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;
60 static guint64 los_marked_cards;
61 static guint64 large_objects;
62 static guint64 bloby_objects;
63 static guint64 los_array_cards;
64 static guint64 los_array_remsets;
67 static guint64 major_card_scan_time;
68 static guint64 los_card_scan_time;
70 static guint64 last_major_scan_time;
71 static guint64 last_los_scan_time;
73 static void sgen_card_tables_collect_stats (gboolean begin);
76 sgen_card_table_number_of_cards_in_range (mword address, mword size)
78 mword end = address + MAX (1, size) - 1;
79 return (end >> CARD_BITS) - (address >> CARD_BITS) + 1;
83 sgen_card_table_wbarrier_set_field (GCObject *obj, gpointer field_ptr, GCObject* value)
85 *(void**)field_ptr = value;
86 if (need_mod_union || sgen_ptr_in_nursery (value))
87 sgen_card_table_mark_address ((mword)field_ptr);
88 sgen_dummy_use (value);
92 sgen_card_table_wbarrier_arrayref_copy (gpointer dest_ptr, gpointer src_ptr, int count)
94 gpointer *dest = dest_ptr;
95 gpointer *src = src_ptr;
97 /*overlapping that required backward copying*/
98 if (src < dest && (src + count) > dest) {
99 gpointer *start = dest;
103 for (; dest >= start; --src, --dest) {
104 gpointer value = *src;
105 SGEN_UPDATE_REFERENCE_ALLOW_NULL (dest, value);
106 if (need_mod_union || sgen_ptr_in_nursery (value))
107 sgen_card_table_mark_address ((mword)dest);
108 sgen_dummy_use (value);
111 gpointer *end = dest + count;
112 for (; dest < end; ++src, ++dest) {
113 gpointer value = *src;
114 SGEN_UPDATE_REFERENCE_ALLOW_NULL (dest, value);
115 if (need_mod_union || sgen_ptr_in_nursery (value))
116 sgen_card_table_mark_address ((mword)dest);
117 sgen_dummy_use (value);
123 sgen_card_table_wbarrier_value_copy (gpointer dest, gpointer src, int count, size_t element_size)
125 size_t size = count * element_size;
127 #ifdef DISABLE_CRITICAL_REGION
131 ENTER_CRITICAL_REGION;
133 mono_gc_memmove_atomic (dest, src, size);
134 sgen_card_table_mark_range ((mword)dest, size);
135 #ifdef DISABLE_CRITICAL_REGION
138 EXIT_CRITICAL_REGION;
143 sgen_card_table_wbarrier_object_copy (GCObject* obj, GCObject *src)
145 size_t size = sgen_client_par_object_get_size (SGEN_LOAD_VTABLE_UNCHECKED (obj), obj);
147 #ifdef DISABLE_CRITICAL_REGION
151 ENTER_CRITICAL_REGION;
153 mono_gc_memmove_aligned ((char*)obj + SGEN_CLIENT_OBJECT_HEADER_SIZE, (char*)src + SGEN_CLIENT_OBJECT_HEADER_SIZE,
154 size - SGEN_CLIENT_OBJECT_HEADER_SIZE);
155 sgen_card_table_mark_range ((mword)obj, size);
156 #ifdef DISABLE_CRITICAL_REGION
159 EXIT_CRITICAL_REGION;
164 sgen_card_table_wbarrier_generic_nostore (gpointer ptr)
166 sgen_card_table_mark_address ((mword)ptr);
169 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
171 guint8 *sgen_shadow_cardtable;
173 #define SGEN_CARDTABLE_END (sgen_cardtable + CARD_COUNT_IN_BYTES)
176 sgen_card_table_region_begin_scanning (mword start, mword size)
178 mword end = start + size;
179 /*XXX this can be improved to work on words and have a single loop induction var */
180 while (start < end) {
181 if (sgen_card_table_card_begin_scanning (start))
183 start += CARD_SIZE_IN_BYTES;
191 sgen_card_table_region_begin_scanning (mword start, mword size)
193 gboolean res = FALSE;
194 guint8 *card = sgen_card_table_get_card_address (start);
195 guint8 *end = card + sgen_card_table_number_of_cards_in_range (start, size);
197 /*XXX this can be improved to work on words and have a branchless body */
198 while (card != end) {
205 memset (sgen_card_table_get_card_address (start), 0, size >> CARD_BITS);
212 /*FIXME this assumes that major blocks are multiple of 4K which is pretty reasonable */
214 sgen_card_table_get_card_data (guint8 *data_dest, mword address, mword cards)
216 mword *start = (mword*)sgen_card_table_get_card_scan_address (address);
217 mword *dest = (mword*)data_dest;
218 mword *end = (mword*)(data_dest + cards);
221 for (; dest < end; ++dest, ++start) {
226 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
235 sgen_card_table_align_pointer (void *ptr)
237 return (void*)((mword)ptr & ~(CARD_SIZE_IN_BYTES - 1));
241 sgen_card_table_mark_range (mword address, mword size)
243 mword num_cards = sgen_card_table_number_of_cards_in_range (address, size);
244 guint8 *start = sgen_card_table_get_card_address (address);
246 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
248 * FIXME: There's a theoretical bug here, namely that the card table is allocated so
249 * far toward the end of the address space that start + num_cards overflows.
251 guint8 *end = start + num_cards;
252 SGEN_ASSERT (0, num_cards <= CARD_COUNT_IN_BYTES, "How did we get an object larger than the card table?");
253 if (end > SGEN_CARDTABLE_END) {
254 memset (start, 1, SGEN_CARDTABLE_END - start);
255 memset (sgen_cardtable, 1, end - sgen_cardtable);
260 memset (start, 1, num_cards);
264 sgen_card_table_is_range_marked (guint8 *cards, mword address, mword size)
266 guint8 *end = cards + sgen_card_table_number_of_cards_in_range (address, size);
268 /*This is safe since this function is only called by code that only passes continuous card blocks*/
269 while (cards != end) {
278 sgen_card_table_record_pointer (gpointer address)
280 *sgen_card_table_get_card_address ((mword)address) = 1;
284 sgen_card_table_find_address (char *addr)
286 return sgen_card_table_address_is_marked ((mword)addr);
290 sgen_card_table_find_address_with_cards (char *cards_start, guint8 *cards, char *addr)
292 cards_start = sgen_card_table_align_pointer (cards_start);
293 return cards [(addr - cards_start) >> CARD_BITS];
297 update_mod_union (guint8 *dest, guint8 *start_card, size_t num_cards)
300 for (i = 0; i < num_cards; ++i)
301 dest [i] |= start_card [i];
305 sgen_card_table_alloc_mod_union (char *obj, mword obj_size)
307 size_t num_cards = sgen_card_table_number_of_cards_in_range ((mword) obj, obj_size);
308 guint8 *mod_union = sgen_alloc_internal_dynamic (num_cards, INTERNAL_MEM_CARDTABLE_MOD_UNION, TRUE);
309 memset (mod_union, 0, num_cards);
314 sgen_card_table_free_mod_union (guint8 *mod_union, char *obj, mword obj_size)
316 size_t num_cards = sgen_card_table_number_of_cards_in_range ((mword) obj, obj_size);
317 sgen_free_internal_dynamic (mod_union, num_cards, INTERNAL_MEM_CARDTABLE_MOD_UNION);
321 sgen_card_table_update_mod_union_from_cards (guint8 *dest, guint8 *start_card, size_t num_cards)
323 SGEN_ASSERT (0, dest, "Why don't we have a mod union?");
324 update_mod_union (dest, start_card, num_cards);
328 sgen_card_table_update_mod_union (guint8 *dest, char *obj, mword obj_size, size_t *out_num_cards)
330 guint8 *start_card = sgen_card_table_get_card_address ((mword)obj);
331 #ifndef SGEN_HAVE_OVERLAPPING_CARDS
332 guint8 *end_card = sgen_card_table_get_card_address ((mword)obj + obj_size - 1) + 1;
336 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
339 rest = num_cards = sgen_card_table_number_of_cards_in_range ((mword) obj, obj_size);
341 while (start_card + rest > SGEN_CARDTABLE_END) {
342 size_t count = SGEN_CARDTABLE_END - start_card;
343 sgen_card_table_update_mod_union_from_cards (dest, start_card, count);
346 start_card = sgen_cardtable;
350 num_cards = end_card - start_card;
353 sgen_card_table_update_mod_union_from_cards (dest, start_card, num_cards);
356 *out_num_cards = num_cards;
359 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
362 move_cards_to_shadow_table (mword start, mword size)
364 guint8 *from = sgen_card_table_get_card_address (start);
365 guint8 *to = sgen_card_table_get_shadow_card_address (start);
366 size_t bytes = sgen_card_table_number_of_cards_in_range (start, size);
368 if (bytes >= CARD_COUNT_IN_BYTES) {
369 memcpy (sgen_shadow_cardtable, sgen_cardtable, CARD_COUNT_IN_BYTES);
370 } else if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
371 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
372 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
374 memcpy (to, from, first_chunk);
375 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
377 memcpy (to, from, bytes);
382 clear_cards (mword start, mword size)
384 guint8 *addr = sgen_card_table_get_card_address (start);
385 size_t bytes = sgen_card_table_number_of_cards_in_range (start, size);
387 if (bytes >= CARD_COUNT_IN_BYTES) {
388 memset (sgen_cardtable, 0, CARD_COUNT_IN_BYTES);
389 } else if (addr + bytes > SGEN_CARDTABLE_END) {
390 size_t first_chunk = SGEN_CARDTABLE_END - addr;
392 memset (addr, 0, first_chunk);
393 memset (sgen_cardtable, 0, bytes - first_chunk);
395 memset (addr, 0, bytes);
403 clear_cards (mword start, mword size)
405 memset (sgen_card_table_get_card_address (start), 0, sgen_card_table_number_of_cards_in_range (start, size));
412 sgen_card_table_clear_cards (void)
414 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
415 sgen_major_collector_iterate_live_block_ranges (clear_cards);
416 sgen_los_iterate_live_block_ranges (clear_cards);
420 sgen_card_table_finish_minor_collection (void)
422 sgen_card_tables_collect_stats (FALSE);
426 sgen_card_table_scan_remsets (ScanCopyContext ctx)
428 SGEN_TV_DECLARE (atv);
429 SGEN_TV_DECLARE (btv);
431 sgen_card_tables_collect_stats (TRUE);
433 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
434 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
436 sgen_major_collector_iterate_live_block_ranges (move_cards_to_shadow_table);
437 sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
440 sgen_card_table_clear_cards ();
442 SGEN_TV_GETTIME (atv);
443 sgen_get_major_collector ()->scan_card_table (FALSE, ctx);
444 SGEN_TV_GETTIME (btv);
445 last_major_scan_time = SGEN_TV_ELAPSED (atv, btv);
446 major_card_scan_time += last_major_scan_time;
447 sgen_los_scan_card_table (FALSE, ctx);
448 SGEN_TV_GETTIME (atv);
449 last_los_scan_time = SGEN_TV_ELAPSED (btv, atv);
450 los_card_scan_time += last_los_scan_time;
454 sgen_get_card_table_configuration (int *shift_bits, gpointer *mask)
456 #ifndef MANAGED_WBARRIER
462 *shift_bits = CARD_BITS;
463 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
464 *mask = (gpointer)CARD_MASK;
469 return sgen_cardtable;
475 sgen_card_table_dump_obj_card (char *object, size_t size, void *dummy)
477 guint8 *start = sgen_card_table_get_card_scan_address (object);
478 guint8 *end = start + sgen_card_table_number_of_cards_in_range (object, size);
480 printf ("--obj %p %d cards [%p %p]--", object, size, start, end);
481 for (; start < end; ++start) {
483 printf ("\n\t[%p] ", start);
484 printf ("%x ", *start);
494 sgen_cardtable_scan_object (char *obj, mword block_obj_size, guint8 *cards, gboolean mod_union, ScanCopyContext ctx)
496 HEAVY_STAT (++large_objects);
498 if (sgen_client_cardtable_scan_object (obj, block_obj_size, cards, mod_union, ctx))
501 HEAVY_STAT (++bloby_objects);
503 if (sgen_card_table_is_range_marked (cards, (mword)obj, block_obj_size))
504 ctx.ops->scan_object (obj, sgen_obj_get_descriptor (obj), ctx.queue);
505 } else if (sgen_card_table_region_begin_scanning ((mword)obj, block_obj_size)) {
506 ctx.ops->scan_object (obj, sgen_obj_get_descriptor (obj), ctx.queue);
509 binary_protocol_card_scan (obj, sgen_safe_object_get_size ((GCObject*)obj));
512 #ifdef CARDTABLE_STATS
515 int total, marked, remarked, gc_marked;
518 static card_stats major_stats, los_stats;
519 static card_stats *cur_stats;
522 count_marked_cards (mword start, mword size)
524 mword end = start + size;
525 while (start <= end) {
526 guint8 card = *sgen_card_table_get_card_address (start);
531 ++cur_stats->gc_marked;
532 start += CARD_SIZE_IN_BYTES;
537 count_remarked_cards (mword start, mword size)
539 mword end = start + size;
540 while (start <= end) {
541 if (sgen_card_table_address_is_marked (start)) {
542 ++cur_stats->remarked;
543 *sgen_card_table_get_card_address (start) = 2;
545 start += CARD_SIZE_IN_BYTES;
552 sgen_card_tables_collect_stats (gboolean begin)
554 #ifdef CARDTABLE_STATS
556 memset (&major_stats, 0, sizeof (card_stats));
557 memset (&los_stats, 0, sizeof (card_stats));
558 cur_stats = &major_stats;
559 sgen_major_collector_iterate_live_block_ranges (count_marked_cards);
560 cur_stats = &los_stats;
561 sgen_los_iterate_live_block_ranges (count_marked_cards);
563 cur_stats = &major_stats;
564 sgen_major_collector_iterate_live_block_ranges (count_remarked_cards);
565 cur_stats = &los_stats;
566 sgen_los_iterate_live_block_ranges (count_remarked_cards);
567 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",
568 major_stats.total, major_stats.marked, major_stats.gc_marked, major_stats.remarked,
569 los_stats.total, los_stats.marked, los_stats.gc_marked, los_stats.remarked,
570 last_major_scan_time / 10000.0f, last_los_scan_time / 10000.0f);
576 sgen_card_table_init (SgenRememberedSet *remset)
578 sgen_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "card table");
580 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
581 sgen_shadow_cardtable = sgen_alloc_os_memory (CARD_COUNT_IN_BYTES, SGEN_ALLOC_INTERNAL | SGEN_ALLOC_ACTIVATE, "shadow card table");
584 #ifdef HEAVY_STATISTICS
585 mono_counters_register ("marked cards", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &marked_cards);
586 mono_counters_register ("scanned cards", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &scanned_cards);
587 mono_counters_register ("remarked cards", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &remarked_cards);
589 mono_counters_register ("los marked cards", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &los_marked_cards);
590 mono_counters_register ("los array cards scanned ", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &los_array_cards);
591 mono_counters_register ("los array remsets", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &los_array_remsets);
592 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &scanned_objects);
593 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &large_objects);
594 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &bloby_objects);
596 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &major_card_scan_time);
597 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &los_card_scan_time);
600 remset->wbarrier_set_field = sgen_card_table_wbarrier_set_field;
601 remset->wbarrier_arrayref_copy = sgen_card_table_wbarrier_arrayref_copy;
602 remset->wbarrier_value_copy = sgen_card_table_wbarrier_value_copy;
603 remset->wbarrier_object_copy = sgen_card_table_wbarrier_object_copy;
604 remset->wbarrier_generic_nostore = sgen_card_table_wbarrier_generic_nostore;
605 remset->record_pointer = sgen_card_table_record_pointer;
607 remset->scan_remsets = sgen_card_table_scan_remsets;
609 remset->finish_minor_collection = sgen_card_table_finish_minor_collection;
610 remset->clear_cards = sgen_card_table_clear_cards;
612 remset->find_address = sgen_card_table_find_address;
613 remset->find_address_with_cards = sgen_card_table_find_address_with_cards;
615 need_mod_union = sgen_get_major_collector ()->is_concurrent;
618 #endif /*HAVE_SGEN_GC*/