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
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 scanned cards", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_scanned_cards);
189 mono_counters_register ("los array cards scanned ", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_cards);
190 mono_counters_register ("los array remsets", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_array_remsets);
191 mono_counters_register ("cardtable scanned objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &scanned_objects);
192 mono_counters_register ("cardtable large objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &large_objects);
193 mono_counters_register ("cardtable bloby objects", MONO_COUNTER_GC | MONO_COUNTER_LONG, &bloby_objects);
195 mono_counters_register ("cardtable major scan time", MONO_COUNTER_GC | MONO_COUNTER_LONG, &major_card_scan_time);
196 mono_counters_register ("cardtable los scan time", MONO_COUNTER_GC | MONO_COUNTER_LONG, &los_card_scan_time);
199 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
202 move_cards_to_shadow_table (mword start, mword size)
204 guint8 *from = sgen_card_table_get_card_address (start);
205 guint8 *to = sgen_card_table_get_shadow_card_address (start);
206 size_t bytes = cards_in_range (start, size);
208 if (to + bytes > SGEN_SHADOW_CARDTABLE_END) {
209 size_t first_chunk = SGEN_SHADOW_CARDTABLE_END - to;
210 size_t second_chunk = MIN (CARD_COUNT_IN_BYTES, bytes) - first_chunk;
212 memcpy (to, from, first_chunk);
213 memcpy (sgen_shadow_cardtable, sgen_cardtable, second_chunk);
215 memcpy (to, from, bytes);
220 clear_cards (mword start, mword size)
222 guint8 *addr = sgen_card_table_get_card_address (start);
223 size_t bytes = cards_in_range (start, size);
225 if (addr + bytes > SGEN_CARDTABLE_END) {
226 size_t first_chunk = SGEN_CARDTABLE_END - addr;
228 memset (addr, 0, first_chunk);
229 memset (sgen_cardtable, 0, bytes - first_chunk);
231 memset (addr, 0, bytes);
239 clear_cards (mword start, mword size)
241 memset (sgen_card_table_get_card_address (start), 0, cards_in_range (start, size));
248 card_table_clear (void)
250 /*XXX we could do this in 2 ways. using mincore or iterating over all sections/los objects */
252 major_collector.iterate_live_block_ranges (clear_cards);
253 mono_sgen_los_iterate_live_block_ranges (clear_cards);
257 scan_from_card_tables (void *start_nursery, void *end_nursery, GrayQueue *queue)
263 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
264 /*FIXME we should have a bit on each block/los object telling if the object have marked cards.*/
266 major_collector.iterate_live_block_ranges (move_cards_to_shadow_table);
267 mono_sgen_los_iterate_live_block_ranges (move_cards_to_shadow_table);
273 major_collector.scan_card_table (queue);
275 last_major_scan_time = TV_ELAPSED_MS (atv, btv);
276 major_card_scan_time += last_major_scan_time;
277 mono_sgen_los_scan_card_table (queue);
279 last_los_scan_time = TV_ELAPSED_MS (btv, atv);
280 los_card_scan_time += last_los_scan_time;
285 mono_gc_get_card_table (int *shift_bits, gpointer *mask)
290 g_assert (sgen_cardtable);
291 *shift_bits = CARD_BITS;
292 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
293 *mask = (gpointer)CARD_MASK;
298 return sgen_cardtable;
303 collect_faulted_cards (void)
305 #define CARD_PAGES (CARD_COUNT_IN_BYTES / 4096)
307 unsigned char faulted [CARD_PAGES] = { 0 };
308 mincore (sgen_cardtable, CARD_COUNT_IN_BYTES, faulted);
310 for (i = 0; i < CARD_PAGES; ++i) {
315 printf ("TOTAL card pages %d faulted %d\n", CARD_PAGES, count);
320 sgen_cardtable_scan_object (char *obj, mword obj_size, guint8 *cards, SgenGrayQueue *queue)
322 MonoVTable *vt = (MonoVTable*)LOAD_VTABLE (obj);
323 MonoClass *klass = vt->klass;
325 HEAVY_STAT (++large_objects);
327 if (!SGEN_VTABLE_HAS_REFERENCES (vt))
331 guint8 *card_data, *card_base;
332 guint8 *card_data_end;
333 char *obj_start = sgen_card_table_align_pointer (obj);
334 char *obj_end = obj + obj_size;
338 MonoArray *arr = (MonoArray*)obj;
339 mword desc = (mword)klass->element_class->gc_descr;
340 int elem_size = mono_array_element_size (klass);
342 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
343 guint8 *overflow_scan_end = NULL;
349 card_data = sgen_card_table_get_card_scan_address ((mword)obj);
351 card_base = card_data;
352 card_count = cards_in_range ((mword)obj, obj_size);
353 card_data_end = card_data + card_count;
356 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
357 /*Check for overflow and if so, setup to scan in two steps*/
358 if (!cards && card_data_end >= SGEN_SHADOW_CARDTABLE_END) {
359 overflow_scan_end = sgen_shadow_cardtable + (card_data_end - SGEN_SHADOW_CARDTABLE_END);
360 card_data_end = SGEN_SHADOW_CARDTABLE_END;
365 /*FIXME use card skipping code*/
366 for (; card_data < card_data_end; ++card_data) {
368 int idx = (card_data - card_base) + extra_idx;
369 char *start = (char*)(obj_start + idx * CARD_SIZE_IN_BYTES);
370 char *card_end = start + CARD_SIZE_IN_BYTES;
376 HEAVY_STAT (++los_marked_cards);
378 sgen_card_table_prepare_card_for_scanning (card_data);
380 card_end = MIN (card_end, obj_end);
382 if (start <= (char*)arr->vector)
385 index = ARRAY_OBJ_INDEX (start, obj, elem_size);
387 elem = (char*)mono_array_addr_with_size ((MonoArray*)obj, elem_size, index);
388 if (klass->element_class->valuetype) {
389 for (; elem < card_end; elem += elem_size)
390 major_collector.minor_scan_vtype (elem, desc, nursery_start, nursery_next, queue);
392 HEAVY_STAT (++los_array_cards);
393 for (; elem < card_end; elem += SIZEOF_VOID_P) {
394 gpointer new, old = *(gpointer*)elem;
395 /*XXX it might be faster to do a nursery check here instead as it avoid a call*/
397 HEAVY_STAT (++los_array_remsets);
398 major_collector.copy_object ((void**)elem, queue);
399 new = *(gpointer*)elem;
400 if (G_UNLIKELY (ptr_in_nursery (new)))
401 mono_sgen_add_to_global_remset (elem);
407 #ifdef SGEN_HAVE_OVERLAPPING_CARDS
408 if (overflow_scan_end) {
409 extra_idx = card_data - card_base;
410 card_base = card_data = sgen_shadow_cardtable;
411 card_data_end = overflow_scan_end;
412 overflow_scan_end = NULL;
418 HEAVY_STAT (++bloby_objects);
420 if (sgen_card_table_is_range_marked (cards, (mword)obj, obj_size))
421 major_collector.minor_scan_object (obj, queue);
422 } else if (sgen_card_table_region_begin_scanning ((mword)obj, obj_size)) {
423 major_collector.minor_scan_object (obj, queue);
428 #ifdef CARDTABLE_STATS
431 int total, marked, remarked;
434 static card_stats major_stats, los_stats;
435 static card_stats *cur_stats;
438 count_marked_cards (mword start, mword size)
440 mword end = start + size;
441 while (start <= end) {
443 if (sgen_card_table_address_is_marked (start))
445 start += CARD_SIZE_IN_BYTES;
450 count_remarked_cards (mword start, mword size)
452 mword end = start + size;
453 while (start <= end) {
454 if (sgen_card_table_address_is_marked (start))
455 ++cur_stats->remarked;
456 start += CARD_SIZE_IN_BYTES;
463 card_tables_collect_stats (gboolean begin)
465 #ifdef CARDTABLE_STATS
467 memset (&major_stats, 0, sizeof (card_stats));
468 memset (&los_stats, 0, sizeof (card_stats));
469 cur_stats = &major_stats;
470 major_collector.iterate_live_block_ranges (count_marked_cards);
471 cur_stats = &los_stats;
472 mono_sgen_los_iterate_live_block_ranges (count_marked_cards);
474 cur_stats = &major_stats;
475 major_collector.iterate_live_block_ranges (count_marked_cards);
476 cur_stats = &los_stats;
477 mono_sgen_los_iterate_live_block_ranges (count_remarked_cards);
478 printf ("cards major (t %d m %d r %d) los (t %d m %d r %d) major_scan %lld los_scan %lld\n",
479 major_stats.total, major_stats.marked, major_stats.remarked,
480 los_stats.total, los_stats.marked, los_stats.remarked,
481 last_major_scan_time, last_los_scan_time);
489 sgen_card_table_mark_address (mword address)
491 g_assert_not_reached ();
495 sgen_card_table_mark_range (mword address, mword size)
497 g_assert_not_reached ();
500 #define sgen_card_table_address_is_marked(p) FALSE
501 #define scan_from_card_tables(start,end,queue)
502 #define card_table_clear()
503 #define card_table_init()
504 #define card_tables_collect_stats(begin)
507 mono_gc_get_card_table (int *shift_bits, gpointer *mask)