2 * sgen-los.c: Large objects space.
5 * Paolo Molaro (lupus@ximian.com)
7 * Copyright 2005-2010 Novell, Inc (http://www.novell.com)
9 * Thread start/stop adapted from Boehm's GC:
10 * Copyright (c) 1994 by Xerox Corporation. All rights reserved.
11 * Copyright (c) 1996 by Silicon Graphics. All rights reserved.
12 * Copyright (c) 1998 by Fergus Henderson. All rights reserved.
13 * Copyright (c) 2000-2004 by Hewlett-Packard Company. All rights reserved.
14 * Copyright 2001-2003 Ximian, Inc
15 * Copyright 2003-2010 Novell, Inc.
16 * Copyright (C) 2012 Xamarin Inc
18 * Licensed under the MIT license. See LICENSE file in the project root for full license information.
27 #include "mono/sgen/sgen-gc.h"
28 #include "mono/sgen/sgen-protocol.h"
29 #include "mono/sgen/sgen-cardtable.h"
30 #include "mono/sgen/sgen-memory-governor.h"
31 #include "mono/sgen/sgen-client.h"
33 #define LOS_SECTION_SIZE (1024 * 1024)
36 * This shouldn't be much smaller or larger than MAX_SMALL_OBJ_SIZE.
37 * Must be at least sizeof (LOSSection).
39 #define LOS_CHUNK_SIZE 4096
40 #define LOS_CHUNK_BITS 12
42 /* Largest object that can be allocated in a section. */
43 #define LOS_SECTION_OBJECT_LIMIT (LOS_SECTION_SIZE - LOS_CHUNK_SIZE - sizeof (LOSObject))
44 //#define LOS_SECTION_OBJECT_LIMIT 0
45 #define LOS_SECTION_NUM_CHUNKS ((LOS_SECTION_SIZE >> LOS_CHUNK_BITS) - 1)
47 #define LOS_SECTION_FOR_OBJ(obj) ((LOSSection*)((mword)(obj) & ~(mword)(LOS_SECTION_SIZE - 1)))
48 #define LOS_CHUNK_INDEX(obj,section) (((char*)(obj) - (char*)(section)) >> LOS_CHUNK_BITS)
50 #define LOS_NUM_FAST_SIZES 32
52 typedef struct _LOSFreeChunks LOSFreeChunks;
53 struct _LOSFreeChunks {
54 LOSFreeChunks *next_size;
58 typedef struct _LOSSection LOSSection;
61 size_t num_free_chunks;
62 unsigned char *free_chunk_map;
65 /* We allow read only access on the list while sweep is not running */
66 LOSObject *los_object_list = NULL;
67 mword los_memory_usage = 0;
69 static LOSSection *los_sections = NULL;
70 static LOSFreeChunks *los_fast_free_lists [LOS_NUM_FAST_SIZES]; /* 0 is for larger sizes */
71 static mword los_num_objects = 0;
72 static int los_num_sections = 0;
75 //#define LOS_CONSISTENCY_CHECK
79 #define LOS_SEGMENT_SIZE (4096 * 1024)
81 static char *los_segment = NULL;
82 static int los_segment_index = 0;
86 sgen_los_object_size (LOSObject *obj)
88 return obj->size & ~1L;
91 #ifdef LOS_CONSISTENCY_CHECK
93 los_consistency_check (void)
98 mword memory_usage = 0;
100 for (obj = los_object_list; obj; obj = obj->next) {
101 mword obj_size = sgen_los_object_size (obj);
102 char *end = obj->data + obj_size;
103 int start_index, num_chunks;
105 memory_usage += obj_size;
107 if (obj_size > LOS_SECTION_OBJECT_LIMIT)
110 section = LOS_SECTION_FOR_OBJ (obj);
112 g_assert (end <= (char*)section + LOS_SECTION_SIZE);
114 start_index = LOS_CHUNK_INDEX (obj, section);
115 num_chunks = (obj_size + sizeof (LOSObject) + LOS_CHUNK_SIZE - 1) >> LOS_CHUNK_BITS;
116 for (i = start_index; i < start_index + num_chunks; ++i)
117 g_assert (!section->free_chunk_map [i]);
120 for (i = 0; i < LOS_NUM_FAST_SIZES; ++i) {
121 LOSFreeChunks *size_chunks;
122 for (size_chunks = los_fast_free_lists [i]; size_chunks; size_chunks = size_chunks->next_size) {
123 LOSSection *section = LOS_SECTION_FOR_OBJ (size_chunks);
124 int j, num_chunks, start_index;
127 g_assert (size_chunks->size >= LOS_NUM_FAST_SIZES * LOS_CHUNK_SIZE);
129 g_assert (size_chunks->size == i * LOS_CHUNK_SIZE);
131 num_chunks = size_chunks->size >> LOS_CHUNK_BITS;
132 start_index = LOS_CHUNK_INDEX (size_chunks, section);
133 for (j = start_index; j < start_index + num_chunks; ++j)
134 g_assert (section->free_chunk_map [j]);
138 g_assert (los_memory_usage == memory_usage);
143 add_free_chunk (LOSFreeChunks *free_chunks, size_t size)
145 size_t num_chunks = size >> LOS_CHUNK_BITS;
147 free_chunks->size = size;
149 if (num_chunks >= LOS_NUM_FAST_SIZES)
151 free_chunks->next_size = los_fast_free_lists [num_chunks];
152 los_fast_free_lists [num_chunks] = free_chunks;
155 static LOSFreeChunks*
156 get_from_size_list (LOSFreeChunks **list, size_t size)
158 LOSFreeChunks *free_chunks = NULL;
160 size_t i, num_chunks, start_index;
163 g_assert ((size & (LOS_CHUNK_SIZE - 1)) == 0);
167 if (free_chunks->size >= size)
169 list = &(*list)->next_size;
175 *list = free_chunks->next_size;
177 if (free_chunks->size > size)
178 add_free_chunk ((LOSFreeChunks*)((char*)free_chunks + size), free_chunks->size - size);
180 num_chunks = size >> LOS_CHUNK_BITS;
182 section = LOS_SECTION_FOR_OBJ (free_chunks);
184 start_index = LOS_CHUNK_INDEX (free_chunks, section);
185 for (i = start_index; i < start_index + num_chunks; ++i) {
186 g_assert (section->free_chunk_map [i]);
187 section->free_chunk_map [i] = 0;
190 section->num_free_chunks -= size >> LOS_CHUNK_BITS;
191 g_assert (section->num_free_chunks >= 0);
197 randomize_los_object_start (gpointer addr, size_t obj_size, size_t alloced_size, size_t addr_alignment)
200 if (alloced_size != obj_size) {
202 * We want to get a random offset between 0 and (alloced_size - obj_size)
203 * We do a prime multiplication to avoid usage of functions which might not
204 * be thread/signal safe (like rand ()). We subtract 1 to avoid common
205 * power by 2 factors.
207 offset = SGEN_ALIGN_DOWN ((((size_t)addr - 1) * 2654435761u) % (alloced_size - obj_size));
209 SGEN_ASSERT (0, (alloced_size - obj_size) < addr_alignment, "Why are we wasting one entire chunk for a los object ?");
210 /* Randomize the location within the reserved chunks to improve cache performance */
211 return (LOSObject*)((guint8*)addr + offset);
216 get_los_section_memory (size_t size)
219 LOSFreeChunks *free_chunks;
221 size_t obj_size = size;
223 size = SGEN_ALIGN_UP_TO (size, LOS_CHUNK_SIZE);
225 num_chunks = size >> LOS_CHUNK_BITS;
227 g_assert (size > 0 && size - sizeof (LOSObject) <= LOS_SECTION_OBJECT_LIMIT);
228 g_assert (num_chunks > 0);
231 if (num_chunks >= LOS_NUM_FAST_SIZES) {
232 free_chunks = get_from_size_list (&los_fast_free_lists [0], size);
235 for (i = num_chunks; i < LOS_NUM_FAST_SIZES; ++i) {
236 free_chunks = get_from_size_list (&los_fast_free_lists [i], size);
241 free_chunks = get_from_size_list (&los_fast_free_lists [0], size);
245 return randomize_los_object_start (free_chunks, obj_size, size, LOS_CHUNK_SIZE);
248 if (!sgen_memgov_try_alloc_space (LOS_SECTION_SIZE, SPACE_LOS))
251 section = (LOSSection *)sgen_alloc_os_memory_aligned (LOS_SECTION_SIZE, LOS_SECTION_SIZE, (SgenAllocFlags)(SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE), NULL);
256 free_chunks = (LOSFreeChunks*)((char*)section + LOS_CHUNK_SIZE);
257 free_chunks->size = LOS_SECTION_SIZE - LOS_CHUNK_SIZE;
258 free_chunks->next_size = los_fast_free_lists [0];
259 los_fast_free_lists [0] = free_chunks;
261 section->num_free_chunks = LOS_SECTION_NUM_CHUNKS;
263 section->free_chunk_map = (unsigned char*)section + sizeof (LOSSection);
264 g_assert (sizeof (LOSSection) + LOS_SECTION_NUM_CHUNKS + 1 <= LOS_CHUNK_SIZE);
265 section->free_chunk_map [0] = 0;
266 memset (section->free_chunk_map + 1, 1, LOS_SECTION_NUM_CHUNKS);
268 section->next = los_sections;
269 los_sections = section;
277 free_los_section_memory (LOSObject *obj, size_t size)
279 LOSSection *section = LOS_SECTION_FOR_OBJ (obj);
280 size_t num_chunks, i, start_index;
282 size = SGEN_ALIGN_UP_TO (size, LOS_CHUNK_SIZE);
284 num_chunks = size >> LOS_CHUNK_BITS;
286 g_assert (size > 0 && size - sizeof (LOSObject) <= LOS_SECTION_OBJECT_LIMIT);
287 g_assert (num_chunks > 0);
289 section->num_free_chunks += num_chunks;
290 g_assert (section->num_free_chunks <= LOS_SECTION_NUM_CHUNKS);
293 * We could free the LOS section here if it's empty, but we
294 * can't unless we also remove its free chunks from the fast
295 * free lists. Instead, we do it in los_sweep().
298 start_index = LOS_CHUNK_INDEX (obj, section);
299 for (i = start_index; i < start_index + num_chunks; ++i) {
300 g_assert (!section->free_chunk_map [i]);
301 section->free_chunk_map [i] = 1;
304 add_free_chunk ((LOSFreeChunks*)SGEN_ALIGN_DOWN_TO ((mword)obj, LOS_CHUNK_SIZE), size);
308 sgen_los_free_object (LOSObject *obj)
310 SGEN_ASSERT (0, !obj->cardtable_mod_union, "We should never free a LOS object with a mod-union table.");
313 mword size = sgen_los_object_size (obj);
314 SGEN_LOG (4, "Freed large object %p, size %lu", obj->data, (unsigned long)size);
315 binary_protocol_empty (obj->data, size);
317 los_memory_usage -= size;
323 if (size > LOS_SECTION_OBJECT_LIMIT) {
324 int pagesize = mono_pagesize ();
325 size += sizeof (LOSObject);
326 size = SGEN_ALIGN_UP_TO (size, pagesize);
327 sgen_free_os_memory ((gpointer)SGEN_ALIGN_DOWN_TO ((mword)obj, pagesize), size, SGEN_ALLOC_HEAP);
328 sgen_memgov_release_space (size, SPACE_LOS);
330 free_los_section_memory (obj, size + sizeof (LOSObject));
331 #ifdef LOS_CONSISTENCY_CHECKS
332 los_consistency_check ();
340 * Objects with size >= MAX_SMALL_SIZE are allocated in the large object space.
341 * They are currently kept track of with a linked list.
342 * They don't move, so there is no need to pin them during collection
343 * and we avoid the memcpy overhead.
346 sgen_los_alloc_large_inner (GCVTable vtable, size_t size)
348 LOSObject *obj = NULL;
351 g_assert (size > SGEN_MAX_SMALL_OBJ_SIZE);
352 g_assert ((size & 1) == 0);
355 * size + sizeof (LOSObject) <= SSIZE_MAX - (mono_pagesize () - 1)
359 * size <= SSIZE_MAX - (mono_pagesize () - 1) - sizeof (LOSObject)
361 if (size > SSIZE_MAX - (mono_pagesize () - 1) - sizeof (LOSObject))
366 los_segment = sgen_alloc_os_memory (LOS_SEGMENT_SIZE, SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE, NULL);
367 los_segment_index = ALIGN_UP (los_segment_index);
369 obj = (LOSObject*)(los_segment + los_segment_index);
370 los_segment_index += size + sizeof (LOSObject);
371 g_assert (los_segment_index <= LOS_SEGMENT_SIZE);
373 sgen_ensure_free_space (size, GENERATION_OLD);
376 obj = malloc (size + sizeof (LOSObject));
377 memset (obj, 0, size + sizeof (LOSObject));
379 if (size > LOS_SECTION_OBJECT_LIMIT) {
380 size_t obj_size = size + sizeof (LOSObject);
381 int pagesize = mono_pagesize ();
382 size_t alloc_size = SGEN_ALIGN_UP_TO (obj_size, pagesize);
383 if (sgen_memgov_try_alloc_space (alloc_size, SPACE_LOS)) {
384 obj = (LOSObject *)sgen_alloc_os_memory (alloc_size, (SgenAllocFlags)(SGEN_ALLOC_HEAP | SGEN_ALLOC_ACTIVATE), NULL);
386 obj = randomize_los_object_start (obj, obj_size, alloc_size, pagesize);
389 obj = get_los_section_memory (size + sizeof (LOSObject));
391 memset (obj, 0, size + sizeof (LOSObject));
397 g_assert (!((mword)obj->data & (SGEN_ALLOC_ALIGN - 1)));
399 vtslot = (void**)obj->data;
401 sgen_update_heap_boundaries ((mword)obj->data, (mword)obj->data + size);
402 obj->next = los_object_list;
404 * We need a memory barrier so we don't expose as head of the los object list
405 * a LOSObject that doesn't have its fields initialized.
407 mono_memory_write_barrier ();
408 los_object_list = obj;
409 los_memory_usage += size;
411 SGEN_LOG (4, "Allocated large object %p, vtable: %p (%s), size: %zd", obj->data, vtable, sgen_client_vtable_get_name (vtable), size);
412 binary_protocol_alloc (obj->data, vtable, size, sgen_client_get_provenance ());
414 #ifdef LOS_CONSISTENCY_CHECK
415 los_consistency_check ();
421 static void sgen_los_unpin_object (GCObject *data);
424 sgen_los_sweep (void)
426 LOSObject *bigobj, *prevbo;
427 LOSSection *section, *prev;
429 int num_sections = 0;
431 /* sweep the big objects list */
433 for (bigobj = los_object_list; bigobj;) {
434 SGEN_ASSERT (0, !SGEN_OBJECT_IS_PINNED (bigobj->data), "Who pinned a LOS object?");
436 if (bigobj->cardtable_mod_union) {
437 sgen_card_table_free_mod_union (bigobj->cardtable_mod_union, (char*)bigobj->data, sgen_los_object_size (bigobj));
438 bigobj->cardtable_mod_union = NULL;
441 if (sgen_los_object_is_pinned (bigobj->data)) {
442 sgen_los_unpin_object (bigobj->data);
443 sgen_update_heap_boundaries ((mword)bigobj->data, (mword)bigobj->data + sgen_los_object_size (bigobj));
446 /* not referenced anywhere, so we can free it */
448 prevbo->next = bigobj->next;
450 los_object_list = bigobj->next;
452 bigobj = bigobj->next;
453 sgen_los_free_object (to_free);
457 bigobj = bigobj->next;
460 /* Try to free memory */
461 for (i = 0; i < LOS_NUM_FAST_SIZES; ++i)
462 los_fast_free_lists [i] = NULL;
465 section = los_sections;
467 if (section->num_free_chunks == LOS_SECTION_NUM_CHUNKS) {
468 LOSSection *next = section->next;
473 sgen_free_os_memory (section, LOS_SECTION_SIZE, SGEN_ALLOC_HEAP);
474 sgen_memgov_release_space (LOS_SECTION_SIZE, SPACE_LOS);
480 for (i = 0; i <= LOS_SECTION_NUM_CHUNKS; ++i) {
481 if (section->free_chunk_map [i]) {
483 for (j = i + 1; j <= LOS_SECTION_NUM_CHUNKS && section->free_chunk_map [j]; ++j)
485 add_free_chunk ((LOSFreeChunks*)((char*)section + (i << LOS_CHUNK_BITS)), (j - i) << LOS_CHUNK_BITS);
491 section = section->next;
496 #ifdef LOS_CONSISTENCY_CHECK
497 los_consistency_check ();
501 g_print ("LOS sections: %d objects: %d usage: %d\n", num_sections, los_num_objects, los_memory_usage);
502 for (i = 0; i < LOS_NUM_FAST_SIZES; ++i) {
504 LOSFreeChunks *free_chunks;
505 for (free_chunks = los_fast_free_lists [i]; free_chunks; free_chunks = free_chunks->next_size)
507 g_print (" %d: %d\n", i, num_chunks);
511 g_assert (los_num_sections == num_sections);
515 sgen_ptr_is_in_los (char *ptr, char **start)
520 for (obj = los_object_list; obj; obj = obj->next) {
521 char *end = (char*)obj->data + sgen_los_object_size (obj);
523 if (ptr >= (char*)obj->data && ptr < end) {
524 *start = (char*)obj->data;
532 sgen_los_iterate_objects (IterateObjectCallbackFunc cb, void *user_data)
536 for (obj = los_object_list; obj; obj = obj->next)
537 cb (obj->data, sgen_los_object_size (obj), user_data);
541 sgen_los_is_valid_object (char *object)
545 for (obj = los_object_list; obj; obj = obj->next) {
546 if ((char*)obj->data == object)
553 mono_sgen_los_describe_pointer (char *ptr)
557 for (obj = los_object_list; obj; obj = obj->next) {
558 const char *los_kind;
562 if ((char*)obj->data > ptr || (char*)obj->data + sgen_los_object_size (obj) <= ptr)
565 size = sgen_los_object_size (obj);
566 pinned = sgen_los_object_is_pinned (obj->data);
568 if (size > LOS_SECTION_OBJECT_LIMIT)
569 los_kind = "huge-los-ptr";
571 los_kind = "los-ptr";
573 if ((char*)obj->data == ptr) {
574 SGEN_LOG (0, "%s (size %d pin %d)\n", los_kind, (int)size, pinned ? 1 : 0);
576 SGEN_LOG (0, "%s (interior-ptr offset %zd size %d pin %d)",
577 los_kind, ptr - (char*)obj->data, (int)size, pinned ? 1 : 0);
586 sgen_los_iterate_live_block_ranges (sgen_cardtable_block_callback callback)
589 for (obj = los_object_list; obj; obj = obj->next) {
590 GCVTable vt = SGEN_LOAD_VTABLE (obj->data);
591 if (SGEN_VTABLE_HAS_REFERENCES (vt))
592 callback ((mword)obj->data, sgen_los_object_size (obj));
597 get_cardtable_mod_union_for_object (LOSObject *obj)
599 mword size = sgen_los_object_size (obj);
600 guint8 *mod_union = obj->cardtable_mod_union;
604 mod_union = sgen_card_table_alloc_mod_union ((char*)obj->data, size);
605 other = (guint8 *)SGEN_CAS_PTR ((gpointer*)&obj->cardtable_mod_union, mod_union, NULL);
607 SGEN_ASSERT (0, obj->cardtable_mod_union == mod_union, "Why did CAS not replace?");
610 sgen_card_table_free_mod_union (mod_union, (char*)obj->data, size);
615 sgen_los_scan_card_table (CardTableScanType scan_type, ScanCopyContext ctx)
619 binary_protocol_los_card_table_scan_start (sgen_timestamp (), scan_type & CARDTABLE_SCAN_MOD_UNION);
620 for (obj = los_object_list; obj; obj = obj->next) {
624 if (!SGEN_OBJECT_HAS_REFERENCES (obj->data))
627 if (scan_type & CARDTABLE_SCAN_MOD_UNION) {
628 if (!sgen_los_object_is_pinned (obj->data))
631 cards = get_cardtable_mod_union_for_object (obj);
633 if (scan_type == CARDTABLE_SCAN_MOD_UNION_PRECLEAN) {
634 guint8 *cards_preclean;
635 mword obj_size = sgen_los_object_size (obj);
636 num_cards = sgen_card_table_number_of_cards_in_range ((mword) obj->data, obj_size);
637 cards_preclean = (guint8 *)sgen_alloc_internal_dynamic (num_cards, INTERNAL_MEM_CARDTABLE_MOD_UNION, TRUE);
639 sgen_card_table_preclean_mod_union (cards, cards_preclean, num_cards);
641 cards = cards_preclean;
647 sgen_cardtable_scan_object (obj->data, sgen_los_object_size (obj), cards, ctx);
649 if (scan_type == CARDTABLE_SCAN_MOD_UNION_PRECLEAN)
650 sgen_free_internal_dynamic (cards, num_cards, INTERNAL_MEM_CARDTABLE_MOD_UNION);
652 binary_protocol_los_card_table_scan_end (sgen_timestamp (), scan_type & CARDTABLE_SCAN_MOD_UNION);
656 sgen_los_count_cards (long long *num_total_cards, long long *num_marked_cards)
659 long long total_cards = 0;
660 long long marked_cards = 0;
662 for (obj = los_object_list; obj; obj = obj->next) {
664 guint8 *cards = sgen_card_table_get_card_scan_address ((mword) obj->data);
665 guint8 *cards_end = sgen_card_table_get_card_scan_address ((mword) obj->data + sgen_los_object_size (obj) - 1);
666 mword num_cards = (cards_end - cards) + 1;
668 if (!SGEN_OBJECT_HAS_REFERENCES (obj->data))
671 total_cards += num_cards;
672 for (i = 0; i < num_cards; ++i) {
678 *num_total_cards = total_cards;
679 *num_marked_cards = marked_cards;
683 sgen_los_update_cardtable_mod_union (void)
687 for (obj = los_object_list; obj; obj = obj->next) {
688 if (!SGEN_OBJECT_HAS_REFERENCES (obj->data))
690 sgen_card_table_update_mod_union (get_cardtable_mod_union_for_object (obj),
691 (char*)obj->data, sgen_los_object_size (obj), NULL);
696 sgen_los_header_for_object (GCObject *data)
699 return (LOSObject*)((char*)data - (int)(&(((LOSObject*)0)->data)));
701 return (LOSObject*)((char*)data - sizeof (LOSObject));
706 sgen_los_pin_object (GCObject *data)
708 LOSObject *obj = sgen_los_header_for_object (data);
709 obj->size = obj->size | 1;
710 binary_protocol_pin (data, (gpointer)SGEN_LOAD_VTABLE (data), sgen_safe_object_get_size (data));
714 sgen_los_unpin_object (GCObject *data)
716 LOSObject *obj = sgen_los_header_for_object (data);
717 obj->size = sgen_los_object_size (obj);
721 sgen_los_object_is_pinned (GCObject *data)
723 LOSObject *obj = sgen_los_header_for_object (data);
724 return obj->size & 1;
728 sgen_los_mark_mod_union_card (GCObject *mono_obj, void **ptr)
730 LOSObject *obj = sgen_los_header_for_object (mono_obj);
731 guint8 *mod_union = get_cardtable_mod_union_for_object (obj);
732 /* The LOSObject structure is not represented within the card space */
733 size_t offset = sgen_card_table_get_card_offset ((char*)ptr, (char*)sgen_card_table_align_pointer((char*)mono_obj));
734 SGEN_ASSERT (0, mod_union, "FIXME: optionally allocate the mod union if it's not here and CAS it in.");
735 mod_union [offset] = 1;
738 #endif /* HAVE_SGEN_GC */