STAT (++large_objects);
390 if (!SGEN_VTABLE_HAS_REFERENCES (vt))
394 guint8 *card_data, *card_base;
395 guint8 *card_data_end;
396 char *obj_start = sgen_card_table_align_pointer (obj);
397 mword obj_size = mono_sgen_par_object_get_size (vt, (MonoObject*)obj);
398 char *obj_end = obj + obj_size;
402 MonoArray *arr = (MonoArray*)obj;
403 mword desc = (mword)klass->element_class->gc_descr;
404 int elem_size = mono_array_element_size (klass);
406 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
407 guint8 *overflow_scan_end = NULL;
413 card_data = sgen_card_table_get_card_scan_address ((mword)obj);
415 card_base = card_data;
416 card_count = cards_in_range ((mword)obj, obj_size);
417 card_data_end = card_data + card_count;
420 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
421 /*Check for overflow and if so, setup to scan in two steps*/
422 if (!cards && card_data_end >= SGEN_SHADOW_CARDTABLE_END) {
423 overflow_scan_end = sgen_shadow_cardtable + (card_data_end - SGEN_SHADOW_CARDTABLE_END);
424 card_data_end = SGEN_SHADOW_CARDTABLE_END;
430 card_data = find_next_card (card_data, card_data_end);
431 for (; card_data < card_data_end; card_data = find_next_card (card_data + 1, card_data_end)) {
433 int idx = (card_data - card_base) + extra_idx;
434 char *start = (char*)(obj_start + idx * CARD_SIZE_IN_BYTES);
435 char *card_end = start + CARD_SIZE_IN_BYTES;
438 HEAVY_STAT (++los_marked_cards);
441 sgen_card_table_prepare_card_for_scanning (card_data);
443 card_end = MIN (card_end, obj_end);
445 if (start <= (char*)arr->vector)
448 index = ARRAY_OBJ_INDEX (start, obj, elem_size);
450 elem = (char*)mono_array_addr_with_size ((MonoArray*)obj, elem_size, index);
451 if (klass->element_class->valuetype) {
452 for (; elem < card_end; elem += elem_size)
453 scan_vtype_func (elem, desc, queue);
455 HEAVY_STAT (++los_array_cards);
456 for (; elem < card_end; elem += SIZEOF_VOID_P) {
457 gpointer new, old = *(gpointer*)elem;
458 if (G_UNLIKELY (ptr_in_nursery (old))) {
459 HEAVY_STAT (++los_array_remsets);
460 copy_func ((void**)elem, queue);
461 new = *(gpointer*)elem;
462 if (G_UNLIKELY (ptr_in_nursery (new)))
463 mono_sgen_add_to_global_remset (elem);
469 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
470 if (overflow_scan_end) {
471 extra_idx = card_data - card_base;
472 card_base = card_data = sgen_shadow_cardtable;
473 card_data_end = overflow_scan_end;
474 overflow_scan_end = NULL;
480 HEAVY_STAT (++bloby_objects);
482 if (sgen_card_table_is_range_marked (cards, (mword)obj, block_obj_size))
483 scan_object_func (obj, queue);
484 } else if (sgen_card_table_region_begin_scanning ((mword)obj, block_obj_size)) {
485 scan_object_func (obj, queue);
490 #ifdef CARDTABLE_STATS
493 int total, marked, remarked;
496 static card_stats major_stats, los_stats;
497 static card_stats *cur_stats;
500 count_marked_cards (mword start, mword size)
502 mword end = start + size;
503 while (start <= end) {
505 if (sgen_card_table_address_is_marked (start))
507 start += CARD_SIZE_IN_BYTES;
512 count_remarked_cards (mword start, mword size)
514 mword end = start + size;
515 while (start <= end) {
516 if (sgen_card_table_address_is_marked (start))
517 ++cur_stats->remarked;
518 start += CARD_SIZE_IN_BYTES;
525 card_tables_collect_stats (gboolean begin)
527 #ifdef CARDTABLE_STATS
529 memset (&major_stats, 0, sizeof (card_stats));
530 memset (&los_stats, 0, sizeof (card_stats));
531 cur_stats = &major_stats;
532 major_collector.iterate_live_block_ranges (count_marked_cards);
533 cur_stats = &los_stats;
534 mono_sgen_los_iterate_live_block_ranges (count_marked_cards);
536 cur_stats = &major_stats;
537 major_collector.iterate_live_block_ranges (count_marked_cards);
538 cur_stats = &los_stats;
539 mono_sgen_los_iterate_live_block_ranges (count_remarked_cards);
540 printf ("cards major (t %d m %d r %d) los (t %d m %d r %d) major_scan %lld los_scan %lld\n",
541 major_stats.total, major_stats.marked, major_stats.remarked,
542 los_stats.total, los_stats.marked, los_stats.remarked,
543 last_major_scan_time, last_los_scan_time);
551 sgen_card_table_mark_address (mword address)
553 g_assert_not_reached ();
557 sgen_card_table_mark_range (mword address, mword size)
559 g_assert_not_reached ();
562 #define sgen_card_table_address_is_marked(p) FALSE
563 #define scan_from_card_tables(start,end,queue)
564 #define card_table_clear()
565 #define card_table_init()
566 #define card_tables_collect_stats(begin)
569 mono_gc_get_card_table (int *shift_bits, gpointer *mask)