2 * sgen-major-copying.c: Simple generational GC.
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.
15 * THIS MATERIAL IS PROVIDED AS IS, WITH ABSOLUTELY NO WARRANTY EXPRESSED
16 * OR IMPLIED. ANY USE IS AT YOUR OWN RISK.
18 * Permission is hereby granted to use or copy this program
19 * for any purpose, provided the above notices are retained on all copies.
20 * Permission to modify the code and to distribute modified code is granted,
21 * provided the above notices are retained, and a notice that the code was
22 * modified is included with the above copyright notice.
25 * Copyright 2001-2003 Ximian, Inc
26 * Copyright 2003-2010 Novell, Inc.
28 * Permission is hereby granted, free of charge, to any person obtaining
29 * a copy of this software and associated documentation files (the
30 * "Software"), to deal in the Software without restriction, including
31 * without limitation the rights to use, copy, modify, merge, publish,
32 * distribute, sublicense, and/or sell copies of the Software, and to
33 * permit persons to whom the Software is furnished to do so, subject to
34 * the following conditions:
36 * The above copyright notice and this permission notice shall be
37 * included in all copies or substantial portions of the Software.
39 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
40 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
41 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
42 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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45 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
50 #include "utils/mono-counters.h"
51 #include "metadata/object-internals.h"
52 #include "metadata/profiler-private.h"
54 #include "metadata/sgen-gc.h"
55 #include "metadata/sgen-protocol.h"
56 #include "metadata/mono-gc.h"
58 #define MAJOR_SECTION_SIZE SGEN_PINNED_CHUNK_SIZE
59 #define BLOCK_FOR_OBJECT(o) SGEN_PINNED_CHUNK_FOR_PTR ((o))
60 #define MAJOR_SECTION_FOR_OBJECT(o) ((GCMemSection*)BLOCK_FOR_OBJECT ((o)))
62 #define MAJOR_OBJ_IS_IN_TO_SPACE(o) (MAJOR_SECTION_FOR_OBJECT ((o))->is_to_space)
64 static int num_major_sections = 0;
66 static GCMemSection *section_list = NULL;
68 static SgenInternalAllocator pinned_allocator;
70 static gboolean have_swept;
73 * used when moving the objects
75 static char *to_space_bumper = NULL;
76 static char *to_space_top = NULL;
77 static GCMemSection *to_space_section = NULL;
79 /* we get this at init */
80 static int nursery_bits;
81 static char *nursery_start;
82 static char *nursery_end;
84 #define ptr_in_nursery(p) (SGEN_PTR_IN_NURSERY ((p), nursery_bits, nursery_start, nursery_end))
86 #ifdef HEAVY_STATISTICS
87 static long stat_major_copy_object_failed_forwarded = 0;
88 static long stat_major_copy_object_failed_pinned = 0;
89 static long stat_major_copy_object_failed_large_pinned = 0;
90 static long stat_major_copy_object_failed_to_space = 0;
94 major_alloc_heap (mword nursery_size, mword nursery_align, int the_nursery_bits)
97 nursery_start = mono_sgen_alloc_os_memory_aligned (nursery_size, nursery_align, TRUE);
99 nursery_start = mono_sgen_alloc_os_memory (nursery_size, TRUE);
101 nursery_end = nursery_start + nursery_size;
102 nursery_bits = the_nursery_bits;
104 return nursery_start;
108 obj_is_from_pinned_alloc (char *p)
110 return BLOCK_FOR_OBJECT (p)->role == MEMORY_ROLE_PINNED;
114 free_pinned_object (char *obj, size_t size)
116 mono_sgen_free_internal_full (&pinned_allocator, obj, size, INTERNAL_MEM_MANAGED);
120 * Allocate a new section of memory to be used as old generation.
123 alloc_major_section (void)
125 GCMemSection *section;
128 section = mono_sgen_alloc_os_memory_aligned (MAJOR_SECTION_SIZE, MAJOR_SECTION_SIZE, TRUE);
129 section->next_data = section->data = (char*)section + SGEN_SIZEOF_GC_MEM_SECTION;
130 g_assert (!((mword)section->data & 7));
131 section->size = MAJOR_SECTION_SIZE - SGEN_SIZEOF_GC_MEM_SECTION;
132 section->end_data = section->data + section->size;
133 mono_sgen_update_heap_boundaries ((mword)section->data, (mword)section->end_data);
134 DEBUG (3, fprintf (gc_debug_file, "New major heap section: (%p-%p), total: %jd\n", section->data, section->end_data, mono_gc_get_heap_size ()));
135 scan_starts = (section->size + SGEN_SCAN_START_SIZE - 1) / SGEN_SCAN_START_SIZE;
136 section->scan_starts = mono_sgen_alloc_internal_dynamic (sizeof (char*) * scan_starts, INTERNAL_MEM_SCAN_STARTS);
137 section->num_scan_start = scan_starts;
138 section->block.role = MEMORY_ROLE_GEN1;
139 section->is_to_space = TRUE;
141 /* add to the section list */
142 section->block.next = section_list;
143 section_list = section;
145 ++num_major_sections;
151 free_major_section (GCMemSection *section)
153 DEBUG (3, fprintf (gc_debug_file, "Freed major section %p (%p-%p)\n", section, section->data, section->end_data));
154 mono_sgen_free_internal_dynamic (section->scan_starts,
155 (section->size + SGEN_SCAN_START_SIZE - 1) / SGEN_SCAN_START_SIZE * sizeof (char*), INTERNAL_MEM_SCAN_STARTS);
156 mono_sgen_free_os_memory (section, MAJOR_SECTION_SIZE);
158 --num_major_sections;
162 new_to_space_section (void)
164 /* FIXME: if the current to_space_section is empty, we don't
165 have to allocate a new one */
167 to_space_section = alloc_major_section ();
168 to_space_bumper = to_space_section->next_data;
169 to_space_top = to_space_section->end_data;
173 to_space_set_next_data (void)
175 g_assert (to_space_bumper >= to_space_section->next_data && to_space_bumper <= to_space_section->end_data);
176 to_space_section->next_data = to_space_bumper;
180 to_space_expand (void)
182 if (to_space_section) {
183 g_assert (to_space_top == to_space_section->end_data);
184 to_space_set_next_data ();
187 new_to_space_section ();
191 major_alloc_object (int size, gboolean has_references)
193 char *dest = to_space_bumper;
194 /* Make sure we have enough space available */
195 if (dest + size > to_space_top) {
197 (dest) = to_space_bumper;
198 DEBUG (8, g_assert (dest + size <= to_space_top));
200 to_space_bumper += size;
201 DEBUG (8, g_assert (to_space_bumper <= to_space_top));
202 to_space_section->scan_starts [(dest - (char*)to_space_section->data)/SGEN_SCAN_START_SIZE] = dest;
207 unset_to_space (void)
209 /* between collections the to_space_bumper is invalidated
210 because degraded allocations might occur, so we set it to
211 NULL, just to make it explicit */
212 to_space_bumper = NULL;
214 /* don't unset to_space_section if we implement the FIXME in
215 new_to_space_section */
216 to_space_section = NULL;
220 major_is_object_live (char *obj)
225 if (ptr_in_nursery (obj))
228 objsize = SGEN_ALIGN_UP (mono_sgen_safe_object_get_size ((MonoObject*)obj));
231 if (objsize > SGEN_MAX_SMALL_OBJ_SIZE)
235 if (obj_is_from_pinned_alloc (obj))
238 /* now we know it's in a major heap section */
239 return MAJOR_SECTION_FOR_OBJECT (obj)->is_to_space;
242 /* size is a multiple of ALLOC_ALIGN */
244 major_alloc_small_pinned_obj (size_t size, gboolean has_references)
246 return mono_sgen_alloc_internal_full (&pinned_allocator, size, INTERNAL_MEM_MANAGED);
250 * size is already rounded up and we hold the GC lock.
253 major_alloc_degraded (MonoVTable *vtable, size_t size)
255 GCMemSection *section;
257 g_assert (size <= SGEN_MAX_SMALL_OBJ_SIZE);
258 HEAVY_STAT (++stat_objects_alloced_degraded);
259 HEAVY_STAT (stat_bytes_alloced_degraded += size);
260 for (section = section_list; section; section = section->block.next) {
261 if ((section->end_data - section->next_data) >= size) {
262 p = (void**)section->next_data;
267 section = alloc_major_section ();
268 section->is_to_space = FALSE;
269 /* FIXME: handle OOM */
270 p = (void**)section->next_data;
271 mono_sgen_register_major_sections_alloced (1);
273 section->next_data += size;
274 DEBUG (3, fprintf (gc_debug_file, "Allocated (degraded) object %p, vtable: %p (%s), size: %zd in section %p\n", p, vtable, vtable->klass->name, size, section));
279 #include "sgen-major-copy-object.h"
282 major_copy_or_mark_object (void **obj_slot, SgenGrayQueue *queue)
285 char *obj = *obj_slot;
288 DEBUG (9, g_assert (current_collection_generation == GENERATION_OLD));
290 HEAVY_STAT (++stat_copy_object_called_major);
292 DEBUG (9, fprintf (gc_debug_file, "Precise copy of %p from %p", obj, obj_slot));
295 * obj must belong to one of:
300 * 4. a non-to-space section of the major heap
301 * 5. a to-space section of the major heap
303 * In addition, objects in 1, 2 and 4 might also be pinned.
304 * Objects in 1 and 4 might be forwarded.
306 * Before we can copy the object we must make sure that we are
307 * allowed to, i.e. that the object not pinned, not already
308 * forwarded and doesn't belong to the LOS, a pinned chunk, or
309 * a to-space section.
311 * We are usually called for to-space objects (5) when we have
312 * two remset entries for the same reference. The first entry
313 * copies the object and updates the reference and the second
314 * calls us with the updated reference that points into
315 * to-space. There might also be other circumstances where we
316 * get to-space objects.
319 if ((forwarded = SGEN_OBJECT_IS_FORWARDED (obj))) {
320 DEBUG (9, g_assert (((MonoVTable*)SGEN_LOAD_VTABLE(obj))->gc_descr));
321 DEBUG (9, fprintf (gc_debug_file, " (already forwarded to %p)\n", forwarded));
322 HEAVY_STAT (++stat_major_copy_object_failed_forwarded);
323 *obj_slot = forwarded;
326 if (SGEN_OBJECT_IS_PINNED (obj)) {
327 DEBUG (9, g_assert (((MonoVTable*)SGEN_LOAD_VTABLE(obj))->gc_descr));
328 DEBUG (9, fprintf (gc_debug_file, " (pinned, no change)\n"));
329 HEAVY_STAT (++stat_major_copy_object_failed_pinned);
333 if (ptr_in_nursery (obj))
337 * At this point we know obj is not pinned, not forwarded and
338 * belongs to 2, 3, 4, or 5.
340 * LOS object (2) are simple, at least until we always follow
341 * the rule: if objsize > SGEN_MAX_SMALL_OBJ_SIZE, pin the
342 * object and return it. At the end of major collections, we
343 * walk the los list and if the object is pinned, it is
344 * marked, otherwise it can be freed.
346 * Pinned chunks (3) and major heap sections (4, 5) both
347 * reside in blocks, which are always aligned, so once we've
348 * eliminated LOS objects, we can just access the block and
349 * see whether it's a pinned chunk or a major heap section.
352 objsize = SGEN_ALIGN_UP (mono_sgen_safe_object_get_size ((MonoObject*)obj));
354 if (G_UNLIKELY (objsize > SGEN_MAX_SMALL_OBJ_SIZE || obj_is_from_pinned_alloc (obj))) {
355 if (SGEN_OBJECT_IS_PINNED (obj))
357 DEBUG (9, fprintf (gc_debug_file, " (marked LOS/Pinned %p (%s), size: %zd)\n", obj, mono_sgen_safe_name (obj), objsize));
358 binary_protocol_pin (obj, (gpointer)SGEN_LOAD_VTABLE (obj), mono_sgen_safe_object_get_size ((MonoObject*)obj));
359 SGEN_PIN_OBJECT (obj);
360 GRAY_OBJECT_ENQUEUE (queue, obj);
361 HEAVY_STAT (++stat_major_copy_object_failed_large_pinned);
366 * Now we know the object is in a major heap section. All we
367 * need to do is check whether it's already in to-space (5) or
370 if (MAJOR_OBJ_IS_IN_TO_SPACE (obj)) {
371 DEBUG (9, g_assert (objsize <= SGEN_MAX_SMALL_OBJ_SIZE));
372 DEBUG (9, fprintf (gc_debug_file, " (already copied)\n"));
373 HEAVY_STAT (++stat_major_copy_object_failed_to_space);
378 HEAVY_STAT (++stat_objects_copied_major);
380 *obj_slot = copy_object_no_checks (obj, queue);
383 #include "sgen-major-scan-object.h"
385 /* FIXME: later reduce code duplication here with build_nursery_fragments().
386 * We don't keep track of section fragments for non-nursery sections yet, so
390 build_section_fragments (GCMemSection *section)
393 char *frag_start, *frag_end;
396 /* clear scan starts */
397 memset (section->scan_starts, 0, section->num_scan_start * sizeof (gpointer));
398 frag_start = section->data;
399 section->next_data = section->data;
400 for (i = 0; i < section->pin_queue_num_entries; ++i) {
401 frag_end = section->pin_queue_start [i];
402 /* remove the pin bit from pinned objects */
403 SGEN_UNPIN_OBJECT (frag_end);
404 if (frag_end >= section->data + section->size) {
405 frag_end = section->data + section->size;
407 section->scan_starts [((char*)frag_end - (char*)section->data)/SGEN_SCAN_START_SIZE] = frag_end;
409 frag_size = frag_end - frag_start;
411 binary_protocol_empty (frag_start, frag_size);
412 memset (frag_start, 0, frag_size);
414 frag_size = SGEN_ALIGN_UP (mono_sgen_safe_object_get_size ((MonoObject*)section->pin_queue_start [i]));
415 frag_start = (char*)section->pin_queue_start [i] + frag_size;
416 section->next_data = MAX (section->next_data, frag_start);
418 frag_end = section->end_data;
419 frag_size = frag_end - frag_start;
421 binary_protocol_empty (frag_start, frag_size);
422 memset (frag_start, 0, frag_size);
427 sweep_pinned_objects_callback (char *ptr, size_t size, void *data)
429 if (SGEN_OBJECT_IS_PINNED (ptr)) {
430 SGEN_UNPIN_OBJECT (ptr);
431 DEBUG (6, fprintf (gc_debug_file, "Unmarked pinned object %p (%s)\n", ptr, mono_sgen_safe_name (ptr)));
433 DEBUG (6, fprintf (gc_debug_file, "Freeing unmarked pinned object %p (%s)\n", ptr, mono_sgen_safe_name (ptr)));
434 free_pinned_object (ptr, size);
439 sweep_pinned_objects (void)
441 mono_sgen_internal_scan_objects (&pinned_allocator, sweep_pinned_objects_callback, NULL);
445 major_iterate_objects (gboolean non_pinned, gboolean pinned, IterateObjectCallbackFunc callback, void *data)
448 GCMemSection *section;
449 for (section = section_list; section; section = section->block.next)
450 mono_sgen_scan_area_with_callback (section->data, section->end_data, callback, data, FALSE);
453 mono_sgen_internal_scan_objects (&pinned_allocator, callback, data);
457 major_free_non_pinned_object (char *obj, size_t size)
459 memset (obj, 0, size);
463 pin_pinned_object_callback (void *addr, size_t slot_size, SgenGrayQueue *queue)
465 binary_protocol_pin (addr, (gpointer)SGEN_LOAD_VTABLE (addr), mono_sgen_safe_object_get_size ((MonoObject*)addr));
466 if (!SGEN_OBJECT_IS_PINNED (addr))
467 mono_sgen_pin_stats_register_object ((char*) addr, mono_sgen_safe_object_get_size ((MonoObject*) addr));
468 SGEN_PIN_OBJECT (addr);
469 GRAY_OBJECT_ENQUEUE (queue, addr);
470 DEBUG (6, fprintf (gc_debug_file, "Marked pinned object %p (%s) from roots\n", addr, mono_sgen_safe_name (addr)));
474 major_find_pin_queue_start_ends (SgenGrayQueue *queue)
476 GCMemSection *section;
478 for (section = section_list; section; section = section->block.next)
479 mono_sgen_find_section_pin_queue_start_end (section);
480 mono_sgen_internal_scan_pinned_objects (&pinned_allocator, (IterateObjectCallbackFunc)pin_pinned_object_callback, queue);
484 major_pin_objects (SgenGrayQueue *queue)
486 GCMemSection *section;
488 for (section = section_list; section; section = section->block.next)
489 mono_sgen_pin_objects_in_section (section, queue);
493 major_init_to_space (void)
495 new_to_space_section ();
501 GCMemSection *section, *prev_section;
503 to_space_set_next_data ();
506 /* unpin objects from the pinned chunks and free the unmarked ones */
507 sweep_pinned_objects ();
509 mono_sgen_internal_update_heap_boundaries (&pinned_allocator);
511 /* free the unused sections */
513 for (section = section_list; section;) {
514 GCMemSection *this_section = section;
516 /* to_space doesn't need handling here */
517 if (section->is_to_space) {
518 section->is_to_space = FALSE;
519 prev_section = section;
520 section = section->block.next;
523 /* no pinning object, so the section is free */
524 if (!section->pin_queue_num_entries) {
525 GCMemSection *to_free;
526 g_assert (!section->pin_queue_start);
528 prev_section->block.next = section->block.next;
530 section_list = section->block.next;
532 section = section->block.next;
533 free_major_section (to_free);
536 DEBUG (6, fprintf (gc_debug_file, "Section %p has still pinned objects (%d)\n", section, section->pin_queue_num_entries));
537 build_section_fragments (section);
539 prev_section = section;
540 section = section->block.next;
543 mono_sgen_update_heap_boundaries ((mword)this_section->data, (mword)this_section->data + this_section->size);
550 major_check_scan_starts (void)
552 GCMemSection *section;
553 for (section = section_list; section; section = section->block.next)
554 mono_sgen_check_section_scan_starts (section);
558 major_dump_heap (FILE *heap_dump_file)
560 GCMemSection *section;
561 for (section = section_list; section; section = section->block.next)
562 mono_sgen_dump_section (section, "old");
563 /* FIXME: dump pinned sections, too */
567 major_get_used_size (void)
570 GCMemSection *section;
571 for (section = section_list; section; section = section->block.next) {
572 /* this is approximate... */
573 tot += section->next_data - section->data;
578 /* only valid during minor collections */
579 static int old_num_major_sections;
582 major_start_nursery_collection (void)
584 old_num_major_sections = num_major_sections;
586 if (!to_space_section) {
587 new_to_space_section ();
589 /* we might have done degraded allocation since the
591 g_assert (to_space_bumper <= to_space_section->next_data);
592 to_space_bumper = to_space_section->next_data;
594 to_space_section->is_to_space = TRUE;
599 major_finish_nursery_collection (void)
601 GCMemSection *section;
602 int sections_alloced;
604 to_space_set_next_data ();
606 for (section = section_list; section; section = section->block.next)
607 section->is_to_space = FALSE;
609 sections_alloced = num_major_sections - old_num_major_sections;
610 mono_sgen_register_major_sections_alloced (sections_alloced);
614 major_finish_major_collection (void)
619 major_ptr_is_in_non_pinned_space (char *ptr)
621 GCMemSection *section;
622 for (section = section_list; section;) {
623 if (ptr >= section->data && ptr < section->data + section->size)
625 section = section->block.next;
631 major_report_pinned_memory_usage (void)
633 mono_sgen_report_internal_mem_usage_full (&pinned_allocator);
637 get_num_major_sections (void)
639 return num_major_sections;
643 mono_sgen_copying_init (SgenMajorCollector *collector)
645 #ifdef HEAVY_STATISTICS
646 mono_counters_register ("# major copy_object() failed forwarded", MONO_COUNTER_GC | MONO_COUNTER_LONG, &stat_major_copy_object_failed_forwarded);
647 mono_counters_register ("# major copy_object() failed pinned", MONO_COUNTER_GC | MONO_COUNTER_LONG, &stat_major_copy_object_failed_pinned);
648 mono_counters_register ("# major copy_object() failed large or pinned chunk", MONO_COUNTER_GC | MONO_COUNTER_LONG, &stat_major_copy_object_failed_large_pinned);
649 mono_counters_register ("# major copy_object() failed to space", MONO_COUNTER_GC | MONO_COUNTER_LONG, &stat_major_copy_object_failed_to_space);
652 collector->section_size = MAJOR_SECTION_SIZE;
653 collector->supports_cardtable = FALSE;
654 collector->is_parallel = FALSE;
656 collector->have_swept = &have_swept;
658 collector->alloc_heap = major_alloc_heap;
659 collector->is_object_live = major_is_object_live;
660 collector->alloc_small_pinned_obj = major_alloc_small_pinned_obj;
661 collector->alloc_degraded = major_alloc_degraded;
662 collector->copy_or_mark_object = major_copy_or_mark_object;
663 collector->alloc_object = major_alloc_object;
664 collector->free_pinned_object = free_pinned_object;
665 collector->iterate_objects = major_iterate_objects;
666 collector->free_non_pinned_object = major_free_non_pinned_object;
667 collector->find_pin_queue_start_ends = major_find_pin_queue_start_ends;
668 collector->pin_objects = major_pin_objects;
669 collector->init_to_space = major_init_to_space;
670 collector->sweep = major_sweep;
671 collector->check_scan_starts = major_check_scan_starts;
672 collector->dump_heap = major_dump_heap;
673 collector->get_used_size = major_get_used_size;
674 collector->start_nursery_collection = major_start_nursery_collection;
675 collector->finish_nursery_collection = major_finish_nursery_collection;
676 collector->finish_major_collection = major_finish_major_collection;
677 collector->ptr_is_in_non_pinned_space = major_ptr_is_in_non_pinned_space;
678 collector->obj_is_from_pinned_alloc = obj_is_from_pinned_alloc;
679 collector->report_pinned_memory_usage = major_report_pinned_memory_usage;
680 collector->get_num_major_sections = get_num_major_sections;
681 collector->handle_gc_param = NULL;
682 collector->print_gc_param_usage = NULL;
684 FILL_COLLECTOR_COPY_OBJECT (collector);
685 FILL_COLLECTOR_SCAN_OBJECT (collector);