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,
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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,
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26 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
27 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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36 #include "metadata/sgen-gc.h"
37 #include "metadata/sgen-cardtable.h"
38 #include "utils/mono-counters.h"
39 #include "utils/mono-time.h"
41 #ifdef SGEN_HAVE_CARDTABLE
43 //#define CARDTABLE_STATS
46 #ifdef HAVE_SYS_MMAN_H
49 #include <sys/types.h>
51 guint8 *sgen_cardtable;
54 #ifdef HEAVY_STATISTICS
55 long long marked_cards;
56 long long scanned_cards;
57 long long scanned_objects;
58 long long remarked_cards;
60 static long long los_marked_cards;
61 static long long large_objects;
62 static long long bloby_objects;
63 static long long los_array_cards;
64 static long long los_array_remsets;
67 static long long major_card_scan_time;
68 static long long los_card_scan_time;
70 static long long last_major_scan_time;
71 static long long last_los_scan_time;
72 /*WARNING: This function returns the number of cards regardless of overflow in case of overlapping cards.*/
74 cards_in_range (mword address, mword size)
76 mword end = address + MAX (1, size) - 1;
77 return (end >> CARD_BITS) - (address >> CARD_BITS) + 1;
80 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
82 guint8 *sgen_shadow_cardtable;
84 #define SGEN_SHADOW_CARDTABLE_END (sgen_shadow_cardtable + CARD_COUNT_IN_BYTES)
85 #define SGEN_CARDTABLE_END (sgen_cardtable + CARD_COUNT_IN_BYTES)
88 sgen_card_table_region_begin_scanning (mword start, mword end)
90 /*XXX this can be improved to work on words and have a single loop induction var */
91 while (start <= end) {
92 if (sgen_card_table_card_begin_scanning (start))
94 start += CARD_SIZE_IN_BYTES;
102 sgen_card_table_region_begin_scanning (mword start, mword size)
104 gboolean res = FALSE;
105 guint8 *card = sgen_card_table_get_card_address (start);
106 guint8 *end = card + cards_in_range (start, size);
108 /*XXX this can be improved to work on words and have a branchless body */
109 while (card != end) {
116 memset (sgen_card_table_get_card_address (start), 0, size >> CARD_BITS);
123 /*FIXME this assumes that major blocks are multiple of 4K which is pretty reasonable */
125 sgen_card_table_get_card_data (guint8 *data_dest, mword address, mword cards)
127 mword *start = (mword*)sgen_card_table_get_card_scan_address (address);
128 mword *dest = (mword*)data_dest;
129 mword *end = (mword*)(data_dest + cards);
132 for (; dest < end; ++dest, ++start) {
137 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
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 memset (sgen_card_table_get_card_address (address), 1, cards_in_range (address, size));
158 sgen_card_table_is_range_marked (guint8 *cards, mword address, mword size)
160 guint8 *end = cards + cards_in_range (address, size);
162 /*This is safe since this function is only called by code that only passes continuous card blocks*/
163 while (cards != end) {
172 sgen_card_table_init (void)
174 sgen_cardtable = mono_sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, TRUE);
176 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
177 sgen_shadow_cardtable = mono_sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, TRUE);
180 #ifdef HEAVY_STATISTICS
181 mono_counters_register ("marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &marked_cards);
182 mono_counters_register ("scanned cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_cards);
183 mono_counters_register ("remarked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &remarked_cards);
185 mono_counters_register ("los marked cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_marked_cards);
186 mono_counters_register ("los array cards scanned ", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_cards);
187 mono_counters_register ("los array remsets", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_remsets);
188 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_objects);
189 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &large_objects);
190 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &bloby_objects);
192 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_LONG, &major_card_scan_time);
193 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_card_scan_time);
196 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
199 move_cards_to_shadow_table (mword start, mword size)
201 guint8 *from = sgen_card_table_get_card_address (start);
202 guint8 *to = sgen_card_table_get_shadow_card_address (start);
203 size_t bytes = cards_in_range (start, size);
205 if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
206 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
207 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
209 memcpy (to, from, first_chunk);
210 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
212 memcpy (to, from, bytes);
217 clear_cards (mword start, mword size)
219 guint8 *addr = sgen_card_table_get_card_address (start);
220 size_t bytes = cards_in_range (start, size);
222 if (addr + bytes > SGEN_CARDTABLE_END) {
223 size_t first_chunk = SGEN_CARDTABLE_END - addr;
225 memset (addr, 0, first_chunk);
226 memset (sgen_cardtable, 0, bytes - first_chunk);
228 memset (addr, 0, bytes);
236 clear_cards (mword start, mword size)
238 memset (sgen_card_table_get_card_address (start), 0, cards_in_range (start, size));
245 sgen_card_table_clear (void)
247 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
248 sgen_major_collector_iterate_live_block_ranges (clear_cards);
249 mono_sgen_los_iterate_live_block_ranges (clear_cards);
253 sgen_scan_from_card_tables (void *start_nursery, void *end_nursery, SgenGrayQueue *queue)
255 SGEN_TV_DECLARE (atv);
256 SGEN_TV_DECLARE (btv);
258 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
259 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
261 sgen_major_collector_iterate_live_block_ranges (move_cards_to_shadow_table);
262 mono_sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
265 sgen_card_table_clear ();
267 SGEN_TV_GETTIME (atv);
268 sgen_major_collector_scan_card_table (queue);
269 SGEN_TV_GETTIME (btv);
270 last_major_scan_time = SGEN_TV_ELAPSED_MS (atv, btv);
271 major_card_scan_time += last_major_scan_time;
272 mono_sgen_los_scan_card_table (queue);
273 SGEN_TV_GETTIME (atv);
274 last_los_scan_time = SGEN_TV_ELAPSED_MS (btv, atv);
275 los_card_scan_time += last_los_scan_time;
279 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
284 *shift_bits = CARD_BITS;
285 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
286 *mask = (gpointer)CARD_MASK;
291 return sgen_cardtable;
296 collect_faulted_cards (void)
298 #define CARD_PAGES (CARD_COUNT_IN_BYTES / 4096)
300 unsigned char faulted [CARD_PAGES] = { 0 };
301 mincore (sgen_cardtable, CARD_COUNT_IN_BYTES, faulted);
303 for (i = 0; i < CARD_PAGES; ++i) {
308 printf ("TOTAL card pages %d faulted %d\n", CARD_PAGES, count);
312 sgen_card_table_dump_obj_card (char *object, size_t size, void *dummy)
314 guint8 *start = sgen_card_table_get_card_scan_address (object);
315 guint8 *end = start + cards_in_range (object, size);
317 printf ("--obj %p %d cards [%p %p]--", object, size, start, end);
318 for (; start < end; ++start) {
320 printf ("\n\t[%p] ", start);
321 printf ("%x ", *start);
330 #define MWORD_MASK (sizeof (mword) - 1)
333 find_card_offset (mword card)
335 /*XXX Use assembly as this generates some pretty bad code */
336 #if defined(__i386__) && defined(__GNUC__)
337 return (__builtin_ffs (card) - 1) / 8;
338 #elif defined(__x86_64__) && defined(__GNUC__)
339 return (__builtin_ffsll (card) - 1) / 8;
340 #elif defined(__s390x__)
341 return (__builtin_ffsll (GUINT64_TO_LE(card)) - 1) / 8;
344 guint8 *ptr = (guint *) &card;
345 for (i = 0; i < sizeof (mword); ++i) {
354 find_next_card (guint8 *card_data, guint8 *end)
356 mword *cards, *cards_end;
359 while ((((mword)card_data) & MWORD_MASK) && card_data < end) {
365 if (card_data == end)
368 cards = (mword*)card_data;
369 cards_end = (mword*)((mword)end & ~MWORD_MASK);
370 while (cards < cards_end) {
373 return (guint8*)cards + find_card_offset (card);
377 card_data = (guint8*)cards_end;
378 while (card_data < end) {
388 sgen_cardtable_scan_object (char *obj, mword block_obj_size, guint8 *cards, SgenGrayQueue *queue)
390 MonoVTable *vt = (MonoVTable*)SGEN_LOAD_VTABLE (obj);
391 MonoClass *klass = vt->klass;
392 CopyOrMarkObjectFunc copy_func = mono_sgen_get_copy_object ();
393 ScanObjectFunc scan_object_func = mono_sgen_get_minor_scan_object ();
394 ScanVTypeFunc scan_vtype_func = mono_sgen_get_minor_scan_vtype ();
396 HEAVY_STAT (++large_objects);
398 if (!SGEN_VTABLE_HAS_REFERENCES (vt))
402 guint8 *card_data, *card_base;
403 guint8 *card_data_end;
404 char *obj_start = sgen_card_table_align_pointer (obj);
405 mword obj_size = mono_sgen_par_object_get_size (vt, (MonoObject*)obj);
406 char *obj_end = obj + obj_size;
410 MonoArray *arr = (MonoArray*)obj;
411 mword desc = (mword)klass->element_class->gc_descr;
412 int elem_size = mono_array_element_size (klass);
414 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
415 guint8 *overflow_scan_end = NULL;
421 card_data = sgen_card_table_get_card_scan_address ((mword)obj);
423 card_base = card_data;
424 card_count = cards_in_range ((mword)obj, obj_size);
425 card_data_end = card_data + card_count;
428 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
429 /*Check for overflow and if so, setup to scan in two steps*/
430 if (!cards && card_data_end >= SGEN_SHADOW_CARDTABLE_END) {
431 overflow_scan_end = sgen_shadow_cardtable + (card_data_end - SGEN_SHADOW_CARDTABLE_END);
432 card_data_end = SGEN_SHADOW_CARDTABLE_END;
438 card_data = find_next_card (card_data, card_data_end);
439 for (; card_data < card_data_end; card_data = find_next_card (card_data + 1, card_data_end)) {
441 int idx = (card_data - card_base) + extra_idx;
442 char *start = (char*)(obj_start + idx * CARD_SIZE_IN_BYTES);
443 char *card_end = start + CARD_SIZE_IN_BYTES;
446 HEAVY_STAT (++los_marked_cards);
449 sgen_card_table_prepare_card_for_scanning (card_data);
451 card_end = MIN (card_end, obj_end);
453 if (start <= (char*)arr->vector)
456 index = ARRAY_OBJ_INDEX (start, obj, elem_size);
458 elem = (char*)mono_array_addr_with_size ((MonoArray*)obj, elem_size, index);
459 if (klass->element_class->valuetype) {
460 for (; elem < card_end; elem += elem_size)
461 scan_vtype_func (elem, desc, queue);
463 HEAVY_STAT (++los_array_cards);
464 for (; elem < card_end; elem += SIZEOF_VOID_P) {
465 gpointer new, old = *(gpointer*)elem;
466 if (G_UNLIKELY (sgen_ptr_in_nursery (old))) {
467 HEAVY_STAT (++los_array_remsets);
468 copy_func ((void**)elem, queue);
469 new = *(gpointer*)elem;
470 if (G_UNLIKELY (sgen_ptr_in_nursery (new)))
471 mono_sgen_add_to_global_remset (elem);
477 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
478 if (overflow_scan_end) {
479 extra_idx = card_data - card_base;
480 card_base = card_data = sgen_shadow_cardtable;
481 card_data_end = overflow_scan_end;
482 overflow_scan_end = NULL;
488 HEAVY_STAT (++bloby_objects);
490 if (sgen_card_table_is_range_marked (cards, (mword)obj, block_obj_size))
491 scan_object_func (obj, queue);
492 } else if (sgen_card_table_region_begin_scanning ((mword)obj, block_obj_size)) {
493 scan_object_func (obj, queue);
498 #ifdef CARDTABLE_STATS
501 int total, marked, remarked;
504 static card_stats major_stats, los_stats;
505 static card_stats *cur_stats;
508 count_marked_cards (mword start, mword size)
510 mword end = start + size;
511 while (start <= end) {
513 if (sgen_card_table_address_is_marked (start))
515 start += CARD_SIZE_IN_BYTES;
520 count_remarked_cards (mword start, mword size)
522 mword end = start + size;
523 while (start <= end) {
524 if (sgen_card_table_address_is_marked (start))
525 ++cur_stats->remarked;
526 start += CARD_SIZE_IN_BYTES;
533 sgen_card_tables_collect_stats (gboolean begin)
535 #ifdef CARDTABLE_STATS
537 memset (&major_stats, 0, sizeof (card_stats));
538 memset (&los_stats, 0, sizeof (card_stats));
539 cur_stats = &major_stats;
540 sgen_major_collector_iterate_live_block_ranges (count_marked_cards);
541 cur_stats = &los_stats;
542 mono_sgen_los_iterate_live_block_ranges (count_marked_cards);
544 cur_stats = &major_stats;
545 sgen_major_collector_iterate_live_block_ranges (count_marked_cards);
546 cur_stats = &los_stats;
547 mono_sgen_los_iterate_live_block_ranges (count_remarked_cards);
548 printf ("cards major (t %d m %d r %d) los (t %d m %d r %d) major_scan %lld los_scan %lld\n",
549 major_stats.total, major_stats.marked, major_stats.remarked,
550 los_stats.total, los_stats.marked, los_stats.remarked,
551 last_major_scan_time, last_los_scan_time);
559 sgen_card_table_mark_address (mword address)
561 g_assert_not_reached ();
565 sgen_card_table_mark_range (mword address, mword size)
567 g_assert_not_reached ();
571 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
578 #endif /*HAVE_SGEN_GC*/