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_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);
1415 sgen_los_scan_card_table (CARDTABLE_SCAN_MOD_UNION_PRECLEAN, ctx);
1417 sgen_scan_pin_queue_objects (ctx);
1421 init_gray_queue (SgenGrayQueue *gc_thread_gray_queue, gboolean use_workers)
1424 sgen_workers_init_distribute_gray_queue ();
1425 sgen_gray_object_queue_init (gc_thread_gray_queue, NULL, TRUE);
1429 enqueue_scan_from_roots_jobs (SgenGrayQueue *gc_thread_gray_queue, char *heap_start, char *heap_end, SgenObjectOperations *ops, gboolean enqueue)
1431 ScanFromRegisteredRootsJob *scrrj;
1432 ScanThreadDataJob *stdj;
1433 ScanFinalizerEntriesJob *sfej;
1435 /* registered roots, this includes static fields */
1437 scrrj = (ScanFromRegisteredRootsJob*)sgen_thread_pool_job_alloc ("scan from registered roots normal", job_scan_from_registered_roots, sizeof (ScanFromRegisteredRootsJob));
1438 scrrj->scan_job.ops = ops;
1439 scrrj->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
1440 scrrj->heap_start = heap_start;
1441 scrrj->heap_end = heap_end;
1442 scrrj->root_type = ROOT_TYPE_NORMAL;
1443 sgen_workers_enqueue_job (&scrrj->scan_job.job, enqueue);
1445 scrrj = (ScanFromRegisteredRootsJob*)sgen_thread_pool_job_alloc ("scan from registered roots wbarrier", job_scan_from_registered_roots, sizeof (ScanFromRegisteredRootsJob));
1446 scrrj->scan_job.ops = ops;
1447 scrrj->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
1448 scrrj->heap_start = heap_start;
1449 scrrj->heap_end = heap_end;
1450 scrrj->root_type = ROOT_TYPE_WBARRIER;
1451 sgen_workers_enqueue_job (&scrrj->scan_job.job, enqueue);
1455 stdj = (ScanThreadDataJob*)sgen_thread_pool_job_alloc ("scan thread data", job_scan_thread_data, sizeof (ScanThreadDataJob));
1456 stdj->scan_job.ops = ops;
1457 stdj->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
1458 stdj->heap_start = heap_start;
1459 stdj->heap_end = heap_end;
1460 sgen_workers_enqueue_job (&stdj->scan_job.job, enqueue);
1462 /* Scan the list of objects ready for finalization. */
1464 sfej = (ScanFinalizerEntriesJob*)sgen_thread_pool_job_alloc ("scan finalizer entries", job_scan_finalizer_entries, sizeof (ScanFinalizerEntriesJob));
1465 sfej->scan_job.ops = ops;
1466 sfej->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
1467 sfej->queue = &fin_ready_queue;
1468 sgen_workers_enqueue_job (&sfej->scan_job.job, enqueue);
1470 sfej = (ScanFinalizerEntriesJob*)sgen_thread_pool_job_alloc ("scan critical finalizer entries", job_scan_finalizer_entries, sizeof (ScanFinalizerEntriesJob));
1471 sfej->scan_job.ops = ops;
1472 sfej->scan_job.gc_thread_gray_queue = gc_thread_gray_queue;
1473 sfej->queue = &critical_fin_queue;
1474 sgen_workers_enqueue_job (&sfej->scan_job.job, enqueue);
1478 * Perform a nursery collection.
1480 * Return whether any objects were late-pinned due to being out of memory.
1483 collect_nursery (const char *reason, gboolean is_overflow, SgenGrayQueue *unpin_queue)
1485 gboolean needs_major;
1486 size_t max_garbage_amount;
1488 mword fragment_total;
1490 SgenGrayQueue gc_thread_gray_queue;
1491 SgenObjectOperations *object_ops;
1492 ScanCopyContext ctx;
1495 SGEN_TV_DECLARE (last_minor_collection_start_tv);
1496 SGEN_TV_DECLARE (last_minor_collection_end_tv);
1498 if (disable_minor_collections)
1501 TV_GETTIME (last_minor_collection_start_tv);
1502 atv = last_minor_collection_start_tv;
1504 binary_protocol_collection_begin (gc_stats.minor_gc_count, GENERATION_NURSERY);
1506 if (sgen_concurrent_collection_in_progress ())
1507 object_ops = &sgen_minor_collector.serial_ops_with_concurrent_major;
1509 object_ops = &sgen_minor_collector.serial_ops;
1511 if (do_verify_nursery || do_dump_nursery_content)
1512 sgen_debug_verify_nursery (do_dump_nursery_content);
1514 current_collection_generation = GENERATION_NURSERY;
1516 SGEN_ASSERT (0, !sgen_collection_is_concurrent (), "Why is the nursery collection concurrent?");
1518 reset_pinned_from_failed_allocation ();
1520 check_scan_starts ();
1522 sgen_nursery_alloc_prepare_for_minor ();
1526 nursery_next = sgen_nursery_alloc_get_upper_alloc_bound ();
1527 /* FIXME: optimize later to use the higher address where an object can be present */
1528 nursery_next = MAX (nursery_next, sgen_get_nursery_end ());
1530 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 ()));
1531 max_garbage_amount = nursery_next - sgen_get_nursery_start ();
1532 g_assert (nursery_section->size >= max_garbage_amount);
1534 /* world must be stopped already */
1536 time_minor_pre_collection_fragment_clear += TV_ELAPSED (atv, btv);
1538 sgen_client_pre_collection_checks ();
1540 nursery_section->next_data = nursery_next;
1542 major_collector.start_nursery_collection ();
1544 sgen_memgov_minor_collection_start ();
1546 init_gray_queue (&gc_thread_gray_queue, FALSE);
1547 ctx = CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, &gc_thread_gray_queue);
1549 gc_stats.minor_gc_count ++;
1551 sgen_process_fin_stage_entries ();
1553 /* pin from pinned handles */
1554 sgen_init_pinning ();
1555 sgen_client_binary_protocol_mark_start (GENERATION_NURSERY);
1556 pin_from_roots (sgen_get_nursery_start (), nursery_next, ctx);
1557 /* pin cemented objects */
1558 sgen_pin_cemented_objects ();
1559 /* identify pinned objects */
1560 sgen_optimize_pin_queue ();
1561 sgen_pinning_setup_section (nursery_section);
1563 pin_objects_in_nursery (FALSE, ctx);
1564 sgen_pinning_trim_queue_to_section (nursery_section);
1566 if (remset_consistency_checks)
1567 sgen_check_remset_consistency ();
1569 if (whole_heap_check_before_collection) {
1570 sgen_clear_nursery_fragments ();
1571 sgen_check_whole_heap (FALSE);
1575 time_minor_pinning += TV_ELAPSED (btv, atv);
1576 SGEN_LOG (2, "Finding pinned pointers: %zd in %lld usecs", sgen_get_pinned_count (), (long long)TV_ELAPSED (btv, atv));
1577 SGEN_LOG (4, "Start scan with %zd pinned objects", sgen_get_pinned_count ());
1579 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan remset", job_remembered_set_scan, sizeof (ScanJob));
1580 sj->ops = object_ops;
1581 sj->gc_thread_gray_queue = &gc_thread_gray_queue;
1582 sgen_workers_enqueue_job (&sj->job, FALSE);
1584 /* we don't have complete write barrier yet, so we scan all the old generation sections */
1586 time_minor_scan_remsets += TV_ELAPSED (atv, btv);
1587 SGEN_LOG (2, "Old generation scan: %lld usecs", (long long)TV_ELAPSED (atv, btv));
1589 sgen_pin_stats_report ();
1591 /* FIXME: Why do we do this at this specific, seemingly random, point? */
1592 sgen_client_collecting_minor (&fin_ready_queue, &critical_fin_queue);
1595 time_minor_scan_pinned += TV_ELAPSED (btv, atv);
1597 enqueue_scan_from_roots_jobs (&gc_thread_gray_queue, sgen_get_nursery_start (), nursery_next, object_ops, FALSE);
1600 time_minor_scan_roots += TV_ELAPSED (atv, btv);
1602 finish_gray_stack (GENERATION_NURSERY, ctx);
1605 time_minor_finish_gray_stack += TV_ELAPSED (btv, atv);
1606 sgen_client_binary_protocol_mark_end (GENERATION_NURSERY);
1608 if (objects_pinned) {
1609 sgen_optimize_pin_queue ();
1610 sgen_pinning_setup_section (nursery_section);
1614 * This is the latest point at which we can do this check, because
1615 * sgen_build_nursery_fragments() unpins nursery objects again.
1617 if (remset_consistency_checks)
1618 sgen_check_remset_consistency ();
1620 /* walk the pin_queue, build up the fragment list of free memory, unmark
1621 * pinned objects as we go, memzero() the empty fragments so they are ready for the
1624 sgen_client_binary_protocol_reclaim_start (GENERATION_NURSERY);
1625 fragment_total = sgen_build_nursery_fragments (nursery_section, unpin_queue);
1626 if (!fragment_total)
1629 /* Clear TLABs for all threads */
1630 sgen_clear_tlabs ();
1632 sgen_client_binary_protocol_reclaim_end (GENERATION_NURSERY);
1634 time_minor_fragment_creation += TV_ELAPSED (atv, btv);
1635 SGEN_LOG (2, "Fragment creation: %lld usecs, %lu bytes available", (long long)TV_ELAPSED (atv, btv), (unsigned long)fragment_total);
1637 if (remset_consistency_checks)
1638 sgen_check_major_refs ();
1640 major_collector.finish_nursery_collection ();
1642 TV_GETTIME (last_minor_collection_end_tv);
1643 gc_stats.minor_gc_time += TV_ELAPSED (last_minor_collection_start_tv, last_minor_collection_end_tv);
1645 sgen_debug_dump_heap ("minor", gc_stats.minor_gc_count - 1, NULL);
1647 /* prepare the pin queue for the next collection */
1648 sgen_finish_pinning ();
1649 if (sgen_have_pending_finalizers ()) {
1650 SGEN_LOG (4, "Finalizer-thread wakeup");
1651 sgen_client_finalize_notify ();
1653 sgen_pin_stats_reset ();
1654 /* clear cemented hash */
1655 sgen_cement_clear_below_threshold ();
1657 sgen_gray_object_queue_dispose (&gc_thread_gray_queue);
1659 remset.finish_minor_collection ();
1661 check_scan_starts ();
1663 binary_protocol_flush_buffers (FALSE);
1665 sgen_memgov_minor_collection_end (reason, is_overflow);
1667 /*objects are late pinned because of lack of memory, so a major is a good call*/
1668 needs_major = objects_pinned > 0;
1669 current_collection_generation = -1;
1672 binary_protocol_collection_end (gc_stats.minor_gc_count - 1, GENERATION_NURSERY, 0, 0);
1674 if (check_nursery_objects_pinned && !sgen_minor_collector.is_split)
1675 sgen_check_nursery_objects_pinned (unpin_queue != NULL);
1681 COPY_OR_MARK_FROM_ROOTS_SERIAL,
1682 COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT,
1683 COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT
1684 } CopyOrMarkFromRootsMode;
1687 major_copy_or_mark_from_roots (SgenGrayQueue *gc_thread_gray_queue, size_t *old_next_pin_slot, CopyOrMarkFromRootsMode mode, SgenObjectOperations *object_ops)
1692 /* FIXME: only use these values for the precise scan
1693 * note that to_space pointers should be excluded anyway...
1695 char *heap_start = NULL;
1696 char *heap_end = (char*)-1;
1697 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, gc_thread_gray_queue);
1698 gboolean concurrent = mode != COPY_OR_MARK_FROM_ROOTS_SERIAL;
1700 SGEN_ASSERT (0, !!concurrent == !!concurrent_collection_in_progress, "We've been called with the wrong mode.");
1702 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1703 /*This cleans up unused fragments */
1704 sgen_nursery_allocator_prepare_for_pinning ();
1706 if (do_concurrent_checks)
1707 sgen_debug_check_nursery_is_clean ();
1709 /* The concurrent collector doesn't touch the nursery. */
1710 sgen_nursery_alloc_prepare_for_major ();
1715 /* Pinning depends on this */
1716 sgen_clear_nursery_fragments ();
1718 if (whole_heap_check_before_collection)
1719 sgen_check_whole_heap (TRUE);
1722 time_major_pre_collection_fragment_clear += TV_ELAPSED (atv, btv);
1724 if (!sgen_collection_is_concurrent ())
1725 nursery_section->next_data = sgen_get_nursery_end ();
1726 /* we should also coalesce scanning from sections close to each other
1727 * and deal with pointers outside of the sections later.
1732 sgen_client_pre_collection_checks ();
1734 if (mode != COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1735 /* Remsets are not useful for a major collection */
1736 remset.clear_cards ();
1739 sgen_process_fin_stage_entries ();
1742 sgen_init_pinning ();
1743 SGEN_LOG (6, "Collecting pinned addresses");
1744 pin_from_roots ((void*)lowest_heap_address, (void*)highest_heap_address, ctx);
1745 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1746 /* Pin cemented objects that were forced */
1747 sgen_pin_cemented_objects ();
1749 sgen_optimize_pin_queue ();
1750 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1752 * Cemented objects that are in the pinned list will be marked. When
1753 * marking concurrently we won't mark mod-union cards for these objects.
1754 * Instead they will remain cemented until the next major collection,
1755 * when we will recheck if they are still pinned in the roots.
1757 sgen_cement_force_pinned ();
1760 sgen_client_collecting_major_1 ();
1763 * pin_queue now contains all candidate pointers, sorted and
1764 * uniqued. We must do two passes now to figure out which
1765 * objects are pinned.
1767 * The first is to find within the pin_queue the area for each
1768 * section. This requires that the pin_queue be sorted. We
1769 * also process the LOS objects and pinned chunks here.
1771 * The second, destructive, pass is to reduce the section
1772 * areas to pointers to the actually pinned objects.
1774 SGEN_LOG (6, "Pinning from sections");
1775 /* first pass for the sections */
1776 sgen_find_section_pin_queue_start_end (nursery_section);
1777 /* identify possible pointers to the insize of large objects */
1778 SGEN_LOG (6, "Pinning from large objects");
1779 for (bigobj = los_object_list; bigobj; bigobj = bigobj->next) {
1781 if (sgen_find_optimized_pin_queue_area ((char*)bigobj->data, (char*)bigobj->data + sgen_los_object_size (bigobj), &dummy, &dummy)) {
1782 binary_protocol_pin (bigobj->data, (gpointer)LOAD_VTABLE (bigobj->data), safe_object_get_size (bigobj->data));
1784 if (sgen_los_object_is_pinned (bigobj->data)) {
1785 SGEN_ASSERT (0, mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT, "LOS objects can only be pinned here after concurrent marking.");
1788 sgen_los_pin_object (bigobj->data);
1789 if (SGEN_OBJECT_HAS_REFERENCES (bigobj->data))
1790 GRAY_OBJECT_ENQUEUE (gc_thread_gray_queue, bigobj->data, sgen_obj_get_descriptor ((GCObject*)bigobj->data));
1791 sgen_pin_stats_register_object (bigobj->data, GENERATION_OLD);
1792 SGEN_LOG (6, "Marked large object %p (%s) size: %lu from roots", bigobj->data,
1793 sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (bigobj->data)),
1794 (unsigned long)sgen_los_object_size (bigobj));
1796 sgen_client_pinned_los_object (bigobj->data);
1800 pin_objects_in_nursery (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT, ctx);
1801 if (check_nursery_objects_pinned && !sgen_minor_collector.is_split)
1802 sgen_check_nursery_objects_pinned (mode != COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT);
1804 major_collector.pin_objects (gc_thread_gray_queue);
1805 if (old_next_pin_slot)
1806 *old_next_pin_slot = sgen_get_pinned_count ();
1809 time_major_pinning += TV_ELAPSED (atv, btv);
1810 SGEN_LOG (2, "Finding pinned pointers: %zd in %lld usecs", sgen_get_pinned_count (), (long long)TV_ELAPSED (atv, btv));
1811 SGEN_LOG (4, "Start scan with %zd pinned objects", sgen_get_pinned_count ());
1813 major_collector.init_to_space ();
1815 SGEN_ASSERT (0, sgen_workers_all_done (), "Why are the workers not done when we start or finish a major collection?");
1816 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1817 if (sgen_workers_have_idle_work ()) {
1819 * We force the finish of the worker with the new object ops context
1820 * which can also do copying. We need to have finished pinning.
1822 /* FIXME Implement parallel copying and get rid of this ineffective hack */
1823 if (major_collector.is_parallel)
1824 sgen_workers_start_all_workers (&major_collector.major_ops_conc_par_start, NULL);
1826 sgen_workers_start_all_workers (object_ops, NULL);
1828 sgen_workers_join ();
1832 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
1833 main_gc_thread = mono_native_thread_self ();
1836 sgen_client_collecting_major_2 ();
1839 time_major_scan_pinned += TV_ELAPSED (btv, atv);
1841 sgen_client_collecting_major_3 (&fin_ready_queue, &critical_fin_queue);
1843 enqueue_scan_from_roots_jobs (gc_thread_gray_queue, heap_start, heap_end, object_ops, FALSE);
1846 time_major_scan_roots += TV_ELAPSED (atv, btv);
1849 * We start the concurrent worker after pinning and after we scanned the roots
1850 * in order to make sure that the worker does not finish before handling all
1853 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1854 if (precleaning_enabled) {
1856 /* Mod union preclean job */
1857 sj = (ScanJob*)sgen_thread_pool_job_alloc ("preclean mod union cardtable", job_mod_union_preclean, sizeof (ScanJob));
1858 sj->ops = object_ops;
1859 sj->gc_thread_gray_queue = NULL;
1860 sgen_workers_start_all_workers (object_ops, &sj->job);
1862 sgen_workers_start_all_workers (object_ops, NULL);
1864 gray_queue_enable_redirect (gc_thread_gray_queue);
1867 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1870 /* Mod union card table */
1871 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan mod union cardtable", job_scan_major_mod_union_card_table, sizeof (ScanJob));
1872 sj->ops = object_ops;
1873 sj->gc_thread_gray_queue = gc_thread_gray_queue;
1874 sgen_workers_enqueue_job (&sj->job, FALSE);
1876 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan LOS mod union cardtable", job_scan_los_mod_union_card_table, sizeof (ScanJob));
1877 sj->ops = object_ops;
1878 sj->gc_thread_gray_queue = gc_thread_gray_queue;
1879 sgen_workers_enqueue_job (&sj->job, FALSE);
1882 time_major_scan_mod_union += TV_ELAPSED (btv, atv);
1885 sgen_pin_stats_report ();
1887 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1888 sgen_finish_pinning ();
1890 sgen_pin_stats_reset ();
1892 if (do_concurrent_checks)
1893 sgen_debug_check_nursery_is_clean ();
1898 major_start_collection (SgenGrayQueue *gc_thread_gray_queue, const char *reason, gboolean concurrent, size_t *old_next_pin_slot)
1900 SgenObjectOperations *object_ops;
1902 binary_protocol_collection_begin (gc_stats.major_gc_count, GENERATION_OLD);
1904 current_collection_generation = GENERATION_OLD;
1906 sgen_workers_assert_gray_queue_is_empty ();
1909 sgen_cement_reset ();
1912 g_assert (major_collector.is_concurrent);
1913 concurrent_collection_in_progress = TRUE;
1915 if (major_collector.is_parallel)
1916 object_ops = &major_collector.major_ops_conc_par_start;
1918 object_ops = &major_collector.major_ops_concurrent_start;
1921 object_ops = &major_collector.major_ops_serial;
1924 reset_pinned_from_failed_allocation ();
1926 sgen_memgov_major_collection_start (concurrent, reason);
1928 //count_ref_nonref_objs ();
1929 //consistency_check ();
1931 check_scan_starts ();
1934 SGEN_LOG (1, "Start major collection %d", gc_stats.major_gc_count);
1935 gc_stats.major_gc_count ++;
1937 if (major_collector.start_major_collection)
1938 major_collector.start_major_collection ();
1940 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);
1944 major_finish_collection (SgenGrayQueue *gc_thread_gray_queue, const char *reason, gboolean is_overflow, size_t old_next_pin_slot, gboolean forced)
1946 ScannedObjectCounts counts;
1947 SgenObjectOperations *object_ops;
1948 mword fragment_total;
1954 if (concurrent_collection_in_progress) {
1955 if (major_collector.is_parallel)
1956 object_ops = &major_collector.major_ops_conc_par_finish;
1958 object_ops = &major_collector.major_ops_concurrent_finish;
1960 major_copy_or_mark_from_roots (gc_thread_gray_queue, NULL, COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT, object_ops);
1962 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
1963 main_gc_thread = NULL;
1966 object_ops = &major_collector.major_ops_serial;
1969 sgen_workers_assert_gray_queue_is_empty ();
1971 finish_gray_stack (GENERATION_OLD, CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, gc_thread_gray_queue));
1973 time_major_finish_gray_stack += TV_ELAPSED (btv, atv);
1975 SGEN_ASSERT (0, sgen_workers_all_done (), "Can't have workers working after joining");
1977 if (objects_pinned) {
1978 g_assert (!concurrent_collection_in_progress);
1981 * This is slow, but we just OOM'd.
1983 * See comment at `sgen_pin_queue_clear_discarded_entries` for how the pin
1984 * queue is laid out at this point.
1986 sgen_pin_queue_clear_discarded_entries (nursery_section, old_next_pin_slot);
1988 * We need to reestablish all pinned nursery objects in the pin queue
1989 * because they're needed for fragment creation. Unpinning happens by
1990 * walking the whole queue, so it's not necessary to reestablish where major
1991 * heap block pins are - all we care is that they're still in there
1994 sgen_optimize_pin_queue ();
1995 sgen_find_section_pin_queue_start_end (nursery_section);
1999 reset_heap_boundaries ();
2000 sgen_update_heap_boundaries ((mword)sgen_get_nursery_start (), (mword)sgen_get_nursery_end ());
2002 /* walk the pin_queue, build up the fragment list of free memory, unmark
2003 * pinned objects as we go, memzero() the empty fragments so they are ready for the
2006 fragment_total = sgen_build_nursery_fragments (nursery_section, NULL);
2007 if (!fragment_total)
2009 SGEN_LOG (4, "Free space in nursery after major %ld", (long)fragment_total);
2011 if (do_concurrent_checks && concurrent_collection_in_progress)
2012 sgen_debug_check_nursery_is_clean ();
2014 /* prepare the pin queue for the next collection */
2015 sgen_finish_pinning ();
2017 /* Clear TLABs for all threads */
2018 sgen_clear_tlabs ();
2020 sgen_pin_stats_reset ();
2022 sgen_cement_clear_below_threshold ();
2024 if (check_mark_bits_after_major_collection)
2025 sgen_check_heap_marked (concurrent_collection_in_progress);
2028 time_major_fragment_creation += TV_ELAPSED (atv, btv);
2030 binary_protocol_sweep_begin (GENERATION_OLD, !major_collector.sweeps_lazily);
2031 sgen_memgov_major_pre_sweep ();
2034 time_major_free_bigobjs += TV_ELAPSED (btv, atv);
2039 time_major_los_sweep += TV_ELAPSED (atv, btv);
2041 major_collector.sweep ();
2043 binary_protocol_sweep_end (GENERATION_OLD, !major_collector.sweeps_lazily);
2046 time_major_sweep += TV_ELAPSED (btv, atv);
2048 sgen_debug_dump_heap ("major", gc_stats.major_gc_count - 1, reason);
2050 if (sgen_have_pending_finalizers ()) {
2051 SGEN_LOG (4, "Finalizer-thread wakeup");
2052 sgen_client_finalize_notify ();
2055 sgen_memgov_major_collection_end (forced, concurrent_collection_in_progress, reason, is_overflow);
2056 current_collection_generation = -1;
2058 memset (&counts, 0, sizeof (ScannedObjectCounts));
2059 major_collector.finish_major_collection (&counts);
2061 sgen_workers_assert_gray_queue_is_empty ();
2063 SGEN_ASSERT (0, sgen_workers_all_done (), "Can't have workers working after major collection has finished");
2064 if (concurrent_collection_in_progress)
2065 concurrent_collection_in_progress = FALSE;
2067 check_scan_starts ();
2069 binary_protocol_flush_buffers (FALSE);
2071 //consistency_check ();
2073 binary_protocol_collection_end (gc_stats.major_gc_count - 1, GENERATION_OLD, counts.num_scanned_objects, counts.num_unique_scanned_objects);
2077 major_do_collection (const char *reason, gboolean is_overflow, gboolean forced)
2079 TV_DECLARE (time_start);
2080 TV_DECLARE (time_end);
2081 size_t old_next_pin_slot;
2082 SgenGrayQueue gc_thread_gray_queue;
2084 if (disable_major_collections)
2087 if (major_collector.get_and_reset_num_major_objects_marked) {
2088 long long num_marked = major_collector.get_and_reset_num_major_objects_marked ();
2089 g_assert (!num_marked);
2092 /* world must be stopped already */
2093 TV_GETTIME (time_start);
2095 init_gray_queue (&gc_thread_gray_queue, FALSE);
2096 major_start_collection (&gc_thread_gray_queue, reason, FALSE, &old_next_pin_slot);
2097 major_finish_collection (&gc_thread_gray_queue, reason, is_overflow, old_next_pin_slot, forced);
2098 sgen_gray_object_queue_dispose (&gc_thread_gray_queue);
2100 TV_GETTIME (time_end);
2101 gc_stats.major_gc_time += TV_ELAPSED (time_start, time_end);
2103 /* FIXME: also report this to the user, preferably in gc-end. */
2104 if (major_collector.get_and_reset_num_major_objects_marked)
2105 major_collector.get_and_reset_num_major_objects_marked ();
2107 return bytes_pinned_from_failed_allocation > 0;
2111 major_start_concurrent_collection (const char *reason)
2113 TV_DECLARE (time_start);
2114 TV_DECLARE (time_end);
2115 long long num_objects_marked;
2116 SgenGrayQueue gc_thread_gray_queue;
2118 if (disable_major_collections)
2121 TV_GETTIME (time_start);
2122 SGEN_TV_GETTIME (time_major_conc_collection_start);
2124 num_objects_marked = major_collector.get_and_reset_num_major_objects_marked ();
2125 g_assert (num_objects_marked == 0);
2127 binary_protocol_concurrent_start ();
2129 init_gray_queue (&gc_thread_gray_queue, TRUE);
2130 // FIXME: store reason and pass it when finishing
2131 major_start_collection (&gc_thread_gray_queue, reason, TRUE, NULL);
2132 sgen_gray_object_queue_dispose (&gc_thread_gray_queue);
2134 num_objects_marked = major_collector.get_and_reset_num_major_objects_marked ();
2136 TV_GETTIME (time_end);
2137 gc_stats.major_gc_time += TV_ELAPSED (time_start, time_end);
2139 current_collection_generation = -1;
2143 * Returns whether the major collection has finished.
2146 major_should_finish_concurrent_collection (void)
2148 return sgen_workers_all_done ();
2152 major_update_concurrent_collection (void)
2154 TV_DECLARE (total_start);
2155 TV_DECLARE (total_end);
2157 TV_GETTIME (total_start);
2159 binary_protocol_concurrent_update ();
2161 major_collector.update_cardtable_mod_union ();
2162 sgen_los_update_cardtable_mod_union ();
2164 TV_GETTIME (total_end);
2165 gc_stats.major_gc_time += TV_ELAPSED (total_start, total_end);
2169 major_finish_concurrent_collection (gboolean forced)
2171 SgenGrayQueue gc_thread_gray_queue;
2172 TV_DECLARE (total_start);
2173 TV_DECLARE (total_end);
2175 TV_GETTIME (total_start);
2177 binary_protocol_concurrent_finish ();
2180 * We need to stop all workers since we're updating the cardtable below.
2181 * The workers will be resumed with a finishing pause context to avoid
2182 * additional cardtable and object scanning.
2184 sgen_workers_stop_all_workers ();
2186 SGEN_TV_GETTIME (time_major_conc_collection_end);
2187 gc_stats.major_gc_time_concurrent += SGEN_TV_ELAPSED (time_major_conc_collection_start, time_major_conc_collection_end);
2189 major_collector.update_cardtable_mod_union ();
2190 sgen_los_update_cardtable_mod_union ();
2192 if (mod_union_consistency_check)
2193 sgen_check_mod_union_consistency ();
2195 current_collection_generation = GENERATION_OLD;
2196 sgen_cement_reset ();
2197 init_gray_queue (&gc_thread_gray_queue, FALSE);
2198 major_finish_collection (&gc_thread_gray_queue, "finishing", FALSE, -1, forced);
2199 sgen_gray_object_queue_dispose (&gc_thread_gray_queue);
2201 TV_GETTIME (total_end);
2202 gc_stats.major_gc_time += TV_ELAPSED (total_start, total_end);
2204 current_collection_generation = -1;
2208 * Ensure an allocation request for @size will succeed by freeing enough memory.
2210 * LOCKING: The GC lock MUST be held.
2213 sgen_ensure_free_space (size_t size, int generation)
2215 int generation_to_collect = -1;
2216 const char *reason = NULL;
2218 if (generation == GENERATION_OLD) {
2219 if (sgen_need_major_collection (size)) {
2220 reason = "LOS overflow";
2221 generation_to_collect = GENERATION_OLD;
2224 if (degraded_mode) {
2225 if (sgen_need_major_collection (size)) {
2226 reason = "Degraded mode overflow";
2227 generation_to_collect = GENERATION_OLD;
2229 } else if (sgen_need_major_collection (size)) {
2230 reason = concurrent_collection_in_progress ? "Forced finish concurrent collection" : "Minor allowance";
2231 generation_to_collect = GENERATION_OLD;
2233 generation_to_collect = GENERATION_NURSERY;
2234 reason = "Nursery full";
2238 if (generation_to_collect == -1) {
2239 if (concurrent_collection_in_progress && sgen_workers_all_done ()) {
2240 generation_to_collect = GENERATION_OLD;
2241 reason = "Finish concurrent collection";
2245 if (generation_to_collect == -1)
2247 sgen_perform_collection (size, generation_to_collect, reason, FALSE, TRUE);
2251 * LOCKING: Assumes the GC lock is held.
2254 sgen_perform_collection (size_t requested_size, int generation_to_collect, const char *reason, gboolean wait_to_finish, gboolean stw)
2256 TV_DECLARE (gc_total_start);
2257 TV_DECLARE (gc_total_end);
2258 int overflow_generation_to_collect = -1;
2259 int oldest_generation_collected = generation_to_collect;
2260 const char *overflow_reason = NULL;
2261 gboolean finish_concurrent = concurrent_collection_in_progress && (major_should_finish_concurrent_collection () || generation_to_collect == GENERATION_OLD);
2263 binary_protocol_collection_requested (generation_to_collect, requested_size, wait_to_finish ? 1 : 0);
2265 SGEN_ASSERT (0, generation_to_collect == GENERATION_NURSERY || generation_to_collect == GENERATION_OLD, "What generation is this?");
2268 sgen_stop_world (generation_to_collect);
2270 SGEN_ASSERT (0, sgen_is_world_stopped (), "We can only collect if the world is stopped");
2273 TV_GETTIME (gc_total_start);
2275 // FIXME: extract overflow reason
2276 // FIXME: minor overflow for concurrent case
2277 if (generation_to_collect == GENERATION_NURSERY && !finish_concurrent) {
2278 if (concurrent_collection_in_progress)
2279 major_update_concurrent_collection ();
2281 if (collect_nursery (reason, FALSE, NULL) && !concurrent_collection_in_progress) {
2282 overflow_generation_to_collect = GENERATION_OLD;
2283 overflow_reason = "Minor overflow";
2285 } else if (finish_concurrent) {
2286 major_finish_concurrent_collection (wait_to_finish);
2287 oldest_generation_collected = GENERATION_OLD;
2289 SGEN_ASSERT (0, generation_to_collect == GENERATION_OLD, "We should have handled nursery collections above");
2290 if (major_collector.is_concurrent && !wait_to_finish) {
2291 collect_nursery ("Concurrent start", FALSE, NULL);
2292 major_start_concurrent_collection (reason);
2293 oldest_generation_collected = GENERATION_NURSERY;
2294 } else if (major_do_collection (reason, FALSE, wait_to_finish)) {
2295 overflow_generation_to_collect = GENERATION_NURSERY;
2296 overflow_reason = "Excessive pinning";
2300 if (overflow_generation_to_collect != -1) {
2301 SGEN_ASSERT (0, !concurrent_collection_in_progress, "We don't yet support overflow collections with the concurrent collector");
2304 * We need to do an overflow collection, either because we ran out of memory
2305 * or the nursery is fully pinned.
2308 if (overflow_generation_to_collect == GENERATION_NURSERY)
2309 collect_nursery (overflow_reason, TRUE, NULL);
2311 major_do_collection (overflow_reason, TRUE, wait_to_finish);
2313 oldest_generation_collected = MAX (oldest_generation_collected, overflow_generation_to_collect);
2316 SGEN_LOG (2, "Heap size: %lu, LOS size: %lu", (unsigned long)sgen_gc_get_total_heap_allocation (), (unsigned long)los_memory_usage);
2318 /* this also sets the proper pointers for the next allocation */
2319 if (generation_to_collect == GENERATION_NURSERY && !sgen_can_alloc_size (requested_size)) {
2320 /* TypeBuilder and MonoMethod are killing mcs with fragmentation */
2321 SGEN_LOG (1, "nursery collection didn't find enough room for %zd alloc (%zd pinned)", requested_size, sgen_get_pinned_count ());
2322 sgen_dump_pin_queue ();
2326 TV_GETTIME (gc_total_end);
2327 time_max = MAX (time_max, TV_ELAPSED (gc_total_start, gc_total_end));
2330 sgen_restart_world (oldest_generation_collected);
2334 * ######################################################################
2335 * ######## Memory allocation from the OS
2336 * ######################################################################
2337 * This section of code deals with getting memory from the OS and
2338 * allocating memory for GC-internal data structures.
2339 * Internal memory can be handled with a freelist for small objects.
2345 G_GNUC_UNUSED static void
2346 report_internal_mem_usage (void)
2348 printf ("Internal memory usage:\n");
2349 sgen_report_internal_mem_usage ();
2350 printf ("Pinned memory usage:\n");
2351 major_collector.report_pinned_memory_usage ();
2355 * ######################################################################
2356 * ######## Finalization support
2357 * ######################################################################
2361 * If the object has been forwarded it means it's still referenced from a root.
2362 * If it is pinned it's still alive as well.
2363 * A LOS object is only alive if we have pinned it.
2364 * Return TRUE if @obj is ready to be finalized.
2366 static inline gboolean
2367 sgen_is_object_alive (GCObject *object)
2369 if (ptr_in_nursery (object))
2370 return sgen_nursery_is_object_alive (object);
2372 return sgen_major_is_object_alive (object);
2376 * This function returns true if @object is either alive and belongs to the
2377 * current collection - major collections are full heap, so old gen objects
2378 * are never alive during a minor collection.
2381 sgen_is_object_alive_and_on_current_collection (GCObject *object)
2383 if (ptr_in_nursery (object))
2384 return sgen_nursery_is_object_alive (object);
2386 if (current_collection_generation == GENERATION_NURSERY)
2389 return sgen_major_is_object_alive (object);
2394 sgen_gc_is_object_ready_for_finalization (GCObject *object)
2396 return !sgen_is_object_alive (object);
2400 sgen_queue_finalization_entry (GCObject *obj)
2402 gboolean critical = sgen_client_object_has_critical_finalizer (obj);
2404 sgen_pointer_queue_add (critical ? &critical_fin_queue : &fin_ready_queue, obj);
2406 sgen_client_object_queued_for_finalization (obj);
2410 sgen_object_is_live (GCObject *obj)
2412 return sgen_is_object_alive_and_on_current_collection (obj);
2416 * `System.GC.WaitForPendingFinalizers` first checks `sgen_have_pending_finalizers()` to
2417 * determine whether it can exit quickly. The latter must therefore only return FALSE if
2418 * all finalizers have really finished running.
2420 * `sgen_gc_invoke_finalizers()` first dequeues a finalizable object, and then finalizes it.
2421 * This means that just checking whether the queues are empty leaves the possibility that an
2422 * object might have been dequeued but not yet finalized. That's why we need the additional
2423 * flag `pending_unqueued_finalizer`.
2426 static volatile gboolean pending_unqueued_finalizer = FALSE;
2427 volatile gboolean sgen_suspend_finalizers = FALSE;
2430 sgen_set_suspend_finalizers (void)
2432 sgen_suspend_finalizers = TRUE;
2436 sgen_gc_invoke_finalizers (void)
2440 g_assert (!pending_unqueued_finalizer);
2442 /* FIXME: batch to reduce lock contention */
2443 while (sgen_have_pending_finalizers ()) {
2449 * We need to set `pending_unqueued_finalizer` before dequeing the
2450 * finalizable object.
2452 if (!sgen_pointer_queue_is_empty (&fin_ready_queue)) {
2453 pending_unqueued_finalizer = TRUE;
2454 mono_memory_write_barrier ();
2455 obj = (GCObject *)sgen_pointer_queue_pop (&fin_ready_queue);
2456 } else if (!sgen_pointer_queue_is_empty (&critical_fin_queue)) {
2457 pending_unqueued_finalizer = TRUE;
2458 mono_memory_write_barrier ();
2459 obj = (GCObject *)sgen_pointer_queue_pop (&critical_fin_queue);
2465 SGEN_LOG (7, "Finalizing object %p (%s)", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
2473 /* the object is on the stack so it is pinned */
2474 /*g_print ("Calling finalizer for object: %p (%s)\n", obj, sgen_client_object_safe_name (obj));*/
2475 sgen_client_run_finalize (obj);
2478 if (pending_unqueued_finalizer) {
2479 mono_memory_write_barrier ();
2480 pending_unqueued_finalizer = FALSE;
2487 sgen_have_pending_finalizers (void)
2489 if (sgen_suspend_finalizers)
2491 return pending_unqueued_finalizer || !sgen_pointer_queue_is_empty (&fin_ready_queue) || !sgen_pointer_queue_is_empty (&critical_fin_queue);
2495 * ######################################################################
2496 * ######## registered roots support
2497 * ######################################################################
2501 * We do not coalesce roots.
2504 sgen_register_root (char *start, size_t size, SgenDescriptor descr, int root_type, int source, const char *msg)
2506 RootRecord new_root;
2509 for (i = 0; i < ROOT_TYPE_NUM; ++i) {
2510 RootRecord *root = (RootRecord *)sgen_hash_table_lookup (&roots_hash [i], start);
2511 /* we allow changing the size and the descriptor (for thread statics etc) */
2513 size_t old_size = root->end_root - start;
2514 root->end_root = start + size;
2515 SGEN_ASSERT (0, !!root->root_desc == !!descr, "Can't change whether a root is precise or conservative.");
2516 SGEN_ASSERT (0, root->source == source, "Can't change a root's source identifier.");
2517 SGEN_ASSERT (0, !!root->msg == !!msg, "Can't change a root's message.");
2518 root->root_desc = descr;
2520 roots_size -= old_size;
2526 new_root.end_root = start + size;
2527 new_root.root_desc = descr;
2528 new_root.source = source;
2531 sgen_hash_table_replace (&roots_hash [root_type], start, &new_root, NULL);
2534 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);
2541 sgen_deregister_root (char* addr)
2547 for (root_type = 0; root_type < ROOT_TYPE_NUM; ++root_type) {
2548 if (sgen_hash_table_remove (&roots_hash [root_type], addr, &root))
2549 roots_size -= (root.end_root - addr);
2555 * ######################################################################
2556 * ######## Thread handling (stop/start code)
2557 * ######################################################################
2561 sgen_get_current_collection_generation (void)
2563 return current_collection_generation;
2567 sgen_thread_register (SgenThreadInfo* info, void *stack_bottom_fallback)
2569 info->tlab_start = info->tlab_next = info->tlab_temp_end = info->tlab_real_end = NULL;
2571 sgen_client_thread_register (info, stack_bottom_fallback);
2577 sgen_thread_unregister (SgenThreadInfo *p)
2579 sgen_client_thread_unregister (p);
2583 * ######################################################################
2584 * ######## Write barriers
2585 * ######################################################################
2589 * Note: the write barriers first do the needed GC work and then do the actual store:
2590 * this way the value is visible to the conservative GC scan after the write barrier
2591 * itself. If a GC interrupts the barrier in the middle, value will be kept alive by
2592 * the conservative scan, otherwise by the remembered set scan.
2596 mono_gc_wbarrier_arrayref_copy (gpointer dest_ptr, gpointer src_ptr, int count)
2598 HEAVY_STAT (++stat_wbarrier_arrayref_copy);
2599 /*This check can be done without taking a lock since dest_ptr array is pinned*/
2600 if (ptr_in_nursery (dest_ptr) || count <= 0) {
2601 mono_gc_memmove_aligned (dest_ptr, src_ptr, count * sizeof (gpointer));
2605 #ifdef SGEN_HEAVY_BINARY_PROTOCOL
2606 if (binary_protocol_is_heavy_enabled ()) {
2608 for (i = 0; i < count; ++i) {
2609 gpointer dest = (gpointer*)dest_ptr + i;
2610 gpointer obj = *((gpointer*)src_ptr + i);
2612 binary_protocol_wbarrier (dest, obj, (gpointer)LOAD_VTABLE (obj));
2617 remset.wbarrier_arrayref_copy (dest_ptr, src_ptr, count);
2621 mono_gc_wbarrier_generic_nostore (gpointer ptr)
2625 HEAVY_STAT (++stat_wbarrier_generic_store);
2627 sgen_client_wbarrier_generic_nostore_check (ptr);
2629 obj = *(gpointer*)ptr;
2631 binary_protocol_wbarrier (ptr, obj, (gpointer)LOAD_VTABLE (obj));
2634 * We need to record old->old pointer locations for the
2635 * concurrent collector.
2637 if (!ptr_in_nursery (obj) && !concurrent_collection_in_progress) {
2638 SGEN_LOG (8, "Skipping remset at %p", ptr);
2642 SGEN_LOG (8, "Adding remset at %p", ptr);
2644 remset.wbarrier_generic_nostore (ptr);
2648 mono_gc_wbarrier_generic_store (gpointer ptr, GCObject* value)
2650 SGEN_LOG (8, "Wbarrier store at %p to %p (%s)", ptr, value, value ? sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (value)) : "null");
2651 SGEN_UPDATE_REFERENCE_ALLOW_NULL (ptr, value);
2652 if (ptr_in_nursery (value) || concurrent_collection_in_progress)
2653 mono_gc_wbarrier_generic_nostore (ptr);
2654 sgen_dummy_use (value);
2657 /* Same as mono_gc_wbarrier_generic_store () but performs the store
2658 * as an atomic operation with release semantics.
2661 mono_gc_wbarrier_generic_store_atomic (gpointer ptr, GCObject *value)
2663 HEAVY_STAT (++stat_wbarrier_generic_store_atomic);
2665 SGEN_LOG (8, "Wbarrier atomic store at %p to %p (%s)", ptr, value, value ? sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (value)) : "null");
2667 InterlockedWritePointer ((volatile gpointer *)ptr, value);
2669 if (ptr_in_nursery (value) || concurrent_collection_in_progress)
2670 mono_gc_wbarrier_generic_nostore (ptr);
2672 sgen_dummy_use (value);
2676 sgen_wbarrier_value_copy_bitmap (gpointer _dest, gpointer _src, int size, unsigned bitmap)
2678 GCObject **dest = (GCObject **)_dest;
2679 GCObject **src = (GCObject **)_src;
2683 mono_gc_wbarrier_generic_store (dest, *src);
2688 size -= SIZEOF_VOID_P;
2694 * ######################################################################
2695 * ######## Other mono public interface functions.
2696 * ######################################################################
2700 sgen_gc_collect (int generation)
2705 sgen_perform_collection (0, generation, "user request", TRUE, TRUE);
2710 sgen_gc_collection_count (int generation)
2712 if (generation == 0)
2713 return gc_stats.minor_gc_count;
2714 return gc_stats.major_gc_count;
2718 sgen_gc_get_used_size (void)
2722 tot = los_memory_usage;
2723 tot += nursery_section->next_data - nursery_section->data;
2724 tot += major_collector.get_used_size ();
2725 /* FIXME: account for pinned objects */
2731 sgen_env_var_error (const char *env_var, const char *fallback, const char *description_format, ...)
2735 va_start (ap, description_format);
2737 fprintf (stderr, "Warning: In environment variable `%s': ", env_var);
2738 vfprintf (stderr, description_format, ap);
2740 fprintf (stderr, " - %s", fallback);
2741 fprintf (stderr, "\n");
2747 parse_double_in_interval (const char *env_var, const char *opt_name, const char *opt, double min, double max, double *result)
2750 double val = strtod (opt, &endptr);
2751 if (endptr == opt) {
2752 sgen_env_var_error (env_var, "Using default value.", "`%s` must be a number.", opt_name);
2755 else if (val < min || val > max) {
2756 sgen_env_var_error (env_var, "Using default value.", "`%s` must be between %.2f - %.2f.", opt_name, min, max);
2768 char *major_collector_opt = NULL;
2769 char *minor_collector_opt = NULL;
2770 char *params_opts = NULL;
2771 char *debug_opts = NULL;
2772 size_t max_heap = 0;
2773 size_t soft_limit = 0;
2775 gboolean debug_print_allowance = FALSE;
2776 double allowance_ratio = 0, save_target = 0;
2777 gboolean cement_enabled = TRUE;
2780 result = InterlockedCompareExchange (&gc_initialized, -1, 0);
2783 /* already inited */
2786 /* being inited by another thread */
2787 mono_thread_info_usleep (1000);
2790 /* we will init it */
2793 g_assert_not_reached ();
2795 } while (result != 0);
2797 SGEN_TV_GETTIME (sgen_init_timestamp);
2799 #ifdef SGEN_WITHOUT_MONO
2800 mono_thread_smr_init ();
2803 mono_coop_mutex_init (&gc_mutex);
2805 gc_debug_file = stderr;
2807 mono_coop_mutex_init (&sgen_interruption_mutex);
2809 if ((env = g_getenv (MONO_GC_PARAMS_NAME)) || gc_params_options) {
2810 params_opts = g_strdup_printf ("%s,%s", gc_params_options ? gc_params_options : "", env ? env : "");
2814 opts = g_strsplit (params_opts, ",", -1);
2815 for (ptr = opts; *ptr; ++ptr) {
2817 if (g_str_has_prefix (opt, "major=")) {
2818 opt = strchr (opt, '=') + 1;
2819 major_collector_opt = g_strdup (opt);
2820 } else if (g_str_has_prefix (opt, "minor=")) {
2821 opt = strchr (opt, '=') + 1;
2822 minor_collector_opt = g_strdup (opt);
2830 sgen_init_internal_allocator ();
2831 sgen_init_nursery_allocator ();
2832 sgen_init_fin_weak_hash ();
2833 sgen_init_hash_table ();
2834 sgen_init_descriptors ();
2835 sgen_init_gray_queues ();
2836 sgen_init_allocator ();
2837 sgen_init_gchandles ();
2839 sgen_register_fixed_internal_mem_type (INTERNAL_MEM_SECTION, SGEN_SIZEOF_GC_MEM_SECTION);
2840 sgen_register_fixed_internal_mem_type (INTERNAL_MEM_GRAY_QUEUE, sizeof (GrayQueueSection));
2842 sgen_client_init ();
2844 if (!minor_collector_opt) {
2845 sgen_simple_nursery_init (&sgen_minor_collector);
2847 if (!strcmp (minor_collector_opt, "simple")) {
2849 sgen_simple_nursery_init (&sgen_minor_collector);
2850 } else if (!strcmp (minor_collector_opt, "split")) {
2851 sgen_split_nursery_init (&sgen_minor_collector);
2853 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using `simple` instead.", "Unknown minor collector `%s'.", minor_collector_opt);
2854 goto use_simple_nursery;
2858 if (!major_collector_opt) {
2860 DEFAULT_MAJOR_INIT (&major_collector);
2861 } else if (!strcmp (major_collector_opt, "marksweep")) {
2862 sgen_marksweep_init (&major_collector);
2863 } else if (!strcmp (major_collector_opt, "marksweep-conc")) {
2864 sgen_marksweep_conc_init (&major_collector);
2865 } else if (!strcmp (major_collector_opt, "marksweep-conc-par")) {
2866 sgen_marksweep_conc_par_init (&major_collector);
2868 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using `" DEFAULT_MAJOR_NAME "` instead.", "Unknown major collector `%s'.", major_collector_opt);
2869 goto use_default_major;
2872 sgen_nursery_size = DEFAULT_NURSERY_SIZE;
2875 gboolean usage_printed = FALSE;
2877 for (ptr = opts; *ptr; ++ptr) {
2879 if (!strcmp (opt, ""))
2881 if (g_str_has_prefix (opt, "major="))
2883 if (g_str_has_prefix (opt, "minor="))
2885 if (g_str_has_prefix (opt, "max-heap-size=")) {
2886 size_t page_size = mono_pagesize ();
2887 size_t max_heap_candidate = 0;
2888 opt = strchr (opt, '=') + 1;
2889 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &max_heap_candidate)) {
2890 max_heap = (max_heap_candidate + page_size - 1) & ~(size_t)(page_size - 1);
2891 if (max_heap != max_heap_candidate)
2892 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Rounding up.", "`max-heap-size` size must be a multiple of %d.", page_size);
2894 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`max-heap-size` must be an integer.");
2898 if (g_str_has_prefix (opt, "soft-heap-limit=")) {
2899 opt = strchr (opt, '=') + 1;
2900 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &soft_limit)) {
2901 if (soft_limit <= 0) {
2902 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`soft-heap-limit` must be positive.");
2906 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`soft-heap-limit` must be an integer.");
2912 if (g_str_has_prefix (opt, "nursery-size=")) {
2914 opt = strchr (opt, '=') + 1;
2915 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &val)) {
2916 if ((val & (val - 1))) {
2917 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.", "`nursery-size` must be a power of two.");
2921 if (val < SGEN_MAX_NURSERY_WASTE) {
2922 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.",
2923 "`nursery-size` must be at least %d bytes.", SGEN_MAX_NURSERY_WASTE);
2927 sgen_nursery_size = val;
2928 sgen_nursery_bits = 0;
2929 while (ONE_P << (++ sgen_nursery_bits) != sgen_nursery_size)
2932 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.", "`nursery-size` must be an integer.");
2938 if (g_str_has_prefix (opt, "save-target-ratio=")) {
2940 opt = strchr (opt, '=') + 1;
2941 if (parse_double_in_interval (MONO_GC_PARAMS_NAME, "save-target-ratio", opt,
2942 SGEN_MIN_SAVE_TARGET_RATIO, SGEN_MAX_SAVE_TARGET_RATIO, &val)) {
2947 if (g_str_has_prefix (opt, "default-allowance-ratio=")) {
2949 opt = strchr (opt, '=') + 1;
2950 if (parse_double_in_interval (MONO_GC_PARAMS_NAME, "default-allowance-ratio", opt,
2951 SGEN_MIN_ALLOWANCE_NURSERY_SIZE_RATIO, SGEN_MAX_ALLOWANCE_NURSERY_SIZE_RATIO, &val)) {
2952 allowance_ratio = val;
2957 if (!strcmp (opt, "cementing")) {
2958 cement_enabled = TRUE;
2961 if (!strcmp (opt, "no-cementing")) {
2962 cement_enabled = FALSE;
2966 if (!strcmp (opt, "precleaning")) {
2967 precleaning_enabled = TRUE;
2970 if (!strcmp (opt, "no-precleaning")) {
2971 precleaning_enabled = FALSE;
2975 if (major_collector.handle_gc_param && major_collector.handle_gc_param (opt))
2978 if (sgen_minor_collector.handle_gc_param && sgen_minor_collector.handle_gc_param (opt))
2981 if (sgen_client_handle_gc_param (opt))
2984 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Ignoring.", "Unknown option `%s`.", opt);
2989 fprintf (stderr, "\n%s must be a comma-delimited list of one or more of the following:\n", MONO_GC_PARAMS_NAME);
2990 fprintf (stderr, " max-heap-size=N (where N is an integer, possibly with a k, m or a g suffix)\n");
2991 fprintf (stderr, " soft-heap-limit=n (where N is an integer, possibly with a k, m or a g suffix)\n");
2992 fprintf (stderr, " nursery-size=N (where N is an integer, possibly with a k, m or a g suffix)\n");
2993 fprintf (stderr, " major=COLLECTOR (where COLLECTOR is `marksweep', `marksweep-conc', `marksweep-par')\n");
2994 fprintf (stderr, " minor=COLLECTOR (where COLLECTOR is `simple' or `split')\n");
2995 fprintf (stderr, " wbarrier=WBARRIER (where WBARRIER is `remset' or `cardtable')\n");
2996 fprintf (stderr, " [no-]cementing\n");
2997 if (major_collector.print_gc_param_usage)
2998 major_collector.print_gc_param_usage ();
2999 if (sgen_minor_collector.print_gc_param_usage)
3000 sgen_minor_collector.print_gc_param_usage ();
3001 sgen_client_print_gc_params_usage ();
3002 fprintf (stderr, " Experimental options:\n");
3003 fprintf (stderr, " save-target-ratio=R (where R must be between %.2f - %.2f).\n", SGEN_MIN_SAVE_TARGET_RATIO, SGEN_MAX_SAVE_TARGET_RATIO);
3004 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);
3005 fprintf (stderr, "\n");
3007 usage_printed = TRUE;
3012 if (major_collector_opt)
3013 g_free (major_collector_opt);
3015 if (minor_collector_opt)
3016 g_free (minor_collector_opt);
3019 g_free (params_opts);
3023 sgen_pinning_init ();
3024 sgen_cement_init (cement_enabled);
3026 if ((env = g_getenv (MONO_GC_DEBUG_NAME)) || gc_debug_options) {
3027 debug_opts = g_strdup_printf ("%s,%s", gc_debug_options ? gc_debug_options : "", env ? env : "");
3031 gboolean usage_printed = FALSE;
3033 opts = g_strsplit (debug_opts, ",", -1);
3034 for (ptr = opts; ptr && *ptr; ptr ++) {
3036 if (!strcmp (opt, ""))
3038 if (opt [0] >= '0' && opt [0] <= '9') {
3039 gc_debug_level = atoi (opt);
3044 char *rf = g_strdup_printf ("%s.%d", opt, mono_process_current_pid ());
3045 gc_debug_file = fopen (rf, "wb");
3047 gc_debug_file = stderr;
3050 } else if (!strcmp (opt, "print-allowance")) {
3051 debug_print_allowance = TRUE;
3052 } else if (!strcmp (opt, "print-pinning")) {
3053 sgen_pin_stats_enable ();
3054 } else if (!strcmp (opt, "verify-before-allocs")) {
3055 verify_before_allocs = 1;
3056 has_per_allocation_action = TRUE;
3057 } else if (g_str_has_prefix (opt, "verify-before-allocs=")) {
3058 char *arg = strchr (opt, '=') + 1;
3059 verify_before_allocs = atoi (arg);
3060 has_per_allocation_action = TRUE;
3061 } else if (!strcmp (opt, "collect-before-allocs")) {
3062 collect_before_allocs = 1;
3063 has_per_allocation_action = TRUE;
3064 } else if (g_str_has_prefix (opt, "collect-before-allocs=")) {
3065 char *arg = strchr (opt, '=') + 1;
3066 has_per_allocation_action = TRUE;
3067 collect_before_allocs = atoi (arg);
3068 } else if (!strcmp (opt, "verify-before-collections")) {
3069 whole_heap_check_before_collection = TRUE;
3070 } else if (!strcmp (opt, "check-remset-consistency")) {
3071 remset_consistency_checks = TRUE;
3072 nursery_clear_policy = CLEAR_AT_GC;
3073 } else if (!strcmp (opt, "mod-union-consistency-check")) {
3074 if (!major_collector.is_concurrent) {
3075 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "`mod-union-consistency-check` only works with concurrent major collector.");
3078 mod_union_consistency_check = TRUE;
3079 } else if (!strcmp (opt, "check-mark-bits")) {
3080 check_mark_bits_after_major_collection = TRUE;
3081 } else if (!strcmp (opt, "check-nursery-pinned")) {
3082 check_nursery_objects_pinned = TRUE;
3083 } else if (!strcmp (opt, "clear-at-gc")) {
3084 nursery_clear_policy = CLEAR_AT_GC;
3085 } else if (!strcmp (opt, "clear-nursery-at-gc")) {
3086 nursery_clear_policy = CLEAR_AT_GC;
3087 } else if (!strcmp (opt, "clear-at-tlab-creation")) {
3088 nursery_clear_policy = CLEAR_AT_TLAB_CREATION;
3089 } else if (!strcmp (opt, "debug-clear-at-tlab-creation")) {
3090 nursery_clear_policy = CLEAR_AT_TLAB_CREATION_DEBUG;
3091 } else if (!strcmp (opt, "check-scan-starts")) {
3092 do_scan_starts_check = TRUE;
3093 } else if (!strcmp (opt, "verify-nursery-at-minor-gc")) {
3094 do_verify_nursery = TRUE;
3095 } else if (!strcmp (opt, "check-concurrent")) {
3096 if (!major_collector.is_concurrent) {
3097 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "`check-concurrent` only works with concurrent major collectors.");
3100 nursery_clear_policy = CLEAR_AT_GC;
3101 do_concurrent_checks = TRUE;
3102 } else if (!strcmp (opt, "dump-nursery-at-minor-gc")) {
3103 do_dump_nursery_content = TRUE;
3104 } else if (!strcmp (opt, "disable-minor")) {
3105 disable_minor_collections = TRUE;
3106 } else if (!strcmp (opt, "disable-major")) {
3107 disable_major_collections = TRUE;
3108 } else if (g_str_has_prefix (opt, "heap-dump=")) {
3109 char *filename = strchr (opt, '=') + 1;
3110 nursery_clear_policy = CLEAR_AT_GC;
3111 sgen_debug_enable_heap_dump (filename);
3112 } else if (g_str_has_prefix (opt, "binary-protocol=")) {
3113 char *filename = strchr (opt, '=') + 1;
3114 char *colon = strrchr (filename, ':');
3117 if (!mono_gc_parse_environment_string_extract_number (colon + 1, &limit)) {
3118 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring limit.", "Binary protocol file size limit must be an integer.");
3123 binary_protocol_init (filename, (long long)limit);
3124 } else if (!strcmp (opt, "nursery-canaries")) {
3125 do_verify_nursery = TRUE;
3126 enable_nursery_canaries = TRUE;
3127 } else if (!sgen_client_handle_gc_debug (opt)) {
3128 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "Unknown option `%s`.", opt);
3133 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);
3134 fprintf (stderr, "Valid <option>s are:\n");
3135 fprintf (stderr, " collect-before-allocs[=<n>]\n");
3136 fprintf (stderr, " verify-before-allocs[=<n>]\n");
3137 fprintf (stderr, " check-remset-consistency\n");
3138 fprintf (stderr, " check-mark-bits\n");
3139 fprintf (stderr, " check-nursery-pinned\n");
3140 fprintf (stderr, " verify-before-collections\n");
3141 fprintf (stderr, " verify-nursery-at-minor-gc\n");
3142 fprintf (stderr, " dump-nursery-at-minor-gc\n");
3143 fprintf (stderr, " disable-minor\n");
3144 fprintf (stderr, " disable-major\n");
3145 fprintf (stderr, " check-concurrent\n");
3146 fprintf (stderr, " clear-[nursery-]at-gc\n");
3147 fprintf (stderr, " clear-at-tlab-creation\n");
3148 fprintf (stderr, " debug-clear-at-tlab-creation\n");
3149 fprintf (stderr, " check-scan-starts\n");
3150 fprintf (stderr, " print-allowance\n");
3151 fprintf (stderr, " print-pinning\n");
3152 fprintf (stderr, " heap-dump=<filename>\n");
3153 fprintf (stderr, " binary-protocol=<filename>[:<file-size-limit>]\n");
3154 fprintf (stderr, " nursery-canaries\n");
3155 sgen_client_print_gc_debug_usage ();
3156 fprintf (stderr, "\n");
3158 usage_printed = TRUE;
3165 g_free (debug_opts);
3167 if (check_mark_bits_after_major_collection)
3168 nursery_clear_policy = CLEAR_AT_GC;
3170 if (major_collector.post_param_init)
3171 major_collector.post_param_init (&major_collector);
3173 if (major_collector.needs_thread_pool) {
3174 int num_workers = 1;
3175 if (major_collector.is_parallel) {
3176 /* FIXME Detect the number of physical cores, instead of logical */
3177 num_workers = mono_cpu_count () / 2;
3178 if (num_workers < 1)
3181 sgen_workers_init (num_workers);
3184 sgen_memgov_init (max_heap, soft_limit, debug_print_allowance, allowance_ratio, save_target);
3186 memset (&remset, 0, sizeof (remset));
3188 sgen_card_table_init (&remset);
3190 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");
3194 sgen_init_bridge ();
3198 sgen_gc_initialized ()
3200 return gc_initialized > 0;
3204 sgen_get_nursery_clear_policy (void)
3206 return nursery_clear_policy;
3212 mono_coop_mutex_lock (&gc_mutex);
3216 sgen_gc_unlock (void)
3218 mono_coop_mutex_unlock (&gc_mutex);
3222 sgen_major_collector_iterate_live_block_ranges (sgen_cardtable_block_callback callback)
3224 major_collector.iterate_live_block_ranges (callback);
3228 sgen_major_collector_iterate_block_ranges (sgen_cardtable_block_callback callback)
3230 major_collector.iterate_block_ranges (callback);
3234 sgen_get_major_collector (void)
3236 return &major_collector;
3240 sgen_get_remset (void)
3246 count_cards (long long *major_total, long long *major_marked, long long *los_total, long long *los_marked)
3248 sgen_get_major_collector ()->count_cards (major_total, major_marked);
3249 sgen_los_count_cards (los_total, los_marked);
3252 static gboolean world_is_stopped = FALSE;
3254 /* LOCKING: assumes the GC lock is held */
3256 sgen_stop_world (int generation)
3258 long long major_total = -1, major_marked = -1, los_total = -1, los_marked = -1;
3260 SGEN_ASSERT (0, !world_is_stopped, "Why are we stopping a stopped world?");
3262 binary_protocol_world_stopping (generation, sgen_timestamp (), (gpointer) (gsize) mono_native_thread_id_get ());
3264 sgen_client_stop_world (generation);
3266 world_is_stopped = TRUE;
3268 if (binary_protocol_is_heavy_enabled ())
3269 count_cards (&major_total, &major_marked, &los_total, &los_marked);
3270 binary_protocol_world_stopped (generation, sgen_timestamp (), major_total, major_marked, los_total, los_marked);
3273 /* LOCKING: assumes the GC lock is held */
3275 sgen_restart_world (int generation)
3277 long long major_total = -1, major_marked = -1, los_total = -1, los_marked = -1;
3280 SGEN_ASSERT (0, world_is_stopped, "Why are we restarting a running world?");
3282 if (binary_protocol_is_heavy_enabled ())
3283 count_cards (&major_total, &major_marked, &los_total, &los_marked);
3284 binary_protocol_world_restarting (generation, sgen_timestamp (), major_total, major_marked, los_total, los_marked);
3286 world_is_stopped = FALSE;
3288 sgen_client_restart_world (generation, &stw_time);
3290 binary_protocol_world_restarted (generation, sgen_timestamp ());
3292 if (sgen_client_bridge_need_processing ())
3293 sgen_client_bridge_processing_finish (generation);
3295 sgen_memgov_collection_end (generation, stw_time);
3299 sgen_is_world_stopped (void)
3301 return world_is_stopped;
3305 sgen_check_whole_heap_stw (void)
3307 sgen_stop_world (0);
3308 sgen_clear_nursery_fragments ();
3309 sgen_check_whole_heap (TRUE);
3310 sgen_restart_world (0);
3314 sgen_timestamp (void)
3316 SGEN_TV_DECLARE (timestamp);
3317 SGEN_TV_GETTIME (timestamp);
3318 return SGEN_TV_ELAPSED (sgen_init_timestamp, timestamp);
3321 #endif /* HAVE_SGEN_GC */