2 * sgen-gc.c: Simple generational GC.
5 * Paolo Molaro (lupus@ximian.com)
6 * Rodrigo Kumpera (kumpera@gmail.com)
8 * Copyright 2005-2011 Novell, Inc (http://www.novell.com)
9 * Copyright 2011 Xamarin Inc (http://www.xamarin.com)
11 * Thread start/stop adapted from Boehm's GC:
12 * Copyright (c) 1994 by Xerox Corporation. All rights reserved.
13 * Copyright (c) 1996 by Silicon Graphics. All rights reserved.
14 * Copyright (c) 1998 by Fergus Henderson. All rights reserved.
15 * Copyright (c) 2000-2004 by Hewlett-Packard Company. All rights reserved.
16 * Copyright 2001-2003 Ximian, Inc
17 * Copyright 2003-2010 Novell, Inc.
18 * Copyright 2011 Xamarin, Inc.
19 * Copyright (C) 2012 Xamarin Inc
21 * Licensed under the MIT license. See LICENSE file in the project root for full license information.
23 * Important: allocation provides always zeroed memory, having to do
24 * a memset after allocation is deadly for performance.
25 * Memory usage at startup is currently as follows:
27 * 64 KB internal space
29 * We should provide a small memory config with half the sizes
31 * We currently try to make as few mono assumptions as possible:
32 * 1) 2-word header with no GC pointers in it (first vtable, second to store the
34 * 2) gc descriptor is the second word in the vtable (first word in the class)
35 * 3) 8 byte alignment is the minimum and enough (not true for special structures (SIMD), FIXME)
36 * 4) there is a function to get an object's size and the number of
37 * elements in an array.
38 * 5) we know the special way bounds are allocated for complex arrays
39 * 6) we know about proxies and how to treat them when domains are unloaded
41 * Always try to keep stack usage to a minimum: no recursive behaviour
42 * and no large stack allocs.
44 * General description.
45 * Objects are initially allocated in a nursery using a fast bump-pointer technique.
46 * When the nursery is full we start a nursery collection: this is performed with a
48 * When the old generation is full we start a copying GC of the old generation as well:
49 * this will be changed to mark&sweep with copying when fragmentation becomes to severe
50 * in the future. Maybe we'll even do both during the same collection like IMMIX.
52 * The things that complicate this description are:
53 * *) pinned objects: we can't move them so we need to keep track of them
54 * *) no precise info of the thread stacks and registers: we need to be able to
55 * quickly find the objects that may be referenced conservatively and pin them
56 * (this makes the first issues more important)
57 * *) large objects are too expensive to be dealt with using copying GC: we handle them
58 * with mark/sweep during major collections
59 * *) some objects need to not move even if they are small (interned strings, Type handles):
60 * we use mark/sweep for them, too: they are not allocated in the nursery, but inside
61 * PinnedChunks regions
67 *) we could have a function pointer in MonoClass to implement
68 customized write barriers for value types
70 *) investigate the stuff needed to advance a thread to a GC-safe
71 point (single-stepping, read from unmapped memory etc) and implement it.
72 This would enable us to inline allocations and write barriers, for example,
73 or at least parts of them, like the write barrier checks.
74 We may need this also for handling precise info on stacks, even simple things
75 as having uninitialized data on the stack and having to wait for the prolog
76 to zero it. Not an issue for the last frame that we scan conservatively.
77 We could always not trust the value in the slots anyway.
79 *) modify the jit to save info about references in stack locations:
80 this can be done just for locals as a start, so that at least
81 part of the stack is handled precisely.
83 *) test/fix endianess issues
85 *) Implement a card table as the write barrier instead of remembered
86 sets? Card tables are not easy to implement with our current
87 memory layout. We have several different kinds of major heap
88 objects: Small objects in regular blocks, small objects in pinned
89 chunks and LOS objects. If we just have a pointer we have no way
90 to tell which kind of object it points into, therefore we cannot
91 know where its card table is. The least we have to do to make
92 this happen is to get rid of write barriers for indirect stores.
95 *) Get rid of write barriers for indirect stores. We can do this by
96 telling the GC to wbarrier-register an object once we do an ldloca
97 or ldelema on it, and to unregister it once it's not used anymore
98 (it can only travel downwards on the stack). The problem with
99 unregistering is that it needs to happen eventually no matter
100 what, even if exceptions are thrown, the thread aborts, etc.
101 Rodrigo suggested that we could do only the registering part and
102 let the collector find out (pessimistically) when it's safe to
103 unregister, namely when the stack pointer of the thread that
104 registered the object is higher than it was when the registering
105 happened. This might make for a good first implementation to get
106 some data on performance.
108 *) Some sort of blacklist support? Blacklists is a concept from the
109 Boehm GC: if during a conservative scan we find pointers to an
110 area which we might use as heap, we mark that area as unusable, so
111 pointer retention by random pinning pointers is reduced.
113 *) experiment with max small object size (very small right now - 2kb,
114 because it's tied to the max freelist size)
116 *) add an option to mmap the whole heap in one chunk: it makes for many
117 simplifications in the checks (put the nursery at the top and just use a single
118 check for inclusion/exclusion): the issue this has is that on 32 bit systems it's
119 not flexible (too much of the address space may be used by default or we can't
120 increase the heap as needed) and we'd need a race-free mechanism to return memory
121 back to the system (mprotect(PROT_NONE) will still keep the memory allocated if it
122 was written to, munmap is needed, but the following mmap may not find the same segment
125 *) memzero the major fragments after restarting the world and optionally a smaller
128 *) investigate having fragment zeroing threads
130 *) separate locks for finalization and other minor stuff to reduce
133 *) try a different copying order to improve memory locality
135 *) a thread abort after a store but before the write barrier will
136 prevent the write barrier from executing
138 *) specialized dynamically generated markers/copiers
140 *) Dynamically adjust TLAB size to the number of threads. If we have
141 too many threads that do allocation, we might need smaller TLABs,
142 and we might get better performance with larger TLABs if we only
143 have a handful of threads. We could sum up the space left in all
144 assigned TLABs and if that's more than some percentage of the
145 nursery size, reduce the TLAB size.
147 *) Explore placing unreachable objects on unused nursery memory.
148 Instead of memset'ng a region to zero, place an int[] covering it.
149 A good place to start is add_nursery_frag. The tricky thing here is
150 placing those objects atomically outside of a collection.
152 *) Allocation should use asymmetric Dekker synchronization:
153 http://blogs.oracle.com/dave/resource/Asymmetric-Dekker-Synchronization.txt
154 This should help weak consistency archs.
161 #define _XOPEN_SOURCE
162 #define _DARWIN_C_SOURCE
168 #ifdef HAVE_PTHREAD_H
171 #ifdef HAVE_PTHREAD_NP_H
172 #include <pthread_np.h>
180 #include "mono/sgen/sgen-gc.h"
181 #include "mono/sgen/sgen-cardtable.h"
182 #include "mono/sgen/sgen-protocol.h"
183 #include "mono/sgen/sgen-memory-governor.h"
184 #include "mono/sgen/sgen-hash-table.h"
185 #include "mono/sgen/sgen-cardtable.h"
186 #include "mono/sgen/sgen-pinning.h"
187 #include "mono/sgen/sgen-workers.h"
188 #include "mono/sgen/sgen-client.h"
189 #include "mono/sgen/sgen-pointer-queue.h"
190 #include "mono/sgen/gc-internal-agnostic.h"
191 #include "mono/utils/mono-proclib.h"
192 #include "mono/utils/mono-memory-model.h"
193 #include "mono/utils/hazard-pointer.h"
195 #include <mono/utils/memcheck.h>
197 #undef pthread_create
199 #undef pthread_detach
202 * ######################################################################
203 * ######## Types and constants used by the GC.
204 * ######################################################################
207 /* 0 means not initialized, 1 is initialized, -1 means in progress */
208 static int gc_initialized = 0;
209 /* If set, check if we need to do something every X allocations */
210 gboolean has_per_allocation_action;
211 /* If set, do a heap check every X allocation */
212 guint32 verify_before_allocs = 0;
213 /* If set, do a minor collection before every X allocation */
214 guint32 collect_before_allocs = 0;
215 /* If set, do a whole heap check before each collection */
216 static gboolean whole_heap_check_before_collection = FALSE;
217 /* If set, do a heap consistency check before each minor collection */
218 static gboolean consistency_check_at_minor_collection = FALSE;
219 /* If set, do a mod union consistency check before each finishing collection pause */
220 static gboolean mod_union_consistency_check = FALSE;
221 /* If set, check whether mark bits are consistent after major collections */
222 static gboolean check_mark_bits_after_major_collection = FALSE;
223 /* If set, check that all nursery objects are pinned/not pinned, depending on context */
224 static gboolean check_nursery_objects_pinned = FALSE;
225 /* If set, do a few checks when the concurrent collector is used */
226 static gboolean do_concurrent_checks = FALSE;
227 /* If set, do a plausibility check on the scan_starts before and after
229 static gboolean do_scan_starts_check = FALSE;
231 static gboolean disable_minor_collections = FALSE;
232 static gboolean disable_major_collections = FALSE;
233 static gboolean do_verify_nursery = FALSE;
234 static gboolean do_dump_nursery_content = FALSE;
235 static gboolean enable_nursery_canaries = FALSE;
237 static gboolean precleaning_enabled = TRUE;
239 #ifdef HEAVY_STATISTICS
240 guint64 stat_objects_alloced_degraded = 0;
241 guint64 stat_bytes_alloced_degraded = 0;
243 guint64 stat_copy_object_called_nursery = 0;
244 guint64 stat_objects_copied_nursery = 0;
245 guint64 stat_copy_object_called_major = 0;
246 guint64 stat_objects_copied_major = 0;
248 guint64 stat_scan_object_called_nursery = 0;
249 guint64 stat_scan_object_called_major = 0;
251 guint64 stat_slots_allocated_in_vain;
253 guint64 stat_nursery_copy_object_failed_from_space = 0;
254 guint64 stat_nursery_copy_object_failed_forwarded = 0;
255 guint64 stat_nursery_copy_object_failed_pinned = 0;
256 guint64 stat_nursery_copy_object_failed_to_space = 0;
258 static guint64 stat_wbarrier_add_to_global_remset = 0;
259 static guint64 stat_wbarrier_arrayref_copy = 0;
260 static guint64 stat_wbarrier_generic_store = 0;
261 static guint64 stat_wbarrier_generic_store_atomic = 0;
262 static guint64 stat_wbarrier_set_root = 0;
265 static guint64 stat_pinned_objects = 0;
267 static guint64 time_minor_pre_collection_fragment_clear = 0;
268 static guint64 time_minor_pinning = 0;
269 static guint64 time_minor_scan_remsets = 0;
270 static guint64 time_minor_scan_pinned = 0;
271 static guint64 time_minor_scan_roots = 0;
272 static guint64 time_minor_finish_gray_stack = 0;
273 static guint64 time_minor_fragment_creation = 0;
275 static guint64 time_major_pre_collection_fragment_clear = 0;
276 static guint64 time_major_pinning = 0;
277 static guint64 time_major_scan_pinned = 0;
278 static guint64 time_major_scan_roots = 0;
279 static guint64 time_major_scan_mod_union = 0;
280 static guint64 time_major_finish_gray_stack = 0;
281 static guint64 time_major_free_bigobjs = 0;
282 static guint64 time_major_los_sweep = 0;
283 static guint64 time_major_sweep = 0;
284 static guint64 time_major_fragment_creation = 0;
286 static guint64 time_max = 0;
288 static SGEN_TV_DECLARE (time_major_conc_collection_start);
289 static SGEN_TV_DECLARE (time_major_conc_collection_end);
291 static SGEN_TV_DECLARE (last_minor_collection_start_tv);
292 static SGEN_TV_DECLARE (last_minor_collection_end_tv);
294 int gc_debug_level = 0;
299 mono_gc_flush_info (void)
301 fflush (gc_debug_file);
305 #define TV_DECLARE SGEN_TV_DECLARE
306 #define TV_GETTIME SGEN_TV_GETTIME
307 #define TV_ELAPSED SGEN_TV_ELAPSED
309 static SGEN_TV_DECLARE (sgen_init_timestamp);
311 NurseryClearPolicy nursery_clear_policy = CLEAR_AT_TLAB_CREATION;
313 #define object_is_forwarded SGEN_OBJECT_IS_FORWARDED
314 #define object_is_pinned SGEN_OBJECT_IS_PINNED
315 #define pin_object SGEN_PIN_OBJECT
317 #define ptr_in_nursery sgen_ptr_in_nursery
319 #define LOAD_VTABLE SGEN_LOAD_VTABLE
322 nursery_canaries_enabled (void)
324 return enable_nursery_canaries;
327 #define safe_object_get_size sgen_safe_object_get_size
330 * ######################################################################
331 * ######## Global data.
332 * ######################################################################
334 MonoCoopMutex gc_mutex;
336 #define SCAN_START_SIZE SGEN_SCAN_START_SIZE
338 size_t degraded_mode = 0;
340 static mword bytes_pinned_from_failed_allocation = 0;
342 GCMemSection *nursery_section = NULL;
343 static volatile mword lowest_heap_address = ~(mword)0;
344 static volatile mword highest_heap_address = 0;
346 MonoCoopMutex sgen_interruption_mutex;
348 int current_collection_generation = -1;
349 static volatile gboolean concurrent_collection_in_progress = FALSE;
351 /* objects that are ready to be finalized */
352 static SgenPointerQueue fin_ready_queue = SGEN_POINTER_QUEUE_INIT (INTERNAL_MEM_FINALIZE_READY);
353 static SgenPointerQueue critical_fin_queue = SGEN_POINTER_QUEUE_INIT (INTERNAL_MEM_FINALIZE_READY);
355 /* registered roots: the key to the hash is the root start address */
357 * Different kinds of roots are kept separate to speed up pin_from_roots () for example.
359 SgenHashTable roots_hash [ROOT_TYPE_NUM] = {
360 SGEN_HASH_TABLE_INIT (INTERNAL_MEM_ROOTS_TABLE, INTERNAL_MEM_ROOT_RECORD, sizeof (RootRecord), sgen_aligned_addr_hash, NULL),
361 SGEN_HASH_TABLE_INIT (INTERNAL_MEM_ROOTS_TABLE, INTERNAL_MEM_ROOT_RECORD, sizeof (RootRecord), sgen_aligned_addr_hash, NULL),
362 SGEN_HASH_TABLE_INIT (INTERNAL_MEM_ROOTS_TABLE, INTERNAL_MEM_ROOT_RECORD, sizeof (RootRecord), sgen_aligned_addr_hash, NULL)
364 static mword roots_size = 0; /* amount of memory in the root set */
366 /* The size of a TLAB */
367 /* The bigger the value, the less often we have to go to the slow path to allocate a new
368 * one, but the more space is wasted by threads not allocating much memory.
370 * FIXME: Make this self-tuning for each thread.
372 guint32 tlab_size = (1024 * 4);
374 #define MAX_SMALL_OBJ_SIZE SGEN_MAX_SMALL_OBJ_SIZE
376 #define ALLOC_ALIGN SGEN_ALLOC_ALIGN
378 #define ALIGN_UP SGEN_ALIGN_UP
380 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
381 MonoNativeThreadId main_gc_thread = NULL;
384 /*Object was pinned during the current collection*/
385 static mword objects_pinned;
388 * ######################################################################
389 * ######## Macros and function declarations.
390 * ######################################################################
393 typedef SgenGrayQueue GrayQueue;
395 /* forward declarations */
396 static void scan_from_registered_roots (char *addr_start, char *addr_end, int root_type, ScanCopyContext ctx);
398 static void pin_from_roots (void *start_nursery, void *end_nursery, ScanCopyContext ctx);
399 static void finish_gray_stack (int generation, ScanCopyContext ctx);
402 SgenMajorCollector major_collector;
403 SgenMinorCollector sgen_minor_collector;
404 /* FIXME: get rid of this */
405 static GrayQueue gray_queue;
407 static SgenRememberedSet remset;
409 /* The gray queue to use from the main collection thread. */
410 #define WORKERS_DISTRIBUTE_GRAY_QUEUE (&gray_queue)
413 * The gray queue a worker job must use. If we're not parallel or
414 * concurrent, we use the main gray queue.
416 static SgenGrayQueue*
417 sgen_workers_get_job_gray_queue (WorkerData *worker_data)
419 return worker_data ? &worker_data->private_gray_queue : WORKERS_DISTRIBUTE_GRAY_QUEUE;
423 gray_queue_redirect (SgenGrayQueue *queue)
425 gboolean wake = FALSE;
428 GrayQueueSection *section = sgen_gray_object_dequeue_section (queue);
431 sgen_section_gray_queue_enqueue ((SgenSectionGrayQueue *)queue->alloc_prepare_data, section);
436 g_assert (concurrent_collection_in_progress);
437 sgen_workers_ensure_awake ();
442 gray_queue_enable_redirect (SgenGrayQueue *queue)
444 if (!concurrent_collection_in_progress)
447 sgen_gray_queue_set_alloc_prepare (queue, gray_queue_redirect, sgen_workers_get_distribute_section_gray_queue ());
448 gray_queue_redirect (queue);
452 sgen_scan_area_with_callback (char *start, char *end, IterateObjectCallbackFunc callback, void *data, gboolean allow_flags, gboolean fail_on_canaries)
454 while (start < end) {
458 if (!*(void**)start) {
459 start += sizeof (void*); /* should be ALLOC_ALIGN, really */
464 if (!(obj = (char *)SGEN_OBJECT_IS_FORWARDED (start)))
470 if (!sgen_client_object_is_array_fill ((GCObject*)obj)) {
471 CHECK_CANARY_FOR_OBJECT ((GCObject*)obj, fail_on_canaries);
472 size = ALIGN_UP (safe_object_get_size ((GCObject*)obj));
473 callback ((GCObject*)obj, size, data);
474 CANARIFY_SIZE (size);
476 size = ALIGN_UP (safe_object_get_size ((GCObject*)obj));
484 * sgen_add_to_global_remset:
486 * The global remset contains locations which point into newspace after
487 * a minor collection. This can happen if the objects they point to are pinned.
489 * LOCKING: If called from a parallel collector, the global remset
490 * lock must be held. For serial collectors that is not necessary.
493 sgen_add_to_global_remset (gpointer ptr, GCObject *obj)
495 SGEN_ASSERT (5, sgen_ptr_in_nursery (obj), "Target pointer of global remset must be in the nursery");
497 HEAVY_STAT (++stat_wbarrier_add_to_global_remset);
499 if (!major_collector.is_concurrent) {
500 SGEN_ASSERT (5, current_collection_generation != -1, "Global remsets can only be added during collections");
502 if (current_collection_generation == -1)
503 SGEN_ASSERT (5, sgen_concurrent_collection_in_progress (), "Global remsets outside of collection pauses can only be added by the concurrent collector");
506 if (!object_is_pinned (obj))
507 SGEN_ASSERT (5, sgen_minor_collector.is_split || sgen_concurrent_collection_in_progress (), "Non-pinned objects can only remain in nursery if it is a split nursery");
508 else if (sgen_cement_lookup_or_register (obj))
511 remset.record_pointer (ptr);
513 sgen_pin_stats_register_global_remset (obj);
515 SGEN_LOG (8, "Adding global remset for %p", ptr);
516 binary_protocol_global_remset (ptr, obj, (gpointer)SGEN_LOAD_VTABLE (obj));
520 * sgen_drain_gray_stack:
522 * Scan objects in the gray stack until the stack is empty. This should be called
523 * frequently after each object is copied, to achieve better locality and cache
528 sgen_drain_gray_stack (ScanCopyContext ctx)
530 ScanObjectFunc scan_func = ctx.ops->scan_object;
531 GrayQueue *queue = ctx.queue;
533 if (ctx.ops->drain_gray_stack)
534 return ctx.ops->drain_gray_stack (queue);
539 GRAY_OBJECT_DEQUEUE (queue, &obj, &desc);
542 SGEN_LOG (9, "Precise gray object scan %p (%s)", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
543 scan_func (obj, desc, queue);
549 * Addresses in the pin queue are already sorted. This function finds
550 * the object header for each address and pins the object. The
551 * addresses must be inside the nursery section. The (start of the)
552 * address array is overwritten with the addresses of the actually
553 * pinned objects. Return the number of pinned objects.
556 pin_objects_from_nursery_pin_queue (gboolean do_scan_objects, ScanCopyContext ctx)
558 GCMemSection *section = nursery_section;
559 void **start = sgen_pinning_get_entry (section->pin_queue_first_entry);
560 void **end = sgen_pinning_get_entry (section->pin_queue_last_entry);
561 void *start_nursery = section->data;
562 void *end_nursery = section->next_data;
567 void *pinning_front = start_nursery;
569 void **definitely_pinned = start;
570 ScanObjectFunc scan_func = ctx.ops->scan_object;
571 SgenGrayQueue *queue = ctx.queue;
573 sgen_nursery_allocator_prepare_for_pinning ();
575 while (start < end) {
576 GCObject *obj_to_pin = NULL;
577 size_t obj_to_pin_size = 0;
582 SGEN_ASSERT (0, addr >= start_nursery && addr < end_nursery, "Potential pinning address out of range");
583 SGEN_ASSERT (0, addr >= last, "Pin queue not sorted");
590 SGEN_LOG (5, "Considering pinning addr %p", addr);
591 /* We've already processed everything up to pinning_front. */
592 if (addr < pinning_front) {
598 * Find the closest scan start <= addr. We might search backward in the
599 * scan_starts array because entries might be NULL. In the worst case we
600 * start at start_nursery.
602 idx = ((char*)addr - (char*)section->data) / SCAN_START_SIZE;
603 SGEN_ASSERT (0, idx < section->num_scan_start, "Scan start index out of range");
604 search_start = (void*)section->scan_starts [idx];
605 if (!search_start || search_start > addr) {
608 search_start = section->scan_starts [idx];
609 if (search_start && search_start <= addr)
612 if (!search_start || search_start > addr)
613 search_start = start_nursery;
617 * If the pinning front is closer than the scan start we found, start
618 * searching at the front.
620 if (search_start < pinning_front)
621 search_start = pinning_front;
624 * Now addr should be in an object a short distance from search_start.
626 * search_start must point to zeroed mem or point to an object.
629 size_t obj_size, canarified_obj_size;
632 if (!*(void**)search_start) {
633 search_start = (void*)ALIGN_UP ((mword)search_start + sizeof (gpointer));
634 /* The loop condition makes sure we don't overrun addr. */
638 canarified_obj_size = obj_size = ALIGN_UP (safe_object_get_size ((GCObject*)search_start));
641 * Filler arrays are marked by an invalid sync word. We don't
642 * consider them for pinning. They are not delimited by canaries,
645 if (!sgen_client_object_is_array_fill ((GCObject*)search_start)) {
646 CHECK_CANARY_FOR_OBJECT (search_start, TRUE);
647 CANARIFY_SIZE (canarified_obj_size);
649 if (addr >= search_start && (char*)addr < (char*)search_start + obj_size) {
650 /* This is the object we're looking for. */
651 obj_to_pin = (GCObject*)search_start;
652 obj_to_pin_size = canarified_obj_size;
657 /* Skip to the next object */
658 search_start = (void*)((char*)search_start + canarified_obj_size);
659 } while (search_start <= addr);
661 /* We've searched past the address we were looking for. */
663 pinning_front = search_start;
664 goto next_pin_queue_entry;
668 * We've found an object to pin. It might still be a dummy array, but we
669 * can advance the pinning front in any case.
671 pinning_front = (char*)obj_to_pin + obj_to_pin_size;
674 * If this is a dummy array marking the beginning of a nursery
675 * fragment, we don't pin it.
677 if (sgen_client_object_is_array_fill (obj_to_pin))
678 goto next_pin_queue_entry;
681 * Finally - pin the object!
683 desc = sgen_obj_get_descriptor_safe (obj_to_pin);
684 if (do_scan_objects) {
685 scan_func (obj_to_pin, desc, queue);
687 SGEN_LOG (4, "Pinned object %p, vtable %p (%s), count %d\n",
688 obj_to_pin, *(void**)obj_to_pin, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj_to_pin)), count);
689 binary_protocol_pin (obj_to_pin,
690 (gpointer)LOAD_VTABLE (obj_to_pin),
691 safe_object_get_size (obj_to_pin));
693 pin_object (obj_to_pin);
694 GRAY_OBJECT_ENQUEUE (queue, obj_to_pin, desc);
695 sgen_pin_stats_register_object (obj_to_pin, obj_to_pin_size);
696 definitely_pinned [count] = obj_to_pin;
700 next_pin_queue_entry:
704 sgen_client_nursery_objects_pinned (definitely_pinned, count);
705 stat_pinned_objects += count;
710 pin_objects_in_nursery (gboolean do_scan_objects, ScanCopyContext ctx)
714 if (nursery_section->pin_queue_first_entry == nursery_section->pin_queue_last_entry)
717 reduced_to = pin_objects_from_nursery_pin_queue (do_scan_objects, ctx);
718 nursery_section->pin_queue_last_entry = nursery_section->pin_queue_first_entry + reduced_to;
722 * This function is only ever called (via `collector_pin_object()` in `sgen-copy-object.h`)
723 * when we can't promote an object because we're out of memory.
726 sgen_pin_object (GCObject *object, GrayQueue *queue)
729 * All pinned objects are assumed to have been staged, so we need to stage as well.
730 * Also, the count of staged objects shows that "late pinning" happened.
732 sgen_pin_stage_ptr (object);
734 SGEN_PIN_OBJECT (object);
735 binary_protocol_pin (object, (gpointer)LOAD_VTABLE (object), safe_object_get_size (object));
738 sgen_pin_stats_register_object (object, safe_object_get_size (object));
740 GRAY_OBJECT_ENQUEUE (queue, object, sgen_obj_get_descriptor_safe (object));
743 /* Sort the addresses in array in increasing order.
744 * Done using a by-the book heap sort. Which has decent and stable performance, is pretty cache efficient.
747 sgen_sort_addresses (void **array, size_t size)
752 for (i = 1; i < size; ++i) {
755 size_t parent = (child - 1) / 2;
757 if (array [parent] >= array [child])
760 tmp = array [parent];
761 array [parent] = array [child];
768 for (i = size - 1; i > 0; --i) {
771 array [i] = array [0];
777 while (root * 2 + 1 <= end) {
778 size_t child = root * 2 + 1;
780 if (child < end && array [child] < array [child + 1])
782 if (array [root] >= array [child])
786 array [root] = array [child];
795 * Scan the memory between start and end and queue values which could be pointers
796 * to the area between start_nursery and end_nursery for later consideration.
797 * Typically used for thread stacks.
800 sgen_conservatively_pin_objects_from (void **start, void **end, void *start_nursery, void *end_nursery, int pin_type)
804 SGEN_ASSERT (0, ((mword)start & (SIZEOF_VOID_P - 1)) == 0, "Why are we scanning for references in unaligned memory ?");
806 #if defined(VALGRIND_MAKE_MEM_DEFINED_IF_ADDRESSABLE) && !defined(_WIN64)
807 VALGRIND_MAKE_MEM_DEFINED_IF_ADDRESSABLE (start, (char*)end - (char*)start);
810 while (start < end) {
812 * *start can point to the middle of an object
813 * note: should we handle pointing at the end of an object?
814 * pinning in C# code disallows pointing at the end of an object
815 * but there is some small chance that an optimizing C compiler
816 * may keep the only reference to an object by pointing
817 * at the end of it. We ignore this small chance for now.
818 * Pointers to the end of an object are indistinguishable
819 * from pointers to the start of the next object in memory
820 * so if we allow that we'd need to pin two objects...
821 * We queue the pointer in an array, the
822 * array will then be sorted and uniqued. This way
823 * we can coalesce several pinning pointers and it should
824 * be faster since we'd do a memory scan with increasing
825 * addresses. Note: we can align the address to the allocation
826 * alignment, so the unique process is more effective.
828 mword addr = (mword)*start;
829 addr &= ~(ALLOC_ALIGN - 1);
830 if (addr >= (mword)start_nursery && addr < (mword)end_nursery) {
831 SGEN_LOG (6, "Pinning address %p from %p", (void*)addr, start);
832 sgen_pin_stage_ptr ((void*)addr);
833 binary_protocol_pin_stage (start, (void*)addr);
834 sgen_pin_stats_register_address ((char*)addr, pin_type);
840 SGEN_LOG (7, "found %d potential pinned heap pointers", count);
844 * The first thing we do in a collection is to identify pinned objects.
845 * This function considers all the areas of memory that need to be
846 * conservatively scanned.
849 pin_from_roots (void *start_nursery, void *end_nursery, ScanCopyContext ctx)
853 SGEN_LOG (2, "Scanning pinned roots (%d bytes, %d/%d entries)", (int)roots_size, roots_hash [ROOT_TYPE_NORMAL].num_entries, roots_hash [ROOT_TYPE_PINNED].num_entries);
854 /* objects pinned from the API are inside these roots */
855 SGEN_HASH_TABLE_FOREACH (&roots_hash [ROOT_TYPE_PINNED], void **, start_root, RootRecord *, root) {
856 SGEN_LOG (6, "Pinned roots %p-%p", start_root, root->end_root);
857 sgen_conservatively_pin_objects_from (start_root, (void**)root->end_root, start_nursery, end_nursery, PIN_TYPE_OTHER);
858 } SGEN_HASH_TABLE_FOREACH_END;
859 /* now deal with the thread stacks
860 * in the future we should be able to conservatively scan only:
861 * *) the cpu registers
862 * *) the unmanaged stack frames
863 * *) the _last_ managed stack frame
864 * *) pointers slots in managed frames
866 sgen_client_scan_thread_data (start_nursery, end_nursery, FALSE, ctx);
870 single_arg_user_copy_or_mark (GCObject **obj, void *gc_data)
872 ScanCopyContext *ctx = (ScanCopyContext *)gc_data;
873 ctx->ops->copy_or_mark_object (obj, ctx->queue);
877 * The memory area from start_root to end_root contains pointers to objects.
878 * Their position is precisely described by @desc (this means that the pointer
879 * can be either NULL or the pointer to the start of an object).
880 * This functions copies them to to_space updates them.
882 * This function is not thread-safe!
885 precisely_scan_objects_from (void** start_root, void** end_root, char* n_start, char *n_end, SgenDescriptor desc, ScanCopyContext ctx)
887 CopyOrMarkObjectFunc copy_func = ctx.ops->copy_or_mark_object;
888 SgenGrayQueue *queue = ctx.queue;
890 switch (desc & ROOT_DESC_TYPE_MASK) {
891 case ROOT_DESC_BITMAP:
892 desc >>= ROOT_DESC_TYPE_SHIFT;
894 if ((desc & 1) && *start_root) {
895 copy_func ((GCObject**)start_root, queue);
896 SGEN_LOG (9, "Overwrote root at %p with %p", start_root, *start_root);
902 case ROOT_DESC_COMPLEX: {
903 gsize *bitmap_data = (gsize *)sgen_get_complex_descriptor_bitmap (desc);
904 gsize bwords = (*bitmap_data) - 1;
905 void **start_run = start_root;
907 while (bwords-- > 0) {
908 gsize bmap = *bitmap_data++;
909 void **objptr = start_run;
911 if ((bmap & 1) && *objptr) {
912 copy_func ((GCObject**)objptr, queue);
913 SGEN_LOG (9, "Overwrote root at %p with %p", objptr, *objptr);
918 start_run += GC_BITS_PER_WORD;
922 case ROOT_DESC_USER: {
923 SgenUserRootMarkFunc marker = sgen_get_user_descriptor_func (desc);
924 marker (start_root, single_arg_user_copy_or_mark, &ctx);
927 case ROOT_DESC_RUN_LEN:
928 g_assert_not_reached ();
930 g_assert_not_reached ();
935 reset_heap_boundaries (void)
937 lowest_heap_address = ~(mword)0;
938 highest_heap_address = 0;
942 sgen_update_heap_boundaries (mword low, mword high)
947 old = lowest_heap_address;
950 } while (SGEN_CAS_PTR ((gpointer*)&lowest_heap_address, (gpointer)low, (gpointer)old) != (gpointer)old);
953 old = highest_heap_address;
956 } while (SGEN_CAS_PTR ((gpointer*)&highest_heap_address, (gpointer)high, (gpointer)old) != (gpointer)old);
960 * Allocate and setup the data structures needed to be able to allocate objects
961 * in the nursery. The nursery is stored in nursery_section.
966 GCMemSection *section;
973 SGEN_LOG (2, "Allocating nursery size: %zu", (size_t)sgen_nursery_size);
974 /* later we will alloc a larger area for the nursery but only activate
975 * what we need. The rest will be used as expansion if we have too many pinned
976 * objects in the existing nursery.
978 /* FIXME: handle OOM */
979 section = (GCMemSection *)sgen_alloc_internal (INTERNAL_MEM_SECTION);
981 alloc_size = sgen_nursery_size;
983 /* If there isn't enough space even for the nursery we should simply abort. */
984 g_assert (sgen_memgov_try_alloc_space (alloc_size, SPACE_NURSERY));
986 data = (char *)major_collector.alloc_heap (alloc_size, alloc_size, DEFAULT_NURSERY_BITS);
987 sgen_update_heap_boundaries ((mword)data, (mword)(data + sgen_nursery_size));
988 SGEN_LOG (4, "Expanding nursery size (%p-%p): %lu, total: %lu", data, data + alloc_size, (unsigned long)sgen_nursery_size, (unsigned long)sgen_gc_get_total_heap_allocation ());
989 section->data = section->next_data = data;
990 section->size = alloc_size;
991 section->end_data = data + sgen_nursery_size;
992 scan_starts = (alloc_size + SCAN_START_SIZE - 1) / SCAN_START_SIZE;
993 section->scan_starts = (char **)sgen_alloc_internal_dynamic (sizeof (char*) * scan_starts, INTERNAL_MEM_SCAN_STARTS, TRUE);
994 section->num_scan_start = scan_starts;
996 nursery_section = section;
998 sgen_nursery_allocator_set_nursery_bounds (data, data + sgen_nursery_size);
1002 mono_gc_get_logfile (void)
1004 return gc_debug_file;
1008 scan_finalizer_entries (SgenPointerQueue *fin_queue, ScanCopyContext ctx)
1010 CopyOrMarkObjectFunc copy_func = ctx.ops->copy_or_mark_object;
1011 SgenGrayQueue *queue = ctx.queue;
1014 for (i = 0; i < fin_queue->next_slot; ++i) {
1015 GCObject *obj = (GCObject *)fin_queue->data [i];
1018 SGEN_LOG (5, "Scan of fin ready object: %p (%s)\n", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
1019 copy_func ((GCObject**)&fin_queue->data [i], queue);
1024 generation_name (int generation)
1026 switch (generation) {
1027 case GENERATION_NURSERY: return "nursery";
1028 case GENERATION_OLD: return "old";
1029 default: g_assert_not_reached ();
1034 sgen_generation_name (int generation)
1036 return generation_name (generation);
1040 finish_gray_stack (int generation, ScanCopyContext ctx)
1044 int done_with_ephemerons, ephemeron_rounds = 0;
1045 char *start_addr = generation == GENERATION_NURSERY ? sgen_get_nursery_start () : NULL;
1046 char *end_addr = generation == GENERATION_NURSERY ? sgen_get_nursery_end () : (char*)-1;
1047 SgenGrayQueue *queue = ctx.queue;
1049 binary_protocol_finish_gray_stack_start (sgen_timestamp (), generation);
1051 * We copied all the reachable objects. Now it's the time to copy
1052 * the objects that were not referenced by the roots, but by the copied objects.
1053 * we built a stack of objects pointed to by gray_start: they are
1054 * additional roots and we may add more items as we go.
1055 * We loop until gray_start == gray_objects which means no more objects have
1056 * been added. Note this is iterative: no recursion is involved.
1057 * We need to walk the LO list as well in search of marked big objects
1058 * (use a flag since this is needed only on major collections). We need to loop
1059 * here as well, so keep a counter of marked LO (increasing it in copy_object).
1060 * To achieve better cache locality and cache usage, we drain the gray stack
1061 * frequently, after each object is copied, and just finish the work here.
1063 sgen_drain_gray_stack (ctx);
1065 SGEN_LOG (2, "%s generation done", generation_name (generation));
1068 Reset bridge data, we might have lingering data from a previous collection if this is a major
1069 collection trigged by minor overflow.
1071 We must reset the gathered bridges since their original block might be evacuated due to major
1072 fragmentation in the meanwhile and the bridge code should not have to deal with that.
1074 if (sgen_client_bridge_need_processing ())
1075 sgen_client_bridge_reset_data ();
1078 * Walk the ephemeron tables marking all values with reachable keys. This must be completely done
1079 * before processing finalizable objects and non-tracking weak links to avoid finalizing/clearing
1080 * objects that are in fact reachable.
1082 done_with_ephemerons = 0;
1084 done_with_ephemerons = sgen_client_mark_ephemerons (ctx);
1085 sgen_drain_gray_stack (ctx);
1087 } while (!done_with_ephemerons);
1089 sgen_client_mark_togglerefs (start_addr, end_addr, ctx);
1091 if (sgen_client_bridge_need_processing ()) {
1092 /*Make sure the gray stack is empty before we process bridge objects so we get liveness right*/
1093 sgen_drain_gray_stack (ctx);
1094 sgen_collect_bridge_objects (generation, ctx);
1095 if (generation == GENERATION_OLD)
1096 sgen_collect_bridge_objects (GENERATION_NURSERY, ctx);
1099 Do the first bridge step here, as the collector liveness state will become useless after that.
1101 An important optimization is to only proccess the possibly dead part of the object graph and skip
1102 over all live objects as we transitively know everything they point must be alive too.
1104 The above invariant is completely wrong if we let the gray queue be drained and mark/copy everything.
1106 This has the unfortunate side effect of making overflow collections perform the first step twice, but
1107 given we now have heuristics that perform major GC in anticipation of minor overflows this should not
1110 sgen_client_bridge_processing_stw_step ();
1114 Make sure we drain the gray stack before processing disappearing links and finalizers.
1115 If we don't make sure it is empty we might wrongly see a live object as dead.
1117 sgen_drain_gray_stack (ctx);
1120 We must clear weak links that don't track resurrection before processing object ready for
1121 finalization so they can be cleared before that.
1123 sgen_null_link_in_range (generation, ctx, FALSE);
1124 if (generation == GENERATION_OLD)
1125 sgen_null_link_in_range (GENERATION_NURSERY, ctx, FALSE);
1128 /* walk the finalization queue and move also the objects that need to be
1129 * finalized: use the finalized objects as new roots so the objects they depend
1130 * on are also not reclaimed. As with the roots above, only objects in the nursery
1131 * are marked/copied.
1133 sgen_finalize_in_range (generation, ctx);
1134 if (generation == GENERATION_OLD)
1135 sgen_finalize_in_range (GENERATION_NURSERY, ctx);
1136 /* drain the new stack that might have been created */
1137 SGEN_LOG (6, "Precise scan of gray area post fin");
1138 sgen_drain_gray_stack (ctx);
1141 * This must be done again after processing finalizable objects since CWL slots are cleared only after the key is finalized.
1143 done_with_ephemerons = 0;
1145 done_with_ephemerons = sgen_client_mark_ephemerons (ctx);
1146 sgen_drain_gray_stack (ctx);
1148 } while (!done_with_ephemerons);
1150 sgen_client_clear_unreachable_ephemerons (ctx);
1153 * We clear togglerefs only after all possible chances of revival are done.
1154 * This is semantically more inline with what users expect and it allows for
1155 * user finalizers to correctly interact with TR objects.
1157 sgen_client_clear_togglerefs (start_addr, end_addr, ctx);
1160 SGEN_LOG (2, "Finalize queue handling scan for %s generation: %lld usecs %d ephemeron rounds", generation_name (generation), TV_ELAPSED (atv, btv), ephemeron_rounds);
1163 * handle disappearing links
1164 * Note we do this after checking the finalization queue because if an object
1165 * survives (at least long enough to be finalized) we don't clear the link.
1166 * This also deals with a possible issue with the monitor reclamation: with the Boehm
1167 * GC a finalized object my lose the monitor because it is cleared before the finalizer is
1170 g_assert (sgen_gray_object_queue_is_empty (queue));
1172 sgen_null_link_in_range (generation, ctx, TRUE);
1173 if (generation == GENERATION_OLD)
1174 sgen_null_link_in_range (GENERATION_NURSERY, ctx, TRUE);
1175 if (sgen_gray_object_queue_is_empty (queue))
1177 sgen_drain_gray_stack (ctx);
1180 g_assert (sgen_gray_object_queue_is_empty (queue));
1182 sgen_gray_object_queue_trim_free_list (queue);
1183 binary_protocol_finish_gray_stack_end (sgen_timestamp (), generation);
1187 sgen_check_section_scan_starts (GCMemSection *section)
1190 for (i = 0; i < section->num_scan_start; ++i) {
1191 if (section->scan_starts [i]) {
1192 mword size = safe_object_get_size ((GCObject*) section->scan_starts [i]);
1193 SGEN_ASSERT (0, size >= SGEN_CLIENT_MINIMUM_OBJECT_SIZE && size <= MAX_SMALL_OBJ_SIZE, "Weird object size at scan starts.");
1199 check_scan_starts (void)
1201 if (!do_scan_starts_check)
1203 sgen_check_section_scan_starts (nursery_section);
1204 major_collector.check_scan_starts ();
1208 scan_from_registered_roots (char *addr_start, char *addr_end, int root_type, ScanCopyContext ctx)
1212 SGEN_HASH_TABLE_FOREACH (&roots_hash [root_type], void **, start_root, RootRecord *, root) {
1213 SGEN_LOG (6, "Precise root scan %p-%p (desc: %p)", start_root, root->end_root, (void*)root->root_desc);
1214 precisely_scan_objects_from (start_root, (void**)root->end_root, addr_start, addr_end, root->root_desc, ctx);
1215 } SGEN_HASH_TABLE_FOREACH_END;
1221 static gboolean inited = FALSE;
1226 mono_counters_register ("Collection max time", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME | MONO_COUNTER_MONOTONIC, &time_max);
1228 mono_counters_register ("Minor fragment clear", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_pre_collection_fragment_clear);
1229 mono_counters_register ("Minor pinning", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_pinning);
1230 mono_counters_register ("Minor scan remembered set", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_remsets);
1231 mono_counters_register ("Minor scan pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_pinned);
1232 mono_counters_register ("Minor scan roots", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_roots);
1233 mono_counters_register ("Minor fragment creation", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_fragment_creation);
1235 mono_counters_register ("Major fragment clear", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_pre_collection_fragment_clear);
1236 mono_counters_register ("Major pinning", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_pinning);
1237 mono_counters_register ("Major scan pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_pinned);
1238 mono_counters_register ("Major scan roots", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_roots);
1239 mono_counters_register ("Major scan mod union", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_mod_union);
1240 mono_counters_register ("Major finish gray stack", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_finish_gray_stack);
1241 mono_counters_register ("Major free big objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_free_bigobjs);
1242 mono_counters_register ("Major LOS sweep", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_los_sweep);
1243 mono_counters_register ("Major sweep", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_sweep);
1244 mono_counters_register ("Major fragment creation", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_fragment_creation);
1246 mono_counters_register ("Number of pinned objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_pinned_objects);
1248 #ifdef HEAVY_STATISTICS
1249 mono_counters_register ("WBarrier remember pointer", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_add_to_global_remset);
1250 mono_counters_register ("WBarrier arrayref copy", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_arrayref_copy);
1251 mono_counters_register ("WBarrier generic store called", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_generic_store);
1252 mono_counters_register ("WBarrier generic atomic store called", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_generic_store_atomic);
1253 mono_counters_register ("WBarrier set root", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_set_root);
1255 mono_counters_register ("# objects allocated degraded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_alloced_degraded);
1256 mono_counters_register ("bytes allocated degraded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_bytes_alloced_degraded);
1258 mono_counters_register ("# copy_object() called (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_copy_object_called_nursery);
1259 mono_counters_register ("# objects copied (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_copied_nursery);
1260 mono_counters_register ("# copy_object() called (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_copy_object_called_major);
1261 mono_counters_register ("# objects copied (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_copied_major);
1263 mono_counters_register ("# scan_object() called (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_scan_object_called_nursery);
1264 mono_counters_register ("# scan_object() called (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_scan_object_called_major);
1266 mono_counters_register ("Slots allocated in vain", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_slots_allocated_in_vain);
1268 mono_counters_register ("# nursery copy_object() failed from space", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_from_space);
1269 mono_counters_register ("# nursery copy_object() failed forwarded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_forwarded);
1270 mono_counters_register ("# nursery copy_object() failed pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_pinned);
1271 mono_counters_register ("# nursery copy_object() failed to space", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_to_space);
1273 sgen_nursery_allocator_init_heavy_stats ();
1281 reset_pinned_from_failed_allocation (void)
1283 bytes_pinned_from_failed_allocation = 0;
1287 sgen_set_pinned_from_failed_allocation (mword objsize)
1289 bytes_pinned_from_failed_allocation += objsize;
1293 sgen_collection_is_concurrent (void)
1295 switch (current_collection_generation) {
1296 case GENERATION_NURSERY:
1298 case GENERATION_OLD:
1299 return concurrent_collection_in_progress;
1301 g_error ("Invalid current generation %d", current_collection_generation);
1307 sgen_concurrent_collection_in_progress (void)
1309 return concurrent_collection_in_progress;
1313 SgenThreadPoolJob job;
1314 SgenObjectOperations *ops;
1318 job_remembered_set_scan (void *worker_data_untyped, SgenThreadPoolJob *job)
1320 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1321 ScanJob *job_data = (ScanJob*)job;
1322 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1323 remset.scan_remsets (ctx);
1327 SgenThreadPoolJob job;
1328 SgenObjectOperations *ops;
1332 } ScanFromRegisteredRootsJob;
1335 job_scan_from_registered_roots (void *worker_data_untyped, SgenThreadPoolJob *job)
1337 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1338 ScanFromRegisteredRootsJob *job_data = (ScanFromRegisteredRootsJob*)job;
1339 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1341 scan_from_registered_roots (job_data->heap_start, job_data->heap_end, job_data->root_type, ctx);
1345 SgenThreadPoolJob job;
1346 SgenObjectOperations *ops;
1349 } ScanThreadDataJob;
1352 job_scan_thread_data (void *worker_data_untyped, SgenThreadPoolJob *job)
1354 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1355 ScanThreadDataJob *job_data = (ScanThreadDataJob*)job;
1356 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1358 sgen_client_scan_thread_data (job_data->heap_start, job_data->heap_end, TRUE, ctx);
1362 SgenThreadPoolJob job;
1363 SgenObjectOperations *ops;
1364 SgenPointerQueue *queue;
1365 } ScanFinalizerEntriesJob;
1368 job_scan_finalizer_entries (void *worker_data_untyped, SgenThreadPoolJob *job)
1370 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1371 ScanFinalizerEntriesJob *job_data = (ScanFinalizerEntriesJob*)job;
1372 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1374 scan_finalizer_entries (job_data->queue, ctx);
1378 job_scan_major_mod_union_card_table (void *worker_data_untyped, SgenThreadPoolJob *job)
1380 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1381 ScanJob *job_data = (ScanJob*)job;
1382 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1384 g_assert (concurrent_collection_in_progress);
1385 major_collector.scan_card_table (CARDTABLE_SCAN_MOD_UNION, ctx);
1389 job_scan_los_mod_union_card_table (void *worker_data_untyped, SgenThreadPoolJob *job)
1391 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1392 ScanJob *job_data = (ScanJob*)job;
1393 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1395 g_assert (concurrent_collection_in_progress);
1396 sgen_los_scan_card_table (CARDTABLE_SCAN_MOD_UNION, ctx);
1400 job_mod_union_preclean (void *worker_data_untyped, SgenThreadPoolJob *job)
1402 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1403 ScanJob *job_data = (ScanJob*)job;
1404 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1406 g_assert (concurrent_collection_in_progress);
1408 major_collector.scan_card_table (CARDTABLE_SCAN_MOD_UNION_PRECLEAN, ctx);
1409 sgen_los_scan_card_table (CARDTABLE_SCAN_MOD_UNION_PRECLEAN, ctx);
1413 init_gray_queue (gboolean use_workers)
1416 sgen_workers_init_distribute_gray_queue ();
1417 sgen_gray_object_queue_init (&gray_queue, NULL);
1421 enqueue_scan_from_roots_jobs (char *heap_start, char *heap_end, SgenObjectOperations *ops, gboolean enqueue)
1423 ScanFromRegisteredRootsJob *scrrj;
1424 ScanThreadDataJob *stdj;
1425 ScanFinalizerEntriesJob *sfej;
1427 /* registered roots, this includes static fields */
1429 scrrj = (ScanFromRegisteredRootsJob*)sgen_thread_pool_job_alloc ("scan from registered roots normal", job_scan_from_registered_roots, sizeof (ScanFromRegisteredRootsJob));
1431 scrrj->heap_start = heap_start;
1432 scrrj->heap_end = heap_end;
1433 scrrj->root_type = ROOT_TYPE_NORMAL;
1434 sgen_workers_enqueue_job (&scrrj->job, enqueue);
1436 scrrj = (ScanFromRegisteredRootsJob*)sgen_thread_pool_job_alloc ("scan from registered roots wbarrier", job_scan_from_registered_roots, sizeof (ScanFromRegisteredRootsJob));
1438 scrrj->heap_start = heap_start;
1439 scrrj->heap_end = heap_end;
1440 scrrj->root_type = ROOT_TYPE_WBARRIER;
1441 sgen_workers_enqueue_job (&scrrj->job, enqueue);
1445 stdj = (ScanThreadDataJob*)sgen_thread_pool_job_alloc ("scan thread data", job_scan_thread_data, sizeof (ScanThreadDataJob));
1446 stdj->heap_start = heap_start;
1447 stdj->heap_end = heap_end;
1448 sgen_workers_enqueue_job (&stdj->job, enqueue);
1450 /* Scan the list of objects ready for finalization. */
1452 sfej = (ScanFinalizerEntriesJob*)sgen_thread_pool_job_alloc ("scan finalizer entries", job_scan_finalizer_entries, sizeof (ScanFinalizerEntriesJob));
1453 sfej->queue = &fin_ready_queue;
1455 sgen_workers_enqueue_job (&sfej->job, enqueue);
1457 sfej = (ScanFinalizerEntriesJob*)sgen_thread_pool_job_alloc ("scan critical finalizer entries", job_scan_finalizer_entries, sizeof (ScanFinalizerEntriesJob));
1458 sfej->queue = &critical_fin_queue;
1460 sgen_workers_enqueue_job (&sfej->job, enqueue);
1464 * Perform a nursery collection.
1466 * Return whether any objects were late-pinned due to being out of memory.
1469 collect_nursery (SgenGrayQueue *unpin_queue, gboolean finish_up_concurrent_mark)
1471 gboolean needs_major;
1472 size_t max_garbage_amount;
1474 mword fragment_total;
1476 SgenObjectOperations *object_ops = &sgen_minor_collector.serial_ops;
1477 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, &gray_queue);
1481 if (disable_minor_collections)
1484 TV_GETTIME (last_minor_collection_start_tv);
1485 atv = last_minor_collection_start_tv;
1487 binary_protocol_collection_begin (gc_stats.minor_gc_count, GENERATION_NURSERY);
1489 if (do_verify_nursery || do_dump_nursery_content)
1490 sgen_debug_verify_nursery (do_dump_nursery_content);
1492 current_collection_generation = GENERATION_NURSERY;
1494 SGEN_ASSERT (0, !sgen_collection_is_concurrent (), "Why is the nursery collection concurrent?");
1496 reset_pinned_from_failed_allocation ();
1498 check_scan_starts ();
1500 sgen_nursery_alloc_prepare_for_minor ();
1504 nursery_next = sgen_nursery_alloc_get_upper_alloc_bound ();
1505 /* FIXME: optimize later to use the higher address where an object can be present */
1506 nursery_next = MAX (nursery_next, sgen_get_nursery_end ());
1508 SGEN_LOG (1, "Start nursery collection %d %p-%p, size: %d", gc_stats.minor_gc_count, sgen_get_nursery_start (), nursery_next, (int)(nursery_next - sgen_get_nursery_start ()));
1509 max_garbage_amount = nursery_next - sgen_get_nursery_start ();
1510 g_assert (nursery_section->size >= max_garbage_amount);
1512 /* world must be stopped already */
1514 time_minor_pre_collection_fragment_clear += TV_ELAPSED (atv, btv);
1516 sgen_client_pre_collection_checks ();
1518 nursery_section->next_data = nursery_next;
1520 major_collector.start_nursery_collection ();
1522 sgen_memgov_minor_collection_start ();
1524 init_gray_queue (FALSE);
1526 gc_stats.minor_gc_count ++;
1528 if (whole_heap_check_before_collection) {
1529 sgen_clear_nursery_fragments ();
1530 sgen_check_whole_heap (finish_up_concurrent_mark);
1532 if (consistency_check_at_minor_collection)
1533 sgen_check_consistency ();
1535 sgen_process_fin_stage_entries ();
1537 /* pin from pinned handles */
1538 sgen_init_pinning ();
1539 sgen_client_binary_protocol_mark_start (GENERATION_NURSERY);
1540 pin_from_roots (sgen_get_nursery_start (), nursery_next, ctx);
1541 /* pin cemented objects */
1542 sgen_pin_cemented_objects ();
1543 /* identify pinned objects */
1544 sgen_optimize_pin_queue ();
1545 sgen_pinning_setup_section (nursery_section);
1547 pin_objects_in_nursery (FALSE, ctx);
1548 sgen_pinning_trim_queue_to_section (nursery_section);
1551 time_minor_pinning += TV_ELAPSED (btv, atv);
1552 SGEN_LOG (2, "Finding pinned pointers: %zd in %lld usecs", sgen_get_pinned_count (), TV_ELAPSED (btv, atv));
1553 SGEN_LOG (4, "Start scan with %zd pinned objects", sgen_get_pinned_count ());
1555 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan remset", job_remembered_set_scan, sizeof (ScanJob));
1556 sj->ops = object_ops;
1557 sgen_workers_enqueue_job (&sj->job, FALSE);
1559 /* we don't have complete write barrier yet, so we scan all the old generation sections */
1561 time_minor_scan_remsets += TV_ELAPSED (atv, btv);
1562 SGEN_LOG (2, "Old generation scan: %lld usecs", TV_ELAPSED (atv, btv));
1564 sgen_pin_stats_print_class_stats ();
1566 /* FIXME: Why do we do this at this specific, seemingly random, point? */
1567 sgen_client_collecting_minor (&fin_ready_queue, &critical_fin_queue);
1570 time_minor_scan_pinned += TV_ELAPSED (btv, atv);
1572 enqueue_scan_from_roots_jobs (sgen_get_nursery_start (), nursery_next, object_ops, FALSE);
1575 time_minor_scan_roots += TV_ELAPSED (atv, btv);
1577 finish_gray_stack (GENERATION_NURSERY, ctx);
1580 time_minor_finish_gray_stack += TV_ELAPSED (btv, atv);
1581 sgen_client_binary_protocol_mark_end (GENERATION_NURSERY);
1583 if (objects_pinned) {
1584 sgen_optimize_pin_queue ();
1585 sgen_pinning_setup_section (nursery_section);
1588 /* walk the pin_queue, build up the fragment list of free memory, unmark
1589 * pinned objects as we go, memzero() the empty fragments so they are ready for the
1592 sgen_client_binary_protocol_reclaim_start (GENERATION_NURSERY);
1593 fragment_total = sgen_build_nursery_fragments (nursery_section, unpin_queue);
1594 if (!fragment_total)
1597 /* Clear TLABs for all threads */
1598 sgen_clear_tlabs ();
1600 sgen_client_binary_protocol_reclaim_end (GENERATION_NURSERY);
1602 time_minor_fragment_creation += TV_ELAPSED (atv, btv);
1603 SGEN_LOG (2, "Fragment creation: %lld usecs, %lu bytes available", TV_ELAPSED (atv, btv), (unsigned long)fragment_total);
1605 if (consistency_check_at_minor_collection)
1606 sgen_check_major_refs ();
1608 major_collector.finish_nursery_collection ();
1610 TV_GETTIME (last_minor_collection_end_tv);
1611 gc_stats.minor_gc_time += TV_ELAPSED (last_minor_collection_start_tv, last_minor_collection_end_tv);
1613 sgen_debug_dump_heap ("minor", gc_stats.minor_gc_count - 1, NULL);
1615 /* prepare the pin queue for the next collection */
1616 sgen_finish_pinning ();
1617 if (sgen_have_pending_finalizers ()) {
1618 SGEN_LOG (4, "Finalizer-thread wakeup");
1619 sgen_client_finalize_notify ();
1621 sgen_pin_stats_reset ();
1622 /* clear cemented hash */
1623 sgen_cement_clear_below_threshold ();
1625 g_assert (sgen_gray_object_queue_is_empty (&gray_queue));
1627 remset.finish_minor_collection ();
1629 check_scan_starts ();
1631 binary_protocol_flush_buffers (FALSE);
1633 sgen_memgov_minor_collection_end ();
1635 /*objects are late pinned because of lack of memory, so a major is a good call*/
1636 needs_major = objects_pinned > 0;
1637 current_collection_generation = -1;
1640 binary_protocol_collection_end (gc_stats.minor_gc_count - 1, GENERATION_NURSERY, 0, 0);
1642 if (check_nursery_objects_pinned && !sgen_minor_collector.is_split)
1643 sgen_check_nursery_objects_pinned (unpin_queue != NULL);
1649 COPY_OR_MARK_FROM_ROOTS_SERIAL,
1650 COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT,
1651 COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT
1652 } CopyOrMarkFromRootsMode;
1655 major_copy_or_mark_from_roots (size_t *old_next_pin_slot, CopyOrMarkFromRootsMode mode, SgenObjectOperations *object_ops)
1660 /* FIXME: only use these values for the precise scan
1661 * note that to_space pointers should be excluded anyway...
1663 char *heap_start = NULL;
1664 char *heap_end = (char*)-1;
1665 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, WORKERS_DISTRIBUTE_GRAY_QUEUE);
1666 gboolean concurrent = mode != COPY_OR_MARK_FROM_ROOTS_SERIAL;
1668 SGEN_ASSERT (0, !!concurrent == !!concurrent_collection_in_progress, "We've been called with the wrong mode.");
1670 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1671 /*This cleans up unused fragments */
1672 sgen_nursery_allocator_prepare_for_pinning ();
1674 if (do_concurrent_checks)
1675 sgen_debug_check_nursery_is_clean ();
1677 /* The concurrent collector doesn't touch the nursery. */
1678 sgen_nursery_alloc_prepare_for_major ();
1681 init_gray_queue (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT);
1685 /* Pinning depends on this */
1686 sgen_clear_nursery_fragments ();
1688 if (whole_heap_check_before_collection)
1689 sgen_check_whole_heap (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT);
1692 time_major_pre_collection_fragment_clear += TV_ELAPSED (atv, btv);
1694 if (!sgen_collection_is_concurrent ())
1695 nursery_section->next_data = sgen_get_nursery_end ();
1696 /* we should also coalesce scanning from sections close to each other
1697 * and deal with pointers outside of the sections later.
1702 sgen_client_pre_collection_checks ();
1704 if (mode != COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1705 /* Remsets are not useful for a major collection */
1706 remset.clear_cards ();
1709 sgen_process_fin_stage_entries ();
1712 sgen_init_pinning ();
1713 SGEN_LOG (6, "Collecting pinned addresses");
1714 pin_from_roots ((void*)lowest_heap_address, (void*)highest_heap_address, ctx);
1715 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1716 /* Pin cemented objects that were forced */
1717 sgen_pin_cemented_objects ();
1719 sgen_optimize_pin_queue ();
1720 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1722 * Cemented objects that are in the pinned list will be marked. When
1723 * marking concurrently we won't mark mod-union cards for these objects.
1724 * Instead they will remain cemented until the next major collection,
1725 * when we will recheck if they are still pinned in the roots.
1727 sgen_cement_force_pinned ();
1730 sgen_client_collecting_major_1 ();
1733 * pin_queue now contains all candidate pointers, sorted and
1734 * uniqued. We must do two passes now to figure out which
1735 * objects are pinned.
1737 * The first is to find within the pin_queue the area for each
1738 * section. This requires that the pin_queue be sorted. We
1739 * also process the LOS objects and pinned chunks here.
1741 * The second, destructive, pass is to reduce the section
1742 * areas to pointers to the actually pinned objects.
1744 SGEN_LOG (6, "Pinning from sections");
1745 /* first pass for the sections */
1746 sgen_find_section_pin_queue_start_end (nursery_section);
1747 /* identify possible pointers to the insize of large objects */
1748 SGEN_LOG (6, "Pinning from large objects");
1749 for (bigobj = los_object_list; bigobj; bigobj = bigobj->next) {
1751 if (sgen_find_optimized_pin_queue_area ((char*)bigobj->data, (char*)bigobj->data + sgen_los_object_size (bigobj), &dummy, &dummy)) {
1752 binary_protocol_pin (bigobj->data, (gpointer)LOAD_VTABLE (bigobj->data), safe_object_get_size (bigobj->data));
1754 if (sgen_los_object_is_pinned (bigobj->data)) {
1755 SGEN_ASSERT (0, mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT, "LOS objects can only be pinned here after concurrent marking.");
1758 sgen_los_pin_object (bigobj->data);
1759 if (SGEN_OBJECT_HAS_REFERENCES (bigobj->data))
1760 GRAY_OBJECT_ENQUEUE (WORKERS_DISTRIBUTE_GRAY_QUEUE, bigobj->data, sgen_obj_get_descriptor ((GCObject*)bigobj->data));
1761 sgen_pin_stats_register_object (bigobj->data, safe_object_get_size (bigobj->data));
1762 SGEN_LOG (6, "Marked large object %p (%s) size: %lu from roots", bigobj->data,
1763 sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (bigobj->data)),
1764 (unsigned long)sgen_los_object_size (bigobj));
1766 sgen_client_pinned_los_object (bigobj->data);
1770 pin_objects_in_nursery (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT, ctx);
1771 if (check_nursery_objects_pinned && !sgen_minor_collector.is_split)
1772 sgen_check_nursery_objects_pinned (mode != COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT);
1774 major_collector.pin_objects (WORKERS_DISTRIBUTE_GRAY_QUEUE);
1775 if (old_next_pin_slot)
1776 *old_next_pin_slot = sgen_get_pinned_count ();
1779 time_major_pinning += TV_ELAPSED (atv, btv);
1780 SGEN_LOG (2, "Finding pinned pointers: %zd in %lld usecs", sgen_get_pinned_count (), TV_ELAPSED (atv, btv));
1781 SGEN_LOG (4, "Start scan with %zd pinned objects", sgen_get_pinned_count ());
1783 major_collector.init_to_space ();
1785 SGEN_ASSERT (0, sgen_workers_all_done (), "Why are the workers not done when we start or finish a major collection?");
1786 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1787 if (sgen_workers_have_idle_work ()) {
1789 * We force the finish of the worker with the new object ops context
1790 * which can also do copying. We need to have finished pinning.
1792 sgen_workers_start_all_workers (object_ops, NULL);
1793 sgen_workers_join ();
1797 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
1798 main_gc_thread = mono_native_thread_self ();
1801 sgen_client_collecting_major_2 ();
1804 time_major_scan_pinned += TV_ELAPSED (btv, atv);
1806 sgen_client_collecting_major_3 (&fin_ready_queue, &critical_fin_queue);
1808 enqueue_scan_from_roots_jobs (heap_start, heap_end, object_ops, FALSE);
1811 time_major_scan_roots += TV_ELAPSED (atv, btv);
1814 * We start the concurrent worker after pinning and after we scanned the roots
1815 * in order to make sure that the worker does not finish before handling all
1818 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1819 if (precleaning_enabled) {
1821 /* Mod union preclean job */
1822 sj = (ScanJob*)sgen_thread_pool_job_alloc ("preclean mod union cardtable", job_mod_union_preclean, sizeof (ScanJob));
1823 sj->ops = object_ops;
1824 sgen_workers_start_all_workers (object_ops, &sj->job);
1826 sgen_workers_start_all_workers (object_ops, NULL);
1828 gray_queue_enable_redirect (WORKERS_DISTRIBUTE_GRAY_QUEUE);
1831 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1834 /* Mod union card table */
1835 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan mod union cardtable", job_scan_major_mod_union_card_table, sizeof (ScanJob));
1836 sj->ops = object_ops;
1837 sgen_workers_enqueue_job (&sj->job, FALSE);
1839 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan LOS mod union cardtable", job_scan_los_mod_union_card_table, sizeof (ScanJob));
1840 sj->ops = object_ops;
1841 sgen_workers_enqueue_job (&sj->job, FALSE);
1844 time_major_scan_mod_union += TV_ELAPSED (btv, atv);
1847 sgen_pin_stats_print_class_stats ();
1851 major_finish_copy_or_mark (CopyOrMarkFromRootsMode mode)
1853 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1854 sgen_finish_pinning ();
1856 sgen_pin_stats_reset ();
1858 if (do_concurrent_checks)
1859 sgen_debug_check_nursery_is_clean ();
1864 major_start_collection (gboolean concurrent, size_t *old_next_pin_slot)
1866 SgenObjectOperations *object_ops;
1868 binary_protocol_collection_begin (gc_stats.major_gc_count, GENERATION_OLD);
1870 current_collection_generation = GENERATION_OLD;
1872 g_assert (sgen_section_gray_queue_is_empty (sgen_workers_get_distribute_section_gray_queue ()));
1875 sgen_cement_reset ();
1878 g_assert (major_collector.is_concurrent);
1879 concurrent_collection_in_progress = TRUE;
1881 object_ops = &major_collector.major_ops_concurrent_start;
1883 object_ops = &major_collector.major_ops_serial;
1886 reset_pinned_from_failed_allocation ();
1888 sgen_memgov_major_collection_start ();
1890 //count_ref_nonref_objs ();
1891 //consistency_check ();
1893 check_scan_starts ();
1896 SGEN_LOG (1, "Start major collection %d", gc_stats.major_gc_count);
1897 gc_stats.major_gc_count ++;
1899 if (major_collector.start_major_collection)
1900 major_collector.start_major_collection ();
1902 major_copy_or_mark_from_roots (old_next_pin_slot, concurrent ? COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT : COPY_OR_MARK_FROM_ROOTS_SERIAL, object_ops);
1903 major_finish_copy_or_mark (concurrent ? COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT : COPY_OR_MARK_FROM_ROOTS_SERIAL);
1907 major_finish_collection (const char *reason, size_t old_next_pin_slot, gboolean forced)
1909 ScannedObjectCounts counts;
1910 SgenObjectOperations *object_ops;
1911 mword fragment_total;
1917 if (concurrent_collection_in_progress) {
1918 object_ops = &major_collector.major_ops_concurrent_finish;
1920 major_copy_or_mark_from_roots (NULL, COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT, object_ops);
1922 major_finish_copy_or_mark (COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT);
1924 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
1925 main_gc_thread = NULL;
1928 object_ops = &major_collector.major_ops_serial;
1931 g_assert (sgen_section_gray_queue_is_empty (sgen_workers_get_distribute_section_gray_queue ()));
1933 /* all the objects in the heap */
1934 finish_gray_stack (GENERATION_OLD, CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, &gray_queue));
1936 time_major_finish_gray_stack += TV_ELAPSED (btv, atv);
1938 SGEN_ASSERT (0, sgen_workers_all_done (), "Can't have workers working after joining");
1940 if (objects_pinned) {
1941 g_assert (!concurrent_collection_in_progress);
1944 * This is slow, but we just OOM'd.
1946 * See comment at `sgen_pin_queue_clear_discarded_entries` for how the pin
1947 * queue is laid out at this point.
1949 sgen_pin_queue_clear_discarded_entries (nursery_section, old_next_pin_slot);
1951 * We need to reestablish all pinned nursery objects in the pin queue
1952 * because they're needed for fragment creation. Unpinning happens by
1953 * walking the whole queue, so it's not necessary to reestablish where major
1954 * heap block pins are - all we care is that they're still in there
1957 sgen_optimize_pin_queue ();
1958 sgen_find_section_pin_queue_start_end (nursery_section);
1962 reset_heap_boundaries ();
1963 sgen_update_heap_boundaries ((mword)sgen_get_nursery_start (), (mword)sgen_get_nursery_end ());
1965 /* walk the pin_queue, build up the fragment list of free memory, unmark
1966 * pinned objects as we go, memzero() the empty fragments so they are ready for the
1969 fragment_total = sgen_build_nursery_fragments (nursery_section, NULL);
1970 if (!fragment_total)
1972 SGEN_LOG (4, "Free space in nursery after major %ld", (long)fragment_total);
1974 if (do_concurrent_checks && concurrent_collection_in_progress)
1975 sgen_debug_check_nursery_is_clean ();
1977 /* prepare the pin queue for the next collection */
1978 sgen_finish_pinning ();
1980 /* Clear TLABs for all threads */
1981 sgen_clear_tlabs ();
1983 sgen_pin_stats_reset ();
1985 sgen_cement_clear_below_threshold ();
1987 if (check_mark_bits_after_major_collection)
1988 sgen_check_heap_marked (concurrent_collection_in_progress);
1991 time_major_fragment_creation += TV_ELAPSED (atv, btv);
1993 binary_protocol_sweep_begin (GENERATION_OLD, !major_collector.sweeps_lazily);
1994 sgen_memgov_major_pre_sweep ();
1997 time_major_free_bigobjs += TV_ELAPSED (btv, atv);
2002 time_major_los_sweep += TV_ELAPSED (atv, btv);
2004 major_collector.sweep ();
2006 binary_protocol_sweep_end (GENERATION_OLD, !major_collector.sweeps_lazily);
2009 time_major_sweep += TV_ELAPSED (btv, atv);
2011 sgen_debug_dump_heap ("major", gc_stats.major_gc_count - 1, reason);
2013 if (sgen_have_pending_finalizers ()) {
2014 SGEN_LOG (4, "Finalizer-thread wakeup");
2015 sgen_client_finalize_notify ();
2018 g_assert (sgen_gray_object_queue_is_empty (&gray_queue));
2020 sgen_memgov_major_collection_end (forced);
2021 current_collection_generation = -1;
2023 memset (&counts, 0, sizeof (ScannedObjectCounts));
2024 major_collector.finish_major_collection (&counts);
2026 g_assert (sgen_section_gray_queue_is_empty (sgen_workers_get_distribute_section_gray_queue ()));
2028 SGEN_ASSERT (0, sgen_workers_all_done (), "Can't have workers working after major collection has finished");
2029 if (concurrent_collection_in_progress)
2030 concurrent_collection_in_progress = FALSE;
2032 check_scan_starts ();
2034 binary_protocol_flush_buffers (FALSE);
2036 //consistency_check ();
2038 binary_protocol_collection_end (gc_stats.major_gc_count - 1, GENERATION_OLD, counts.num_scanned_objects, counts.num_unique_scanned_objects);
2042 major_do_collection (const char *reason, gboolean forced)
2044 TV_DECLARE (time_start);
2045 TV_DECLARE (time_end);
2046 size_t old_next_pin_slot;
2048 if (disable_major_collections)
2051 if (major_collector.get_and_reset_num_major_objects_marked) {
2052 long long num_marked = major_collector.get_and_reset_num_major_objects_marked ();
2053 g_assert (!num_marked);
2056 /* world must be stopped already */
2057 TV_GETTIME (time_start);
2059 major_start_collection (FALSE, &old_next_pin_slot);
2060 major_finish_collection (reason, old_next_pin_slot, forced);
2062 TV_GETTIME (time_end);
2063 gc_stats.major_gc_time += TV_ELAPSED (time_start, time_end);
2065 /* FIXME: also report this to the user, preferably in gc-end. */
2066 if (major_collector.get_and_reset_num_major_objects_marked)
2067 major_collector.get_and_reset_num_major_objects_marked ();
2069 return bytes_pinned_from_failed_allocation > 0;
2073 major_start_concurrent_collection (const char *reason)
2075 TV_DECLARE (time_start);
2076 TV_DECLARE (time_end);
2077 long long num_objects_marked;
2079 if (disable_major_collections)
2082 TV_GETTIME (time_start);
2083 SGEN_TV_GETTIME (time_major_conc_collection_start);
2085 num_objects_marked = major_collector.get_and_reset_num_major_objects_marked ();
2086 g_assert (num_objects_marked == 0);
2088 binary_protocol_concurrent_start ();
2090 // FIXME: store reason and pass it when finishing
2091 major_start_collection (TRUE, NULL);
2093 gray_queue_redirect (&gray_queue);
2095 num_objects_marked = major_collector.get_and_reset_num_major_objects_marked ();
2097 TV_GETTIME (time_end);
2098 gc_stats.major_gc_time += TV_ELAPSED (time_start, time_end);
2100 current_collection_generation = -1;
2104 * Returns whether the major collection has finished.
2107 major_should_finish_concurrent_collection (void)
2109 SGEN_ASSERT (0, sgen_gray_object_queue_is_empty (&gray_queue), "Why is the gray queue not empty before we have started doing anything?");
2110 return sgen_workers_all_done ();
2114 major_update_concurrent_collection (void)
2116 TV_DECLARE (total_start);
2117 TV_DECLARE (total_end);
2119 TV_GETTIME (total_start);
2121 binary_protocol_concurrent_update ();
2123 major_collector.update_cardtable_mod_union ();
2124 sgen_los_update_cardtable_mod_union ();
2126 TV_GETTIME (total_end);
2127 gc_stats.major_gc_time += TV_ELAPSED (total_start, total_end);
2131 major_finish_concurrent_collection (gboolean forced)
2133 TV_DECLARE (total_start);
2134 TV_DECLARE (total_end);
2136 TV_GETTIME (total_start);
2138 binary_protocol_concurrent_finish ();
2141 * We need to stop all workers since we're updating the cardtable below.
2142 * The workers will be resumed with a finishing pause context to avoid
2143 * additional cardtable and object scanning.
2145 sgen_workers_stop_all_workers ();
2147 SGEN_TV_GETTIME (time_major_conc_collection_end);
2148 gc_stats.major_gc_time_concurrent += SGEN_TV_ELAPSED (time_major_conc_collection_start, time_major_conc_collection_end);
2150 major_collector.update_cardtable_mod_union ();
2151 sgen_los_update_cardtable_mod_union ();
2153 if (mod_union_consistency_check)
2154 sgen_check_mod_union_consistency ();
2156 current_collection_generation = GENERATION_OLD;
2157 sgen_cement_reset ();
2158 major_finish_collection ("finishing", -1, forced);
2160 if (whole_heap_check_before_collection)
2161 sgen_check_whole_heap (FALSE);
2163 TV_GETTIME (total_end);
2164 gc_stats.major_gc_time += TV_ELAPSED (total_start, total_end) - TV_ELAPSED (last_minor_collection_start_tv, last_minor_collection_end_tv);
2166 current_collection_generation = -1;
2170 * Ensure an allocation request for @size will succeed by freeing enough memory.
2172 * LOCKING: The GC lock MUST be held.
2175 sgen_ensure_free_space (size_t size, int generation)
2177 int generation_to_collect = -1;
2178 const char *reason = NULL;
2180 if (generation == GENERATION_OLD) {
2181 if (sgen_need_major_collection (size)) {
2182 reason = "LOS overflow";
2183 generation_to_collect = GENERATION_OLD;
2186 if (degraded_mode) {
2187 if (sgen_need_major_collection (size)) {
2188 reason = "Degraded mode overflow";
2189 generation_to_collect = GENERATION_OLD;
2191 } else if (sgen_need_major_collection (size)) {
2192 reason = concurrent_collection_in_progress ? "Forced finish concurrent collection" : "Minor allowance";
2193 generation_to_collect = GENERATION_OLD;
2195 generation_to_collect = GENERATION_NURSERY;
2196 reason = "Nursery full";
2200 if (generation_to_collect == -1) {
2201 if (concurrent_collection_in_progress && sgen_workers_all_done ()) {
2202 generation_to_collect = GENERATION_OLD;
2203 reason = "Finish concurrent collection";
2207 if (generation_to_collect == -1)
2209 sgen_perform_collection (size, generation_to_collect, reason, FALSE);
2213 * LOCKING: Assumes the GC lock is held.
2216 sgen_perform_collection (size_t requested_size, int generation_to_collect, const char *reason, gboolean wait_to_finish)
2218 TV_DECLARE (gc_start);
2219 TV_DECLARE (gc_end);
2220 TV_DECLARE (gc_total_start);
2221 TV_DECLARE (gc_total_end);
2222 GGTimingInfo infos [2];
2223 int overflow_generation_to_collect = -1;
2224 int oldest_generation_collected = generation_to_collect;
2225 const char *overflow_reason = NULL;
2227 binary_protocol_collection_requested (generation_to_collect, requested_size, wait_to_finish ? 1 : 0);
2229 SGEN_ASSERT (0, generation_to_collect == GENERATION_NURSERY || generation_to_collect == GENERATION_OLD, "What generation is this?");
2231 TV_GETTIME (gc_start);
2233 sgen_stop_world (generation_to_collect);
2235 TV_GETTIME (gc_total_start);
2237 if (concurrent_collection_in_progress) {
2239 * If the concurrent worker is finished or we are asked to do a major collection
2240 * then we finish the concurrent collection.
2242 gboolean finish = major_should_finish_concurrent_collection () || generation_to_collect == GENERATION_OLD;
2245 major_finish_concurrent_collection (wait_to_finish);
2246 oldest_generation_collected = GENERATION_OLD;
2248 SGEN_ASSERT (0, generation_to_collect == GENERATION_NURSERY, "Why aren't we finishing the concurrent collection?");
2249 major_update_concurrent_collection ();
2250 collect_nursery (NULL, FALSE);
2256 SGEN_ASSERT (0, !concurrent_collection_in_progress, "Why did this not get handled above?");
2259 * There's no concurrent collection in progress. Collect the generation we're asked
2260 * to collect. If the major collector is concurrent and we're not forced to wait,
2261 * start a concurrent collection.
2263 // FIXME: extract overflow reason
2264 if (generation_to_collect == GENERATION_NURSERY) {
2265 if (collect_nursery (NULL, FALSE)) {
2266 overflow_generation_to_collect = GENERATION_OLD;
2267 overflow_reason = "Minor overflow";
2270 if (major_collector.is_concurrent && !wait_to_finish) {
2271 collect_nursery (NULL, FALSE);
2272 major_start_concurrent_collection (reason);
2273 // FIXME: set infos[0] properly
2277 if (major_do_collection (reason, wait_to_finish)) {
2278 overflow_generation_to_collect = GENERATION_NURSERY;
2279 overflow_reason = "Excessive pinning";
2283 TV_GETTIME (gc_end);
2285 memset (infos, 0, sizeof (infos));
2286 infos [0].generation = generation_to_collect;
2287 infos [0].reason = reason;
2288 infos [0].is_overflow = FALSE;
2289 infos [1].generation = -1;
2290 infos [0].total_time = SGEN_TV_ELAPSED (gc_start, gc_end);
2292 SGEN_ASSERT (0, !concurrent_collection_in_progress, "Why did this not get handled above?");
2294 if (overflow_generation_to_collect != -1) {
2296 * We need to do an overflow collection, either because we ran out of memory
2297 * or the nursery is fully pinned.
2300 infos [1].generation = overflow_generation_to_collect;
2301 infos [1].reason = overflow_reason;
2302 infos [1].is_overflow = TRUE;
2305 if (overflow_generation_to_collect == GENERATION_NURSERY)
2306 collect_nursery (NULL, FALSE);
2308 major_do_collection (overflow_reason, wait_to_finish);
2310 TV_GETTIME (gc_end);
2311 infos [1].total_time = SGEN_TV_ELAPSED (gc_start, gc_end);
2313 oldest_generation_collected = MAX (oldest_generation_collected, overflow_generation_to_collect);
2316 SGEN_LOG (2, "Heap size: %lu, LOS size: %lu", (unsigned long)sgen_gc_get_total_heap_allocation (), (unsigned long)los_memory_usage);
2318 /* this also sets the proper pointers for the next allocation */
2319 if (generation_to_collect == GENERATION_NURSERY && !sgen_can_alloc_size (requested_size)) {
2320 /* TypeBuilder and MonoMethod are killing mcs with fragmentation */
2321 SGEN_LOG (1, "nursery collection didn't find enough room for %zd alloc (%zd pinned)", requested_size, sgen_get_pinned_count ());
2322 sgen_dump_pin_queue ();
2327 g_assert (sgen_gray_object_queue_is_empty (&gray_queue));
2329 TV_GETTIME (gc_total_end);
2330 time_max = MAX (time_max, TV_ELAPSED (gc_total_start, gc_total_end));
2332 sgen_restart_world (oldest_generation_collected, infos);
2336 * ######################################################################
2337 * ######## Memory allocation from the OS
2338 * ######################################################################
2339 * This section of code deals with getting memory from the OS and
2340 * allocating memory for GC-internal data structures.
2341 * Internal memory can be handled with a freelist for small objects.
2347 G_GNUC_UNUSED static void
2348 report_internal_mem_usage (void)
2350 printf ("Internal memory usage:\n");
2351 sgen_report_internal_mem_usage ();
2352 printf ("Pinned memory usage:\n");
2353 major_collector.report_pinned_memory_usage ();
2357 * ######################################################################
2358 * ######## Finalization support
2359 * ######################################################################
2363 * If the object has been forwarded it means it's still referenced from a root.
2364 * If it is pinned it's still alive as well.
2365 * A LOS object is only alive if we have pinned it.
2366 * Return TRUE if @obj is ready to be finalized.
2368 static inline gboolean
2369 sgen_is_object_alive (GCObject *object)
2371 if (ptr_in_nursery (object))
2372 return sgen_nursery_is_object_alive (object);
2374 return sgen_major_is_object_alive (object);
2378 * This function returns true if @object is either alive and belongs to the
2379 * current collection - major collections are full heap, so old gen objects
2380 * are never alive during a minor collection.
2383 sgen_is_object_alive_and_on_current_collection (GCObject *object)
2385 if (ptr_in_nursery (object))
2386 return sgen_nursery_is_object_alive (object);
2388 if (current_collection_generation == GENERATION_NURSERY)
2391 return sgen_major_is_object_alive (object);
2396 sgen_gc_is_object_ready_for_finalization (GCObject *object)
2398 return !sgen_is_object_alive (object);
2402 sgen_queue_finalization_entry (GCObject *obj)
2404 gboolean critical = sgen_client_object_has_critical_finalizer (obj);
2406 sgen_pointer_queue_add (critical ? &critical_fin_queue : &fin_ready_queue, obj);
2408 sgen_client_object_queued_for_finalization (obj);
2412 sgen_object_is_live (GCObject *obj)
2414 return sgen_is_object_alive_and_on_current_collection (obj);
2418 * `System.GC.WaitForPendingFinalizers` first checks `sgen_have_pending_finalizers()` to
2419 * determine whether it can exit quickly. The latter must therefore only return FALSE if
2420 * all finalizers have really finished running.
2422 * `sgen_gc_invoke_finalizers()` first dequeues a finalizable object, and then finalizes it.
2423 * This means that just checking whether the queues are empty leaves the possibility that an
2424 * object might have been dequeued but not yet finalized. That's why we need the additional
2425 * flag `pending_unqueued_finalizer`.
2428 static volatile gboolean pending_unqueued_finalizer = FALSE;
2431 sgen_gc_invoke_finalizers (void)
2435 g_assert (!pending_unqueued_finalizer);
2437 /* FIXME: batch to reduce lock contention */
2438 while (sgen_have_pending_finalizers ()) {
2444 * We need to set `pending_unqueued_finalizer` before dequeing the
2445 * finalizable object.
2447 if (!sgen_pointer_queue_is_empty (&fin_ready_queue)) {
2448 pending_unqueued_finalizer = TRUE;
2449 mono_memory_write_barrier ();
2450 obj = (GCObject *)sgen_pointer_queue_pop (&fin_ready_queue);
2451 } else if (!sgen_pointer_queue_is_empty (&critical_fin_queue)) {
2452 pending_unqueued_finalizer = TRUE;
2453 mono_memory_write_barrier ();
2454 obj = (GCObject *)sgen_pointer_queue_pop (&critical_fin_queue);
2460 SGEN_LOG (7, "Finalizing object %p (%s)", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
2468 /* the object is on the stack so it is pinned */
2469 /*g_print ("Calling finalizer for object: %p (%s)\n", obj, sgen_client_object_safe_name (obj));*/
2470 sgen_client_run_finalize (obj);
2473 if (pending_unqueued_finalizer) {
2474 mono_memory_write_barrier ();
2475 pending_unqueued_finalizer = FALSE;
2482 sgen_have_pending_finalizers (void)
2484 return pending_unqueued_finalizer || !sgen_pointer_queue_is_empty (&fin_ready_queue) || !sgen_pointer_queue_is_empty (&critical_fin_queue);
2488 * ######################################################################
2489 * ######## registered roots support
2490 * ######################################################################
2494 * We do not coalesce roots.
2497 sgen_register_root (char *start, size_t size, SgenDescriptor descr, int root_type, int source, const char *msg)
2499 RootRecord new_root;
2502 for (i = 0; i < ROOT_TYPE_NUM; ++i) {
2503 RootRecord *root = (RootRecord *)sgen_hash_table_lookup (&roots_hash [i], start);
2504 /* we allow changing the size and the descriptor (for thread statics etc) */
2506 size_t old_size = root->end_root - start;
2507 root->end_root = start + size;
2508 SGEN_ASSERT (0, !!root->root_desc == !!descr, "Can't change whether a root is precise or conservative.");
2509 SGEN_ASSERT (0, root->source == source, "Can't change a root's source identifier.");
2510 SGEN_ASSERT (0, !!root->msg == !!msg, "Can't change a root's message.");
2511 root->root_desc = descr;
2513 roots_size -= old_size;
2519 new_root.end_root = start + size;
2520 new_root.root_desc = descr;
2521 new_root.source = source;
2524 sgen_hash_table_replace (&roots_hash [root_type], start, &new_root, NULL);
2527 SGEN_LOG (3, "Added root for range: %p-%p, descr: %llx (%d/%d bytes)", start, new_root.end_root, (long long)descr, (int)size, (int)roots_size);
2534 sgen_deregister_root (char* addr)
2540 for (root_type = 0; root_type < ROOT_TYPE_NUM; ++root_type) {
2541 if (sgen_hash_table_remove (&roots_hash [root_type], addr, &root))
2542 roots_size -= (root.end_root - addr);
2548 * ######################################################################
2549 * ######## Thread handling (stop/start code)
2550 * ######################################################################
2554 sgen_get_current_collection_generation (void)
2556 return current_collection_generation;
2560 sgen_thread_register (SgenThreadInfo* info, void *stack_bottom_fallback)
2562 #ifndef HAVE_KW_THREAD
2563 info->tlab_start = info->tlab_next = info->tlab_temp_end = info->tlab_real_end = NULL;
2566 sgen_init_tlab_info (info);
2568 sgen_client_thread_register (info, stack_bottom_fallback);
2574 sgen_thread_unregister (SgenThreadInfo *p)
2576 sgen_client_thread_unregister (p);
2580 * ######################################################################
2581 * ######## Write barriers
2582 * ######################################################################
2586 * Note: the write barriers first do the needed GC work and then do the actual store:
2587 * this way the value is visible to the conservative GC scan after the write barrier
2588 * itself. If a GC interrupts the barrier in the middle, value will be kept alive by
2589 * the conservative scan, otherwise by the remembered set scan.
2593 mono_gc_wbarrier_arrayref_copy (gpointer dest_ptr, gpointer src_ptr, int count)
2595 HEAVY_STAT (++stat_wbarrier_arrayref_copy);
2596 /*This check can be done without taking a lock since dest_ptr array is pinned*/
2597 if (ptr_in_nursery (dest_ptr) || count <= 0) {
2598 mono_gc_memmove_aligned (dest_ptr, src_ptr, count * sizeof (gpointer));
2602 #ifdef SGEN_HEAVY_BINARY_PROTOCOL
2603 if (binary_protocol_is_heavy_enabled ()) {
2605 for (i = 0; i < count; ++i) {
2606 gpointer dest = (gpointer*)dest_ptr + i;
2607 gpointer obj = *((gpointer*)src_ptr + i);
2609 binary_protocol_wbarrier (dest, obj, (gpointer)LOAD_VTABLE (obj));
2614 remset.wbarrier_arrayref_copy (dest_ptr, src_ptr, count);
2618 mono_gc_wbarrier_generic_nostore (gpointer ptr)
2622 HEAVY_STAT (++stat_wbarrier_generic_store);
2624 sgen_client_wbarrier_generic_nostore_check (ptr);
2626 obj = *(gpointer*)ptr;
2628 binary_protocol_wbarrier (ptr, obj, (gpointer)LOAD_VTABLE (obj));
2631 * We need to record old->old pointer locations for the
2632 * concurrent collector.
2634 if (!ptr_in_nursery (obj) && !concurrent_collection_in_progress) {
2635 SGEN_LOG (8, "Skipping remset at %p", ptr);
2639 SGEN_LOG (8, "Adding remset at %p", ptr);
2641 remset.wbarrier_generic_nostore (ptr);
2645 mono_gc_wbarrier_generic_store (gpointer ptr, GCObject* value)
2647 SGEN_LOG (8, "Wbarrier store at %p to %p (%s)", ptr, value, value ? sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (value)) : "null");
2648 SGEN_UPDATE_REFERENCE_ALLOW_NULL (ptr, value);
2649 if (ptr_in_nursery (value) || concurrent_collection_in_progress)
2650 mono_gc_wbarrier_generic_nostore (ptr);
2651 sgen_dummy_use (value);
2654 /* Same as mono_gc_wbarrier_generic_store () but performs the store
2655 * as an atomic operation with release semantics.
2658 mono_gc_wbarrier_generic_store_atomic (gpointer ptr, GCObject *value)
2660 HEAVY_STAT (++stat_wbarrier_generic_store_atomic);
2662 SGEN_LOG (8, "Wbarrier atomic store at %p to %p (%s)", ptr, value, value ? sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (value)) : "null");
2664 InterlockedWritePointer ((volatile gpointer *)ptr, value);
2666 if (ptr_in_nursery (value) || concurrent_collection_in_progress)
2667 mono_gc_wbarrier_generic_nostore (ptr);
2669 sgen_dummy_use (value);
2673 sgen_wbarrier_value_copy_bitmap (gpointer _dest, gpointer _src, int size, unsigned bitmap)
2675 GCObject **dest = (GCObject **)_dest;
2676 GCObject **src = (GCObject **)_src;
2680 mono_gc_wbarrier_generic_store (dest, *src);
2685 size -= SIZEOF_VOID_P;
2691 * ######################################################################
2692 * ######## Other mono public interface functions.
2693 * ######################################################################
2697 sgen_gc_collect (int generation)
2702 sgen_perform_collection (0, generation, "user request", TRUE);
2707 sgen_gc_collection_count (int generation)
2709 if (generation == 0)
2710 return gc_stats.minor_gc_count;
2711 return gc_stats.major_gc_count;
2715 sgen_gc_get_used_size (void)
2719 tot = los_memory_usage;
2720 tot += nursery_section->next_data - nursery_section->data;
2721 tot += major_collector.get_used_size ();
2722 /* FIXME: account for pinned objects */
2728 sgen_env_var_error (const char *env_var, const char *fallback, const char *description_format, ...)
2732 va_start (ap, description_format);
2734 fprintf (stderr, "Warning: In environment variable `%s': ", env_var);
2735 vfprintf (stderr, description_format, ap);
2737 fprintf (stderr, " - %s", fallback);
2738 fprintf (stderr, "\n");
2744 parse_double_in_interval (const char *env_var, const char *opt_name, const char *opt, double min, double max, double *result)
2747 double val = strtod (opt, &endptr);
2748 if (endptr == opt) {
2749 sgen_env_var_error (env_var, "Using default value.", "`%s` must be a number.", opt_name);
2752 else if (val < min || val > max) {
2753 sgen_env_var_error (env_var, "Using default value.", "`%s` must be between %.2f - %.2f.", opt_name, min, max);
2765 char *major_collector_opt = NULL;
2766 char *minor_collector_opt = NULL;
2767 size_t max_heap = 0;
2768 size_t soft_limit = 0;
2770 gboolean debug_print_allowance = FALSE;
2771 double allowance_ratio = 0, save_target = 0;
2772 gboolean cement_enabled = TRUE;
2775 result = InterlockedCompareExchange (&gc_initialized, -1, 0);
2778 /* already inited */
2781 /* being inited by another thread */
2782 mono_thread_info_usleep (1000);
2785 /* we will init it */
2788 g_assert_not_reached ();
2790 } while (result != 0);
2792 SGEN_TV_GETTIME (sgen_init_timestamp);
2794 #ifdef SGEN_WITHOUT_MONO
2795 mono_thread_smr_init ();
2798 mono_coop_mutex_init (&gc_mutex);
2800 gc_debug_file = stderr;
2802 mono_coop_mutex_init (&sgen_interruption_mutex);
2804 if ((env = g_getenv (MONO_GC_PARAMS_NAME))) {
2805 opts = g_strsplit (env, ",", -1);
2806 for (ptr = opts; *ptr; ++ptr) {
2808 if (g_str_has_prefix (opt, "major=")) {
2809 opt = strchr (opt, '=') + 1;
2810 major_collector_opt = g_strdup (opt);
2811 } else if (g_str_has_prefix (opt, "minor=")) {
2812 opt = strchr (opt, '=') + 1;
2813 minor_collector_opt = g_strdup (opt);
2821 sgen_init_internal_allocator ();
2822 sgen_init_nursery_allocator ();
2823 sgen_init_fin_weak_hash ();
2824 sgen_init_hash_table ();
2825 sgen_init_descriptors ();
2826 sgen_init_gray_queues ();
2827 sgen_init_allocator ();
2828 sgen_init_gchandles ();
2830 sgen_register_fixed_internal_mem_type (INTERNAL_MEM_SECTION, SGEN_SIZEOF_GC_MEM_SECTION);
2831 sgen_register_fixed_internal_mem_type (INTERNAL_MEM_GRAY_QUEUE, sizeof (GrayQueueSection));
2833 sgen_client_init ();
2835 if (!minor_collector_opt) {
2836 sgen_simple_nursery_init (&sgen_minor_collector);
2838 if (!strcmp (minor_collector_opt, "simple")) {
2840 sgen_simple_nursery_init (&sgen_minor_collector);
2841 } else if (!strcmp (minor_collector_opt, "split")) {
2842 sgen_split_nursery_init (&sgen_minor_collector);
2844 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using `simple` instead.", "Unknown minor collector `%s'.", minor_collector_opt);
2845 goto use_simple_nursery;
2849 if (!major_collector_opt || !strcmp (major_collector_opt, "marksweep")) {
2850 use_marksweep_major:
2851 sgen_marksweep_init (&major_collector);
2852 } else if (!major_collector_opt || !strcmp (major_collector_opt, "marksweep-conc")) {
2853 sgen_marksweep_conc_init (&major_collector);
2855 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using `marksweep` instead.", "Unknown major collector `%s'.", major_collector_opt);
2856 goto use_marksweep_major;
2859 sgen_nursery_size = DEFAULT_NURSERY_SIZE;
2862 gboolean usage_printed = FALSE;
2864 for (ptr = opts; *ptr; ++ptr) {
2866 if (!strcmp (opt, ""))
2868 if (g_str_has_prefix (opt, "major="))
2870 if (g_str_has_prefix (opt, "minor="))
2872 if (g_str_has_prefix (opt, "max-heap-size=")) {
2873 size_t page_size = mono_pagesize ();
2874 size_t max_heap_candidate = 0;
2875 opt = strchr (opt, '=') + 1;
2876 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &max_heap_candidate)) {
2877 max_heap = (max_heap_candidate + page_size - 1) & ~(size_t)(page_size - 1);
2878 if (max_heap != max_heap_candidate)
2879 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Rounding up.", "`max-heap-size` size must be a multiple of %d.", page_size);
2881 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`max-heap-size` must be an integer.");
2885 if (g_str_has_prefix (opt, "soft-heap-limit=")) {
2886 opt = strchr (opt, '=') + 1;
2887 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &soft_limit)) {
2888 if (soft_limit <= 0) {
2889 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`soft-heap-limit` must be positive.");
2893 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`soft-heap-limit` must be an integer.");
2899 if (g_str_has_prefix (opt, "nursery-size=")) {
2901 opt = strchr (opt, '=') + 1;
2902 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &val)) {
2903 if ((val & (val - 1))) {
2904 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.", "`nursery-size` must be a power of two.");
2908 if (val < SGEN_MAX_NURSERY_WASTE) {
2909 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.",
2910 "`nursery-size` must be at least %d bytes.", SGEN_MAX_NURSERY_WASTE);
2914 sgen_nursery_size = val;
2915 sgen_nursery_bits = 0;
2916 while (ONE_P << (++ sgen_nursery_bits) != sgen_nursery_size)
2919 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.", "`nursery-size` must be an integer.");
2925 if (g_str_has_prefix (opt, "save-target-ratio=")) {
2927 opt = strchr (opt, '=') + 1;
2928 if (parse_double_in_interval (MONO_GC_PARAMS_NAME, "save-target-ratio", opt,
2929 SGEN_MIN_SAVE_TARGET_RATIO, SGEN_MAX_SAVE_TARGET_RATIO, &val)) {
2934 if (g_str_has_prefix (opt, "default-allowance-ratio=")) {
2936 opt = strchr (opt, '=') + 1;
2937 if (parse_double_in_interval (MONO_GC_PARAMS_NAME, "default-allowance-ratio", opt,
2938 SGEN_MIN_ALLOWANCE_NURSERY_SIZE_RATIO, SGEN_MIN_ALLOWANCE_NURSERY_SIZE_RATIO, &val)) {
2939 allowance_ratio = val;
2944 if (!strcmp (opt, "cementing")) {
2945 cement_enabled = TRUE;
2948 if (!strcmp (opt, "no-cementing")) {
2949 cement_enabled = FALSE;
2953 if (!strcmp (opt, "precleaning")) {
2954 precleaning_enabled = TRUE;
2957 if (!strcmp (opt, "no-precleaning")) {
2958 precleaning_enabled = FALSE;
2962 if (major_collector.handle_gc_param && major_collector.handle_gc_param (opt))
2965 if (sgen_minor_collector.handle_gc_param && sgen_minor_collector.handle_gc_param (opt))
2968 if (sgen_client_handle_gc_param (opt))
2971 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Ignoring.", "Unknown option `%s`.", opt);
2976 fprintf (stderr, "\n%s must be a comma-delimited list of one or more of the following:\n", MONO_GC_PARAMS_NAME);
2977 fprintf (stderr, " max-heap-size=N (where N is an integer, possibly with a k, m or a g suffix)\n");
2978 fprintf (stderr, " soft-heap-limit=n (where N is an integer, possibly with a k, m or a g suffix)\n");
2979 fprintf (stderr, " nursery-size=N (where N is an integer, possibly with a k, m or a g suffix)\n");
2980 fprintf (stderr, " major=COLLECTOR (where COLLECTOR is `marksweep', `marksweep-conc', `marksweep-par')\n");
2981 fprintf (stderr, " minor=COLLECTOR (where COLLECTOR is `simple' or `split')\n");
2982 fprintf (stderr, " wbarrier=WBARRIER (where WBARRIER is `remset' or `cardtable')\n");
2983 fprintf (stderr, " [no-]cementing\n");
2984 if (major_collector.print_gc_param_usage)
2985 major_collector.print_gc_param_usage ();
2986 if (sgen_minor_collector.print_gc_param_usage)
2987 sgen_minor_collector.print_gc_param_usage ();
2988 sgen_client_print_gc_params_usage ();
2989 fprintf (stderr, " Experimental options:\n");
2990 fprintf (stderr, " save-target-ratio=R (where R must be between %.2f - %.2f).\n", SGEN_MIN_SAVE_TARGET_RATIO, SGEN_MAX_SAVE_TARGET_RATIO);
2991 fprintf (stderr, " default-allowance-ratio=R (where R must be between %.2f - %.2f).\n", SGEN_MIN_ALLOWANCE_NURSERY_SIZE_RATIO, SGEN_MAX_ALLOWANCE_NURSERY_SIZE_RATIO);
2992 fprintf (stderr, "\n");
2994 usage_printed = TRUE;
2999 if (major_collector_opt)
3000 g_free (major_collector_opt);
3002 if (minor_collector_opt)
3003 g_free (minor_collector_opt);
3007 sgen_cement_init (cement_enabled);
3009 if ((env = g_getenv (MONO_GC_DEBUG_NAME))) {
3010 gboolean usage_printed = FALSE;
3012 opts = g_strsplit (env, ",", -1);
3013 for (ptr = opts; ptr && *ptr; ptr ++) {
3015 if (!strcmp (opt, ""))
3017 if (opt [0] >= '0' && opt [0] <= '9') {
3018 gc_debug_level = atoi (opt);
3023 char *rf = g_strdup_printf ("%s.%d", opt, mono_process_current_pid ());
3024 gc_debug_file = fopen (rf, "wb");
3026 gc_debug_file = stderr;
3029 } else if (!strcmp (opt, "print-allowance")) {
3030 debug_print_allowance = TRUE;
3031 } else if (!strcmp (opt, "print-pinning")) {
3032 sgen_pin_stats_enable ();
3033 } else if (!strcmp (opt, "verify-before-allocs")) {
3034 verify_before_allocs = 1;
3035 has_per_allocation_action = TRUE;
3036 } else if (g_str_has_prefix (opt, "verify-before-allocs=")) {
3037 char *arg = strchr (opt, '=') + 1;
3038 verify_before_allocs = atoi (arg);
3039 has_per_allocation_action = TRUE;
3040 } else if (!strcmp (opt, "collect-before-allocs")) {
3041 collect_before_allocs = 1;
3042 has_per_allocation_action = TRUE;
3043 } else if (g_str_has_prefix (opt, "collect-before-allocs=")) {
3044 char *arg = strchr (opt, '=') + 1;
3045 has_per_allocation_action = TRUE;
3046 collect_before_allocs = atoi (arg);
3047 } else if (!strcmp (opt, "verify-before-collections")) {
3048 whole_heap_check_before_collection = TRUE;
3049 } else if (!strcmp (opt, "check-at-minor-collections")) {
3050 consistency_check_at_minor_collection = TRUE;
3051 nursery_clear_policy = CLEAR_AT_GC;
3052 } else if (!strcmp (opt, "mod-union-consistency-check")) {
3053 if (!major_collector.is_concurrent) {
3054 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "`mod-union-consistency-check` only works with concurrent major collector.");
3057 mod_union_consistency_check = TRUE;
3058 } else if (!strcmp (opt, "check-mark-bits")) {
3059 check_mark_bits_after_major_collection = TRUE;
3060 } else if (!strcmp (opt, "check-nursery-pinned")) {
3061 check_nursery_objects_pinned = TRUE;
3062 } else if (!strcmp (opt, "clear-at-gc")) {
3063 nursery_clear_policy = CLEAR_AT_GC;
3064 } else if (!strcmp (opt, "clear-nursery-at-gc")) {
3065 nursery_clear_policy = CLEAR_AT_GC;
3066 } else if (!strcmp (opt, "clear-at-tlab-creation")) {
3067 nursery_clear_policy = CLEAR_AT_TLAB_CREATION;
3068 } else if (!strcmp (opt, "debug-clear-at-tlab-creation")) {
3069 nursery_clear_policy = CLEAR_AT_TLAB_CREATION_DEBUG;
3070 } else if (!strcmp (opt, "check-scan-starts")) {
3071 do_scan_starts_check = TRUE;
3072 } else if (!strcmp (opt, "verify-nursery-at-minor-gc")) {
3073 do_verify_nursery = TRUE;
3074 } else if (!strcmp (opt, "check-concurrent")) {
3075 if (!major_collector.is_concurrent) {
3076 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "`check-concurrent` only works with concurrent major collectors.");
3079 nursery_clear_policy = CLEAR_AT_GC;
3080 do_concurrent_checks = TRUE;
3081 } else if (!strcmp (opt, "dump-nursery-at-minor-gc")) {
3082 do_dump_nursery_content = TRUE;
3083 } else if (!strcmp (opt, "disable-minor")) {
3084 disable_minor_collections = TRUE;
3085 } else if (!strcmp (opt, "disable-major")) {
3086 disable_major_collections = TRUE;
3087 } else if (g_str_has_prefix (opt, "heap-dump=")) {
3088 char *filename = strchr (opt, '=') + 1;
3089 nursery_clear_policy = CLEAR_AT_GC;
3090 sgen_debug_enable_heap_dump (filename);
3091 } else if (g_str_has_prefix (opt, "binary-protocol=")) {
3092 char *filename = strchr (opt, '=') + 1;
3093 char *colon = strrchr (filename, ':');
3096 if (!mono_gc_parse_environment_string_extract_number (colon + 1, &limit)) {
3097 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring limit.", "Binary protocol file size limit must be an integer.");
3102 binary_protocol_init (filename, (long long)limit);
3103 } else if (!strcmp (opt, "nursery-canaries")) {
3104 do_verify_nursery = TRUE;
3105 enable_nursery_canaries = TRUE;
3106 } else if (!sgen_client_handle_gc_debug (opt)) {
3107 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "Unknown option `%s`.", opt);
3112 fprintf (stderr, "\n%s must be of the format [<l>[:<filename>]|<option>]+ where <l> is a debug level 0-9.\n", MONO_GC_DEBUG_NAME);
3113 fprintf (stderr, "Valid <option>s are:\n");
3114 fprintf (stderr, " collect-before-allocs[=<n>]\n");
3115 fprintf (stderr, " verify-before-allocs[=<n>]\n");
3116 fprintf (stderr, " check-at-minor-collections\n");
3117 fprintf (stderr, " check-mark-bits\n");
3118 fprintf (stderr, " check-nursery-pinned\n");
3119 fprintf (stderr, " verify-before-collections\n");
3120 fprintf (stderr, " verify-nursery-at-minor-gc\n");
3121 fprintf (stderr, " dump-nursery-at-minor-gc\n");
3122 fprintf (stderr, " disable-minor\n");
3123 fprintf (stderr, " disable-major\n");
3124 fprintf (stderr, " check-concurrent\n");
3125 fprintf (stderr, " clear-[nursery-]at-gc\n");
3126 fprintf (stderr, " clear-at-tlab-creation\n");
3127 fprintf (stderr, " debug-clear-at-tlab-creation\n");
3128 fprintf (stderr, " check-scan-starts\n");
3129 fprintf (stderr, " print-allowance\n");
3130 fprintf (stderr, " print-pinning\n");
3131 fprintf (stderr, " heap-dump=<filename>\n");
3132 fprintf (stderr, " binary-protocol=<filename>[:<file-size-limit>]\n");
3133 fprintf (stderr, " nursery-canaries\n");
3134 sgen_client_print_gc_debug_usage ();
3135 fprintf (stderr, "\n");
3137 usage_printed = TRUE;
3143 if (check_mark_bits_after_major_collection)
3144 nursery_clear_policy = CLEAR_AT_GC;
3146 if (major_collector.post_param_init)
3147 major_collector.post_param_init (&major_collector);
3149 if (major_collector.needs_thread_pool)
3150 sgen_workers_init (1);
3152 sgen_memgov_init (max_heap, soft_limit, debug_print_allowance, allowance_ratio, save_target);
3154 memset (&remset, 0, sizeof (remset));
3156 sgen_card_table_init (&remset);
3158 sgen_register_root (NULL, 0, sgen_make_user_root_descriptor (sgen_mark_normal_gc_handles), ROOT_TYPE_NORMAL, MONO_ROOT_SOURCE_GC_HANDLE, "normal gc handles");
3164 sgen_get_nursery_clear_policy (void)
3166 return nursery_clear_policy;
3172 mono_coop_mutex_lock (&gc_mutex);
3176 sgen_gc_unlock (void)
3178 mono_coop_mutex_unlock (&gc_mutex);
3182 sgen_major_collector_iterate_live_block_ranges (sgen_cardtable_block_callback callback)
3184 major_collector.iterate_live_block_ranges (callback);
3188 sgen_get_major_collector (void)
3190 return &major_collector;
3194 sgen_get_remset (void)
3200 count_cards (long long *major_total, long long *major_marked, long long *los_total, long long *los_marked)
3202 sgen_get_major_collector ()->count_cards (major_total, major_marked);
3203 sgen_los_count_cards (los_total, los_marked);
3206 static gboolean world_is_stopped = FALSE;
3208 /* LOCKING: assumes the GC lock is held */
3210 sgen_stop_world (int generation)
3212 long long major_total = -1, major_marked = -1, los_total = -1, los_marked = -1;
3214 SGEN_ASSERT (0, !world_is_stopped, "Why are we stopping a stopped world?");
3216 binary_protocol_world_stopping (generation, sgen_timestamp (), (gpointer) (gsize) mono_native_thread_id_get ());
3218 sgen_client_stop_world (generation);
3220 world_is_stopped = TRUE;
3222 if (binary_protocol_is_heavy_enabled ())
3223 count_cards (&major_total, &major_marked, &los_total, &los_marked);
3224 binary_protocol_world_stopped (generation, sgen_timestamp (), major_total, major_marked, los_total, los_marked);
3227 /* LOCKING: assumes the GC lock is held */
3229 sgen_restart_world (int generation, GGTimingInfo *timing)
3231 long long major_total = -1, major_marked = -1, los_total = -1, los_marked = -1;
3233 SGEN_ASSERT (0, world_is_stopped, "Why are we restarting a running world?");
3235 if (binary_protocol_is_heavy_enabled ())
3236 count_cards (&major_total, &major_marked, &los_total, &los_marked);
3237 binary_protocol_world_restarting (generation, sgen_timestamp (), major_total, major_marked, los_total, los_marked);
3239 sgen_client_restart_world (generation, timing);
3241 world_is_stopped = FALSE;
3243 binary_protocol_world_restarted (generation, sgen_timestamp ());
3245 if (sgen_client_bridge_need_processing ())
3246 sgen_client_bridge_processing_finish (generation);
3248 sgen_memgov_collection_end (generation, timing, timing ? 2 : 0);
3252 sgen_is_world_stopped (void)
3254 return world_is_stopped;
3258 sgen_check_whole_heap_stw (void)
3260 sgen_stop_world (0);
3261 sgen_clear_nursery_fragments ();
3262 sgen_check_whole_heap (FALSE);
3263 sgen_restart_world (0, NULL);
3267 sgen_timestamp (void)
3269 SGEN_TV_DECLARE (timestamp);
3270 SGEN_TV_GETTIME (timestamp);
3271 return SGEN_TV_ELAPSED (sgen_init_timestamp, timestamp);
3274 #endif /* HAVE_SGEN_GC */