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 remset consistency check at various opportunities */
218 static gboolean remset_consistency_checks = 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 int gc_debug_level = 0;
293 static char* gc_params_options;
294 static char* gc_debug_options;
298 mono_gc_flush_info (void)
300 fflush (gc_debug_file);
304 #define TV_DECLARE SGEN_TV_DECLARE
305 #define TV_GETTIME SGEN_TV_GETTIME
306 #define TV_ELAPSED SGEN_TV_ELAPSED
308 static SGEN_TV_DECLARE (sgen_init_timestamp);
310 NurseryClearPolicy nursery_clear_policy = CLEAR_AT_TLAB_CREATION;
312 #define object_is_forwarded SGEN_OBJECT_IS_FORWARDED
313 #define object_is_pinned SGEN_OBJECT_IS_PINNED
314 #define pin_object SGEN_PIN_OBJECT
316 #define ptr_in_nursery sgen_ptr_in_nursery
318 #define LOAD_VTABLE SGEN_LOAD_VTABLE
321 nursery_canaries_enabled (void)
323 return enable_nursery_canaries;
326 #define safe_object_get_size sgen_safe_object_get_size
328 #if defined(HAVE_CONC_GC_AS_DEFAULT)
329 /* Use concurrent major on deskstop platforms */
330 #define DEFAULT_MAJOR_INIT sgen_marksweep_conc_init
331 #define DEFAULT_MAJOR_NAME "marksweep-conc"
333 #define DEFAULT_MAJOR_INIT sgen_marksweep_init
334 #define DEFAULT_MAJOR_NAME "marksweep"
338 * ######################################################################
339 * ######## Global data.
340 * ######################################################################
342 MonoCoopMutex gc_mutex;
344 #define SCAN_START_SIZE SGEN_SCAN_START_SIZE
346 size_t degraded_mode = 0;
348 static mword bytes_pinned_from_failed_allocation = 0;
350 GCMemSection *nursery_section = NULL;
351 static volatile mword lowest_heap_address = ~(mword)0;
352 static volatile mword highest_heap_address = 0;
354 MonoCoopMutex sgen_interruption_mutex;
356 int current_collection_generation = -1;
357 static volatile gboolean concurrent_collection_in_progress = FALSE;
359 /* objects that are ready to be finalized */
360 static SgenPointerQueue fin_ready_queue = SGEN_POINTER_QUEUE_INIT (INTERNAL_MEM_FINALIZE_READY);
361 static SgenPointerQueue critical_fin_queue = SGEN_POINTER_QUEUE_INIT (INTERNAL_MEM_FINALIZE_READY);
363 /* registered roots: the key to the hash is the root start address */
365 * Different kinds of roots are kept separate to speed up pin_from_roots () for example.
367 SgenHashTable roots_hash [ROOT_TYPE_NUM] = {
368 SGEN_HASH_TABLE_INIT (INTERNAL_MEM_ROOTS_TABLE, INTERNAL_MEM_ROOT_RECORD, sizeof (RootRecord), sgen_aligned_addr_hash, NULL),
369 SGEN_HASH_TABLE_INIT (INTERNAL_MEM_ROOTS_TABLE, INTERNAL_MEM_ROOT_RECORD, sizeof (RootRecord), sgen_aligned_addr_hash, NULL),
370 SGEN_HASH_TABLE_INIT (INTERNAL_MEM_ROOTS_TABLE, INTERNAL_MEM_ROOT_RECORD, sizeof (RootRecord), sgen_aligned_addr_hash, NULL)
372 static mword roots_size = 0; /* amount of memory in the root set */
374 /* The size of a TLAB */
375 /* The bigger the value, the less often we have to go to the slow path to allocate a new
376 * one, but the more space is wasted by threads not allocating much memory.
378 * FIXME: Make this self-tuning for each thread.
380 guint32 tlab_size = (1024 * 4);
382 #define MAX_SMALL_OBJ_SIZE SGEN_MAX_SMALL_OBJ_SIZE
384 #define ALLOC_ALIGN SGEN_ALLOC_ALIGN
386 #define ALIGN_UP SGEN_ALIGN_UP
388 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
389 MonoNativeThreadId main_gc_thread = NULL;
392 /*Object was pinned during the current collection*/
393 static mword objects_pinned;
396 * ######################################################################
397 * ######## Macros and function declarations.
398 * ######################################################################
401 /* forward declarations */
402 static void scan_from_registered_roots (char *addr_start, char *addr_end, int root_type, ScanCopyContext ctx);
404 static void pin_from_roots (void *start_nursery, void *end_nursery, ScanCopyContext ctx);
405 static void finish_gray_stack (int generation, ScanCopyContext ctx);
408 SgenMajorCollector major_collector;
409 SgenMinorCollector sgen_minor_collector;
411 static SgenRememberedSet remset;
414 * The gray queue a worker job must use. If we're not parallel or
415 * concurrent, we use the main gray queue.
417 static SgenGrayQueue*
418 sgen_workers_get_job_gray_queue (WorkerData *worker_data, SgenGrayQueue *default_gray_queue)
421 return &worker_data->private_gray_queue;
422 SGEN_ASSERT (0, default_gray_queue, "Why don't we have a default gray queue when we're not running in a worker thread?");
423 return default_gray_queue;
427 gray_queue_enable_redirect (SgenGrayQueue *queue)
429 SGEN_ASSERT (0, concurrent_collection_in_progress, "Where are we redirecting the gray queue to, without a concurrent collection?");
431 sgen_gray_queue_set_alloc_prepare (queue, sgen_workers_take_from_queue_and_awake);
432 sgen_workers_take_from_queue_and_awake (queue);
436 sgen_scan_area_with_callback (char *start, char *end, IterateObjectCallbackFunc callback, void *data, gboolean allow_flags, gboolean fail_on_canaries)
438 while (start < end) {
442 if (!*(void**)start) {
443 start += sizeof (void*); /* should be ALLOC_ALIGN, really */
448 if (!(obj = (char *)SGEN_OBJECT_IS_FORWARDED (start)))
454 if (!sgen_client_object_is_array_fill ((GCObject*)obj)) {
455 CHECK_CANARY_FOR_OBJECT ((GCObject*)obj, fail_on_canaries);
456 size = ALIGN_UP (safe_object_get_size ((GCObject*)obj));
457 callback ((GCObject*)obj, size, data);
458 CANARIFY_SIZE (size);
460 size = ALIGN_UP (safe_object_get_size ((GCObject*)obj));
468 * sgen_add_to_global_remset:
470 * The global remset contains locations which point into newspace after
471 * a minor collection. This can happen if the objects they point to are pinned.
473 * LOCKING: If called from a parallel collector, the global remset
474 * lock must be held. For serial collectors that is not necessary.
477 sgen_add_to_global_remset (gpointer ptr, GCObject *obj)
479 SGEN_ASSERT (5, sgen_ptr_in_nursery (obj), "Target pointer of global remset must be in the nursery");
481 HEAVY_STAT (++stat_wbarrier_add_to_global_remset);
483 if (!major_collector.is_concurrent) {
484 SGEN_ASSERT (5, current_collection_generation != -1, "Global remsets can only be added during collections");
486 if (current_collection_generation == -1)
487 SGEN_ASSERT (5, sgen_concurrent_collection_in_progress (), "Global remsets outside of collection pauses can only be added by the concurrent collector");
490 if (!object_is_pinned (obj))
491 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");
492 else if (sgen_cement_lookup_or_register (obj))
495 remset.record_pointer (ptr);
497 sgen_pin_stats_register_global_remset (obj);
499 SGEN_LOG (8, "Adding global remset for %p", ptr);
500 binary_protocol_global_remset (ptr, obj, (gpointer)SGEN_LOAD_VTABLE (obj));
504 * sgen_drain_gray_stack:
506 * Scan objects in the gray stack until the stack is empty. This should be called
507 * frequently after each object is copied, to achieve better locality and cache
512 sgen_drain_gray_stack (ScanCopyContext ctx)
514 ScanObjectFunc scan_func = ctx.ops->scan_object;
515 SgenGrayQueue *queue = ctx.queue;
517 if (ctx.ops->drain_gray_stack)
518 return ctx.ops->drain_gray_stack (queue);
523 GRAY_OBJECT_DEQUEUE (queue, &obj, &desc);
526 SGEN_LOG (9, "Precise gray object scan %p (%s)", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
527 scan_func (obj, desc, queue);
533 * Addresses in the pin queue are already sorted. This function finds
534 * the object header for each address and pins the object. The
535 * addresses must be inside the nursery section. The (start of the)
536 * address array is overwritten with the addresses of the actually
537 * pinned objects. Return the number of pinned objects.
540 pin_objects_from_nursery_pin_queue (gboolean do_scan_objects, ScanCopyContext ctx)
542 GCMemSection *section = nursery_section;
543 void **start = sgen_pinning_get_entry (section->pin_queue_first_entry);
544 void **end = sgen_pinning_get_entry (section->pin_queue_last_entry);
545 void *start_nursery = section->data;
546 void *end_nursery = section->next_data;
551 void *pinning_front = start_nursery;
553 void **definitely_pinned = start;
554 ScanObjectFunc scan_func = ctx.ops->scan_object;
555 SgenGrayQueue *queue = ctx.queue;
557 sgen_nursery_allocator_prepare_for_pinning ();
559 while (start < end) {
560 GCObject *obj_to_pin = NULL;
561 size_t obj_to_pin_size = 0;
566 SGEN_ASSERT (0, addr >= start_nursery && addr < end_nursery, "Potential pinning address out of range");
567 SGEN_ASSERT (0, addr >= last, "Pin queue not sorted");
574 SGEN_LOG (5, "Considering pinning addr %p", addr);
575 /* We've already processed everything up to pinning_front. */
576 if (addr < pinning_front) {
582 * Find the closest scan start <= addr. We might search backward in the
583 * scan_starts array because entries might be NULL. In the worst case we
584 * start at start_nursery.
586 idx = ((char*)addr - (char*)section->data) / SCAN_START_SIZE;
587 SGEN_ASSERT (0, idx < section->num_scan_start, "Scan start index out of range");
588 search_start = (void*)section->scan_starts [idx];
589 if (!search_start || search_start > addr) {
592 search_start = section->scan_starts [idx];
593 if (search_start && search_start <= addr)
596 if (!search_start || search_start > addr)
597 search_start = start_nursery;
601 * If the pinning front is closer than the scan start we found, start
602 * searching at the front.
604 if (search_start < pinning_front)
605 search_start = pinning_front;
608 * Now addr should be in an object a short distance from search_start.
610 * search_start must point to zeroed mem or point to an object.
613 size_t obj_size, canarified_obj_size;
616 if (!*(void**)search_start) {
617 search_start = (void*)ALIGN_UP ((mword)search_start + sizeof (gpointer));
618 /* The loop condition makes sure we don't overrun addr. */
622 canarified_obj_size = obj_size = ALIGN_UP (safe_object_get_size ((GCObject*)search_start));
625 * Filler arrays are marked by an invalid sync word. We don't
626 * consider them for pinning. They are not delimited by canaries,
629 if (!sgen_client_object_is_array_fill ((GCObject*)search_start)) {
630 CHECK_CANARY_FOR_OBJECT (search_start, TRUE);
631 CANARIFY_SIZE (canarified_obj_size);
633 if (addr >= search_start && (char*)addr < (char*)search_start + obj_size) {
634 /* This is the object we're looking for. */
635 obj_to_pin = (GCObject*)search_start;
636 obj_to_pin_size = canarified_obj_size;
641 /* Skip to the next object */
642 search_start = (void*)((char*)search_start + canarified_obj_size);
643 } while (search_start <= addr);
645 /* We've searched past the address we were looking for. */
647 pinning_front = search_start;
648 goto next_pin_queue_entry;
652 * We've found an object to pin. It might still be a dummy array, but we
653 * can advance the pinning front in any case.
655 pinning_front = (char*)obj_to_pin + obj_to_pin_size;
658 * If this is a dummy array marking the beginning of a nursery
659 * fragment, we don't pin it.
661 if (sgen_client_object_is_array_fill (obj_to_pin))
662 goto next_pin_queue_entry;
665 * Finally - pin the object!
667 desc = sgen_obj_get_descriptor_safe (obj_to_pin);
668 if (do_scan_objects) {
669 scan_func (obj_to_pin, desc, queue);
671 SGEN_LOG (4, "Pinned object %p, vtable %p (%s), count %d\n",
672 obj_to_pin, *(void**)obj_to_pin, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj_to_pin)), count);
673 binary_protocol_pin (obj_to_pin,
674 (gpointer)LOAD_VTABLE (obj_to_pin),
675 safe_object_get_size (obj_to_pin));
677 pin_object (obj_to_pin);
678 GRAY_OBJECT_ENQUEUE (queue, obj_to_pin, desc);
679 sgen_pin_stats_register_object (obj_to_pin, GENERATION_NURSERY);
680 definitely_pinned [count] = obj_to_pin;
683 if (concurrent_collection_in_progress)
684 sgen_pinning_register_pinned_in_nursery (obj_to_pin);
686 next_pin_queue_entry:
690 sgen_client_nursery_objects_pinned (definitely_pinned, count);
691 stat_pinned_objects += count;
696 pin_objects_in_nursery (gboolean do_scan_objects, ScanCopyContext ctx)
700 if (nursery_section->pin_queue_first_entry == nursery_section->pin_queue_last_entry)
703 reduced_to = pin_objects_from_nursery_pin_queue (do_scan_objects, ctx);
704 nursery_section->pin_queue_last_entry = nursery_section->pin_queue_first_entry + reduced_to;
708 * This function is only ever called (via `collector_pin_object()` in `sgen-copy-object.h`)
709 * when we can't promote an object because we're out of memory.
712 sgen_pin_object (GCObject *object, SgenGrayQueue *queue)
714 SGEN_ASSERT (0, sgen_ptr_in_nursery (object), "We're only supposed to use this for pinning nursery objects when out of memory.");
717 * All pinned objects are assumed to have been staged, so we need to stage as well.
718 * Also, the count of staged objects shows that "late pinning" happened.
720 sgen_pin_stage_ptr (object);
722 SGEN_PIN_OBJECT (object);
723 binary_protocol_pin (object, (gpointer)LOAD_VTABLE (object), safe_object_get_size (object));
726 sgen_pin_stats_register_object (object, GENERATION_NURSERY);
728 GRAY_OBJECT_ENQUEUE (queue, object, sgen_obj_get_descriptor_safe (object));
731 /* Sort the addresses in array in increasing order.
732 * Done using a by-the book heap sort. Which has decent and stable performance, is pretty cache efficient.
735 sgen_sort_addresses (void **array, size_t size)
740 for (i = 1; i < size; ++i) {
743 size_t parent = (child - 1) / 2;
745 if (array [parent] >= array [child])
748 tmp = array [parent];
749 array [parent] = array [child];
756 for (i = size - 1; i > 0; --i) {
759 array [i] = array [0];
765 while (root * 2 + 1 <= end) {
766 size_t child = root * 2 + 1;
768 if (child < end && array [child] < array [child + 1])
770 if (array [root] >= array [child])
774 array [root] = array [child];
783 * Scan the memory between start and end and queue values which could be pointers
784 * to the area between start_nursery and end_nursery for later consideration.
785 * Typically used for thread stacks.
788 sgen_conservatively_pin_objects_from (void **start, void **end, void *start_nursery, void *end_nursery, int pin_type)
792 SGEN_ASSERT (0, ((mword)start & (SIZEOF_VOID_P - 1)) == 0, "Why are we scanning for references in unaligned memory ?");
794 #if defined(VALGRIND_MAKE_MEM_DEFINED_IF_ADDRESSABLE) && !defined(_WIN64)
795 VALGRIND_MAKE_MEM_DEFINED_IF_ADDRESSABLE (start, (char*)end - (char*)start);
798 while (start < end) {
800 * *start can point to the middle of an object
801 * note: should we handle pointing at the end of an object?
802 * pinning in C# code disallows pointing at the end of an object
803 * but there is some small chance that an optimizing C compiler
804 * may keep the only reference to an object by pointing
805 * at the end of it. We ignore this small chance for now.
806 * Pointers to the end of an object are indistinguishable
807 * from pointers to the start of the next object in memory
808 * so if we allow that we'd need to pin two objects...
809 * We queue the pointer in an array, the
810 * array will then be sorted and uniqued. This way
811 * we can coalesce several pinning pointers and it should
812 * be faster since we'd do a memory scan with increasing
813 * addresses. Note: we can align the address to the allocation
814 * alignment, so the unique process is more effective.
816 mword addr = (mword)*start;
817 addr &= ~(ALLOC_ALIGN - 1);
818 if (addr >= (mword)start_nursery && addr < (mword)end_nursery) {
819 SGEN_LOG (6, "Pinning address %p from %p", (void*)addr, start);
820 sgen_pin_stage_ptr ((void*)addr);
821 binary_protocol_pin_stage (start, (void*)addr);
822 sgen_pin_stats_register_address ((char*)addr, pin_type);
828 SGEN_LOG (7, "found %d potential pinned heap pointers", count);
832 * The first thing we do in a collection is to identify pinned objects.
833 * This function considers all the areas of memory that need to be
834 * conservatively scanned.
837 pin_from_roots (void *start_nursery, void *end_nursery, ScanCopyContext ctx)
841 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);
842 /* objects pinned from the API are inside these roots */
843 SGEN_HASH_TABLE_FOREACH (&roots_hash [ROOT_TYPE_PINNED], void **, start_root, RootRecord *, root) {
844 SGEN_LOG (6, "Pinned roots %p-%p", start_root, root->end_root);
845 sgen_conservatively_pin_objects_from (start_root, (void**)root->end_root, start_nursery, end_nursery, PIN_TYPE_OTHER);
846 } SGEN_HASH_TABLE_FOREACH_END;
847 /* now deal with the thread stacks
848 * in the future we should be able to conservatively scan only:
849 * *) the cpu registers
850 * *) the unmanaged stack frames
851 * *) the _last_ managed stack frame
852 * *) pointers slots in managed frames
854 sgen_client_scan_thread_data (start_nursery, end_nursery, FALSE, ctx);
858 single_arg_user_copy_or_mark (GCObject **obj, void *gc_data)
860 ScanCopyContext *ctx = (ScanCopyContext *)gc_data;
861 ctx->ops->copy_or_mark_object (obj, ctx->queue);
865 * The memory area from start_root to end_root contains pointers to objects.
866 * Their position is precisely described by @desc (this means that the pointer
867 * can be either NULL or the pointer to the start of an object).
868 * This functions copies them to to_space updates them.
870 * This function is not thread-safe!
873 precisely_scan_objects_from (void** start_root, void** end_root, char* n_start, char *n_end, SgenDescriptor desc, ScanCopyContext ctx)
875 CopyOrMarkObjectFunc copy_func = ctx.ops->copy_or_mark_object;
876 SgenGrayQueue *queue = ctx.queue;
878 switch (desc & ROOT_DESC_TYPE_MASK) {
879 case ROOT_DESC_BITMAP:
880 desc >>= ROOT_DESC_TYPE_SHIFT;
882 if ((desc & 1) && *start_root) {
883 copy_func ((GCObject**)start_root, queue);
884 SGEN_LOG (9, "Overwrote root at %p with %p", start_root, *start_root);
890 case ROOT_DESC_COMPLEX: {
891 gsize *bitmap_data = (gsize *)sgen_get_complex_descriptor_bitmap (desc);
892 gsize bwords = (*bitmap_data) - 1;
893 void **start_run = start_root;
895 while (bwords-- > 0) {
896 gsize bmap = *bitmap_data++;
897 void **objptr = start_run;
899 if ((bmap & 1) && *objptr) {
900 copy_func ((GCObject**)objptr, queue);
901 SGEN_LOG (9, "Overwrote root at %p with %p", objptr, *objptr);
906 start_run += GC_BITS_PER_WORD;
910 case ROOT_DESC_USER: {
911 SgenUserRootMarkFunc marker = sgen_get_user_descriptor_func (desc);
912 marker (start_root, single_arg_user_copy_or_mark, &ctx);
915 case ROOT_DESC_RUN_LEN:
916 g_assert_not_reached ();
918 g_assert_not_reached ();
923 reset_heap_boundaries (void)
925 lowest_heap_address = ~(mword)0;
926 highest_heap_address = 0;
930 sgen_update_heap_boundaries (mword low, mword high)
935 old = lowest_heap_address;
938 } while (SGEN_CAS_PTR ((gpointer*)&lowest_heap_address, (gpointer)low, (gpointer)old) != (gpointer)old);
941 old = highest_heap_address;
944 } while (SGEN_CAS_PTR ((gpointer*)&highest_heap_address, (gpointer)high, (gpointer)old) != (gpointer)old);
948 * Allocate and setup the data structures needed to be able to allocate objects
949 * in the nursery. The nursery is stored in nursery_section.
954 GCMemSection *section;
961 SGEN_LOG (2, "Allocating nursery size: %zu", (size_t)sgen_nursery_size);
962 /* later we will alloc a larger area for the nursery but only activate
963 * what we need. The rest will be used as expansion if we have too many pinned
964 * objects in the existing nursery.
966 /* FIXME: handle OOM */
967 section = (GCMemSection *)sgen_alloc_internal (INTERNAL_MEM_SECTION);
969 alloc_size = sgen_nursery_size;
971 /* If there isn't enough space even for the nursery we should simply abort. */
972 g_assert (sgen_memgov_try_alloc_space (alloc_size, SPACE_NURSERY));
974 data = (char *)major_collector.alloc_heap (alloc_size, alloc_size, DEFAULT_NURSERY_BITS);
975 sgen_update_heap_boundaries ((mword)data, (mword)(data + sgen_nursery_size));
976 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 ());
977 section->data = section->next_data = data;
978 section->size = alloc_size;
979 section->end_data = data + sgen_nursery_size;
980 scan_starts = (alloc_size + SCAN_START_SIZE - 1) / SCAN_START_SIZE;
981 section->scan_starts = (char **)sgen_alloc_internal_dynamic (sizeof (char*) * scan_starts, INTERNAL_MEM_SCAN_STARTS, TRUE);
982 section->num_scan_start = scan_starts;
984 nursery_section = section;
986 sgen_nursery_allocator_set_nursery_bounds (data, data + sgen_nursery_size);
990 mono_gc_get_logfile (void)
992 return gc_debug_file;
996 mono_gc_params_set (const char* options)
998 if (gc_params_options)
999 g_free (gc_params_options);
1001 gc_params_options = g_strdup (options);
1005 mono_gc_debug_set (const char* options)
1007 if (gc_debug_options)
1008 g_free (gc_debug_options);
1010 gc_debug_options = g_strdup (options);
1014 scan_finalizer_entries (SgenPointerQueue *fin_queue, ScanCopyContext ctx)
1016 CopyOrMarkObjectFunc copy_func = ctx.ops->copy_or_mark_object;
1017 SgenGrayQueue *queue = ctx.queue;
1020 for (i = 0; i < fin_queue->next_slot; ++i) {
1021 GCObject *obj = (GCObject *)fin_queue->data [i];
1024 SGEN_LOG (5, "Scan of fin ready object: %p (%s)\n", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
1025 copy_func ((GCObject**)&fin_queue->data [i], queue);
1030 generation_name (int generation)
1032 switch (generation) {
1033 case GENERATION_NURSERY: return "nursery";
1034 case GENERATION_OLD: return "old";
1035 default: g_assert_not_reached ();
1040 sgen_generation_name (int generation)
1042 return generation_name (generation);
1046 finish_gray_stack (int generation, ScanCopyContext ctx)
1050 int done_with_ephemerons, ephemeron_rounds = 0;
1051 char *start_addr = generation == GENERATION_NURSERY ? sgen_get_nursery_start () : NULL;
1052 char *end_addr = generation == GENERATION_NURSERY ? sgen_get_nursery_end () : (char*)-1;
1053 SgenGrayQueue *queue = ctx.queue;
1055 binary_protocol_finish_gray_stack_start (sgen_timestamp (), generation);
1057 * We copied all the reachable objects. Now it's the time to copy
1058 * the objects that were not referenced by the roots, but by the copied objects.
1059 * we built a stack of objects pointed to by gray_start: they are
1060 * additional roots and we may add more items as we go.
1061 * We loop until gray_start == gray_objects which means no more objects have
1062 * been added. Note this is iterative: no recursion is involved.
1063 * We need to walk the LO list as well in search of marked big objects
1064 * (use a flag since this is needed only on major collections). We need to loop
1065 * here as well, so keep a counter of marked LO (increasing it in copy_object).
1066 * To achieve better cache locality and cache usage, we drain the gray stack
1067 * frequently, after each object is copied, and just finish the work here.
1069 sgen_drain_gray_stack (ctx);
1071 SGEN_LOG (2, "%s generation done", generation_name (generation));
1074 Reset bridge data, we might have lingering data from a previous collection if this is a major
1075 collection trigged by minor overflow.
1077 We must reset the gathered bridges since their original block might be evacuated due to major
1078 fragmentation in the meanwhile and the bridge code should not have to deal with that.
1080 if (sgen_client_bridge_need_processing ())
1081 sgen_client_bridge_reset_data ();
1084 * Mark all strong toggleref objects. This must be done before we walk ephemerons or finalizers
1085 * to ensure they see the full set of live objects.
1087 sgen_client_mark_togglerefs (start_addr, end_addr, ctx);
1090 * Walk the ephemeron tables marking all values with reachable keys. This must be completely done
1091 * before processing finalizable objects and non-tracking weak links to avoid finalizing/clearing
1092 * objects that are in fact reachable.
1094 done_with_ephemerons = 0;
1096 done_with_ephemerons = sgen_client_mark_ephemerons (ctx);
1097 sgen_drain_gray_stack (ctx);
1099 } while (!done_with_ephemerons);
1101 if (sgen_client_bridge_need_processing ()) {
1102 /*Make sure the gray stack is empty before we process bridge objects so we get liveness right*/
1103 sgen_drain_gray_stack (ctx);
1104 sgen_collect_bridge_objects (generation, ctx);
1105 if (generation == GENERATION_OLD)
1106 sgen_collect_bridge_objects (GENERATION_NURSERY, ctx);
1109 Do the first bridge step here, as the collector liveness state will become useless after that.
1111 An important optimization is to only proccess the possibly dead part of the object graph and skip
1112 over all live objects as we transitively know everything they point must be alive too.
1114 The above invariant is completely wrong if we let the gray queue be drained and mark/copy everything.
1116 This has the unfortunate side effect of making overflow collections perform the first step twice, but
1117 given we now have heuristics that perform major GC in anticipation of minor overflows this should not
1120 sgen_client_bridge_processing_stw_step ();
1124 Make sure we drain the gray stack before processing disappearing links and finalizers.
1125 If we don't make sure it is empty we might wrongly see a live object as dead.
1127 sgen_drain_gray_stack (ctx);
1130 We must clear weak links that don't track resurrection before processing object ready for
1131 finalization so they can be cleared before that.
1133 sgen_null_link_in_range (generation, ctx, FALSE);
1134 if (generation == GENERATION_OLD)
1135 sgen_null_link_in_range (GENERATION_NURSERY, ctx, FALSE);
1138 /* walk the finalization queue and move also the objects that need to be
1139 * finalized: use the finalized objects as new roots so the objects they depend
1140 * on are also not reclaimed. As with the roots above, only objects in the nursery
1141 * are marked/copied.
1143 sgen_finalize_in_range (generation, ctx);
1144 if (generation == GENERATION_OLD)
1145 sgen_finalize_in_range (GENERATION_NURSERY, ctx);
1146 /* drain the new stack that might have been created */
1147 SGEN_LOG (6, "Precise scan of gray area post fin");
1148 sgen_drain_gray_stack (ctx);
1151 * This must be done again after processing finalizable objects since CWL slots are cleared only after the key is finalized.
1153 done_with_ephemerons = 0;
1155 done_with_ephemerons = sgen_client_mark_ephemerons (ctx);
1156 sgen_drain_gray_stack (ctx);
1158 } while (!done_with_ephemerons);
1160 sgen_client_clear_unreachable_ephemerons (ctx);
1163 * We clear togglerefs only after all possible chances of revival are done.
1164 * This is semantically more inline with what users expect and it allows for
1165 * user finalizers to correctly interact with TR objects.
1167 sgen_client_clear_togglerefs (start_addr, end_addr, ctx);
1170 SGEN_LOG (2, "Finalize queue handling scan for %s generation: %lld usecs %d ephemeron rounds", generation_name (generation), (long long)TV_ELAPSED (atv, btv), ephemeron_rounds);
1173 * handle disappearing links
1174 * Note we do this after checking the finalization queue because if an object
1175 * survives (at least long enough to be finalized) we don't clear the link.
1176 * This also deals with a possible issue with the monitor reclamation: with the Boehm
1177 * GC a finalized object my lose the monitor because it is cleared before the finalizer is
1180 g_assert (sgen_gray_object_queue_is_empty (queue));
1182 sgen_null_link_in_range (generation, ctx, TRUE);
1183 if (generation == GENERATION_OLD)
1184 sgen_null_link_in_range (GENERATION_NURSERY, ctx, TRUE);
1185 if (sgen_gray_object_queue_is_empty (queue))
1187 sgen_drain_gray_stack (ctx);
1190 g_assert (sgen_gray_object_queue_is_empty (queue));
1192 binary_protocol_finish_gray_stack_end (sgen_timestamp (), generation);
1196 sgen_check_section_scan_starts (GCMemSection *section)
1199 for (i = 0; i < section->num_scan_start; ++i) {
1200 if (section->scan_starts [i]) {
1201 mword size = safe_object_get_size ((GCObject*) section->scan_starts [i]);
1202 SGEN_ASSERT (0, size >= SGEN_CLIENT_MINIMUM_OBJECT_SIZE && size <= MAX_SMALL_OBJ_SIZE, "Weird object size at scan starts.");
1208 check_scan_starts (void)
1210 if (!do_scan_starts_check)
1212 sgen_check_section_scan_starts (nursery_section);
1213 major_collector.check_scan_starts ();
1217 scan_from_registered_roots (char *addr_start, char *addr_end, int root_type, ScanCopyContext ctx)
1221 SGEN_HASH_TABLE_FOREACH (&roots_hash [root_type], void **, start_root, RootRecord *, root) {
1222 SGEN_LOG (6, "Precise root scan %p-%p (desc: %p)", start_root, root->end_root, (void*)root->root_desc);
1223 precisely_scan_objects_from (start_root, (void**)root->end_root, addr_start, addr_end, root->root_desc, ctx);
1224 } SGEN_HASH_TABLE_FOREACH_END;
1230 static gboolean inited = FALSE;
1235 mono_counters_register ("Collection max time", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME | MONO_COUNTER_MONOTONIC, &time_max);
1237 mono_counters_register ("Minor fragment clear", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_pre_collection_fragment_clear);
1238 mono_counters_register ("Minor pinning", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_pinning);
1239 mono_counters_register ("Minor scan remembered set", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_remsets);
1240 mono_counters_register ("Minor scan pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_pinned);
1241 mono_counters_register ("Minor scan roots", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_roots);
1242 mono_counters_register ("Minor fragment creation", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_fragment_creation);
1244 mono_counters_register ("Major fragment clear", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_pre_collection_fragment_clear);
1245 mono_counters_register ("Major pinning", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_pinning);
1246 mono_counters_register ("Major scan pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_pinned);
1247 mono_counters_register ("Major scan roots", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_roots);
1248 mono_counters_register ("Major scan mod union", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_mod_union);
1249 mono_counters_register ("Major finish gray stack", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_finish_gray_stack);
1250 mono_counters_register ("Major free big objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_free_bigobjs);
1251 mono_counters_register ("Major LOS sweep", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_los_sweep);
1252 mono_counters_register ("Major sweep", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_sweep);
1253 mono_counters_register ("Major fragment creation", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_fragment_creation);
1255 mono_counters_register ("Number of pinned objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_pinned_objects);
1257 #ifdef HEAVY_STATISTICS
1258 mono_counters_register ("WBarrier remember pointer", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_add_to_global_remset);
1259 mono_counters_register ("WBarrier arrayref copy", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_arrayref_copy);
1260 mono_counters_register ("WBarrier generic store called", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_generic_store);
1261 mono_counters_register ("WBarrier generic atomic store called", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_generic_store_atomic);
1262 mono_counters_register ("WBarrier set root", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_set_root);
1264 mono_counters_register ("# objects allocated degraded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_alloced_degraded);
1265 mono_counters_register ("bytes allocated degraded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_bytes_alloced_degraded);
1267 mono_counters_register ("# copy_object() called (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_copy_object_called_nursery);
1268 mono_counters_register ("# objects copied (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_copied_nursery);
1269 mono_counters_register ("# copy_object() called (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_copy_object_called_major);
1270 mono_counters_register ("# objects copied (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_copied_major);
1272 mono_counters_register ("# scan_object() called (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_scan_object_called_nursery);
1273 mono_counters_register ("# scan_object() called (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_scan_object_called_major);
1275 mono_counters_register ("Slots allocated in vain", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_slots_allocated_in_vain);
1277 mono_counters_register ("# nursery copy_object() failed from space", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_from_space);
1278 mono_counters_register ("# nursery copy_object() failed forwarded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_forwarded);
1279 mono_counters_register ("# nursery copy_object() failed pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_pinned);
1280 mono_counters_register ("# nursery copy_object() failed to space", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_to_space);
1282 sgen_nursery_allocator_init_heavy_stats ();
1290 reset_pinned_from_failed_allocation (void)
1292 bytes_pinned_from_failed_allocation = 0;
1296 sgen_set_pinned_from_failed_allocation (mword objsize)
1298 bytes_pinned_from_failed_allocation += objsize;
1302 sgen_collection_is_concurrent (void)
1304 switch (current_collection_generation) {
1305 case GENERATION_NURSERY:
1307 case GENERATION_OLD:
1308 return concurrent_collection_in_progress;
1310 g_error ("Invalid current generation %d", current_collection_generation);
1316 sgen_concurrent_collection_in_progress (void)
1318 return concurrent_collection_in_progress;
1322 SgenThreadPoolJob job;
1323 SgenObjectOperations *ops;
1324 SgenGrayQueue *gc_thread_gray_queue;
1327 static ScanCopyContext
1328 scan_copy_context_for_scan_job (void *worker_data_untyped, ScanJob *job)
1330 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1332 return CONTEXT_FROM_OBJECT_OPERATIONS (job->ops, sgen_workers_get_job_gray_queue (worker_data, job->gc_thread_gray_queue));
1336 job_remembered_set_scan (void *worker_data_untyped, SgenThreadPoolJob *job)
1338 remset.scan_remsets (scan_copy_context_for_scan_job (worker_data_untyped, (ScanJob*)job));
1346 } ScanFromRegisteredRootsJob;
1349 job_scan_from_registered_roots (void *worker_data_untyped, SgenThreadPoolJob *job)
1351 ScanFromRegisteredRootsJob *job_data = (ScanFromRegisteredRootsJob*)job;
1352 ScanCopyContext ctx = scan_copy_context_for_scan_job (worker_data_untyped, &job_data->scan_job);
1354 scan_from_registered_roots (job_data->heap_start, job_data->heap_end, job_data->root_type, ctx);
1361 } ScanThreadDataJob;
1364 job_scan_thread_data (void *worker_data_untyped, SgenThreadPoolJob *job)
1366 ScanThreadDataJob *job_data = (ScanThreadDataJob*)job;
1367 ScanCopyContext ctx = scan_copy_context_for_scan_job (worker_data_untyped, &job_data->scan_job);
1369 sgen_client_scan_thread_data (job_data->heap_start, job_data->heap_end, TRUE, ctx);
1374 SgenPointerQueue *queue;
1375 } ScanFinalizerEntriesJob;
1378 job_scan_finalizer_entries (void *worker_data_untyped, SgenThreadPoolJob *job)
1380 ScanFinalizerEntriesJob *job_data = (ScanFinalizerEntriesJob*)job;
1381 ScanCopyContext ctx = scan_copy_context_for_scan_job (worker_data_untyped, &job_data->scan_job);
1383 scan_finalizer_entries (job_data->queue, ctx);
1387 job_scan_major_mod_union_card_table (void *worker_data_untyped, SgenThreadPoolJob *job)
1389 ScanJob *job_data = (ScanJob*)job;
1390 ScanCopyContext ctx = scan_copy_context_for_scan_job (worker_data_untyped, job_data);
1392 g_assert (concurrent_collection_in_progress);
1393 major_collector.scan_card_table (CARDTABLE_SCAN_MOD_UNION, ctx);
1397 job_scan_los_mod_union_card_table (void *worker_data_untyped, SgenThreadPoolJob *job)
1399 ScanJob *job_data = (ScanJob*)job;
1400 ScanCopyContext ctx = scan_copy_context_for_scan_job (worker_data_untyped, job_data);
1402 g_assert (concurrent_collection_in_progress);
1403 sgen_los_scan_card_table (CARDTABLE_SCAN_MOD_UNION, ctx);
1407 job_major_mod_union_preclean (void *worker_data_untyped, SgenThreadPoolJob *job)
1409 ScanJob *job_data = (ScanJob*)job;
1410 ScanCopyContext ctx = scan_copy_context_for_scan_job (worker_data_untyped, job_data);
1412 g_assert (concurrent_collection_in_progress);
1414 major_collector.scan_card_table (CARDTABLE_SCAN_MOD_UNION_PRECLEAN, ctx);
1418 job_los_mod_union_preclean (void *worker_data_untyped, SgenThreadPoolJob *job)
1420 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1421 ScanJob *job_data = (ScanJob*)job;
1422 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1424 g_assert (concurrent_collection_in_progress);
1426 sgen_los_scan_card_table (CARDTABLE_SCAN_MOD_UNION_PRECLEAN, ctx);
1430 job_scan_last_pinned (void *worker_data_untyped, SgenThreadPoolJob *job)
1432 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1433 ScanJob *job_data = (ScanJob*)job;
1434 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1436 g_assert (concurrent_collection_in_progress);
1438 sgen_scan_pin_queue_objects (ctx);
1442 workers_finish_callback (void)
1445 /* Mod union preclean job */
1446 sj = (ScanJob*)sgen_thread_pool_job_alloc ("preclean mod union cardtable", job_major_mod_union_preclean, sizeof (ScanJob));
1447 sj->ops = sgen_workers_get_idle_func_object_ops ();
1448 sj->gc_thread_gray_queue = NULL;
1449 sgen_workers_enqueue_job (&sj->job, TRUE);
1451 sj = (ScanJob*)sgen_thread_pool_job_alloc ("preclean los mod union cardtable", job_los_mod_union_preclean, sizeof (ScanJob));
1452 sj->ops = sgen_workers_get_idle_func_object_ops ();
1453 sj->gc_thread_gray_queue = NULL;
1454 sgen_workers_enqueue_job (&sj->job, TRUE);
1456 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan last pinned", job_scan_last_pinned, sizeof (ScanJob));
1457 sj->ops = sgen_workers_get_idle_func_object_ops ();
1458 sj->gc_thread_gray_queue = NULL;
1459 sgen_workers_enqueue_job (&sj->job, TRUE);
1463 init_gray_queue (SgenGrayQueue *gc_thread_gray_queue, gboolean use_workers)
1466 sgen_workers_init_distribute_gray_queue ();
1467 sgen_gray_object_queue_init (gc_thread_gray_queue, NULL, TRUE);
1471 enqueue_scan_from_roots_jobs (SgenGrayQueue *gc_thread_gray_queue, char *heap_start, char *heap_end, SgenObjectOperations *ops, gboolean enqueue)
1473 ScanFromRegisteredRootsJob *scrrj;
1474 ScanThreadDataJob *stdj;
1475 ScanFinalizerEntriesJob *sfej;
1477 /* registered roots, this includes static fields */
1479 scrrj = (ScanFromRegisteredRootsJob*)sgen_thread_pool_job_alloc ("scan from registered roots normal", job_scan_from_registered_roots, sizeof (ScanFromRegisteredRootsJob));
1480 scrrj->scan_job.ops = ops;
1481 scrrj->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
1482 scrrj->heap_start = heap_start;
1483 scrrj->heap_end = heap_end;
1484 scrrj->root_type = ROOT_TYPE_NORMAL;
1485 sgen_workers_enqueue_job (&scrrj->scan_job.job, enqueue);
1487 scrrj = (ScanFromRegisteredRootsJob*)sgen_thread_pool_job_alloc ("scan from registered roots wbarrier", job_scan_from_registered_roots, sizeof (ScanFromRegisteredRootsJob));
1488 scrrj->scan_job.ops = ops;
1489 scrrj->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
1490 scrrj->heap_start = heap_start;
1491 scrrj->heap_end = heap_end;
1492 scrrj->root_type = ROOT_TYPE_WBARRIER;
1493 sgen_workers_enqueue_job (&scrrj->scan_job.job, enqueue);
1497 stdj = (ScanThreadDataJob*)sgen_thread_pool_job_alloc ("scan thread data", job_scan_thread_data, sizeof (ScanThreadDataJob));
1498 stdj->scan_job.ops = ops;
1499 stdj->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
1500 stdj->heap_start = heap_start;
1501 stdj->heap_end = heap_end;
1502 sgen_workers_enqueue_job (&stdj->scan_job.job, enqueue);
1504 /* Scan the list of objects ready for finalization. */
1506 sfej = (ScanFinalizerEntriesJob*)sgen_thread_pool_job_alloc ("scan finalizer entries", job_scan_finalizer_entries, sizeof (ScanFinalizerEntriesJob));
1507 sfej->scan_job.ops = ops;
1508 sfej->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
1509 sfej->queue = &fin_ready_queue;
1510 sgen_workers_enqueue_job (&sfej->scan_job.job, enqueue);
1512 sfej = (ScanFinalizerEntriesJob*)sgen_thread_pool_job_alloc ("scan critical finalizer entries", job_scan_finalizer_entries, sizeof (ScanFinalizerEntriesJob));
1513 sfej->scan_job.ops = ops;
1514 sfej->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
1515 sfej->queue = &critical_fin_queue;
1516 sgen_workers_enqueue_job (&sfej->scan_job.job, enqueue);
1520 * Perform a nursery collection.
1522 * Return whether any objects were late-pinned due to being out of memory.
1525 collect_nursery (const char *reason, gboolean is_overflow, SgenGrayQueue *unpin_queue)
1527 gboolean needs_major;
1528 size_t max_garbage_amount;
1530 mword fragment_total;
1532 SgenGrayQueue gc_thread_gray_queue;
1533 SgenObjectOperations *object_ops;
1534 ScanCopyContext ctx;
1537 SGEN_TV_DECLARE (last_minor_collection_start_tv);
1538 SGEN_TV_DECLARE (last_minor_collection_end_tv);
1540 if (disable_minor_collections)
1543 TV_GETTIME (last_minor_collection_start_tv);
1544 atv = last_minor_collection_start_tv;
1546 binary_protocol_collection_begin (gc_stats.minor_gc_count, GENERATION_NURSERY);
1548 if (sgen_concurrent_collection_in_progress ())
1549 object_ops = &sgen_minor_collector.serial_ops_with_concurrent_major;
1551 object_ops = &sgen_minor_collector.serial_ops;
1553 if (do_verify_nursery || do_dump_nursery_content)
1554 sgen_debug_verify_nursery (do_dump_nursery_content);
1556 current_collection_generation = GENERATION_NURSERY;
1558 SGEN_ASSERT (0, !sgen_collection_is_concurrent (), "Why is the nursery collection concurrent?");
1560 reset_pinned_from_failed_allocation ();
1562 check_scan_starts ();
1564 sgen_nursery_alloc_prepare_for_minor ();
1568 nursery_next = sgen_nursery_alloc_get_upper_alloc_bound ();
1569 /* FIXME: optimize later to use the higher address where an object can be present */
1570 nursery_next = MAX (nursery_next, sgen_get_nursery_end ());
1572 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 ()));
1573 max_garbage_amount = nursery_next - sgen_get_nursery_start ();
1574 g_assert (nursery_section->size >= max_garbage_amount);
1576 /* world must be stopped already */
1578 time_minor_pre_collection_fragment_clear += TV_ELAPSED (atv, btv);
1580 sgen_client_pre_collection_checks ();
1582 nursery_section->next_data = nursery_next;
1584 major_collector.start_nursery_collection ();
1586 sgen_memgov_minor_collection_start ();
1588 init_gray_queue (&gc_thread_gray_queue, FALSE);
1589 ctx = CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, &gc_thread_gray_queue);
1591 gc_stats.minor_gc_count ++;
1593 sgen_process_fin_stage_entries ();
1595 /* pin from pinned handles */
1596 sgen_init_pinning ();
1597 sgen_client_binary_protocol_mark_start (GENERATION_NURSERY);
1598 pin_from_roots (sgen_get_nursery_start (), nursery_next, ctx);
1599 /* pin cemented objects */
1600 sgen_pin_cemented_objects ();
1601 /* identify pinned objects */
1602 sgen_optimize_pin_queue ();
1603 sgen_pinning_setup_section (nursery_section);
1605 pin_objects_in_nursery (FALSE, ctx);
1606 sgen_pinning_trim_queue_to_section (nursery_section);
1608 if (remset_consistency_checks)
1609 sgen_check_remset_consistency ();
1611 if (whole_heap_check_before_collection) {
1612 sgen_clear_nursery_fragments ();
1613 sgen_check_whole_heap (FALSE);
1617 time_minor_pinning += TV_ELAPSED (btv, atv);
1618 SGEN_LOG (2, "Finding pinned pointers: %zd in %lld usecs", sgen_get_pinned_count (), (long long)TV_ELAPSED (btv, atv));
1619 SGEN_LOG (4, "Start scan with %zd pinned objects", sgen_get_pinned_count ());
1621 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan remset", job_remembered_set_scan, sizeof (ScanJob));
1622 sj->ops = object_ops;
1623 sj->gc_thread_gray_queue = &gc_thread_gray_queue;
1624 sgen_workers_enqueue_job (&sj->job, FALSE);
1626 /* we don't have complete write barrier yet, so we scan all the old generation sections */
1628 time_minor_scan_remsets += TV_ELAPSED (atv, btv);
1629 SGEN_LOG (2, "Old generation scan: %lld usecs", (long long)TV_ELAPSED (atv, btv));
1631 sgen_pin_stats_report ();
1633 /* FIXME: Why do we do this at this specific, seemingly random, point? */
1634 sgen_client_collecting_minor (&fin_ready_queue, &critical_fin_queue);
1637 time_minor_scan_pinned += TV_ELAPSED (btv, atv);
1639 enqueue_scan_from_roots_jobs (&gc_thread_gray_queue, sgen_get_nursery_start (), nursery_next, object_ops, FALSE);
1642 time_minor_scan_roots += TV_ELAPSED (atv, btv);
1644 finish_gray_stack (GENERATION_NURSERY, ctx);
1647 time_minor_finish_gray_stack += TV_ELAPSED (btv, atv);
1648 sgen_client_binary_protocol_mark_end (GENERATION_NURSERY);
1650 if (objects_pinned) {
1651 sgen_optimize_pin_queue ();
1652 sgen_pinning_setup_section (nursery_section);
1656 * This is the latest point at which we can do this check, because
1657 * sgen_build_nursery_fragments() unpins nursery objects again.
1659 if (remset_consistency_checks)
1660 sgen_check_remset_consistency ();
1662 /* walk the pin_queue, build up the fragment list of free memory, unmark
1663 * pinned objects as we go, memzero() the empty fragments so they are ready for the
1666 sgen_client_binary_protocol_reclaim_start (GENERATION_NURSERY);
1667 fragment_total = sgen_build_nursery_fragments (nursery_section, unpin_queue);
1668 if (!fragment_total)
1671 /* Clear TLABs for all threads */
1672 sgen_clear_tlabs ();
1674 sgen_client_binary_protocol_reclaim_end (GENERATION_NURSERY);
1676 time_minor_fragment_creation += TV_ELAPSED (atv, btv);
1677 SGEN_LOG (2, "Fragment creation: %lld usecs, %lu bytes available", (long long)TV_ELAPSED (atv, btv), (unsigned long)fragment_total);
1679 if (remset_consistency_checks)
1680 sgen_check_major_refs ();
1682 major_collector.finish_nursery_collection ();
1684 TV_GETTIME (last_minor_collection_end_tv);
1685 gc_stats.minor_gc_time += TV_ELAPSED (last_minor_collection_start_tv, last_minor_collection_end_tv);
1687 sgen_debug_dump_heap ("minor", gc_stats.minor_gc_count - 1, NULL);
1689 /* prepare the pin queue for the next collection */
1690 sgen_finish_pinning ();
1691 if (sgen_have_pending_finalizers ()) {
1692 SGEN_LOG (4, "Finalizer-thread wakeup");
1693 sgen_client_finalize_notify ();
1695 sgen_pin_stats_reset ();
1696 /* clear cemented hash */
1697 sgen_cement_clear_below_threshold ();
1699 sgen_gray_object_queue_dispose (&gc_thread_gray_queue);
1701 remset.finish_minor_collection ();
1703 check_scan_starts ();
1705 binary_protocol_flush_buffers (FALSE);
1707 sgen_memgov_minor_collection_end (reason, is_overflow);
1709 /*objects are late pinned because of lack of memory, so a major is a good call*/
1710 needs_major = objects_pinned > 0;
1711 current_collection_generation = -1;
1714 binary_protocol_collection_end (gc_stats.minor_gc_count - 1, GENERATION_NURSERY, 0, 0);
1716 if (check_nursery_objects_pinned && !sgen_minor_collector.is_split)
1717 sgen_check_nursery_objects_pinned (unpin_queue != NULL);
1723 COPY_OR_MARK_FROM_ROOTS_SERIAL,
1724 COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT,
1725 COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT
1726 } CopyOrMarkFromRootsMode;
1729 major_copy_or_mark_from_roots (SgenGrayQueue *gc_thread_gray_queue, size_t *old_next_pin_slot, CopyOrMarkFromRootsMode mode, SgenObjectOperations *object_ops)
1734 /* FIXME: only use these values for the precise scan
1735 * note that to_space pointers should be excluded anyway...
1737 char *heap_start = NULL;
1738 char *heap_end = (char*)-1;
1739 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, gc_thread_gray_queue);
1740 gboolean concurrent = mode != COPY_OR_MARK_FROM_ROOTS_SERIAL;
1742 SGEN_ASSERT (0, !!concurrent == !!concurrent_collection_in_progress, "We've been called with the wrong mode.");
1744 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1745 /*This cleans up unused fragments */
1746 sgen_nursery_allocator_prepare_for_pinning ();
1748 if (do_concurrent_checks)
1749 sgen_debug_check_nursery_is_clean ();
1751 /* The concurrent collector doesn't touch the nursery. */
1752 sgen_nursery_alloc_prepare_for_major ();
1757 /* Pinning depends on this */
1758 sgen_clear_nursery_fragments ();
1760 if (whole_heap_check_before_collection)
1761 sgen_check_whole_heap (TRUE);
1764 time_major_pre_collection_fragment_clear += TV_ELAPSED (atv, btv);
1766 if (!sgen_collection_is_concurrent ())
1767 nursery_section->next_data = sgen_get_nursery_end ();
1768 /* we should also coalesce scanning from sections close to each other
1769 * and deal with pointers outside of the sections later.
1774 sgen_client_pre_collection_checks ();
1776 if (mode != COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1777 /* Remsets are not useful for a major collection */
1778 remset.clear_cards ();
1781 sgen_process_fin_stage_entries ();
1784 sgen_init_pinning ();
1785 SGEN_LOG (6, "Collecting pinned addresses");
1786 pin_from_roots ((void*)lowest_heap_address, (void*)highest_heap_address, ctx);
1787 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1788 /* Pin cemented objects that were forced */
1789 sgen_pin_cemented_objects ();
1791 sgen_optimize_pin_queue ();
1792 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1794 * Cemented objects that are in the pinned list will be marked. When
1795 * marking concurrently we won't mark mod-union cards for these objects.
1796 * Instead they will remain cemented until the next major collection,
1797 * when we will recheck if they are still pinned in the roots.
1799 sgen_cement_force_pinned ();
1802 sgen_client_collecting_major_1 ();
1805 * pin_queue now contains all candidate pointers, sorted and
1806 * uniqued. We must do two passes now to figure out which
1807 * objects are pinned.
1809 * The first is to find within the pin_queue the area for each
1810 * section. This requires that the pin_queue be sorted. We
1811 * also process the LOS objects and pinned chunks here.
1813 * The second, destructive, pass is to reduce the section
1814 * areas to pointers to the actually pinned objects.
1816 SGEN_LOG (6, "Pinning from sections");
1817 /* first pass for the sections */
1818 sgen_find_section_pin_queue_start_end (nursery_section);
1819 /* identify possible pointers to the insize of large objects */
1820 SGEN_LOG (6, "Pinning from large objects");
1821 for (bigobj = los_object_list; bigobj; bigobj = bigobj->next) {
1823 if (sgen_find_optimized_pin_queue_area ((char*)bigobj->data, (char*)bigobj->data + sgen_los_object_size (bigobj), &dummy, &dummy)) {
1824 binary_protocol_pin (bigobj->data, (gpointer)LOAD_VTABLE (bigobj->data), safe_object_get_size (bigobj->data));
1826 if (sgen_los_object_is_pinned (bigobj->data)) {
1827 SGEN_ASSERT (0, mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT, "LOS objects can only be pinned here after concurrent marking.");
1830 sgen_los_pin_object (bigobj->data);
1831 if (SGEN_OBJECT_HAS_REFERENCES (bigobj->data))
1832 GRAY_OBJECT_ENQUEUE (gc_thread_gray_queue, bigobj->data, sgen_obj_get_descriptor ((GCObject*)bigobj->data));
1833 sgen_pin_stats_register_object (bigobj->data, GENERATION_OLD);
1834 SGEN_LOG (6, "Marked large object %p (%s) size: %lu from roots", bigobj->data,
1835 sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (bigobj->data)),
1836 (unsigned long)sgen_los_object_size (bigobj));
1838 sgen_client_pinned_los_object (bigobj->data);
1842 pin_objects_in_nursery (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT, ctx);
1843 if (check_nursery_objects_pinned && !sgen_minor_collector.is_split)
1844 sgen_check_nursery_objects_pinned (mode != COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT);
1846 major_collector.pin_objects (gc_thread_gray_queue);
1847 if (old_next_pin_slot)
1848 *old_next_pin_slot = sgen_get_pinned_count ();
1851 time_major_pinning += TV_ELAPSED (atv, btv);
1852 SGEN_LOG (2, "Finding pinned pointers: %zd in %lld usecs", sgen_get_pinned_count (), (long long)TV_ELAPSED (atv, btv));
1853 SGEN_LOG (4, "Start scan with %zd pinned objects", sgen_get_pinned_count ());
1855 major_collector.init_to_space ();
1857 SGEN_ASSERT (0, sgen_workers_all_done (), "Why are the workers not done when we start or finish a major collection?");
1858 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1859 if (sgen_workers_have_idle_work ()) {
1861 * We force the finish of the worker with the new object ops context
1862 * which can also do copying. We need to have finished pinning.
1864 /* FIXME Implement parallel copying and get rid of this ineffective hack */
1865 if (major_collector.is_parallel)
1866 sgen_workers_start_all_workers (&major_collector.major_ops_conc_par_start, NULL);
1868 sgen_workers_start_all_workers (object_ops, NULL);
1870 sgen_workers_join ();
1874 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
1875 main_gc_thread = mono_native_thread_self ();
1878 sgen_client_collecting_major_2 ();
1881 time_major_scan_pinned += TV_ELAPSED (btv, atv);
1883 sgen_client_collecting_major_3 (&fin_ready_queue, &critical_fin_queue);
1885 enqueue_scan_from_roots_jobs (gc_thread_gray_queue, heap_start, heap_end, object_ops, FALSE);
1888 time_major_scan_roots += TV_ELAPSED (atv, btv);
1891 * We start the concurrent worker after pinning and after we scanned the roots
1892 * in order to make sure that the worker does not finish before handling all
1895 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1896 if (precleaning_enabled) {
1897 sgen_workers_start_all_workers (object_ops, workers_finish_callback);
1899 sgen_workers_start_all_workers (object_ops, NULL);
1901 gray_queue_enable_redirect (gc_thread_gray_queue);
1904 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1907 /* Mod union card table */
1908 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan mod union cardtable", job_scan_major_mod_union_card_table, sizeof (ScanJob));
1909 sj->ops = object_ops;
1910 sj->gc_thread_gray_queue = gc_thread_gray_queue;
1911 sgen_workers_enqueue_job (&sj->job, FALSE);
1913 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan LOS mod union cardtable", job_scan_los_mod_union_card_table, sizeof (ScanJob));
1914 sj->ops = object_ops;
1915 sj->gc_thread_gray_queue = gc_thread_gray_queue;
1916 sgen_workers_enqueue_job (&sj->job, FALSE);
1919 time_major_scan_mod_union += TV_ELAPSED (btv, atv);
1922 sgen_pin_stats_report ();
1924 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1925 sgen_finish_pinning ();
1927 sgen_pin_stats_reset ();
1929 if (do_concurrent_checks)
1930 sgen_debug_check_nursery_is_clean ();
1935 major_start_collection (SgenGrayQueue *gc_thread_gray_queue, const char *reason, gboolean concurrent, size_t *old_next_pin_slot)
1937 SgenObjectOperations *object_ops;
1939 binary_protocol_collection_begin (gc_stats.major_gc_count, GENERATION_OLD);
1941 current_collection_generation = GENERATION_OLD;
1943 sgen_workers_assert_gray_queue_is_empty ();
1946 sgen_cement_reset ();
1949 g_assert (major_collector.is_concurrent);
1950 concurrent_collection_in_progress = TRUE;
1952 if (major_collector.is_parallel)
1953 object_ops = &major_collector.major_ops_conc_par_start;
1955 object_ops = &major_collector.major_ops_concurrent_start;
1958 object_ops = &major_collector.major_ops_serial;
1961 reset_pinned_from_failed_allocation ();
1963 sgen_memgov_major_collection_start (concurrent, reason);
1965 //count_ref_nonref_objs ();
1966 //consistency_check ();
1968 check_scan_starts ();
1971 SGEN_LOG (1, "Start major collection %d", gc_stats.major_gc_count);
1972 gc_stats.major_gc_count ++;
1974 if (major_collector.start_major_collection)
1975 major_collector.start_major_collection ();
1977 major_copy_or_mark_from_roots (gc_thread_gray_queue, old_next_pin_slot, concurrent ? COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT : COPY_OR_MARK_FROM_ROOTS_SERIAL, object_ops);
1981 major_finish_collection (SgenGrayQueue *gc_thread_gray_queue, const char *reason, gboolean is_overflow, size_t old_next_pin_slot, gboolean forced)
1983 ScannedObjectCounts counts;
1984 SgenObjectOperations *object_ops;
1985 mword fragment_total;
1991 if (concurrent_collection_in_progress) {
1992 if (major_collector.is_parallel)
1993 object_ops = &major_collector.major_ops_conc_par_finish;
1995 object_ops = &major_collector.major_ops_concurrent_finish;
1997 major_copy_or_mark_from_roots (gc_thread_gray_queue, NULL, COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT, object_ops);
1999 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
2000 main_gc_thread = NULL;
2003 object_ops = &major_collector.major_ops_serial;
2006 sgen_workers_assert_gray_queue_is_empty ();
2008 finish_gray_stack (GENERATION_OLD, CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, gc_thread_gray_queue));
2010 time_major_finish_gray_stack += TV_ELAPSED (btv, atv);
2012 SGEN_ASSERT (0, sgen_workers_all_done (), "Can't have workers working after joining");
2014 if (objects_pinned) {
2015 g_assert (!concurrent_collection_in_progress);
2018 * This is slow, but we just OOM'd.
2020 * See comment at `sgen_pin_queue_clear_discarded_entries` for how the pin
2021 * queue is laid out at this point.
2023 sgen_pin_queue_clear_discarded_entries (nursery_section, old_next_pin_slot);
2025 * We need to reestablish all pinned nursery objects in the pin queue
2026 * because they're needed for fragment creation. Unpinning happens by
2027 * walking the whole queue, so it's not necessary to reestablish where major
2028 * heap block pins are - all we care is that they're still in there
2031 sgen_optimize_pin_queue ();
2032 sgen_find_section_pin_queue_start_end (nursery_section);
2036 reset_heap_boundaries ();
2037 sgen_update_heap_boundaries ((mword)sgen_get_nursery_start (), (mword)sgen_get_nursery_end ());
2039 /* walk the pin_queue, build up the fragment list of free memory, unmark
2040 * pinned objects as we go, memzero() the empty fragments so they are ready for the
2043 fragment_total = sgen_build_nursery_fragments (nursery_section, NULL);
2044 if (!fragment_total)
2046 SGEN_LOG (4, "Free space in nursery after major %ld", (long)fragment_total);
2048 if (do_concurrent_checks && concurrent_collection_in_progress)
2049 sgen_debug_check_nursery_is_clean ();
2051 /* prepare the pin queue for the next collection */
2052 sgen_finish_pinning ();
2054 /* Clear TLABs for all threads */
2055 sgen_clear_tlabs ();
2057 sgen_pin_stats_reset ();
2059 sgen_cement_clear_below_threshold ();
2061 if (check_mark_bits_after_major_collection)
2062 sgen_check_heap_marked (concurrent_collection_in_progress);
2065 time_major_fragment_creation += TV_ELAPSED (atv, btv);
2067 binary_protocol_sweep_begin (GENERATION_OLD, !major_collector.sweeps_lazily);
2068 sgen_memgov_major_pre_sweep ();
2071 time_major_free_bigobjs += TV_ELAPSED (btv, atv);
2076 time_major_los_sweep += TV_ELAPSED (atv, btv);
2078 major_collector.sweep ();
2080 binary_protocol_sweep_end (GENERATION_OLD, !major_collector.sweeps_lazily);
2083 time_major_sweep += TV_ELAPSED (btv, atv);
2085 sgen_debug_dump_heap ("major", gc_stats.major_gc_count - 1, reason);
2087 if (sgen_have_pending_finalizers ()) {
2088 SGEN_LOG (4, "Finalizer-thread wakeup");
2089 sgen_client_finalize_notify ();
2092 sgen_memgov_major_collection_end (forced, concurrent_collection_in_progress, reason, is_overflow);
2093 current_collection_generation = -1;
2095 memset (&counts, 0, sizeof (ScannedObjectCounts));
2096 major_collector.finish_major_collection (&counts);
2098 sgen_workers_assert_gray_queue_is_empty ();
2100 SGEN_ASSERT (0, sgen_workers_all_done (), "Can't have workers working after major collection has finished");
2101 if (concurrent_collection_in_progress)
2102 concurrent_collection_in_progress = FALSE;
2104 check_scan_starts ();
2106 binary_protocol_flush_buffers (FALSE);
2108 //consistency_check ();
2110 binary_protocol_collection_end (gc_stats.major_gc_count - 1, GENERATION_OLD, counts.num_scanned_objects, counts.num_unique_scanned_objects);
2114 major_do_collection (const char *reason, gboolean is_overflow, gboolean forced)
2116 TV_DECLARE (time_start);
2117 TV_DECLARE (time_end);
2118 size_t old_next_pin_slot;
2119 SgenGrayQueue gc_thread_gray_queue;
2121 if (disable_major_collections)
2124 if (major_collector.get_and_reset_num_major_objects_marked) {
2125 long long num_marked = major_collector.get_and_reset_num_major_objects_marked ();
2126 g_assert (!num_marked);
2129 /* world must be stopped already */
2130 TV_GETTIME (time_start);
2132 init_gray_queue (&gc_thread_gray_queue, FALSE);
2133 major_start_collection (&gc_thread_gray_queue, reason, FALSE, &old_next_pin_slot);
2134 major_finish_collection (&gc_thread_gray_queue, reason, is_overflow, old_next_pin_slot, forced);
2135 sgen_gray_object_queue_dispose (&gc_thread_gray_queue);
2137 TV_GETTIME (time_end);
2138 gc_stats.major_gc_time += TV_ELAPSED (time_start, time_end);
2140 /* FIXME: also report this to the user, preferably in gc-end. */
2141 if (major_collector.get_and_reset_num_major_objects_marked)
2142 major_collector.get_and_reset_num_major_objects_marked ();
2144 return bytes_pinned_from_failed_allocation > 0;
2148 major_start_concurrent_collection (const char *reason)
2150 TV_DECLARE (time_start);
2151 TV_DECLARE (time_end);
2152 long long num_objects_marked;
2153 SgenGrayQueue gc_thread_gray_queue;
2155 if (disable_major_collections)
2158 TV_GETTIME (time_start);
2159 SGEN_TV_GETTIME (time_major_conc_collection_start);
2161 num_objects_marked = major_collector.get_and_reset_num_major_objects_marked ();
2162 g_assert (num_objects_marked == 0);
2164 binary_protocol_concurrent_start ();
2166 init_gray_queue (&gc_thread_gray_queue, TRUE);
2167 // FIXME: store reason and pass it when finishing
2168 major_start_collection (&gc_thread_gray_queue, reason, TRUE, NULL);
2169 sgen_gray_object_queue_dispose (&gc_thread_gray_queue);
2171 num_objects_marked = major_collector.get_and_reset_num_major_objects_marked ();
2173 TV_GETTIME (time_end);
2174 gc_stats.major_gc_time += TV_ELAPSED (time_start, time_end);
2176 current_collection_generation = -1;
2180 * Returns whether the major collection has finished.
2183 major_should_finish_concurrent_collection (void)
2185 return sgen_workers_all_done ();
2189 major_update_concurrent_collection (void)
2191 TV_DECLARE (total_start);
2192 TV_DECLARE (total_end);
2194 TV_GETTIME (total_start);
2196 binary_protocol_concurrent_update ();
2198 major_collector.update_cardtable_mod_union ();
2199 sgen_los_update_cardtable_mod_union ();
2201 TV_GETTIME (total_end);
2202 gc_stats.major_gc_time += TV_ELAPSED (total_start, total_end);
2206 major_finish_concurrent_collection (gboolean forced)
2208 SgenGrayQueue gc_thread_gray_queue;
2209 TV_DECLARE (total_start);
2210 TV_DECLARE (total_end);
2212 TV_GETTIME (total_start);
2214 binary_protocol_concurrent_finish ();
2217 * We need to stop all workers since we're updating the cardtable below.
2218 * The workers will be resumed with a finishing pause context to avoid
2219 * additional cardtable and object scanning.
2221 sgen_workers_stop_all_workers ();
2223 SGEN_TV_GETTIME (time_major_conc_collection_end);
2224 gc_stats.major_gc_time_concurrent += SGEN_TV_ELAPSED (time_major_conc_collection_start, time_major_conc_collection_end);
2226 major_collector.update_cardtable_mod_union ();
2227 sgen_los_update_cardtable_mod_union ();
2229 if (mod_union_consistency_check)
2230 sgen_check_mod_union_consistency ();
2232 current_collection_generation = GENERATION_OLD;
2233 sgen_cement_reset ();
2234 init_gray_queue (&gc_thread_gray_queue, FALSE);
2235 major_finish_collection (&gc_thread_gray_queue, "finishing", FALSE, -1, forced);
2236 sgen_gray_object_queue_dispose (&gc_thread_gray_queue);
2238 TV_GETTIME (total_end);
2239 gc_stats.major_gc_time += TV_ELAPSED (total_start, total_end);
2241 current_collection_generation = -1;
2245 * Ensure an allocation request for @size will succeed by freeing enough memory.
2247 * LOCKING: The GC lock MUST be held.
2250 sgen_ensure_free_space (size_t size, int generation)
2252 int generation_to_collect = -1;
2253 const char *reason = NULL;
2255 if (generation == GENERATION_OLD) {
2256 if (sgen_need_major_collection (size)) {
2257 reason = "LOS overflow";
2258 generation_to_collect = GENERATION_OLD;
2261 if (degraded_mode) {
2262 if (sgen_need_major_collection (size)) {
2263 reason = "Degraded mode overflow";
2264 generation_to_collect = GENERATION_OLD;
2266 } else if (sgen_need_major_collection (size)) {
2267 reason = concurrent_collection_in_progress ? "Forced finish concurrent collection" : "Minor allowance";
2268 generation_to_collect = GENERATION_OLD;
2270 generation_to_collect = GENERATION_NURSERY;
2271 reason = "Nursery full";
2275 if (generation_to_collect == -1) {
2276 if (concurrent_collection_in_progress && sgen_workers_all_done ()) {
2277 generation_to_collect = GENERATION_OLD;
2278 reason = "Finish concurrent collection";
2282 if (generation_to_collect == -1)
2284 sgen_perform_collection (size, generation_to_collect, reason, FALSE, TRUE);
2288 * LOCKING: Assumes the GC lock is held.
2291 sgen_perform_collection (size_t requested_size, int generation_to_collect, const char *reason, gboolean wait_to_finish, gboolean stw)
2293 TV_DECLARE (gc_total_start);
2294 TV_DECLARE (gc_total_end);
2295 int overflow_generation_to_collect = -1;
2296 int oldest_generation_collected = generation_to_collect;
2297 const char *overflow_reason = NULL;
2298 gboolean finish_concurrent = concurrent_collection_in_progress && (major_should_finish_concurrent_collection () || generation_to_collect == GENERATION_OLD);
2300 binary_protocol_collection_requested (generation_to_collect, requested_size, wait_to_finish ? 1 : 0);
2302 SGEN_ASSERT (0, generation_to_collect == GENERATION_NURSERY || generation_to_collect == GENERATION_OLD, "What generation is this?");
2305 sgen_stop_world (generation_to_collect);
2307 SGEN_ASSERT (0, sgen_is_world_stopped (), "We can only collect if the world is stopped");
2310 TV_GETTIME (gc_total_start);
2312 // FIXME: extract overflow reason
2313 // FIXME: minor overflow for concurrent case
2314 if (generation_to_collect == GENERATION_NURSERY && !finish_concurrent) {
2315 if (concurrent_collection_in_progress)
2316 major_update_concurrent_collection ();
2318 if (collect_nursery (reason, FALSE, NULL) && !concurrent_collection_in_progress) {
2319 overflow_generation_to_collect = GENERATION_OLD;
2320 overflow_reason = "Minor overflow";
2322 } else if (finish_concurrent) {
2323 major_finish_concurrent_collection (wait_to_finish);
2324 oldest_generation_collected = GENERATION_OLD;
2326 SGEN_ASSERT (0, generation_to_collect == GENERATION_OLD, "We should have handled nursery collections above");
2327 if (major_collector.is_concurrent && !wait_to_finish) {
2328 collect_nursery ("Concurrent start", FALSE, NULL);
2329 major_start_concurrent_collection (reason);
2330 oldest_generation_collected = GENERATION_NURSERY;
2331 } else if (major_do_collection (reason, FALSE, wait_to_finish)) {
2332 overflow_generation_to_collect = GENERATION_NURSERY;
2333 overflow_reason = "Excessive pinning";
2337 if (overflow_generation_to_collect != -1) {
2338 SGEN_ASSERT (0, !concurrent_collection_in_progress, "We don't yet support overflow collections with the concurrent collector");
2341 * We need to do an overflow collection, either because we ran out of memory
2342 * or the nursery is fully pinned.
2345 if (overflow_generation_to_collect == GENERATION_NURSERY)
2346 collect_nursery (overflow_reason, TRUE, NULL);
2348 major_do_collection (overflow_reason, TRUE, wait_to_finish);
2350 oldest_generation_collected = MAX (oldest_generation_collected, overflow_generation_to_collect);
2353 SGEN_LOG (2, "Heap size: %lu, LOS size: %lu", (unsigned long)sgen_gc_get_total_heap_allocation (), (unsigned long)los_memory_usage);
2355 /* this also sets the proper pointers for the next allocation */
2356 if (generation_to_collect == GENERATION_NURSERY && !sgen_can_alloc_size (requested_size)) {
2357 /* TypeBuilder and MonoMethod are killing mcs with fragmentation */
2358 SGEN_LOG (1, "nursery collection didn't find enough room for %zd alloc (%zd pinned)", requested_size, sgen_get_pinned_count ());
2359 sgen_dump_pin_queue ();
2363 TV_GETTIME (gc_total_end);
2364 time_max = MAX (time_max, TV_ELAPSED (gc_total_start, gc_total_end));
2367 sgen_restart_world (oldest_generation_collected);
2371 * ######################################################################
2372 * ######## Memory allocation from the OS
2373 * ######################################################################
2374 * This section of code deals with getting memory from the OS and
2375 * allocating memory for GC-internal data structures.
2376 * Internal memory can be handled with a freelist for small objects.
2382 G_GNUC_UNUSED static void
2383 report_internal_mem_usage (void)
2385 printf ("Internal memory usage:\n");
2386 sgen_report_internal_mem_usage ();
2387 printf ("Pinned memory usage:\n");
2388 major_collector.report_pinned_memory_usage ();
2392 * ######################################################################
2393 * ######## Finalization support
2394 * ######################################################################
2398 * If the object has been forwarded it means it's still referenced from a root.
2399 * If it is pinned it's still alive as well.
2400 * A LOS object is only alive if we have pinned it.
2401 * Return TRUE if @obj is ready to be finalized.
2403 static inline gboolean
2404 sgen_is_object_alive (GCObject *object)
2406 if (ptr_in_nursery (object))
2407 return sgen_nursery_is_object_alive (object);
2409 return sgen_major_is_object_alive (object);
2413 * This function returns true if @object is either alive and belongs to the
2414 * current collection - major collections are full heap, so old gen objects
2415 * are never alive during a minor collection.
2418 sgen_is_object_alive_and_on_current_collection (GCObject *object)
2420 if (ptr_in_nursery (object))
2421 return sgen_nursery_is_object_alive (object);
2423 if (current_collection_generation == GENERATION_NURSERY)
2426 return sgen_major_is_object_alive (object);
2431 sgen_gc_is_object_ready_for_finalization (GCObject *object)
2433 return !sgen_is_object_alive (object);
2437 sgen_queue_finalization_entry (GCObject *obj)
2439 gboolean critical = sgen_client_object_has_critical_finalizer (obj);
2441 sgen_pointer_queue_add (critical ? &critical_fin_queue : &fin_ready_queue, obj);
2443 sgen_client_object_queued_for_finalization (obj);
2447 sgen_object_is_live (GCObject *obj)
2449 return sgen_is_object_alive_and_on_current_collection (obj);
2453 * `System.GC.WaitForPendingFinalizers` first checks `sgen_have_pending_finalizers()` to
2454 * determine whether it can exit quickly. The latter must therefore only return FALSE if
2455 * all finalizers have really finished running.
2457 * `sgen_gc_invoke_finalizers()` first dequeues a finalizable object, and then finalizes it.
2458 * This means that just checking whether the queues are empty leaves the possibility that an
2459 * object might have been dequeued but not yet finalized. That's why we need the additional
2460 * flag `pending_unqueued_finalizer`.
2463 static volatile gboolean pending_unqueued_finalizer = FALSE;
2464 volatile gboolean sgen_suspend_finalizers = FALSE;
2467 sgen_set_suspend_finalizers (void)
2469 sgen_suspend_finalizers = TRUE;
2473 sgen_gc_invoke_finalizers (void)
2477 g_assert (!pending_unqueued_finalizer);
2479 /* FIXME: batch to reduce lock contention */
2480 while (sgen_have_pending_finalizers ()) {
2486 * We need to set `pending_unqueued_finalizer` before dequeing the
2487 * finalizable object.
2489 if (!sgen_pointer_queue_is_empty (&fin_ready_queue)) {
2490 pending_unqueued_finalizer = TRUE;
2491 mono_memory_write_barrier ();
2492 obj = (GCObject *)sgen_pointer_queue_pop (&fin_ready_queue);
2493 } else if (!sgen_pointer_queue_is_empty (&critical_fin_queue)) {
2494 pending_unqueued_finalizer = TRUE;
2495 mono_memory_write_barrier ();
2496 obj = (GCObject *)sgen_pointer_queue_pop (&critical_fin_queue);
2502 SGEN_LOG (7, "Finalizing object %p (%s)", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
2510 /* the object is on the stack so it is pinned */
2511 /*g_print ("Calling finalizer for object: %p (%s)\n", obj, sgen_client_object_safe_name (obj));*/
2512 sgen_client_run_finalize (obj);
2515 if (pending_unqueued_finalizer) {
2516 mono_memory_write_barrier ();
2517 pending_unqueued_finalizer = FALSE;
2524 sgen_have_pending_finalizers (void)
2526 if (sgen_suspend_finalizers)
2528 return pending_unqueued_finalizer || !sgen_pointer_queue_is_empty (&fin_ready_queue) || !sgen_pointer_queue_is_empty (&critical_fin_queue);
2532 * ######################################################################
2533 * ######## registered roots support
2534 * ######################################################################
2538 * We do not coalesce roots.
2541 sgen_register_root (char *start, size_t size, SgenDescriptor descr, int root_type, int source, const char *msg)
2543 RootRecord new_root;
2546 for (i = 0; i < ROOT_TYPE_NUM; ++i) {
2547 RootRecord *root = (RootRecord *)sgen_hash_table_lookup (&roots_hash [i], start);
2548 /* we allow changing the size and the descriptor (for thread statics etc) */
2550 size_t old_size = root->end_root - start;
2551 root->end_root = start + size;
2552 SGEN_ASSERT (0, !!root->root_desc == !!descr, "Can't change whether a root is precise or conservative.");
2553 SGEN_ASSERT (0, root->source == source, "Can't change a root's source identifier.");
2554 SGEN_ASSERT (0, !!root->msg == !!msg, "Can't change a root's message.");
2555 root->root_desc = descr;
2557 roots_size -= old_size;
2563 new_root.end_root = start + size;
2564 new_root.root_desc = descr;
2565 new_root.source = source;
2568 sgen_hash_table_replace (&roots_hash [root_type], start, &new_root, NULL);
2571 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);
2578 sgen_deregister_root (char* addr)
2584 for (root_type = 0; root_type < ROOT_TYPE_NUM; ++root_type) {
2585 if (sgen_hash_table_remove (&roots_hash [root_type], addr, &root))
2586 roots_size -= (root.end_root - addr);
2592 * ######################################################################
2593 * ######## Thread handling (stop/start code)
2594 * ######################################################################
2598 sgen_get_current_collection_generation (void)
2600 return current_collection_generation;
2604 sgen_thread_register (SgenThreadInfo* info, void *stack_bottom_fallback)
2606 info->tlab_start = info->tlab_next = info->tlab_temp_end = info->tlab_real_end = NULL;
2608 sgen_client_thread_register (info, stack_bottom_fallback);
2614 sgen_thread_unregister (SgenThreadInfo *p)
2616 sgen_client_thread_unregister (p);
2620 * ######################################################################
2621 * ######## Write barriers
2622 * ######################################################################
2626 * Note: the write barriers first do the needed GC work and then do the actual store:
2627 * this way the value is visible to the conservative GC scan after the write barrier
2628 * itself. If a GC interrupts the barrier in the middle, value will be kept alive by
2629 * the conservative scan, otherwise by the remembered set scan.
2633 mono_gc_wbarrier_arrayref_copy (gpointer dest_ptr, gpointer src_ptr, int count)
2635 HEAVY_STAT (++stat_wbarrier_arrayref_copy);
2636 /*This check can be done without taking a lock since dest_ptr array is pinned*/
2637 if (ptr_in_nursery (dest_ptr) || count <= 0) {
2638 mono_gc_memmove_aligned (dest_ptr, src_ptr, count * sizeof (gpointer));
2642 #ifdef SGEN_HEAVY_BINARY_PROTOCOL
2643 if (binary_protocol_is_heavy_enabled ()) {
2645 for (i = 0; i < count; ++i) {
2646 gpointer dest = (gpointer*)dest_ptr + i;
2647 gpointer obj = *((gpointer*)src_ptr + i);
2649 binary_protocol_wbarrier (dest, obj, (gpointer)LOAD_VTABLE (obj));
2654 remset.wbarrier_arrayref_copy (dest_ptr, src_ptr, count);
2658 mono_gc_wbarrier_generic_nostore (gpointer ptr)
2662 HEAVY_STAT (++stat_wbarrier_generic_store);
2664 sgen_client_wbarrier_generic_nostore_check (ptr);
2666 obj = *(gpointer*)ptr;
2668 binary_protocol_wbarrier (ptr, obj, (gpointer)LOAD_VTABLE (obj));
2671 * We need to record old->old pointer locations for the
2672 * concurrent collector.
2674 if (!ptr_in_nursery (obj) && !concurrent_collection_in_progress) {
2675 SGEN_LOG (8, "Skipping remset at %p", ptr);
2679 SGEN_LOG (8, "Adding remset at %p", ptr);
2681 remset.wbarrier_generic_nostore (ptr);
2685 mono_gc_wbarrier_generic_store (gpointer ptr, GCObject* value)
2687 SGEN_LOG (8, "Wbarrier store at %p to %p (%s)", ptr, value, value ? sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (value)) : "null");
2688 SGEN_UPDATE_REFERENCE_ALLOW_NULL (ptr, value);
2689 if (ptr_in_nursery (value) || concurrent_collection_in_progress)
2690 mono_gc_wbarrier_generic_nostore (ptr);
2691 sgen_dummy_use (value);
2694 /* Same as mono_gc_wbarrier_generic_store () but performs the store
2695 * as an atomic operation with release semantics.
2698 mono_gc_wbarrier_generic_store_atomic (gpointer ptr, GCObject *value)
2700 HEAVY_STAT (++stat_wbarrier_generic_store_atomic);
2702 SGEN_LOG (8, "Wbarrier atomic store at %p to %p (%s)", ptr, value, value ? sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (value)) : "null");
2704 InterlockedWritePointer ((volatile gpointer *)ptr, value);
2706 if (ptr_in_nursery (value) || concurrent_collection_in_progress)
2707 mono_gc_wbarrier_generic_nostore (ptr);
2709 sgen_dummy_use (value);
2713 sgen_wbarrier_value_copy_bitmap (gpointer _dest, gpointer _src, int size, unsigned bitmap)
2715 GCObject **dest = (GCObject **)_dest;
2716 GCObject **src = (GCObject **)_src;
2720 mono_gc_wbarrier_generic_store (dest, *src);
2725 size -= SIZEOF_VOID_P;
2731 * ######################################################################
2732 * ######## Other mono public interface functions.
2733 * ######################################################################
2737 sgen_gc_collect (int generation)
2742 sgen_perform_collection (0, generation, "user request", TRUE, TRUE);
2747 sgen_gc_collection_count (int generation)
2749 if (generation == 0)
2750 return gc_stats.minor_gc_count;
2751 return gc_stats.major_gc_count;
2755 sgen_gc_get_used_size (void)
2759 tot = los_memory_usage;
2760 tot += nursery_section->next_data - nursery_section->data;
2761 tot += major_collector.get_used_size ();
2762 /* FIXME: account for pinned objects */
2768 sgen_env_var_error (const char *env_var, const char *fallback, const char *description_format, ...)
2772 va_start (ap, description_format);
2774 fprintf (stderr, "Warning: In environment variable `%s': ", env_var);
2775 vfprintf (stderr, description_format, ap);
2777 fprintf (stderr, " - %s", fallback);
2778 fprintf (stderr, "\n");
2784 parse_double_in_interval (const char *env_var, const char *opt_name, const char *opt, double min, double max, double *result)
2787 double val = strtod (opt, &endptr);
2788 if (endptr == opt) {
2789 sgen_env_var_error (env_var, "Using default value.", "`%s` must be a number.", opt_name);
2792 else if (val < min || val > max) {
2793 sgen_env_var_error (env_var, "Using default value.", "`%s` must be between %.2f - %.2f.", opt_name, min, max);
2805 char *major_collector_opt = NULL;
2806 char *minor_collector_opt = NULL;
2807 char *params_opts = NULL;
2808 char *debug_opts = NULL;
2809 size_t max_heap = 0;
2810 size_t soft_limit = 0;
2812 gboolean debug_print_allowance = FALSE;
2813 double allowance_ratio = 0, save_target = 0;
2814 gboolean cement_enabled = TRUE;
2817 result = InterlockedCompareExchange (&gc_initialized, -1, 0);
2820 /* already inited */
2823 /* being inited by another thread */
2824 mono_thread_info_usleep (1000);
2827 /* we will init it */
2830 g_assert_not_reached ();
2832 } while (result != 0);
2834 SGEN_TV_GETTIME (sgen_init_timestamp);
2836 #ifdef SGEN_WITHOUT_MONO
2837 mono_thread_smr_init ();
2840 mono_coop_mutex_init (&gc_mutex);
2842 gc_debug_file = stderr;
2844 mono_coop_mutex_init (&sgen_interruption_mutex);
2846 if ((env = g_getenv (MONO_GC_PARAMS_NAME)) || gc_params_options) {
2847 params_opts = g_strdup_printf ("%s,%s", gc_params_options ? gc_params_options : "", env ? env : "");
2851 opts = g_strsplit (params_opts, ",", -1);
2852 for (ptr = opts; *ptr; ++ptr) {
2854 if (g_str_has_prefix (opt, "major=")) {
2855 opt = strchr (opt, '=') + 1;
2856 major_collector_opt = g_strdup (opt);
2857 } else if (g_str_has_prefix (opt, "minor=")) {
2858 opt = strchr (opt, '=') + 1;
2859 minor_collector_opt = g_strdup (opt);
2867 sgen_init_internal_allocator ();
2868 sgen_init_nursery_allocator ();
2869 sgen_init_fin_weak_hash ();
2870 sgen_init_hash_table ();
2871 sgen_init_descriptors ();
2872 sgen_init_gray_queues ();
2873 sgen_init_allocator ();
2874 sgen_init_gchandles ();
2876 sgen_register_fixed_internal_mem_type (INTERNAL_MEM_SECTION, SGEN_SIZEOF_GC_MEM_SECTION);
2877 sgen_register_fixed_internal_mem_type (INTERNAL_MEM_GRAY_QUEUE, sizeof (GrayQueueSection));
2879 sgen_client_init ();
2881 if (!minor_collector_opt) {
2882 sgen_simple_nursery_init (&sgen_minor_collector);
2884 if (!strcmp (minor_collector_opt, "simple")) {
2886 sgen_simple_nursery_init (&sgen_minor_collector);
2887 } else if (!strcmp (minor_collector_opt, "split")) {
2888 sgen_split_nursery_init (&sgen_minor_collector);
2890 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using `simple` instead.", "Unknown minor collector `%s'.", minor_collector_opt);
2891 goto use_simple_nursery;
2895 if (!major_collector_opt) {
2897 DEFAULT_MAJOR_INIT (&major_collector);
2898 } else if (!strcmp (major_collector_opt, "marksweep")) {
2899 sgen_marksweep_init (&major_collector);
2900 } else if (!strcmp (major_collector_opt, "marksweep-conc")) {
2901 sgen_marksweep_conc_init (&major_collector);
2902 } else if (!strcmp (major_collector_opt, "marksweep-conc-par")) {
2903 sgen_marksweep_conc_par_init (&major_collector);
2905 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using `" DEFAULT_MAJOR_NAME "` instead.", "Unknown major collector `%s'.", major_collector_opt);
2906 goto use_default_major;
2909 sgen_nursery_size = DEFAULT_NURSERY_SIZE;
2912 gboolean usage_printed = FALSE;
2914 for (ptr = opts; *ptr; ++ptr) {
2916 if (!strcmp (opt, ""))
2918 if (g_str_has_prefix (opt, "major="))
2920 if (g_str_has_prefix (opt, "minor="))
2922 if (g_str_has_prefix (opt, "max-heap-size=")) {
2923 size_t page_size = mono_pagesize ();
2924 size_t max_heap_candidate = 0;
2925 opt = strchr (opt, '=') + 1;
2926 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &max_heap_candidate)) {
2927 max_heap = (max_heap_candidate + page_size - 1) & ~(size_t)(page_size - 1);
2928 if (max_heap != max_heap_candidate)
2929 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Rounding up.", "`max-heap-size` size must be a multiple of %d.", page_size);
2931 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`max-heap-size` must be an integer.");
2935 if (g_str_has_prefix (opt, "soft-heap-limit=")) {
2936 opt = strchr (opt, '=') + 1;
2937 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &soft_limit)) {
2938 if (soft_limit <= 0) {
2939 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`soft-heap-limit` must be positive.");
2943 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`soft-heap-limit` must be an integer.");
2949 if (g_str_has_prefix (opt, "nursery-size=")) {
2951 opt = strchr (opt, '=') + 1;
2952 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &val)) {
2953 if ((val & (val - 1))) {
2954 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.", "`nursery-size` must be a power of two.");
2958 if (val < SGEN_MAX_NURSERY_WASTE) {
2959 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.",
2960 "`nursery-size` must be at least %d bytes.", SGEN_MAX_NURSERY_WASTE);
2964 sgen_nursery_size = val;
2965 sgen_nursery_bits = 0;
2966 while (ONE_P << (++ sgen_nursery_bits) != sgen_nursery_size)
2969 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.", "`nursery-size` must be an integer.");
2975 if (g_str_has_prefix (opt, "save-target-ratio=")) {
2977 opt = strchr (opt, '=') + 1;
2978 if (parse_double_in_interval (MONO_GC_PARAMS_NAME, "save-target-ratio", opt,
2979 SGEN_MIN_SAVE_TARGET_RATIO, SGEN_MAX_SAVE_TARGET_RATIO, &val)) {
2984 if (g_str_has_prefix (opt, "default-allowance-ratio=")) {
2986 opt = strchr (opt, '=') + 1;
2987 if (parse_double_in_interval (MONO_GC_PARAMS_NAME, "default-allowance-ratio", opt,
2988 SGEN_MIN_ALLOWANCE_NURSERY_SIZE_RATIO, SGEN_MAX_ALLOWANCE_NURSERY_SIZE_RATIO, &val)) {
2989 allowance_ratio = val;
2994 if (!strcmp (opt, "cementing")) {
2995 cement_enabled = TRUE;
2998 if (!strcmp (opt, "no-cementing")) {
2999 cement_enabled = FALSE;
3003 if (!strcmp (opt, "precleaning")) {
3004 precleaning_enabled = TRUE;
3007 if (!strcmp (opt, "no-precleaning")) {
3008 precleaning_enabled = FALSE;
3012 if (major_collector.handle_gc_param && major_collector.handle_gc_param (opt))
3015 if (sgen_minor_collector.handle_gc_param && sgen_minor_collector.handle_gc_param (opt))
3018 if (sgen_client_handle_gc_param (opt))
3021 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Ignoring.", "Unknown option `%s`.", opt);
3026 fprintf (stderr, "\n%s must be a comma-delimited list of one or more of the following:\n", MONO_GC_PARAMS_NAME);
3027 fprintf (stderr, " max-heap-size=N (where N is an integer, possibly with a k, m or a g suffix)\n");
3028 fprintf (stderr, " soft-heap-limit=n (where N is an integer, possibly with a k, m or a g suffix)\n");
3029 fprintf (stderr, " nursery-size=N (where N is an integer, possibly with a k, m or a g suffix)\n");
3030 fprintf (stderr, " major=COLLECTOR (where COLLECTOR is `marksweep', `marksweep-conc', `marksweep-par')\n");
3031 fprintf (stderr, " minor=COLLECTOR (where COLLECTOR is `simple' or `split')\n");
3032 fprintf (stderr, " wbarrier=WBARRIER (where WBARRIER is `remset' or `cardtable')\n");
3033 fprintf (stderr, " [no-]cementing\n");
3034 if (major_collector.print_gc_param_usage)
3035 major_collector.print_gc_param_usage ();
3036 if (sgen_minor_collector.print_gc_param_usage)
3037 sgen_minor_collector.print_gc_param_usage ();
3038 sgen_client_print_gc_params_usage ();
3039 fprintf (stderr, " Experimental options:\n");
3040 fprintf (stderr, " save-target-ratio=R (where R must be between %.2f - %.2f).\n", SGEN_MIN_SAVE_TARGET_RATIO, SGEN_MAX_SAVE_TARGET_RATIO);
3041 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);
3042 fprintf (stderr, "\n");
3044 usage_printed = TRUE;
3049 if (major_collector_opt)
3050 g_free (major_collector_opt);
3052 if (minor_collector_opt)
3053 g_free (minor_collector_opt);
3056 g_free (params_opts);
3060 sgen_pinning_init ();
3061 sgen_cement_init (cement_enabled);
3063 if ((env = g_getenv (MONO_GC_DEBUG_NAME)) || gc_debug_options) {
3064 debug_opts = g_strdup_printf ("%s,%s", gc_debug_options ? gc_debug_options : "", env ? env : "");
3068 gboolean usage_printed = FALSE;
3070 opts = g_strsplit (debug_opts, ",", -1);
3071 for (ptr = opts; ptr && *ptr; ptr ++) {
3073 if (!strcmp (opt, ""))
3075 if (opt [0] >= '0' && opt [0] <= '9') {
3076 gc_debug_level = atoi (opt);
3081 char *rf = g_strdup_printf ("%s.%d", opt, mono_process_current_pid ());
3082 gc_debug_file = fopen (rf, "wb");
3084 gc_debug_file = stderr;
3087 } else if (!strcmp (opt, "print-allowance")) {
3088 debug_print_allowance = TRUE;
3089 } else if (!strcmp (opt, "print-pinning")) {
3090 sgen_pin_stats_enable ();
3091 } else if (!strcmp (opt, "verify-before-allocs")) {
3092 verify_before_allocs = 1;
3093 has_per_allocation_action = TRUE;
3094 } else if (g_str_has_prefix (opt, "verify-before-allocs=")) {
3095 char *arg = strchr (opt, '=') + 1;
3096 verify_before_allocs = atoi (arg);
3097 has_per_allocation_action = TRUE;
3098 } else if (!strcmp (opt, "collect-before-allocs")) {
3099 collect_before_allocs = 1;
3100 has_per_allocation_action = TRUE;
3101 } else if (g_str_has_prefix (opt, "collect-before-allocs=")) {
3102 char *arg = strchr (opt, '=') + 1;
3103 has_per_allocation_action = TRUE;
3104 collect_before_allocs = atoi (arg);
3105 } else if (!strcmp (opt, "verify-before-collections")) {
3106 whole_heap_check_before_collection = TRUE;
3107 } else if (!strcmp (opt, "check-remset-consistency")) {
3108 remset_consistency_checks = TRUE;
3109 nursery_clear_policy = CLEAR_AT_GC;
3110 } else if (!strcmp (opt, "mod-union-consistency-check")) {
3111 if (!major_collector.is_concurrent) {
3112 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "`mod-union-consistency-check` only works with concurrent major collector.");
3115 mod_union_consistency_check = TRUE;
3116 } else if (!strcmp (opt, "check-mark-bits")) {
3117 check_mark_bits_after_major_collection = TRUE;
3118 } else if (!strcmp (opt, "check-nursery-pinned")) {
3119 check_nursery_objects_pinned = TRUE;
3120 } else if (!strcmp (opt, "clear-at-gc")) {
3121 nursery_clear_policy = CLEAR_AT_GC;
3122 } else if (!strcmp (opt, "clear-nursery-at-gc")) {
3123 nursery_clear_policy = CLEAR_AT_GC;
3124 } else if (!strcmp (opt, "clear-at-tlab-creation")) {
3125 nursery_clear_policy = CLEAR_AT_TLAB_CREATION;
3126 } else if (!strcmp (opt, "debug-clear-at-tlab-creation")) {
3127 nursery_clear_policy = CLEAR_AT_TLAB_CREATION_DEBUG;
3128 } else if (!strcmp (opt, "check-scan-starts")) {
3129 do_scan_starts_check = TRUE;
3130 } else if (!strcmp (opt, "verify-nursery-at-minor-gc")) {
3131 do_verify_nursery = TRUE;
3132 } else if (!strcmp (opt, "check-concurrent")) {
3133 if (!major_collector.is_concurrent) {
3134 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "`check-concurrent` only works with concurrent major collectors.");
3137 nursery_clear_policy = CLEAR_AT_GC;
3138 do_concurrent_checks = TRUE;
3139 } else if (!strcmp (opt, "dump-nursery-at-minor-gc")) {
3140 do_dump_nursery_content = TRUE;
3141 } else if (!strcmp (opt, "disable-minor")) {
3142 disable_minor_collections = TRUE;
3143 } else if (!strcmp (opt, "disable-major")) {
3144 disable_major_collections = TRUE;
3145 } else if (g_str_has_prefix (opt, "heap-dump=")) {
3146 char *filename = strchr (opt, '=') + 1;
3147 nursery_clear_policy = CLEAR_AT_GC;
3148 sgen_debug_enable_heap_dump (filename);
3149 } else if (g_str_has_prefix (opt, "binary-protocol=")) {
3150 char *filename = strchr (opt, '=') + 1;
3151 char *colon = strrchr (filename, ':');
3154 if (!mono_gc_parse_environment_string_extract_number (colon + 1, &limit)) {
3155 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring limit.", "Binary protocol file size limit must be an integer.");
3160 binary_protocol_init (filename, (long long)limit);
3161 } else if (!strcmp (opt, "nursery-canaries")) {
3162 do_verify_nursery = TRUE;
3163 enable_nursery_canaries = TRUE;
3164 } else if (!sgen_client_handle_gc_debug (opt)) {
3165 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "Unknown option `%s`.", opt);
3170 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);
3171 fprintf (stderr, "Valid <option>s are:\n");
3172 fprintf (stderr, " collect-before-allocs[=<n>]\n");
3173 fprintf (stderr, " verify-before-allocs[=<n>]\n");
3174 fprintf (stderr, " check-remset-consistency\n");
3175 fprintf (stderr, " check-mark-bits\n");
3176 fprintf (stderr, " check-nursery-pinned\n");
3177 fprintf (stderr, " verify-before-collections\n");
3178 fprintf (stderr, " verify-nursery-at-minor-gc\n");
3179 fprintf (stderr, " dump-nursery-at-minor-gc\n");
3180 fprintf (stderr, " disable-minor\n");
3181 fprintf (stderr, " disable-major\n");
3182 fprintf (stderr, " check-concurrent\n");
3183 fprintf (stderr, " clear-[nursery-]at-gc\n");
3184 fprintf (stderr, " clear-at-tlab-creation\n");
3185 fprintf (stderr, " debug-clear-at-tlab-creation\n");
3186 fprintf (stderr, " check-scan-starts\n");
3187 fprintf (stderr, " print-allowance\n");
3188 fprintf (stderr, " print-pinning\n");
3189 fprintf (stderr, " heap-dump=<filename>\n");
3190 fprintf (stderr, " binary-protocol=<filename>[:<file-size-limit>]\n");
3191 fprintf (stderr, " nursery-canaries\n");
3192 sgen_client_print_gc_debug_usage ();
3193 fprintf (stderr, "\n");
3195 usage_printed = TRUE;
3202 g_free (debug_opts);
3204 if (check_mark_bits_after_major_collection)
3205 nursery_clear_policy = CLEAR_AT_GC;
3207 if (major_collector.post_param_init)
3208 major_collector.post_param_init (&major_collector);
3210 if (major_collector.needs_thread_pool) {
3211 int num_workers = 1;
3212 if (major_collector.is_parallel) {
3213 /* FIXME Detect the number of physical cores, instead of logical */
3214 num_workers = mono_cpu_count () / 2;
3215 if (num_workers < 1)
3218 sgen_workers_init (num_workers);
3221 sgen_memgov_init (max_heap, soft_limit, debug_print_allowance, allowance_ratio, save_target);
3223 memset (&remset, 0, sizeof (remset));
3225 sgen_card_table_init (&remset);
3227 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");
3231 sgen_init_bridge ();
3235 sgen_gc_initialized ()
3237 return gc_initialized > 0;
3241 sgen_get_nursery_clear_policy (void)
3243 return nursery_clear_policy;
3249 mono_coop_mutex_lock (&gc_mutex);
3253 sgen_gc_unlock (void)
3255 mono_coop_mutex_unlock (&gc_mutex);
3259 sgen_major_collector_iterate_live_block_ranges (sgen_cardtable_block_callback callback)
3261 major_collector.iterate_live_block_ranges (callback);
3265 sgen_major_collector_iterate_block_ranges (sgen_cardtable_block_callback callback)
3267 major_collector.iterate_block_ranges (callback);
3271 sgen_get_major_collector (void)
3273 return &major_collector;
3277 sgen_get_remset (void)
3283 count_cards (long long *major_total, long long *major_marked, long long *los_total, long long *los_marked)
3285 sgen_get_major_collector ()->count_cards (major_total, major_marked);
3286 sgen_los_count_cards (los_total, los_marked);
3289 static gboolean world_is_stopped = FALSE;
3291 /* LOCKING: assumes the GC lock is held */
3293 sgen_stop_world (int generation)
3295 long long major_total = -1, major_marked = -1, los_total = -1, los_marked = -1;
3297 SGEN_ASSERT (0, !world_is_stopped, "Why are we stopping a stopped world?");
3299 binary_protocol_world_stopping (generation, sgen_timestamp (), (gpointer) (gsize) mono_native_thread_id_get ());
3301 sgen_client_stop_world (generation);
3303 world_is_stopped = TRUE;
3305 if (binary_protocol_is_heavy_enabled ())
3306 count_cards (&major_total, &major_marked, &los_total, &los_marked);
3307 binary_protocol_world_stopped (generation, sgen_timestamp (), major_total, major_marked, los_total, los_marked);
3310 /* LOCKING: assumes the GC lock is held */
3312 sgen_restart_world (int generation)
3314 long long major_total = -1, major_marked = -1, los_total = -1, los_marked = -1;
3317 SGEN_ASSERT (0, world_is_stopped, "Why are we restarting a running world?");
3319 if (binary_protocol_is_heavy_enabled ())
3320 count_cards (&major_total, &major_marked, &los_total, &los_marked);
3321 binary_protocol_world_restarting (generation, sgen_timestamp (), major_total, major_marked, los_total, los_marked);
3323 world_is_stopped = FALSE;
3325 sgen_client_restart_world (generation, &stw_time);
3327 binary_protocol_world_restarted (generation, sgen_timestamp ());
3329 if (sgen_client_bridge_need_processing ())
3330 sgen_client_bridge_processing_finish (generation);
3332 sgen_memgov_collection_end (generation, stw_time);
3336 sgen_is_world_stopped (void)
3338 return world_is_stopped;
3342 sgen_check_whole_heap_stw (void)
3344 sgen_stop_world (0);
3345 sgen_clear_nursery_fragments ();
3346 sgen_check_whole_heap (TRUE);
3347 sgen_restart_world (0);
3351 sgen_timestamp (void)
3353 SGEN_TV_DECLARE (timestamp);
3354 SGEN_TV_GETTIME (timestamp);
3355 return SGEN_TV_ELAPSED (sgen_init_timestamp, timestamp);
3358 #endif /* HAVE_SGEN_GC */