2 * sgen-cardtable.c: Card table implementation for sgen
5 * Rodrigo Kumpera (rkumpera@novell.com)
7 * Copyright 2001-2003 Ximian, Inc
8 * Copyright 2003-2010 Novell, Inc.
9 * Copyright 2011 Xamarin Inc (http://www.xamarin.com)
10 * Copyright (C) 2012 Xamarin Inc
12 * This library is free software; you can redistribute it and/or
13 * modify it under the terms of the GNU Library General Public
14 * License 2.0 as published by the Free Software Foundation;
16 * This library is distributed in the hope that it will be useful,
17 * but WITHOUT ANY WARRANTY; without even the implied warranty of
18 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
19 * Library General Public License for more details.
21 * You should have received a copy of the GNU Library General Public
22 * License 2.0 along with this library; if not, write to the Free
23 * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
31 #include "mono/sgen/sgen-gc.h"
32 #include "mono/sgen/sgen-cardtable.h"
33 #include "mono/sgen/sgen-memory-governor.h"
34 #include "mono/sgen/sgen-protocol.h"
35 #include "mono/sgen/sgen-layout-stats.h"
36 #include "mono/sgen/sgen-client.h"
37 #include "mono/sgen/gc-internal-agnostic.h"
38 #include "mono/utils/mono-memory-model.h"
40 //#define CARDTABLE_STATS
45 #ifdef HAVE_SYS_MMAN_H
48 #include <sys/types.h>
50 guint8 *sgen_cardtable;
52 static gboolean need_mod_union;
54 #ifdef HEAVY_STATISTICS
56 guint64 scanned_cards;
57 guint64 scanned_objects;
58 guint64 remarked_cards;
59 static guint64 large_objects;
60 static guint64 bloby_objects;
62 static guint64 major_card_scan_time;
63 static guint64 los_card_scan_time;
65 static guint64 last_major_scan_time;
66 static guint64 last_los_scan_time;
68 static void sgen_card_tables_collect_stats (gboolean begin);
71 sgen_card_table_number_of_cards_in_range (mword address, mword size)
73 mword end = address + MAX (1, size) - 1;
74 return (end >> CARD_BITS) - (address >> CARD_BITS) + 1;
78 sgen_card_table_wbarrier_set_field (GCObject *obj, gpointer field_ptr, GCObject* value)
80 *(void**)field_ptr = value;
81 if (need_mod_union || sgen_ptr_in_nursery (value))
82 sgen_card_table_mark_address ((mword)field_ptr);
83 sgen_dummy_use (value);
87 sgen_card_table_wbarrier_arrayref_copy (gpointer dest_ptr, gpointer src_ptr, int count)
89 gpointer *dest = dest_ptr;
90 gpointer *src = src_ptr;
92 /*overlapping that required backward copying*/
93 if (src < dest && (src + count) > dest) {
94 gpointer *start = dest;
98 for (; dest >= start; --src, --dest) {
99 gpointer value = *src;
100 SGEN_UPDATE_REFERENCE_ALLOW_NULL (dest, value);
101 if (need_mod_union || sgen_ptr_in_nursery (value))
102 sgen_card_table_mark_address ((mword)dest);
103 sgen_dummy_use (value);
106 gpointer *end = dest + count;
107 for (; dest < end; ++src, ++dest) {
108 gpointer value = *src;
109 SGEN_UPDATE_REFERENCE_ALLOW_NULL (dest, value);
110 if (need_mod_union || sgen_ptr_in_nursery (value))
111 sgen_card_table_mark_address ((mword)dest);
112 sgen_dummy_use (value);
118 sgen_card_table_wbarrier_value_copy (gpointer dest, gpointer src, int count, size_t element_size)
120 size_t size = count * element_size;
122 #ifdef DISABLE_CRITICAL_REGION
126 ENTER_CRITICAL_REGION;
128 mono_gc_memmove_atomic (dest, src, size);
129 sgen_card_table_mark_range ((mword)dest, size);
130 #ifdef DISABLE_CRITICAL_REGION
133 EXIT_CRITICAL_REGION;
138 sgen_card_table_wbarrier_object_copy (GCObject* obj, GCObject *src)
140 size_t size = sgen_client_par_object_get_size (SGEN_LOAD_VTABLE_UNCHECKED (obj), obj);
142 #ifdef DISABLE_CRITICAL_REGION
146 ENTER_CRITICAL_REGION;
148 mono_gc_memmove_aligned ((char*)obj + SGEN_CLIENT_OBJECT_HEADER_SIZE, (char*)src + SGEN_CLIENT_OBJECT_HEADER_SIZE,
149 size - SGEN_CLIENT_OBJECT_HEADER_SIZE);
150 sgen_card_table_mark_range ((mword)obj, size);
151 #ifdef DISABLE_CRITICAL_REGION
154 EXIT_CRITICAL_REGION;
159 sgen_card_table_wbarrier_generic_nostore (gpointer ptr)
161 sgen_card_table_mark_address ((mword)ptr);
164 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
166 guint8 *sgen_shadow_cardtable;
168 #define SGEN_CARDTABLE_END (sgen_cardtable + CARD_COUNT_IN_BYTES)
171 sgen_card_table_region_begin_scanning (mword start, mword size)
173 mword end = start + size;
174 /*XXX this can be improved to work on words and have a single loop induction var */
175 while (start < end) {
176 if (sgen_card_table_card_begin_scanning (start))
178 start += CARD_SIZE_IN_BYTES;
186 sgen_card_table_region_begin_scanning (mword start, mword size)
188 gboolean res = FALSE;
189 guint8 *card = sgen_card_table_get_card_address (start);
190 guint8 *end = card + sgen_card_table_number_of_cards_in_range (start, size);
192 /*XXX this can be improved to work on words and have a branchless body */
193 while (card != end) {
200 memset (sgen_card_table_get_card_address (start), 0, size >> CARD_BITS);
207 /*FIXME this assumes that major blocks are multiple of 4K which is pretty reasonable */
209 sgen_card_table_get_card_data (guint8 *data_dest, mword address, mword cards)
211 mword *start = (mword*)sgen_card_table_get_card_scan_address (address);
212 mword *dest = (mword*)data_dest;
213 mword *end = (mword*)(data_dest + cards);
216 for (; dest < end; ++dest, ++start) {
221 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
230 sgen_card_table_align_pointer (void *ptr)
232 return (void*)((mword)ptr & ~(CARD_SIZE_IN_BYTES - 1));
236 sgen_card_table_mark_range (mword address, mword size)
238 mword num_cards = sgen_card_table_number_of_cards_in_range (address, size);
239 guint8 *start = sgen_card_table_get_card_address (address);
241 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
243 * FIXME: There's a theoretical bug here, namely that the card table is allocated so
244 * far toward the end of the address space that start + num_cards overflows.
246 guint8 *end = start + num_cards;
247 SGEN_ASSERT (0, num_cards <= CARD_COUNT_IN_BYTES, "How did we get an object larger than the card table?");
248 if (end > SGEN_CARDTABLE_END) {
249 memset (start, 1, SGEN_CARDTABLE_END - start);
250 memset (sgen_cardtable, 1, end - sgen_cardtable);
255 memset (start, 1, num_cards);
259 sgen_card_table_is_range_marked (guint8 *cards, mword address, mword size)
261 guint8 *end = cards + sgen_card_table_number_of_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_record_pointer (gpointer address)
275 *sgen_card_table_get_card_address ((mword)address) = 1;
279 sgen_card_table_find_address (char *addr)
281 return sgen_card_table_address_is_marked ((mword)addr);
285 sgen_card_table_find_address_with_cards (char *cards_start, guint8 *cards, char *addr)
287 cards_start = sgen_card_table_align_pointer (cards_start);
288 return cards [(addr - cards_start) >> CARD_BITS];
292 update_mod_union (guint8 *dest, guint8 *start_card, size_t num_cards)
295 for (i = 0; i < num_cards; ++i)
296 dest [i] |= start_card [i];
300 sgen_card_table_alloc_mod_union (char *obj, mword obj_size)
302 size_t num_cards = sgen_card_table_number_of_cards_in_range ((mword) obj, obj_size);
303 guint8 *mod_union = sgen_alloc_internal_dynamic (num_cards, INTERNAL_MEM_CARDTABLE_MOD_UNION, TRUE);
304 memset (mod_union, 0, num_cards);
309 sgen_card_table_free_mod_union (guint8 *mod_union, char *obj, mword obj_size)
311 size_t num_cards = sgen_card_table_number_of_cards_in_range ((mword) obj, obj_size);
312 sgen_free_internal_dynamic (mod_union, num_cards, INTERNAL_MEM_CARDTABLE_MOD_UNION);
316 sgen_card_table_update_mod_union_from_cards (guint8 *dest, guint8 *start_card, size_t num_cards)
318 SGEN_ASSERT (0, dest, "Why don't we have a mod union?");
319 update_mod_union (dest, start_card, num_cards);
323 sgen_card_table_update_mod_union (guint8 *dest, char *obj, mword obj_size, size_t *out_num_cards)
325 guint8 *start_card = sgen_card_table_get_card_address ((mword)obj);
326 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
327 guint8 *end_card = sgen_card_table_get_card_address ((mword)obj + obj_size - 1) + 1;
331 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
334 rest = num_cards = sgen_card_table_number_of_cards_in_range ((mword) obj, obj_size);
336 while (start_card + rest > SGEN_CARDTABLE_END) {
337 size_t count = SGEN_CARDTABLE_END - start_card;
338 sgen_card_table_update_mod_union_from_cards (dest, start_card, count);
341 start_card = sgen_cardtable;
345 num_cards = end_card - start_card;
348 sgen_card_table_update_mod_union_from_cards (dest, start_card, num_cards);
351 *out_num_cards = num_cards;
354 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
357 move_cards_to_shadow_table (mword start, mword size)
359 guint8 *from = sgen_card_table_get_card_address (start);
360 guint8 *to = sgen_card_table_get_shadow_card_address (start);
361 size_t bytes = sgen_card_table_number_of_cards_in_range (start, size);
363 if (bytes >= CARD_COUNT_IN_BYTES) {
364 memcpy (sgen_shadow_cardtable, sgen_cardtable, CARD_COUNT_IN_BYTES);
365 } else if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
366 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
367 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
369 memcpy (to, from, first_chunk);
370 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
372 memcpy (to, from, bytes);
377 clear_cards (mword start, mword size)
379 guint8 *addr = sgen_card_table_get_card_address (start);
380 size_t bytes = sgen_card_table_number_of_cards_in_range (start, size);
382 if (bytes >= CARD_COUNT_IN_BYTES) {
383 memset (sgen_cardtable, 0, CARD_COUNT_IN_BYTES);
384 } else if (addr + bytes > SGEN_CARDTABLE_END) {
385 size_t first_chunk = SGEN_CARDTABLE_END - addr;
387 memset (addr, 0, first_chunk);
388 memset (sgen_cardtable, 0, bytes - first_chunk);
390 memset (addr, 0, bytes);
398 clear_cards (mword start, mword size)
400 memset (sgen_card_table_get_card_address (start), 0, sgen_card_table_number_of_cards_in_range (start, size));
407 sgen_card_table_clear_cards (void)
409 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
410 sgen_major_collector_iterate_live_block_ranges (clear_cards);
411 sgen_los_iterate_live_block_ranges (clear_cards);
415 sgen_card_table_finish_minor_collection (void)
417 sgen_card_tables_collect_stats (FALSE);
421 sgen_card_table_scan_remsets (ScanCopyContext ctx)
423 SGEN_TV_DECLARE (atv);
424 SGEN_TV_DECLARE (btv);
426 sgen_card_tables_collect_stats (TRUE);
428 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
429 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
431 sgen_major_collector_iterate_live_block_ranges (move_cards_to_shadow_table);
432 sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
435 sgen_card_table_clear_cards ();
437 SGEN_TV_GETTIME (atv);
438 sgen_get_major_collector ()->scan_card_table (FALSE, ctx);
439 SGEN_TV_GETTIME (btv);
440 last_major_scan_time = SGEN_TV_ELAPSED (atv, btv);
441 major_card_scan_time += last_major_scan_time;
442 sgen_los_scan_card_table (FALSE, ctx);
443 SGEN_TV_GETTIME (atv);
444 last_los_scan_time = SGEN_TV_ELAPSED (btv, atv);
445 los_card_scan_time += last_los_scan_time;
449 sgen_get_card_table_configuration (int *shift_bits, gpointer *mask)
451 #ifndef MANAGED_WBARRIER
457 *shift_bits = CARD_BITS;
458 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
459 *mask = (gpointer)CARD_MASK;
464 return sgen_cardtable;
470 sgen_card_table_dump_obj_card (char *object, size_t size, void *dummy)
472 guint8 *start = sgen_card_table_get_card_scan_address (object);
473 guint8 *end = start + sgen_card_table_number_of_cards_in_range (object, size);
475 printf ("--obj %p %d cards [%p %p]--", object, size, start, end);
476 for (; start < end; ++start) {
478 printf ("\n\t[%p] ", start);
479 printf ("%x ", *start);
489 sgen_cardtable_scan_object (char *obj, mword block_obj_size, guint8 *cards, gboolean mod_union, ScanCopyContext ctx)
491 HEAVY_STAT (++large_objects);
493 if (sgen_client_cardtable_scan_object (obj, block_obj_size, cards, mod_union, ctx))
496 HEAVY_STAT (++bloby_objects);
498 if (sgen_card_table_is_range_marked (cards, (mword)obj, block_obj_size))
499 ctx.ops->scan_object (obj, sgen_obj_get_descriptor (obj), ctx.queue);
500 } else if (sgen_card_table_region_begin_scanning ((mword)obj, block_obj_size)) {
501 ctx.ops->scan_object (obj, sgen_obj_get_descriptor (obj), ctx.queue);
504 binary_protocol_card_scan (obj, sgen_safe_object_get_size ((GCObject*)obj));
507 #ifdef CARDTABLE_STATS
510 int total, marked, remarked, gc_marked;
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) {
521 guint8 card = *sgen_card_table_get_card_address (start);
526 ++cur_stats->gc_marked;
527 start += CARD_SIZE_IN_BYTES;
532 count_remarked_cards (mword start, mword size)
534 mword end = start + size;
535 while (start <= end) {
536 if (sgen_card_table_address_is_marked (start)) {
537 ++cur_stats->remarked;
538 *sgen_card_table_get_card_address (start) = 2;
540 start += CARD_SIZE_IN_BYTES;
547 sgen_card_tables_collect_stats (gboolean begin)
549 #ifdef CARDTABLE_STATS
551 memset (&major_stats, 0, sizeof (card_stats));
552 memset (&los_stats, 0, sizeof (card_stats));
553 cur_stats = &major_stats;
554 sgen_major_collector_iterate_live_block_ranges (count_marked_cards);
555 cur_stats = &los_stats;
556 sgen_los_iterate_live_block_ranges (count_marked_cards);
558 cur_stats = &major_stats;
559 sgen_major_collector_iterate_live_block_ranges (count_remarked_cards);
560 cur_stats = &los_stats;
561 sgen_los_iterate_live_block_ranges (count_remarked_cards);
562 printf ("cards major (t %d m %d g %d r %d) los (t %d m %d g %d r %d) major_scan %.2fms los_scan %.2fms\n",
563 major_stats.total, major_stats.marked, major_stats.gc_marked, major_stats.remarked,
564 los_stats.total, los_stats.marked, los_stats.gc_marked, los_stats.remarked,
565 last_major_scan_time / 10000.0f, last_los_scan_time / 10000.0f);
571 sgen_card_table_init (SgenRememberedSet *remset)
573 sgen_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "card table");
575 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
576 sgen_shadow_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "shadow card table");
579 #ifdef HEAVY_STATISTICS
580 mono_counters_register ("marked cards", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &marked_cards);
581 mono_counters_register ("scanned cards", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &scanned_cards);
582 mono_counters_register ("remarked cards", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &remarked_cards);
584 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &scanned_objects);
585 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &large_objects);
586 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &bloby_objects);
588 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &major_card_scan_time);
589 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &los_card_scan_time);
592 remset->wbarrier_set_field = sgen_card_table_wbarrier_set_field;
593 remset->wbarrier_arrayref_copy = sgen_card_table_wbarrier_arrayref_copy;
594 remset->wbarrier_value_copy = sgen_card_table_wbarrier_value_copy;
595 remset->wbarrier_object_copy = sgen_card_table_wbarrier_object_copy;
596 remset->wbarrier_generic_nostore = sgen_card_table_wbarrier_generic_nostore;
597 remset->record_pointer = sgen_card_table_record_pointer;
599 remset->scan_remsets = sgen_card_table_scan_remsets;
601 remset->finish_minor_collection = sgen_card_table_finish_minor_collection;
602 remset->clear_cards = sgen_card_table_clear_cards;
604 remset->find_address = sgen_card_table_find_address;
605 remset->find_address_with_cards = sgen_card_table_find_address_with_cards;
607 need_mod_union = sgen_get_major_collector ()->is_concurrent;
610 #endif /*HAVE_SGEN_GC*/