2 * sgen-gc.c: Simple generational GC.
5 * Paolo Molaro (lupus@ximian.com)
6 * Rodrigo Kumpera (kumpera@gmail.com)
8 * Copyright 2005-2011 Novell, Inc (http://www.novell.com)
9 * Copyright 2011 Xamarin Inc (http://www.xamarin.com)
11 * Thread start/stop adapted from Boehm's GC:
12 * Copyright (c) 1994 by Xerox Corporation. All rights reserved.
13 * Copyright (c) 1996 by Silicon Graphics. All rights reserved.
14 * Copyright (c) 1998 by Fergus Henderson. All rights reserved.
15 * Copyright (c) 2000-2004 by Hewlett-Packard Company. All rights reserved.
16 * Copyright 2001-2003 Ximian, Inc
17 * Copyright 2003-2010 Novell, Inc.
18 * Copyright 2011 Xamarin, Inc.
19 * Copyright (C) 2012 Xamarin Inc
21 * Licensed under the MIT license. See LICENSE file in the project root for full license information.
23 * Important: allocation provides always zeroed memory, having to do
24 * a memset after allocation is deadly for performance.
25 * Memory usage at startup is currently as follows:
27 * 64 KB internal space
29 * We should provide a small memory config with half the sizes
31 * We currently try to make as few mono assumptions as possible:
32 * 1) 2-word header with no GC pointers in it (first vtable, second to store the
34 * 2) gc descriptor is the second word in the vtable (first word in the class)
35 * 3) 8 byte alignment is the minimum and enough (not true for special structures (SIMD), FIXME)
36 * 4) there is a function to get an object's size and the number of
37 * elements in an array.
38 * 5) we know the special way bounds are allocated for complex arrays
39 * 6) we know about proxies and how to treat them when domains are unloaded
41 * Always try to keep stack usage to a minimum: no recursive behaviour
42 * and no large stack allocs.
44 * General description.
45 * Objects are initially allocated in a nursery using a fast bump-pointer technique.
46 * When the nursery is full we start a nursery collection: this is performed with a
48 * When the old generation is full we start a copying GC of the old generation as well:
49 * this will be changed to mark&sweep with copying when fragmentation becomes to severe
50 * in the future. Maybe we'll even do both during the same collection like IMMIX.
52 * The things that complicate this description are:
53 * *) pinned objects: we can't move them so we need to keep track of them
54 * *) no precise info of the thread stacks and registers: we need to be able to
55 * quickly find the objects that may be referenced conservatively and pin them
56 * (this makes the first issues more important)
57 * *) large objects are too expensive to be dealt with using copying GC: we handle them
58 * with mark/sweep during major collections
59 * *) some objects need to not move even if they are small (interned strings, Type handles):
60 * we use mark/sweep for them, too: they are not allocated in the nursery, but inside
61 * PinnedChunks regions
67 *) we could have a function pointer in MonoClass to implement
68 customized write barriers for value types
70 *) investigate the stuff needed to advance a thread to a GC-safe
71 point (single-stepping, read from unmapped memory etc) and implement it.
72 This would enable us to inline allocations and write barriers, for example,
73 or at least parts of them, like the write barrier checks.
74 We may need this also for handling precise info on stacks, even simple things
75 as having uninitialized data on the stack and having to wait for the prolog
76 to zero it. Not an issue for the last frame that we scan conservatively.
77 We could always not trust the value in the slots anyway.
79 *) modify the jit to save info about references in stack locations:
80 this can be done just for locals as a start, so that at least
81 part of the stack is handled precisely.
83 *) test/fix endianess issues
85 *) Implement a card table as the write barrier instead of remembered
86 sets? Card tables are not easy to implement with our current
87 memory layout. We have several different kinds of major heap
88 objects: Small objects in regular blocks, small objects in pinned
89 chunks and LOS objects. If we just have a pointer we have no way
90 to tell which kind of object it points into, therefore we cannot
91 know where its card table is. The least we have to do to make
92 this happen is to get rid of write barriers for indirect stores.
95 *) Get rid of write barriers for indirect stores. We can do this by
96 telling the GC to wbarrier-register an object once we do an ldloca
97 or ldelema on it, and to unregister it once it's not used anymore
98 (it can only travel downwards on the stack). The problem with
99 unregistering is that it needs to happen eventually no matter
100 what, even if exceptions are thrown, the thread aborts, etc.
101 Rodrigo suggested that we could do only the registering part and
102 let the collector find out (pessimistically) when it's safe to
103 unregister, namely when the stack pointer of the thread that
104 registered the object is higher than it was when the registering
105 happened. This might make for a good first implementation to get
106 some data on performance.
108 *) Some sort of blacklist support? Blacklists is a concept from the
109 Boehm GC: if during a conservative scan we find pointers to an
110 area which we might use as heap, we mark that area as unusable, so
111 pointer retention by random pinning pointers is reduced.
113 *) experiment with max small object size (very small right now - 2kb,
114 because it's tied to the max freelist size)
116 *) add an option to mmap the whole heap in one chunk: it makes for many
117 simplifications in the checks (put the nursery at the top and just use a single
118 check for inclusion/exclusion): the issue this has is that on 32 bit systems it's
119 not flexible (too much of the address space may be used by default or we can't
120 increase the heap as needed) and we'd need a race-free mechanism to return memory
121 back to the system (mprotect(PROT_NONE) will still keep the memory allocated if it
122 was written to, munmap is needed, but the following mmap may not find the same segment
125 *) memzero the major fragments after restarting the world and optionally a smaller
128 *) investigate having fragment zeroing threads
130 *) separate locks for finalization and other minor stuff to reduce
133 *) try a different copying order to improve memory locality
135 *) a thread abort after a store but before the write barrier will
136 prevent the write barrier from executing
138 *) specialized dynamically generated markers/copiers
140 *) Dynamically adjust TLAB size to the number of threads. If we have
141 too many threads that do allocation, we might need smaller TLABs,
142 and we might get better performance with larger TLABs if we only
143 have a handful of threads. We could sum up the space left in all
144 assigned TLABs and if that's more than some percentage of the
145 nursery size, reduce the TLAB size.
147 *) Explore placing unreachable objects on unused nursery memory.
148 Instead of memset'ng a region to zero, place an int[] covering it.
149 A good place to start is add_nursery_frag. The tricky thing here is
150 placing those objects atomically outside of a collection.
152 *) Allocation should use asymmetric Dekker synchronization:
153 http://blogs.oracle.com/dave/resource/Asymmetric-Dekker-Synchronization.txt
154 This should help weak consistency archs.
161 #define _XOPEN_SOURCE
162 #define _DARWIN_C_SOURCE
168 #ifdef HAVE_PTHREAD_H
171 #ifdef HAVE_PTHREAD_NP_H
172 #include <pthread_np.h>
180 #include "mono/sgen/sgen-gc.h"
181 #include "mono/sgen/sgen-cardtable.h"
182 #include "mono/sgen/sgen-protocol.h"
183 #include "mono/sgen/sgen-memory-governor.h"
184 #include "mono/sgen/sgen-hash-table.h"
185 #include "mono/sgen/sgen-cardtable.h"
186 #include "mono/sgen/sgen-pinning.h"
187 #include "mono/sgen/sgen-workers.h"
188 #include "mono/sgen/sgen-client.h"
189 #include "mono/sgen/sgen-pointer-queue.h"
190 #include "mono/sgen/gc-internal-agnostic.h"
191 #include "mono/utils/mono-proclib.h"
192 #include "mono/utils/mono-memory-model.h"
193 #include "mono/utils/hazard-pointer.h"
195 #include <mono/utils/memcheck.h>
197 #undef pthread_create
199 #undef pthread_detach
202 * ######################################################################
203 * ######## Types and constants used by the GC.
204 * ######################################################################
207 /* 0 means not initialized, 1 is initialized, -1 means in progress */
208 static int gc_initialized = 0;
209 /* If set, check if we need to do something every X allocations */
210 gboolean has_per_allocation_action;
211 /* If set, do a heap check every X allocation */
212 guint32 verify_before_allocs = 0;
213 /* If set, do a minor collection before every X allocation */
214 guint32 collect_before_allocs = 0;
215 /* If set, do a whole heap check before each collection */
216 static gboolean whole_heap_check_before_collection = FALSE;
217 /* If set, do a heap consistency check before each minor collection */
218 static gboolean consistency_check_at_minor_collection = FALSE;
219 /* If set, do a mod union consistency check before each finishing collection pause */
220 static gboolean mod_union_consistency_check = FALSE;
221 /* If set, check whether mark bits are consistent after major collections */
222 static gboolean check_mark_bits_after_major_collection = FALSE;
223 /* If set, check that all nursery objects are pinned/not pinned, depending on context */
224 static gboolean check_nursery_objects_pinned = FALSE;
225 /* If set, do a few checks when the concurrent collector is used */
226 static gboolean do_concurrent_checks = FALSE;
227 /* If set, do a plausibility check on the scan_starts before and after
229 static gboolean do_scan_starts_check = FALSE;
231 static gboolean disable_minor_collections = FALSE;
232 static gboolean disable_major_collections = FALSE;
233 static gboolean do_verify_nursery = FALSE;
234 static gboolean do_dump_nursery_content = FALSE;
235 static gboolean enable_nursery_canaries = FALSE;
237 static gboolean precleaning_enabled = TRUE;
239 #ifdef HEAVY_STATISTICS
240 guint64 stat_objects_alloced_degraded = 0;
241 guint64 stat_bytes_alloced_degraded = 0;
243 guint64 stat_copy_object_called_nursery = 0;
244 guint64 stat_objects_copied_nursery = 0;
245 guint64 stat_copy_object_called_major = 0;
246 guint64 stat_objects_copied_major = 0;
248 guint64 stat_scan_object_called_nursery = 0;
249 guint64 stat_scan_object_called_major = 0;
251 guint64 stat_slots_allocated_in_vain;
253 guint64 stat_nursery_copy_object_failed_from_space = 0;
254 guint64 stat_nursery_copy_object_failed_forwarded = 0;
255 guint64 stat_nursery_copy_object_failed_pinned = 0;
256 guint64 stat_nursery_copy_object_failed_to_space = 0;
258 static guint64 stat_wbarrier_add_to_global_remset = 0;
259 static guint64 stat_wbarrier_arrayref_copy = 0;
260 static guint64 stat_wbarrier_generic_store = 0;
261 static guint64 stat_wbarrier_generic_store_atomic = 0;
262 static guint64 stat_wbarrier_set_root = 0;
265 static guint64 stat_pinned_objects = 0;
267 static guint64 time_minor_pre_collection_fragment_clear = 0;
268 static guint64 time_minor_pinning = 0;
269 static guint64 time_minor_scan_remsets = 0;
270 static guint64 time_minor_scan_pinned = 0;
271 static guint64 time_minor_scan_roots = 0;
272 static guint64 time_minor_finish_gray_stack = 0;
273 static guint64 time_minor_fragment_creation = 0;
275 static guint64 time_major_pre_collection_fragment_clear = 0;
276 static guint64 time_major_pinning = 0;
277 static guint64 time_major_scan_pinned = 0;
278 static guint64 time_major_scan_roots = 0;
279 static guint64 time_major_scan_mod_union = 0;
280 static guint64 time_major_finish_gray_stack = 0;
281 static guint64 time_major_free_bigobjs = 0;
282 static guint64 time_major_los_sweep = 0;
283 static guint64 time_major_sweep = 0;
284 static guint64 time_major_fragment_creation = 0;
286 static guint64 time_max = 0;
288 static SGEN_TV_DECLARE (time_major_conc_collection_start);
289 static SGEN_TV_DECLARE (time_major_conc_collection_end);
291 static SGEN_TV_DECLARE (last_minor_collection_start_tv);
292 static SGEN_TV_DECLARE (last_minor_collection_end_tv);
294 int gc_debug_level = 0;
299 mono_gc_flush_info (void)
301 fflush (gc_debug_file);
305 #define TV_DECLARE SGEN_TV_DECLARE
306 #define TV_GETTIME SGEN_TV_GETTIME
307 #define TV_ELAPSED SGEN_TV_ELAPSED
309 static SGEN_TV_DECLARE (sgen_init_timestamp);
311 NurseryClearPolicy nursery_clear_policy = CLEAR_AT_TLAB_CREATION;
313 #define object_is_forwarded SGEN_OBJECT_IS_FORWARDED
314 #define object_is_pinned SGEN_OBJECT_IS_PINNED
315 #define pin_object SGEN_PIN_OBJECT
317 #define ptr_in_nursery sgen_ptr_in_nursery
319 #define LOAD_VTABLE SGEN_LOAD_VTABLE
322 nursery_canaries_enabled (void)
324 return enable_nursery_canaries;
327 #define safe_object_get_size sgen_safe_object_get_size
330 * ######################################################################
331 * ######## Global data.
332 * ######################################################################
334 MonoCoopMutex gc_mutex;
336 #define SCAN_START_SIZE SGEN_SCAN_START_SIZE
338 size_t degraded_mode = 0;
340 static mword bytes_pinned_from_failed_allocation = 0;
342 GCMemSection *nursery_section = NULL;
343 static volatile mword lowest_heap_address = ~(mword)0;
344 static volatile mword highest_heap_address = 0;
346 MonoCoopMutex sgen_interruption_mutex;
348 int current_collection_generation = -1;
349 static volatile gboolean concurrent_collection_in_progress = FALSE;
351 /* objects that are ready to be finalized */
352 static SgenPointerQueue fin_ready_queue = SGEN_POINTER_QUEUE_INIT (INTERNAL_MEM_FINALIZE_READY);
353 static SgenPointerQueue critical_fin_queue = SGEN_POINTER_QUEUE_INIT (INTERNAL_MEM_FINALIZE_READY);
355 /* registered roots: the key to the hash is the root start address */
357 * Different kinds of roots are kept separate to speed up pin_from_roots () for example.
359 SgenHashTable roots_hash [ROOT_TYPE_NUM] = {
360 SGEN_HASH_TABLE_INIT (INTERNAL_MEM_ROOTS_TABLE, INTERNAL_MEM_ROOT_RECORD, sizeof (RootRecord), sgen_aligned_addr_hash, NULL),
361 SGEN_HASH_TABLE_INIT (INTERNAL_MEM_ROOTS_TABLE, INTERNAL_MEM_ROOT_RECORD, sizeof (RootRecord), sgen_aligned_addr_hash, NULL),
362 SGEN_HASH_TABLE_INIT (INTERNAL_MEM_ROOTS_TABLE, INTERNAL_MEM_ROOT_RECORD, sizeof (RootRecord), sgen_aligned_addr_hash, NULL)
364 static mword roots_size = 0; /* amount of memory in the root set */
366 /* The size of a TLAB */
367 /* The bigger the value, the less often we have to go to the slow path to allocate a new
368 * one, but the more space is wasted by threads not allocating much memory.
370 * FIXME: Make this self-tuning for each thread.
372 guint32 tlab_size = (1024 * 4);
374 #define MAX_SMALL_OBJ_SIZE SGEN_MAX_SMALL_OBJ_SIZE
376 #define ALLOC_ALIGN SGEN_ALLOC_ALIGN
378 #define ALIGN_UP SGEN_ALIGN_UP
380 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
381 MonoNativeThreadId main_gc_thread = NULL;
384 /*Object was pinned during the current collection*/
385 static mword objects_pinned;
388 * ######################################################################
389 * ######## Macros and function declarations.
390 * ######################################################################
393 typedef SgenGrayQueue GrayQueue;
395 /* forward declarations */
396 static void scan_from_registered_roots (char *addr_start, char *addr_end, int root_type, ScanCopyContext ctx);
398 static void pin_from_roots (void *start_nursery, void *end_nursery, ScanCopyContext ctx);
399 static void finish_gray_stack (int generation, ScanCopyContext ctx);
402 SgenMajorCollector major_collector;
403 SgenMinorCollector sgen_minor_collector;
404 /* FIXME: get rid of this */
405 static GrayQueue gray_queue;
407 static SgenRememberedSet remset;
409 /* The gray queue to use from the main collection thread. */
410 #define WORKERS_DISTRIBUTE_GRAY_QUEUE (&gray_queue)
413 * The gray queue a worker job must use. If we're not parallel or
414 * concurrent, we use the main gray queue.
416 static SgenGrayQueue*
417 sgen_workers_get_job_gray_queue (WorkerData *worker_data)
419 return worker_data ? &worker_data->private_gray_queue : WORKERS_DISTRIBUTE_GRAY_QUEUE;
423 gray_queue_redirect (SgenGrayQueue *queue)
425 gboolean wake = FALSE;
428 GrayQueueSection *section = sgen_gray_object_dequeue_section (queue);
431 sgen_section_gray_queue_enqueue ((SgenSectionGrayQueue *)queue->alloc_prepare_data, section);
436 g_assert (concurrent_collection_in_progress);
437 sgen_workers_ensure_awake ();
442 gray_queue_enable_redirect (SgenGrayQueue *queue)
444 if (!concurrent_collection_in_progress)
447 sgen_gray_queue_set_alloc_prepare (queue, gray_queue_redirect, sgen_workers_get_distribute_section_gray_queue ());
448 gray_queue_redirect (queue);
452 sgen_scan_area_with_callback (char *start, char *end, IterateObjectCallbackFunc callback, void *data, gboolean allow_flags, gboolean fail_on_canaries)
454 while (start < end) {
458 if (!*(void**)start) {
459 start += sizeof (void*); /* should be ALLOC_ALIGN, really */
464 if (!(obj = (char *)SGEN_OBJECT_IS_FORWARDED (start)))
470 if (!sgen_client_object_is_array_fill ((GCObject*)obj)) {
471 CHECK_CANARY_FOR_OBJECT ((GCObject*)obj, fail_on_canaries);
472 size = ALIGN_UP (safe_object_get_size ((GCObject*)obj));
473 callback ((GCObject*)obj, size, data);
474 CANARIFY_SIZE (size);
476 size = ALIGN_UP (safe_object_get_size ((GCObject*)obj));
484 * sgen_add_to_global_remset:
486 * The global remset contains locations which point into newspace after
487 * a minor collection. This can happen if the objects they point to are pinned.
489 * LOCKING: If called from a parallel collector, the global remset
490 * lock must be held. For serial collectors that is not necessary.
493 sgen_add_to_global_remset (gpointer ptr, GCObject *obj)
495 SGEN_ASSERT (5, sgen_ptr_in_nursery (obj), "Target pointer of global remset must be in the nursery");
497 HEAVY_STAT (++stat_wbarrier_add_to_global_remset);
499 if (!major_collector.is_concurrent) {
500 SGEN_ASSERT (5, current_collection_generation != -1, "Global remsets can only be added during collections");
502 if (current_collection_generation == -1)
503 SGEN_ASSERT (5, sgen_concurrent_collection_in_progress (), "Global remsets outside of collection pauses can only be added by the concurrent collector");
506 if (!object_is_pinned (obj))
507 SGEN_ASSERT (5, sgen_minor_collector.is_split || sgen_concurrent_collection_in_progress (), "Non-pinned objects can only remain in nursery if it is a split nursery");
508 else if (sgen_cement_lookup_or_register (obj))
511 remset.record_pointer (ptr);
513 sgen_pin_stats_register_global_remset (obj);
515 SGEN_LOG (8, "Adding global remset for %p", ptr);
516 binary_protocol_global_remset (ptr, obj, (gpointer)SGEN_LOAD_VTABLE (obj));
520 * sgen_drain_gray_stack:
522 * Scan objects in the gray stack until the stack is empty. This should be called
523 * frequently after each object is copied, to achieve better locality and cache
528 sgen_drain_gray_stack (ScanCopyContext ctx)
530 ScanObjectFunc scan_func = ctx.ops->scan_object;
531 GrayQueue *queue = ctx.queue;
533 if (ctx.ops->drain_gray_stack)
534 return ctx.ops->drain_gray_stack (queue);
539 GRAY_OBJECT_DEQUEUE (queue, &obj, &desc);
542 SGEN_LOG (9, "Precise gray object scan %p (%s)", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
543 scan_func (obj, desc, queue);
549 * Addresses in the pin queue are already sorted. This function finds
550 * the object header for each address and pins the object. The
551 * addresses must be inside the nursery section. The (start of the)
552 * address array is overwritten with the addresses of the actually
553 * pinned objects. Return the number of pinned objects.
556 pin_objects_from_nursery_pin_queue (gboolean do_scan_objects, ScanCopyContext ctx)
558 GCMemSection *section = nursery_section;
559 void **start = sgen_pinning_get_entry (section->pin_queue_first_entry);
560 void **end = sgen_pinning_get_entry (section->pin_queue_last_entry);
561 void *start_nursery = section->data;
562 void *end_nursery = section->next_data;
567 void *pinning_front = start_nursery;
569 void **definitely_pinned = start;
570 ScanObjectFunc scan_func = ctx.ops->scan_object;
571 SgenGrayQueue *queue = ctx.queue;
573 sgen_nursery_allocator_prepare_for_pinning ();
575 while (start < end) {
576 GCObject *obj_to_pin = NULL;
577 size_t obj_to_pin_size = 0;
582 SGEN_ASSERT (0, addr >= start_nursery && addr < end_nursery, "Potential pinning address out of range");
583 SGEN_ASSERT (0, addr >= last, "Pin queue not sorted");
590 SGEN_LOG (5, "Considering pinning addr %p", addr);
591 /* We've already processed everything up to pinning_front. */
592 if (addr < pinning_front) {
598 * Find the closest scan start <= addr. We might search backward in the
599 * scan_starts array because entries might be NULL. In the worst case we
600 * start at start_nursery.
602 idx = ((char*)addr - (char*)section->data) / SCAN_START_SIZE;
603 SGEN_ASSERT (0, idx < section->num_scan_start, "Scan start index out of range");
604 search_start = (void*)section->scan_starts [idx];
605 if (!search_start || search_start > addr) {
608 search_start = section->scan_starts [idx];
609 if (search_start && search_start <= addr)
612 if (!search_start || search_start > addr)
613 search_start = start_nursery;
617 * If the pinning front is closer than the scan start we found, start
618 * searching at the front.
620 if (search_start < pinning_front)
621 search_start = pinning_front;
624 * Now addr should be in an object a short distance from search_start.
626 * search_start must point to zeroed mem or point to an object.
629 size_t obj_size, canarified_obj_size;
632 if (!*(void**)search_start) {
633 search_start = (void*)ALIGN_UP ((mword)search_start + sizeof (gpointer));
634 /* The loop condition makes sure we don't overrun addr. */
638 canarified_obj_size = obj_size = ALIGN_UP (safe_object_get_size ((GCObject*)search_start));
641 * Filler arrays are marked by an invalid sync word. We don't
642 * consider them for pinning. They are not delimited by canaries,
645 if (!sgen_client_object_is_array_fill ((GCObject*)search_start)) {
646 CHECK_CANARY_FOR_OBJECT (search_start, TRUE);
647 CANARIFY_SIZE (canarified_obj_size);
649 if (addr >= search_start && (char*)addr < (char*)search_start + obj_size) {
650 /* This is the object we're looking for. */
651 obj_to_pin = (GCObject*)search_start;
652 obj_to_pin_size = canarified_obj_size;
657 /* Skip to the next object */
658 search_start = (void*)((char*)search_start + canarified_obj_size);
659 } while (search_start <= addr);
661 /* We've searched past the address we were looking for. */
663 pinning_front = search_start;
664 goto next_pin_queue_entry;
668 * We've found an object to pin. It might still be a dummy array, but we
669 * can advance the pinning front in any case.
671 pinning_front = (char*)obj_to_pin + obj_to_pin_size;
674 * If this is a dummy array marking the beginning of a nursery
675 * fragment, we don't pin it.
677 if (sgen_client_object_is_array_fill (obj_to_pin))
678 goto next_pin_queue_entry;
681 * Finally - pin the object!
683 desc = sgen_obj_get_descriptor_safe (obj_to_pin);
684 if (do_scan_objects) {
685 scan_func (obj_to_pin, desc, queue);
687 SGEN_LOG (4, "Pinned object %p, vtable %p (%s), count %d\n",
688 obj_to_pin, *(void**)obj_to_pin, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj_to_pin)), count);
689 binary_protocol_pin (obj_to_pin,
690 (gpointer)LOAD_VTABLE (obj_to_pin),
691 safe_object_get_size (obj_to_pin));
693 pin_object (obj_to_pin);
694 GRAY_OBJECT_ENQUEUE (queue, obj_to_pin, desc);
695 sgen_pin_stats_register_object (obj_to_pin, obj_to_pin_size);
696 definitely_pinned [count] = obj_to_pin;
699 if (concurrent_collection_in_progress)
700 sgen_pinning_register_pinned_in_nursery (obj_to_pin);
702 next_pin_queue_entry:
706 sgen_client_nursery_objects_pinned (definitely_pinned, count);
707 stat_pinned_objects += count;
712 pin_objects_in_nursery (gboolean do_scan_objects, ScanCopyContext ctx)
716 if (nursery_section->pin_queue_first_entry == nursery_section->pin_queue_last_entry)
719 reduced_to = pin_objects_from_nursery_pin_queue (do_scan_objects, ctx);
720 nursery_section->pin_queue_last_entry = nursery_section->pin_queue_first_entry + reduced_to;
724 * This function is only ever called (via `collector_pin_object()` in `sgen-copy-object.h`)
725 * when we can't promote an object because we're out of memory.
728 sgen_pin_object (GCObject *object, GrayQueue *queue)
730 SGEN_ASSERT (0, sgen_ptr_in_nursery (object), "We're only supposed to use this for pinning nursery objects when out of memory.");
733 * All pinned objects are assumed to have been staged, so we need to stage as well.
734 * Also, the count of staged objects shows that "late pinning" happened.
736 sgen_pin_stage_ptr (object);
738 SGEN_PIN_OBJECT (object);
739 binary_protocol_pin (object, (gpointer)LOAD_VTABLE (object), safe_object_get_size (object));
742 sgen_pin_stats_register_object (object, safe_object_get_size (object));
744 GRAY_OBJECT_ENQUEUE (queue, object, sgen_obj_get_descriptor_safe (object));
747 /* Sort the addresses in array in increasing order.
748 * Done using a by-the book heap sort. Which has decent and stable performance, is pretty cache efficient.
751 sgen_sort_addresses (void **array, size_t size)
756 for (i = 1; i < size; ++i) {
759 size_t parent = (child - 1) / 2;
761 if (array [parent] >= array [child])
764 tmp = array [parent];
765 array [parent] = array [child];
772 for (i = size - 1; i > 0; --i) {
775 array [i] = array [0];
781 while (root * 2 + 1 <= end) {
782 size_t child = root * 2 + 1;
784 if (child < end && array [child] < array [child + 1])
786 if (array [root] >= array [child])
790 array [root] = array [child];
799 * Scan the memory between start and end and queue values which could be pointers
800 * to the area between start_nursery and end_nursery for later consideration.
801 * Typically used for thread stacks.
804 sgen_conservatively_pin_objects_from (void **start, void **end, void *start_nursery, void *end_nursery, int pin_type)
808 SGEN_ASSERT (0, ((mword)start & (SIZEOF_VOID_P - 1)) == 0, "Why are we scanning for references in unaligned memory ?");
810 #if defined(VALGRIND_MAKE_MEM_DEFINED_IF_ADDRESSABLE) && !defined(_WIN64)
811 VALGRIND_MAKE_MEM_DEFINED_IF_ADDRESSABLE (start, (char*)end - (char*)start);
814 while (start < end) {
816 * *start can point to the middle of an object
817 * note: should we handle pointing at the end of an object?
818 * pinning in C# code disallows pointing at the end of an object
819 * but there is some small chance that an optimizing C compiler
820 * may keep the only reference to an object by pointing
821 * at the end of it. We ignore this small chance for now.
822 * Pointers to the end of an object are indistinguishable
823 * from pointers to the start of the next object in memory
824 * so if we allow that we'd need to pin two objects...
825 * We queue the pointer in an array, the
826 * array will then be sorted and uniqued. This way
827 * we can coalesce several pinning pointers and it should
828 * be faster since we'd do a memory scan with increasing
829 * addresses. Note: we can align the address to the allocation
830 * alignment, so the unique process is more effective.
832 mword addr = (mword)*start;
833 addr &= ~(ALLOC_ALIGN - 1);
834 if (addr >= (mword)start_nursery && addr < (mword)end_nursery) {
835 SGEN_LOG (6, "Pinning address %p from %p", (void*)addr, start);
836 sgen_pin_stage_ptr ((void*)addr);
837 binary_protocol_pin_stage (start, (void*)addr);
838 sgen_pin_stats_register_address ((char*)addr, pin_type);
844 SGEN_LOG (7, "found %d potential pinned heap pointers", count);
848 * The first thing we do in a collection is to identify pinned objects.
849 * This function considers all the areas of memory that need to be
850 * conservatively scanned.
853 pin_from_roots (void *start_nursery, void *end_nursery, ScanCopyContext ctx)
857 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);
858 /* objects pinned from the API are inside these roots */
859 SGEN_HASH_TABLE_FOREACH (&roots_hash [ROOT_TYPE_PINNED], void **, start_root, RootRecord *, root) {
860 SGEN_LOG (6, "Pinned roots %p-%p", start_root, root->end_root);
861 sgen_conservatively_pin_objects_from (start_root, (void**)root->end_root, start_nursery, end_nursery, PIN_TYPE_OTHER);
862 } SGEN_HASH_TABLE_FOREACH_END;
863 /* now deal with the thread stacks
864 * in the future we should be able to conservatively scan only:
865 * *) the cpu registers
866 * *) the unmanaged stack frames
867 * *) the _last_ managed stack frame
868 * *) pointers slots in managed frames
870 sgen_client_scan_thread_data (start_nursery, end_nursery, FALSE, ctx);
874 single_arg_user_copy_or_mark (GCObject **obj, void *gc_data)
876 ScanCopyContext *ctx = (ScanCopyContext *)gc_data;
877 ctx->ops->copy_or_mark_object (obj, ctx->queue);
881 * The memory area from start_root to end_root contains pointers to objects.
882 * Their position is precisely described by @desc (this means that the pointer
883 * can be either NULL or the pointer to the start of an object).
884 * This functions copies them to to_space updates them.
886 * This function is not thread-safe!
889 precisely_scan_objects_from (void** start_root, void** end_root, char* n_start, char *n_end, SgenDescriptor desc, ScanCopyContext ctx)
891 CopyOrMarkObjectFunc copy_func = ctx.ops->copy_or_mark_object;
892 SgenGrayQueue *queue = ctx.queue;
894 switch (desc & ROOT_DESC_TYPE_MASK) {
895 case ROOT_DESC_BITMAP:
896 desc >>= ROOT_DESC_TYPE_SHIFT;
898 if ((desc & 1) && *start_root) {
899 copy_func ((GCObject**)start_root, queue);
900 SGEN_LOG (9, "Overwrote root at %p with %p", start_root, *start_root);
906 case ROOT_DESC_COMPLEX: {
907 gsize *bitmap_data = (gsize *)sgen_get_complex_descriptor_bitmap (desc);
908 gsize bwords = (*bitmap_data) - 1;
909 void **start_run = start_root;
911 while (bwords-- > 0) {
912 gsize bmap = *bitmap_data++;
913 void **objptr = start_run;
915 if ((bmap & 1) && *objptr) {
916 copy_func ((GCObject**)objptr, queue);
917 SGEN_LOG (9, "Overwrote root at %p with %p", objptr, *objptr);
922 start_run += GC_BITS_PER_WORD;
926 case ROOT_DESC_USER: {
927 SgenUserRootMarkFunc marker = sgen_get_user_descriptor_func (desc);
928 marker (start_root, single_arg_user_copy_or_mark, &ctx);
931 case ROOT_DESC_RUN_LEN:
932 g_assert_not_reached ();
934 g_assert_not_reached ();
939 reset_heap_boundaries (void)
941 lowest_heap_address = ~(mword)0;
942 highest_heap_address = 0;
946 sgen_update_heap_boundaries (mword low, mword high)
951 old = lowest_heap_address;
954 } while (SGEN_CAS_PTR ((gpointer*)&lowest_heap_address, (gpointer)low, (gpointer)old) != (gpointer)old);
957 old = highest_heap_address;
960 } while (SGEN_CAS_PTR ((gpointer*)&highest_heap_address, (gpointer)high, (gpointer)old) != (gpointer)old);
964 * Allocate and setup the data structures needed to be able to allocate objects
965 * in the nursery. The nursery is stored in nursery_section.
970 GCMemSection *section;
977 SGEN_LOG (2, "Allocating nursery size: %zu", (size_t)sgen_nursery_size);
978 /* later we will alloc a larger area for the nursery but only activate
979 * what we need. The rest will be used as expansion if we have too many pinned
980 * objects in the existing nursery.
982 /* FIXME: handle OOM */
983 section = (GCMemSection *)sgen_alloc_internal (INTERNAL_MEM_SECTION);
985 alloc_size = sgen_nursery_size;
987 /* If there isn't enough space even for the nursery we should simply abort. */
988 g_assert (sgen_memgov_try_alloc_space (alloc_size, SPACE_NURSERY));
990 data = (char *)major_collector.alloc_heap (alloc_size, alloc_size, DEFAULT_NURSERY_BITS);
991 sgen_update_heap_boundaries ((mword)data, (mword)(data + sgen_nursery_size));
992 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 ());
993 section->data = section->next_data = data;
994 section->size = alloc_size;
995 section->end_data = data + sgen_nursery_size;
996 scan_starts = (alloc_size + SCAN_START_SIZE - 1) / SCAN_START_SIZE;
997 section->scan_starts = (char **)sgen_alloc_internal_dynamic (sizeof (char*) * scan_starts, INTERNAL_MEM_SCAN_STARTS, TRUE);
998 section->num_scan_start = scan_starts;
1000 nursery_section = section;
1002 sgen_nursery_allocator_set_nursery_bounds (data, data + sgen_nursery_size);
1006 mono_gc_get_logfile (void)
1008 return gc_debug_file;
1012 scan_finalizer_entries (SgenPointerQueue *fin_queue, ScanCopyContext ctx)
1014 CopyOrMarkObjectFunc copy_func = ctx.ops->copy_or_mark_object;
1015 SgenGrayQueue *queue = ctx.queue;
1018 for (i = 0; i < fin_queue->next_slot; ++i) {
1019 GCObject *obj = (GCObject *)fin_queue->data [i];
1022 SGEN_LOG (5, "Scan of fin ready object: %p (%s)\n", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
1023 copy_func ((GCObject**)&fin_queue->data [i], queue);
1028 generation_name (int generation)
1030 switch (generation) {
1031 case GENERATION_NURSERY: return "nursery";
1032 case GENERATION_OLD: return "old";
1033 default: g_assert_not_reached ();
1038 sgen_generation_name (int generation)
1040 return generation_name (generation);
1044 finish_gray_stack (int generation, ScanCopyContext ctx)
1048 int done_with_ephemerons, ephemeron_rounds = 0;
1049 char *start_addr = generation == GENERATION_NURSERY ? sgen_get_nursery_start () : NULL;
1050 char *end_addr = generation == GENERATION_NURSERY ? sgen_get_nursery_end () : (char*)-1;
1051 SgenGrayQueue *queue = ctx.queue;
1053 binary_protocol_finish_gray_stack_start (sgen_timestamp (), generation);
1055 * We copied all the reachable objects. Now it's the time to copy
1056 * the objects that were not referenced by the roots, but by the copied objects.
1057 * we built a stack of objects pointed to by gray_start: they are
1058 * additional roots and we may add more items as we go.
1059 * We loop until gray_start == gray_objects which means no more objects have
1060 * been added. Note this is iterative: no recursion is involved.
1061 * We need to walk the LO list as well in search of marked big objects
1062 * (use a flag since this is needed only on major collections). We need to loop
1063 * here as well, so keep a counter of marked LO (increasing it in copy_object).
1064 * To achieve better cache locality and cache usage, we drain the gray stack
1065 * frequently, after each object is copied, and just finish the work here.
1067 sgen_drain_gray_stack (ctx);
1069 SGEN_LOG (2, "%s generation done", generation_name (generation));
1072 Reset bridge data, we might have lingering data from a previous collection if this is a major
1073 collection trigged by minor overflow.
1075 We must reset the gathered bridges since their original block might be evacuated due to major
1076 fragmentation in the meanwhile and the bridge code should not have to deal with that.
1078 if (sgen_client_bridge_need_processing ())
1079 sgen_client_bridge_reset_data ();
1082 * Mark all strong toggleref objects. This must be done before we walk ephemerons or finalizers
1083 * to ensure they see the full set of live objects.
1085 sgen_client_mark_togglerefs (start_addr, end_addr, ctx);
1088 * Walk the ephemeron tables marking all values with reachable keys. This must be completely done
1089 * before processing finalizable objects and non-tracking weak links to avoid finalizing/clearing
1090 * objects that are in fact reachable.
1092 done_with_ephemerons = 0;
1094 done_with_ephemerons = sgen_client_mark_ephemerons (ctx);
1095 sgen_drain_gray_stack (ctx);
1097 } while (!done_with_ephemerons);
1099 if (sgen_client_bridge_need_processing ()) {
1100 /*Make sure the gray stack is empty before we process bridge objects so we get liveness right*/
1101 sgen_drain_gray_stack (ctx);
1102 sgen_collect_bridge_objects (generation, ctx);
1103 if (generation == GENERATION_OLD)
1104 sgen_collect_bridge_objects (GENERATION_NURSERY, ctx);
1107 Do the first bridge step here, as the collector liveness state will become useless after that.
1109 An important optimization is to only proccess the possibly dead part of the object graph and skip
1110 over all live objects as we transitively know everything they point must be alive too.
1112 The above invariant is completely wrong if we let the gray queue be drained and mark/copy everything.
1114 This has the unfortunate side effect of making overflow collections perform the first step twice, but
1115 given we now have heuristics that perform major GC in anticipation of minor overflows this should not
1118 sgen_client_bridge_processing_stw_step ();
1122 Make sure we drain the gray stack before processing disappearing links and finalizers.
1123 If we don't make sure it is empty we might wrongly see a live object as dead.
1125 sgen_drain_gray_stack (ctx);
1128 We must clear weak links that don't track resurrection before processing object ready for
1129 finalization so they can be cleared before that.
1131 sgen_null_link_in_range (generation, ctx, FALSE);
1132 if (generation == GENERATION_OLD)
1133 sgen_null_link_in_range (GENERATION_NURSERY, ctx, FALSE);
1136 /* walk the finalization queue and move also the objects that need to be
1137 * finalized: use the finalized objects as new roots so the objects they depend
1138 * on are also not reclaimed. As with the roots above, only objects in the nursery
1139 * are marked/copied.
1141 sgen_finalize_in_range (generation, ctx);
1142 if (generation == GENERATION_OLD)
1143 sgen_finalize_in_range (GENERATION_NURSERY, ctx);
1144 /* drain the new stack that might have been created */
1145 SGEN_LOG (6, "Precise scan of gray area post fin");
1146 sgen_drain_gray_stack (ctx);
1149 * This must be done again after processing finalizable objects since CWL slots are cleared only after the key is finalized.
1151 done_with_ephemerons = 0;
1153 done_with_ephemerons = sgen_client_mark_ephemerons (ctx);
1154 sgen_drain_gray_stack (ctx);
1156 } while (!done_with_ephemerons);
1158 sgen_client_clear_unreachable_ephemerons (ctx);
1161 * We clear togglerefs only after all possible chances of revival are done.
1162 * This is semantically more inline with what users expect and it allows for
1163 * user finalizers to correctly interact with TR objects.
1165 sgen_client_clear_togglerefs (start_addr, end_addr, ctx);
1168 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);
1171 * handle disappearing links
1172 * Note we do this after checking the finalization queue because if an object
1173 * survives (at least long enough to be finalized) we don't clear the link.
1174 * This also deals with a possible issue with the monitor reclamation: with the Boehm
1175 * GC a finalized object my lose the monitor because it is cleared before the finalizer is
1178 g_assert (sgen_gray_object_queue_is_empty (queue));
1180 sgen_null_link_in_range (generation, ctx, TRUE);
1181 if (generation == GENERATION_OLD)
1182 sgen_null_link_in_range (GENERATION_NURSERY, ctx, TRUE);
1183 if (sgen_gray_object_queue_is_empty (queue))
1185 sgen_drain_gray_stack (ctx);
1188 g_assert (sgen_gray_object_queue_is_empty (queue));
1190 sgen_gray_object_queue_trim_free_list (queue);
1191 binary_protocol_finish_gray_stack_end (sgen_timestamp (), generation);
1195 sgen_check_section_scan_starts (GCMemSection *section)
1198 for (i = 0; i < section->num_scan_start; ++i) {
1199 if (section->scan_starts [i]) {
1200 mword size = safe_object_get_size ((GCObject*) section->scan_starts [i]);
1201 SGEN_ASSERT (0, size >= SGEN_CLIENT_MINIMUM_OBJECT_SIZE && size <= MAX_SMALL_OBJ_SIZE, "Weird object size at scan starts.");
1207 check_scan_starts (void)
1209 if (!do_scan_starts_check)
1211 sgen_check_section_scan_starts (nursery_section);
1212 major_collector.check_scan_starts ();
1216 scan_from_registered_roots (char *addr_start, char *addr_end, int root_type, ScanCopyContext ctx)
1220 SGEN_HASH_TABLE_FOREACH (&roots_hash [root_type], void **, start_root, RootRecord *, root) {
1221 SGEN_LOG (6, "Precise root scan %p-%p (desc: %p)", start_root, root->end_root, (void*)root->root_desc);
1222 precisely_scan_objects_from (start_root, (void**)root->end_root, addr_start, addr_end, root->root_desc, ctx);
1223 } SGEN_HASH_TABLE_FOREACH_END;
1229 static gboolean inited = FALSE;
1234 mono_counters_register ("Collection max time", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME | MONO_COUNTER_MONOTONIC, &time_max);
1236 mono_counters_register ("Minor fragment clear", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_pre_collection_fragment_clear);
1237 mono_counters_register ("Minor pinning", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_pinning);
1238 mono_counters_register ("Minor scan remembered set", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_remsets);
1239 mono_counters_register ("Minor scan pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_pinned);
1240 mono_counters_register ("Minor scan roots", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_roots);
1241 mono_counters_register ("Minor fragment creation", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_fragment_creation);
1243 mono_counters_register ("Major fragment clear", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_pre_collection_fragment_clear);
1244 mono_counters_register ("Major pinning", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_pinning);
1245 mono_counters_register ("Major scan pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_pinned);
1246 mono_counters_register ("Major scan roots", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_roots);
1247 mono_counters_register ("Major scan mod union", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_mod_union);
1248 mono_counters_register ("Major finish gray stack", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_finish_gray_stack);
1249 mono_counters_register ("Major free big objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_free_bigobjs);
1250 mono_counters_register ("Major LOS sweep", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_los_sweep);
1251 mono_counters_register ("Major sweep", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_sweep);
1252 mono_counters_register ("Major fragment creation", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_fragment_creation);
1254 mono_counters_register ("Number of pinned objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_pinned_objects);
1256 #ifdef HEAVY_STATISTICS
1257 mono_counters_register ("WBarrier remember pointer", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_add_to_global_remset);
1258 mono_counters_register ("WBarrier arrayref copy", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_arrayref_copy);
1259 mono_counters_register ("WBarrier generic store called", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_generic_store);
1260 mono_counters_register ("WBarrier generic atomic store called", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_generic_store_atomic);
1261 mono_counters_register ("WBarrier set root", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_set_root);
1263 mono_counters_register ("# objects allocated degraded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_alloced_degraded);
1264 mono_counters_register ("bytes allocated degraded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_bytes_alloced_degraded);
1266 mono_counters_register ("# copy_object() called (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_copy_object_called_nursery);
1267 mono_counters_register ("# objects copied (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_copied_nursery);
1268 mono_counters_register ("# copy_object() called (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_copy_object_called_major);
1269 mono_counters_register ("# objects copied (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_copied_major);
1271 mono_counters_register ("# scan_object() called (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_scan_object_called_nursery);
1272 mono_counters_register ("# scan_object() called (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_scan_object_called_major);
1274 mono_counters_register ("Slots allocated in vain", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_slots_allocated_in_vain);
1276 mono_counters_register ("# nursery copy_object() failed from space", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_from_space);
1277 mono_counters_register ("# nursery copy_object() failed forwarded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_forwarded);
1278 mono_counters_register ("# nursery copy_object() failed pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_pinned);
1279 mono_counters_register ("# nursery copy_object() failed to space", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_to_space);
1281 sgen_nursery_allocator_init_heavy_stats ();
1289 reset_pinned_from_failed_allocation (void)
1291 bytes_pinned_from_failed_allocation = 0;
1295 sgen_set_pinned_from_failed_allocation (mword objsize)
1297 bytes_pinned_from_failed_allocation += objsize;
1301 sgen_collection_is_concurrent (void)
1303 switch (current_collection_generation) {
1304 case GENERATION_NURSERY:
1306 case GENERATION_OLD:
1307 return concurrent_collection_in_progress;
1309 g_error ("Invalid current generation %d", current_collection_generation);
1315 sgen_concurrent_collection_in_progress (void)
1317 return concurrent_collection_in_progress;
1321 SgenThreadPoolJob job;
1322 SgenObjectOperations *ops;
1326 job_remembered_set_scan (void *worker_data_untyped, SgenThreadPoolJob *job)
1328 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1329 ScanJob *job_data = (ScanJob*)job;
1330 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1331 remset.scan_remsets (ctx);
1335 SgenThreadPoolJob job;
1336 SgenObjectOperations *ops;
1340 } ScanFromRegisteredRootsJob;
1343 job_scan_from_registered_roots (void *worker_data_untyped, SgenThreadPoolJob *job)
1345 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1346 ScanFromRegisteredRootsJob *job_data = (ScanFromRegisteredRootsJob*)job;
1347 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1349 scan_from_registered_roots (job_data->heap_start, job_data->heap_end, job_data->root_type, ctx);
1353 SgenThreadPoolJob job;
1354 SgenObjectOperations *ops;
1357 } ScanThreadDataJob;
1360 job_scan_thread_data (void *worker_data_untyped, SgenThreadPoolJob *job)
1362 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1363 ScanThreadDataJob *job_data = (ScanThreadDataJob*)job;
1364 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1366 sgen_client_scan_thread_data (job_data->heap_start, job_data->heap_end, TRUE, ctx);
1370 SgenThreadPoolJob job;
1371 SgenObjectOperations *ops;
1372 SgenPointerQueue *queue;
1373 } ScanFinalizerEntriesJob;
1376 job_scan_finalizer_entries (void *worker_data_untyped, SgenThreadPoolJob *job)
1378 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1379 ScanFinalizerEntriesJob *job_data = (ScanFinalizerEntriesJob*)job;
1380 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1382 scan_finalizer_entries (job_data->queue, ctx);
1386 job_scan_major_mod_union_card_table (void *worker_data_untyped, SgenThreadPoolJob *job)
1388 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1389 ScanJob *job_data = (ScanJob*)job;
1390 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_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 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1400 ScanJob *job_data = (ScanJob*)job;
1401 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1403 g_assert (concurrent_collection_in_progress);
1404 sgen_los_scan_card_table (CARDTABLE_SCAN_MOD_UNION, ctx);
1408 job_mod_union_preclean (void *worker_data_untyped, SgenThreadPoolJob *job)
1410 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1411 ScanJob *job_data = (ScanJob*)job;
1412 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1414 g_assert (concurrent_collection_in_progress);
1416 major_collector.scan_card_table (CARDTABLE_SCAN_MOD_UNION_PRECLEAN, ctx);
1417 sgen_los_scan_card_table (CARDTABLE_SCAN_MOD_UNION_PRECLEAN, ctx);
1419 sgen_scan_pin_queue_objects (ctx);
1423 init_gray_queue (gboolean use_workers)
1426 sgen_workers_init_distribute_gray_queue ();
1427 sgen_gray_object_queue_init (&gray_queue, NULL);
1431 enqueue_scan_from_roots_jobs (char *heap_start, char *heap_end, SgenObjectOperations *ops, gboolean enqueue)
1433 ScanFromRegisteredRootsJob *scrrj;
1434 ScanThreadDataJob *stdj;
1435 ScanFinalizerEntriesJob *sfej;
1437 /* registered roots, this includes static fields */
1439 scrrj = (ScanFromRegisteredRootsJob*)sgen_thread_pool_job_alloc ("scan from registered roots normal", job_scan_from_registered_roots, sizeof (ScanFromRegisteredRootsJob));
1441 scrrj->heap_start = heap_start;
1442 scrrj->heap_end = heap_end;
1443 scrrj->root_type = ROOT_TYPE_NORMAL;
1444 sgen_workers_enqueue_job (&scrrj->job, enqueue);
1446 scrrj = (ScanFromRegisteredRootsJob*)sgen_thread_pool_job_alloc ("scan from registered roots wbarrier", job_scan_from_registered_roots, sizeof (ScanFromRegisteredRootsJob));
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->job, enqueue);
1455 stdj = (ScanThreadDataJob*)sgen_thread_pool_job_alloc ("scan thread data", job_scan_thread_data, sizeof (ScanThreadDataJob));
1456 stdj->heap_start = heap_start;
1457 stdj->heap_end = heap_end;
1458 sgen_workers_enqueue_job (&stdj->job, enqueue);
1460 /* Scan the list of objects ready for finalization. */
1462 sfej = (ScanFinalizerEntriesJob*)sgen_thread_pool_job_alloc ("scan finalizer entries", job_scan_finalizer_entries, sizeof (ScanFinalizerEntriesJob));
1463 sfej->queue = &fin_ready_queue;
1465 sgen_workers_enqueue_job (&sfej->job, enqueue);
1467 sfej = (ScanFinalizerEntriesJob*)sgen_thread_pool_job_alloc ("scan critical finalizer entries", job_scan_finalizer_entries, sizeof (ScanFinalizerEntriesJob));
1468 sfej->queue = &critical_fin_queue;
1470 sgen_workers_enqueue_job (&sfej->job, enqueue);
1474 * Perform a nursery collection.
1476 * Return whether any objects were late-pinned due to being out of memory.
1479 collect_nursery (SgenGrayQueue *unpin_queue, gboolean finish_up_concurrent_mark)
1481 gboolean needs_major;
1482 size_t max_garbage_amount;
1484 mword fragment_total;
1486 SgenObjectOperations *object_ops = &sgen_minor_collector.serial_ops;
1487 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, &gray_queue);
1491 if (disable_minor_collections)
1494 TV_GETTIME (last_minor_collection_start_tv);
1495 atv = last_minor_collection_start_tv;
1497 binary_protocol_collection_begin (gc_stats.minor_gc_count, GENERATION_NURSERY);
1499 if (do_verify_nursery || do_dump_nursery_content)
1500 sgen_debug_verify_nursery (do_dump_nursery_content);
1502 current_collection_generation = GENERATION_NURSERY;
1504 SGEN_ASSERT (0, !sgen_collection_is_concurrent (), "Why is the nursery collection concurrent?");
1506 reset_pinned_from_failed_allocation ();
1508 check_scan_starts ();
1510 sgen_nursery_alloc_prepare_for_minor ();
1514 nursery_next = sgen_nursery_alloc_get_upper_alloc_bound ();
1515 /* FIXME: optimize later to use the higher address where an object can be present */
1516 nursery_next = MAX (nursery_next, sgen_get_nursery_end ());
1518 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 ()));
1519 max_garbage_amount = nursery_next - sgen_get_nursery_start ();
1520 g_assert (nursery_section->size >= max_garbage_amount);
1522 /* world must be stopped already */
1524 time_minor_pre_collection_fragment_clear += TV_ELAPSED (atv, btv);
1526 sgen_client_pre_collection_checks ();
1528 nursery_section->next_data = nursery_next;
1530 major_collector.start_nursery_collection ();
1532 sgen_memgov_minor_collection_start ();
1534 init_gray_queue (FALSE);
1536 gc_stats.minor_gc_count ++;
1538 if (whole_heap_check_before_collection) {
1539 sgen_clear_nursery_fragments ();
1540 sgen_check_whole_heap (finish_up_concurrent_mark);
1542 if (consistency_check_at_minor_collection)
1543 sgen_check_consistency ();
1545 sgen_process_fin_stage_entries ();
1547 /* pin from pinned handles */
1548 sgen_init_pinning ();
1549 sgen_client_binary_protocol_mark_start (GENERATION_NURSERY);
1550 pin_from_roots (sgen_get_nursery_start (), nursery_next, ctx);
1551 /* pin cemented objects */
1552 sgen_pin_cemented_objects ();
1553 /* identify pinned objects */
1554 sgen_optimize_pin_queue ();
1555 sgen_pinning_setup_section (nursery_section);
1557 pin_objects_in_nursery (FALSE, ctx);
1558 sgen_pinning_trim_queue_to_section (nursery_section);
1561 time_minor_pinning += TV_ELAPSED (btv, atv);
1562 SGEN_LOG (2, "Finding pinned pointers: %zd in %lld usecs", sgen_get_pinned_count (), (long long)TV_ELAPSED (btv, atv));
1563 SGEN_LOG (4, "Start scan with %zd pinned objects", sgen_get_pinned_count ());
1565 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan remset", job_remembered_set_scan, sizeof (ScanJob));
1566 sj->ops = object_ops;
1567 sgen_workers_enqueue_job (&sj->job, FALSE);
1569 /* we don't have complete write barrier yet, so we scan all the old generation sections */
1571 time_minor_scan_remsets += TV_ELAPSED (atv, btv);
1572 SGEN_LOG (2, "Old generation scan: %lld usecs", (long long)TV_ELAPSED (atv, btv));
1574 sgen_pin_stats_print_class_stats ();
1576 /* FIXME: Why do we do this at this specific, seemingly random, point? */
1577 sgen_client_collecting_minor (&fin_ready_queue, &critical_fin_queue);
1580 time_minor_scan_pinned += TV_ELAPSED (btv, atv);
1582 enqueue_scan_from_roots_jobs (sgen_get_nursery_start (), nursery_next, object_ops, FALSE);
1585 time_minor_scan_roots += TV_ELAPSED (atv, btv);
1587 finish_gray_stack (GENERATION_NURSERY, ctx);
1590 time_minor_finish_gray_stack += TV_ELAPSED (btv, atv);
1591 sgen_client_binary_protocol_mark_end (GENERATION_NURSERY);
1593 if (objects_pinned) {
1594 sgen_optimize_pin_queue ();
1595 sgen_pinning_setup_section (nursery_section);
1598 /* walk the pin_queue, build up the fragment list of free memory, unmark
1599 * pinned objects as we go, memzero() the empty fragments so they are ready for the
1602 sgen_client_binary_protocol_reclaim_start (GENERATION_NURSERY);
1603 fragment_total = sgen_build_nursery_fragments (nursery_section, unpin_queue);
1604 if (!fragment_total)
1607 /* Clear TLABs for all threads */
1608 sgen_clear_tlabs ();
1610 sgen_client_binary_protocol_reclaim_end (GENERATION_NURSERY);
1612 time_minor_fragment_creation += TV_ELAPSED (atv, btv);
1613 SGEN_LOG (2, "Fragment creation: %lld usecs, %lu bytes available", (long long)TV_ELAPSED (atv, btv), (unsigned long)fragment_total);
1615 if (consistency_check_at_minor_collection)
1616 sgen_check_major_refs ();
1618 major_collector.finish_nursery_collection ();
1620 TV_GETTIME (last_minor_collection_end_tv);
1621 gc_stats.minor_gc_time += TV_ELAPSED (last_minor_collection_start_tv, last_minor_collection_end_tv);
1623 sgen_debug_dump_heap ("minor", gc_stats.minor_gc_count - 1, NULL);
1625 /* prepare the pin queue for the next collection */
1626 sgen_finish_pinning ();
1627 if (sgen_have_pending_finalizers ()) {
1628 SGEN_LOG (4, "Finalizer-thread wakeup");
1629 sgen_client_finalize_notify ();
1631 sgen_pin_stats_reset ();
1632 /* clear cemented hash */
1633 sgen_cement_clear_below_threshold ();
1635 g_assert (sgen_gray_object_queue_is_empty (&gray_queue));
1637 remset.finish_minor_collection ();
1639 check_scan_starts ();
1641 binary_protocol_flush_buffers (FALSE);
1643 sgen_memgov_minor_collection_end ();
1645 /*objects are late pinned because of lack of memory, so a major is a good call*/
1646 needs_major = objects_pinned > 0;
1647 current_collection_generation = -1;
1650 binary_protocol_collection_end (gc_stats.minor_gc_count - 1, GENERATION_NURSERY, 0, 0);
1652 if (check_nursery_objects_pinned && !sgen_minor_collector.is_split)
1653 sgen_check_nursery_objects_pinned (unpin_queue != NULL);
1659 COPY_OR_MARK_FROM_ROOTS_SERIAL,
1660 COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT,
1661 COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT
1662 } CopyOrMarkFromRootsMode;
1665 major_copy_or_mark_from_roots (size_t *old_next_pin_slot, CopyOrMarkFromRootsMode mode, SgenObjectOperations *object_ops)
1670 /* FIXME: only use these values for the precise scan
1671 * note that to_space pointers should be excluded anyway...
1673 char *heap_start = NULL;
1674 char *heap_end = (char*)-1;
1675 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, WORKERS_DISTRIBUTE_GRAY_QUEUE);
1676 gboolean concurrent = mode != COPY_OR_MARK_FROM_ROOTS_SERIAL;
1678 SGEN_ASSERT (0, !!concurrent == !!concurrent_collection_in_progress, "We've been called with the wrong mode.");
1680 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1681 /*This cleans up unused fragments */
1682 sgen_nursery_allocator_prepare_for_pinning ();
1684 if (do_concurrent_checks)
1685 sgen_debug_check_nursery_is_clean ();
1687 /* The concurrent collector doesn't touch the nursery. */
1688 sgen_nursery_alloc_prepare_for_major ();
1691 init_gray_queue (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT);
1695 /* Pinning depends on this */
1696 sgen_clear_nursery_fragments ();
1698 if (whole_heap_check_before_collection)
1699 sgen_check_whole_heap (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT);
1702 time_major_pre_collection_fragment_clear += TV_ELAPSED (atv, btv);
1704 if (!sgen_collection_is_concurrent ())
1705 nursery_section->next_data = sgen_get_nursery_end ();
1706 /* we should also coalesce scanning from sections close to each other
1707 * and deal with pointers outside of the sections later.
1712 sgen_client_pre_collection_checks ();
1714 if (mode != COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1715 /* Remsets are not useful for a major collection */
1716 remset.clear_cards ();
1719 sgen_process_fin_stage_entries ();
1722 sgen_init_pinning ();
1723 SGEN_LOG (6, "Collecting pinned addresses");
1724 pin_from_roots ((void*)lowest_heap_address, (void*)highest_heap_address, ctx);
1725 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1726 /* Pin cemented objects that were forced */
1727 sgen_pin_cemented_objects ();
1729 sgen_optimize_pin_queue ();
1730 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1732 * Cemented objects that are in the pinned list will be marked. When
1733 * marking concurrently we won't mark mod-union cards for these objects.
1734 * Instead they will remain cemented until the next major collection,
1735 * when we will recheck if they are still pinned in the roots.
1737 sgen_cement_force_pinned ();
1740 sgen_client_collecting_major_1 ();
1743 * pin_queue now contains all candidate pointers, sorted and
1744 * uniqued. We must do two passes now to figure out which
1745 * objects are pinned.
1747 * The first is to find within the pin_queue the area for each
1748 * section. This requires that the pin_queue be sorted. We
1749 * also process the LOS objects and pinned chunks here.
1751 * The second, destructive, pass is to reduce the section
1752 * areas to pointers to the actually pinned objects.
1754 SGEN_LOG (6, "Pinning from sections");
1755 /* first pass for the sections */
1756 sgen_find_section_pin_queue_start_end (nursery_section);
1757 /* identify possible pointers to the insize of large objects */
1758 SGEN_LOG (6, "Pinning from large objects");
1759 for (bigobj = los_object_list; bigobj; bigobj = bigobj->next) {
1761 if (sgen_find_optimized_pin_queue_area ((char*)bigobj->data, (char*)bigobj->data + sgen_los_object_size (bigobj), &dummy, &dummy)) {
1762 binary_protocol_pin (bigobj->data, (gpointer)LOAD_VTABLE (bigobj->data), safe_object_get_size (bigobj->data));
1764 if (sgen_los_object_is_pinned (bigobj->data)) {
1765 SGEN_ASSERT (0, mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT, "LOS objects can only be pinned here after concurrent marking.");
1768 sgen_los_pin_object (bigobj->data);
1769 if (SGEN_OBJECT_HAS_REFERENCES (bigobj->data))
1770 GRAY_OBJECT_ENQUEUE (WORKERS_DISTRIBUTE_GRAY_QUEUE, bigobj->data, sgen_obj_get_descriptor ((GCObject*)bigobj->data));
1771 sgen_pin_stats_register_object (bigobj->data, safe_object_get_size (bigobj->data));
1772 SGEN_LOG (6, "Marked large object %p (%s) size: %lu from roots", bigobj->data,
1773 sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (bigobj->data)),
1774 (unsigned long)sgen_los_object_size (bigobj));
1776 sgen_client_pinned_los_object (bigobj->data);
1780 pin_objects_in_nursery (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT, ctx);
1781 if (check_nursery_objects_pinned && !sgen_minor_collector.is_split)
1782 sgen_check_nursery_objects_pinned (mode != COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT);
1784 major_collector.pin_objects (WORKERS_DISTRIBUTE_GRAY_QUEUE);
1785 if (old_next_pin_slot)
1786 *old_next_pin_slot = sgen_get_pinned_count ();
1789 time_major_pinning += TV_ELAPSED (atv, btv);
1790 SGEN_LOG (2, "Finding pinned pointers: %zd in %lld usecs", sgen_get_pinned_count (), (long long)TV_ELAPSED (atv, btv));
1791 SGEN_LOG (4, "Start scan with %zd pinned objects", sgen_get_pinned_count ());
1793 major_collector.init_to_space ();
1795 SGEN_ASSERT (0, sgen_workers_all_done (), "Why are the workers not done when we start or finish a major collection?");
1796 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1797 if (sgen_workers_have_idle_work ()) {
1799 * We force the finish of the worker with the new object ops context
1800 * which can also do copying. We need to have finished pinning.
1802 sgen_workers_start_all_workers (object_ops, NULL);
1803 sgen_workers_join ();
1807 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
1808 main_gc_thread = mono_native_thread_self ();
1811 sgen_client_collecting_major_2 ();
1814 time_major_scan_pinned += TV_ELAPSED (btv, atv);
1816 sgen_client_collecting_major_3 (&fin_ready_queue, &critical_fin_queue);
1818 enqueue_scan_from_roots_jobs (heap_start, heap_end, object_ops, FALSE);
1821 time_major_scan_roots += TV_ELAPSED (atv, btv);
1824 * We start the concurrent worker after pinning and after we scanned the roots
1825 * in order to make sure that the worker does not finish before handling all
1828 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1829 if (precleaning_enabled) {
1831 /* Mod union preclean job */
1832 sj = (ScanJob*)sgen_thread_pool_job_alloc ("preclean mod union cardtable", job_mod_union_preclean, sizeof (ScanJob));
1833 sj->ops = object_ops;
1834 sgen_workers_start_all_workers (object_ops, &sj->job);
1836 sgen_workers_start_all_workers (object_ops, NULL);
1838 gray_queue_enable_redirect (WORKERS_DISTRIBUTE_GRAY_QUEUE);
1841 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1844 /* Mod union card table */
1845 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan mod union cardtable", job_scan_major_mod_union_card_table, sizeof (ScanJob));
1846 sj->ops = object_ops;
1847 sgen_workers_enqueue_job (&sj->job, FALSE);
1849 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan LOS mod union cardtable", job_scan_los_mod_union_card_table, sizeof (ScanJob));
1850 sj->ops = object_ops;
1851 sgen_workers_enqueue_job (&sj->job, FALSE);
1854 time_major_scan_mod_union += TV_ELAPSED (btv, atv);
1857 sgen_pin_stats_print_class_stats ();
1861 major_finish_copy_or_mark (CopyOrMarkFromRootsMode mode)
1863 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1864 sgen_finish_pinning ();
1866 sgen_pin_stats_reset ();
1868 if (do_concurrent_checks)
1869 sgen_debug_check_nursery_is_clean ();
1874 major_start_collection (gboolean concurrent, size_t *old_next_pin_slot)
1876 SgenObjectOperations *object_ops;
1878 binary_protocol_collection_begin (gc_stats.major_gc_count, GENERATION_OLD);
1880 current_collection_generation = GENERATION_OLD;
1882 g_assert (sgen_section_gray_queue_is_empty (sgen_workers_get_distribute_section_gray_queue ()));
1885 sgen_cement_reset ();
1888 g_assert (major_collector.is_concurrent);
1889 concurrent_collection_in_progress = TRUE;
1891 object_ops = &major_collector.major_ops_concurrent_start;
1893 object_ops = &major_collector.major_ops_serial;
1896 reset_pinned_from_failed_allocation ();
1898 sgen_memgov_major_collection_start ();
1900 //count_ref_nonref_objs ();
1901 //consistency_check ();
1903 check_scan_starts ();
1906 SGEN_LOG (1, "Start major collection %d", gc_stats.major_gc_count);
1907 gc_stats.major_gc_count ++;
1909 if (major_collector.start_major_collection)
1910 major_collector.start_major_collection ();
1912 major_copy_or_mark_from_roots (old_next_pin_slot, concurrent ? COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT : COPY_OR_MARK_FROM_ROOTS_SERIAL, object_ops);
1913 major_finish_copy_or_mark (concurrent ? COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT : COPY_OR_MARK_FROM_ROOTS_SERIAL);
1917 major_finish_collection (const char *reason, size_t old_next_pin_slot, gboolean forced)
1919 ScannedObjectCounts counts;
1920 SgenObjectOperations *object_ops;
1921 mword fragment_total;
1927 if (concurrent_collection_in_progress) {
1928 object_ops = &major_collector.major_ops_concurrent_finish;
1930 major_copy_or_mark_from_roots (NULL, COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT, object_ops);
1932 major_finish_copy_or_mark (COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT);
1934 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
1935 main_gc_thread = NULL;
1938 object_ops = &major_collector.major_ops_serial;
1941 g_assert (sgen_section_gray_queue_is_empty (sgen_workers_get_distribute_section_gray_queue ()));
1943 /* all the objects in the heap */
1944 finish_gray_stack (GENERATION_OLD, CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, &gray_queue));
1946 time_major_finish_gray_stack += TV_ELAPSED (btv, atv);
1948 SGEN_ASSERT (0, sgen_workers_all_done (), "Can't have workers working after joining");
1950 if (objects_pinned) {
1951 g_assert (!concurrent_collection_in_progress);
1954 * This is slow, but we just OOM'd.
1956 * See comment at `sgen_pin_queue_clear_discarded_entries` for how the pin
1957 * queue is laid out at this point.
1959 sgen_pin_queue_clear_discarded_entries (nursery_section, old_next_pin_slot);
1961 * We need to reestablish all pinned nursery objects in the pin queue
1962 * because they're needed for fragment creation. Unpinning happens by
1963 * walking the whole queue, so it's not necessary to reestablish where major
1964 * heap block pins are - all we care is that they're still in there
1967 sgen_optimize_pin_queue ();
1968 sgen_find_section_pin_queue_start_end (nursery_section);
1972 reset_heap_boundaries ();
1973 sgen_update_heap_boundaries ((mword)sgen_get_nursery_start (), (mword)sgen_get_nursery_end ());
1975 /* walk the pin_queue, build up the fragment list of free memory, unmark
1976 * pinned objects as we go, memzero() the empty fragments so they are ready for the
1979 fragment_total = sgen_build_nursery_fragments (nursery_section, NULL);
1980 if (!fragment_total)
1982 SGEN_LOG (4, "Free space in nursery after major %ld", (long)fragment_total);
1984 if (do_concurrent_checks && concurrent_collection_in_progress)
1985 sgen_debug_check_nursery_is_clean ();
1987 /* prepare the pin queue for the next collection */
1988 sgen_finish_pinning ();
1990 /* Clear TLABs for all threads */
1991 sgen_clear_tlabs ();
1993 sgen_pin_stats_reset ();
1995 sgen_cement_clear_below_threshold ();
1997 if (check_mark_bits_after_major_collection)
1998 sgen_check_heap_marked (concurrent_collection_in_progress);
2001 time_major_fragment_creation += TV_ELAPSED (atv, btv);
2003 binary_protocol_sweep_begin (GENERATION_OLD, !major_collector.sweeps_lazily);
2004 sgen_memgov_major_pre_sweep ();
2007 time_major_free_bigobjs += TV_ELAPSED (btv, atv);
2012 time_major_los_sweep += TV_ELAPSED (atv, btv);
2014 major_collector.sweep ();
2016 binary_protocol_sweep_end (GENERATION_OLD, !major_collector.sweeps_lazily);
2019 time_major_sweep += TV_ELAPSED (btv, atv);
2021 sgen_debug_dump_heap ("major", gc_stats.major_gc_count - 1, reason);
2023 if (sgen_have_pending_finalizers ()) {
2024 SGEN_LOG (4, "Finalizer-thread wakeup");
2025 sgen_client_finalize_notify ();
2028 g_assert (sgen_gray_object_queue_is_empty (&gray_queue));
2030 sgen_memgov_major_collection_end (forced);
2031 current_collection_generation = -1;
2033 memset (&counts, 0, sizeof (ScannedObjectCounts));
2034 major_collector.finish_major_collection (&counts);
2036 g_assert (sgen_section_gray_queue_is_empty (sgen_workers_get_distribute_section_gray_queue ()));
2038 SGEN_ASSERT (0, sgen_workers_all_done (), "Can't have workers working after major collection has finished");
2039 if (concurrent_collection_in_progress)
2040 concurrent_collection_in_progress = FALSE;
2042 check_scan_starts ();
2044 binary_protocol_flush_buffers (FALSE);
2046 //consistency_check ();
2048 binary_protocol_collection_end (gc_stats.major_gc_count - 1, GENERATION_OLD, counts.num_scanned_objects, counts.num_unique_scanned_objects);
2052 major_do_collection (const char *reason, gboolean forced)
2054 TV_DECLARE (time_start);
2055 TV_DECLARE (time_end);
2056 size_t old_next_pin_slot;
2058 if (disable_major_collections)
2061 if (major_collector.get_and_reset_num_major_objects_marked) {
2062 long long num_marked = major_collector.get_and_reset_num_major_objects_marked ();
2063 g_assert (!num_marked);
2066 /* world must be stopped already */
2067 TV_GETTIME (time_start);
2069 major_start_collection (FALSE, &old_next_pin_slot);
2070 major_finish_collection (reason, old_next_pin_slot, forced);
2072 TV_GETTIME (time_end);
2073 gc_stats.major_gc_time += TV_ELAPSED (time_start, time_end);
2075 /* FIXME: also report this to the user, preferably in gc-end. */
2076 if (major_collector.get_and_reset_num_major_objects_marked)
2077 major_collector.get_and_reset_num_major_objects_marked ();
2079 return bytes_pinned_from_failed_allocation > 0;
2083 major_start_concurrent_collection (const char *reason)
2085 TV_DECLARE (time_start);
2086 TV_DECLARE (time_end);
2087 long long num_objects_marked;
2089 if (disable_major_collections)
2092 TV_GETTIME (time_start);
2093 SGEN_TV_GETTIME (time_major_conc_collection_start);
2095 num_objects_marked = major_collector.get_and_reset_num_major_objects_marked ();
2096 g_assert (num_objects_marked == 0);
2098 binary_protocol_concurrent_start ();
2100 // FIXME: store reason and pass it when finishing
2101 major_start_collection (TRUE, NULL);
2103 gray_queue_redirect (&gray_queue);
2105 num_objects_marked = major_collector.get_and_reset_num_major_objects_marked ();
2107 TV_GETTIME (time_end);
2108 gc_stats.major_gc_time += TV_ELAPSED (time_start, time_end);
2110 current_collection_generation = -1;
2114 * Returns whether the major collection has finished.
2117 major_should_finish_concurrent_collection (void)
2119 SGEN_ASSERT (0, sgen_gray_object_queue_is_empty (&gray_queue), "Why is the gray queue not empty before we have started doing anything?");
2120 return sgen_workers_all_done ();
2124 major_update_concurrent_collection (void)
2126 TV_DECLARE (total_start);
2127 TV_DECLARE (total_end);
2129 TV_GETTIME (total_start);
2131 binary_protocol_concurrent_update ();
2133 major_collector.update_cardtable_mod_union ();
2134 sgen_los_update_cardtable_mod_union ();
2136 TV_GETTIME (total_end);
2137 gc_stats.major_gc_time += TV_ELAPSED (total_start, total_end);
2141 major_finish_concurrent_collection (gboolean forced)
2143 TV_DECLARE (total_start);
2144 TV_DECLARE (total_end);
2146 TV_GETTIME (total_start);
2148 binary_protocol_concurrent_finish ();
2151 * We need to stop all workers since we're updating the cardtable below.
2152 * The workers will be resumed with a finishing pause context to avoid
2153 * additional cardtable and object scanning.
2155 sgen_workers_stop_all_workers ();
2157 SGEN_TV_GETTIME (time_major_conc_collection_end);
2158 gc_stats.major_gc_time_concurrent += SGEN_TV_ELAPSED (time_major_conc_collection_start, time_major_conc_collection_end);
2160 major_collector.update_cardtable_mod_union ();
2161 sgen_los_update_cardtable_mod_union ();
2163 if (mod_union_consistency_check)
2164 sgen_check_mod_union_consistency ();
2166 current_collection_generation = GENERATION_OLD;
2167 sgen_cement_reset ();
2168 major_finish_collection ("finishing", -1, forced);
2170 if (whole_heap_check_before_collection)
2171 sgen_check_whole_heap (FALSE);
2173 TV_GETTIME (total_end);
2174 gc_stats.major_gc_time += TV_ELAPSED (total_start, total_end) - TV_ELAPSED (last_minor_collection_start_tv, last_minor_collection_end_tv);
2176 current_collection_generation = -1;
2180 * Ensure an allocation request for @size will succeed by freeing enough memory.
2182 * LOCKING: The GC lock MUST be held.
2185 sgen_ensure_free_space (size_t size, int generation)
2187 int generation_to_collect = -1;
2188 const char *reason = NULL;
2190 if (generation == GENERATION_OLD) {
2191 if (sgen_need_major_collection (size)) {
2192 reason = "LOS overflow";
2193 generation_to_collect = GENERATION_OLD;
2196 if (degraded_mode) {
2197 if (sgen_need_major_collection (size)) {
2198 reason = "Degraded mode overflow";
2199 generation_to_collect = GENERATION_OLD;
2201 } else if (sgen_need_major_collection (size)) {
2202 reason = concurrent_collection_in_progress ? "Forced finish concurrent collection" : "Minor allowance";
2203 generation_to_collect = GENERATION_OLD;
2205 generation_to_collect = GENERATION_NURSERY;
2206 reason = "Nursery full";
2210 if (generation_to_collect == -1) {
2211 if (concurrent_collection_in_progress && sgen_workers_all_done ()) {
2212 generation_to_collect = GENERATION_OLD;
2213 reason = "Finish concurrent collection";
2217 if (generation_to_collect == -1)
2219 sgen_perform_collection (size, generation_to_collect, reason, FALSE);
2223 * LOCKING: Assumes the GC lock is held.
2226 sgen_perform_collection (size_t requested_size, int generation_to_collect, const char *reason, gboolean wait_to_finish)
2228 TV_DECLARE (gc_start);
2229 TV_DECLARE (gc_end);
2230 TV_DECLARE (gc_total_start);
2231 TV_DECLARE (gc_total_end);
2232 GGTimingInfo infos [2];
2233 int overflow_generation_to_collect = -1;
2234 int oldest_generation_collected = generation_to_collect;
2235 const char *overflow_reason = NULL;
2236 gboolean finish_concurrent = concurrent_collection_in_progress && (major_should_finish_concurrent_collection () || generation_to_collect == GENERATION_OLD);
2238 binary_protocol_collection_requested (generation_to_collect, requested_size, wait_to_finish ? 1 : 0);
2240 SGEN_ASSERT (0, generation_to_collect == GENERATION_NURSERY || generation_to_collect == GENERATION_OLD, "What generation is this?");
2242 TV_GETTIME (gc_start);
2244 sgen_stop_world (generation_to_collect);
2246 TV_GETTIME (gc_total_start);
2248 // FIXME: extract overflow reason
2249 // FIXME: minor overflow for concurrent case
2250 if (generation_to_collect == GENERATION_NURSERY && !finish_concurrent) {
2251 if (concurrent_collection_in_progress)
2252 major_update_concurrent_collection ();
2254 if (collect_nursery (NULL, FALSE) && !concurrent_collection_in_progress) {
2255 overflow_generation_to_collect = GENERATION_OLD;
2256 overflow_reason = "Minor overflow";
2258 } else if (finish_concurrent) {
2259 major_finish_concurrent_collection (wait_to_finish);
2260 oldest_generation_collected = GENERATION_OLD;
2262 SGEN_ASSERT (0, generation_to_collect == GENERATION_OLD, "We should have handled nursery collections above");
2263 if (major_collector.is_concurrent && !wait_to_finish) {
2264 collect_nursery (NULL, FALSE);
2265 major_start_concurrent_collection (reason);
2266 oldest_generation_collected = GENERATION_NURSERY;
2267 } else if (major_do_collection (reason, wait_to_finish)) {
2268 overflow_generation_to_collect = GENERATION_NURSERY;
2269 overflow_reason = "Excessive pinning";
2273 TV_GETTIME (gc_end);
2275 memset (infos, 0, sizeof (infos));
2276 infos [0].generation = oldest_generation_collected;
2277 infos [0].reason = reason;
2278 infos [0].is_overflow = FALSE;
2279 infos [1].generation = -1;
2280 infos [0].total_time = SGEN_TV_ELAPSED (gc_start, gc_end);
2282 if (overflow_generation_to_collect != -1) {
2283 SGEN_ASSERT (0, !concurrent_collection_in_progress, "We don't yet support overflow collections with the concurrent collector");
2286 * We need to do an overflow collection, either because we ran out of memory
2287 * or the nursery is fully pinned.
2290 infos [1].generation = overflow_generation_to_collect;
2291 infos [1].reason = overflow_reason;
2292 infos [1].is_overflow = TRUE;
2295 if (overflow_generation_to_collect == GENERATION_NURSERY)
2296 collect_nursery (NULL, FALSE);
2298 major_do_collection (overflow_reason, wait_to_finish);
2300 TV_GETTIME (gc_end);
2301 infos [1].total_time = SGEN_TV_ELAPSED (gc_start, gc_end);
2303 oldest_generation_collected = MAX (oldest_generation_collected, overflow_generation_to_collect);
2306 SGEN_LOG (2, "Heap size: %lu, LOS size: %lu", (unsigned long)sgen_gc_get_total_heap_allocation (), (unsigned long)los_memory_usage);
2308 /* this also sets the proper pointers for the next allocation */
2309 if (generation_to_collect == GENERATION_NURSERY && !sgen_can_alloc_size (requested_size)) {
2310 /* TypeBuilder and MonoMethod are killing mcs with fragmentation */
2311 SGEN_LOG (1, "nursery collection didn't find enough room for %zd alloc (%zd pinned)", requested_size, sgen_get_pinned_count ());
2312 sgen_dump_pin_queue ();
2316 g_assert (sgen_gray_object_queue_is_empty (&gray_queue));
2318 TV_GETTIME (gc_total_end);
2319 time_max = MAX (time_max, TV_ELAPSED (gc_total_start, gc_total_end));
2321 sgen_restart_world (oldest_generation_collected, infos);
2325 * ######################################################################
2326 * ######## Memory allocation from the OS
2327 * ######################################################################
2328 * This section of code deals with getting memory from the OS and
2329 * allocating memory for GC-internal data structures.
2330 * Internal memory can be handled with a freelist for small objects.
2336 G_GNUC_UNUSED static void
2337 report_internal_mem_usage (void)
2339 printf ("Internal memory usage:\n");
2340 sgen_report_internal_mem_usage ();
2341 printf ("Pinned memory usage:\n");
2342 major_collector.report_pinned_memory_usage ();
2346 * ######################################################################
2347 * ######## Finalization support
2348 * ######################################################################
2352 * If the object has been forwarded it means it's still referenced from a root.
2353 * If it is pinned it's still alive as well.
2354 * A LOS object is only alive if we have pinned it.
2355 * Return TRUE if @obj is ready to be finalized.
2357 static inline gboolean
2358 sgen_is_object_alive (GCObject *object)
2360 if (ptr_in_nursery (object))
2361 return sgen_nursery_is_object_alive (object);
2363 return sgen_major_is_object_alive (object);
2367 * This function returns true if @object is either alive and belongs to the
2368 * current collection - major collections are full heap, so old gen objects
2369 * are never alive during a minor collection.
2372 sgen_is_object_alive_and_on_current_collection (GCObject *object)
2374 if (ptr_in_nursery (object))
2375 return sgen_nursery_is_object_alive (object);
2377 if (current_collection_generation == GENERATION_NURSERY)
2380 return sgen_major_is_object_alive (object);
2385 sgen_gc_is_object_ready_for_finalization (GCObject *object)
2387 return !sgen_is_object_alive (object);
2391 sgen_queue_finalization_entry (GCObject *obj)
2393 gboolean critical = sgen_client_object_has_critical_finalizer (obj);
2395 sgen_pointer_queue_add (critical ? &critical_fin_queue : &fin_ready_queue, obj);
2397 sgen_client_object_queued_for_finalization (obj);
2401 sgen_object_is_live (GCObject *obj)
2403 return sgen_is_object_alive_and_on_current_collection (obj);
2407 * `System.GC.WaitForPendingFinalizers` first checks `sgen_have_pending_finalizers()` to
2408 * determine whether it can exit quickly. The latter must therefore only return FALSE if
2409 * all finalizers have really finished running.
2411 * `sgen_gc_invoke_finalizers()` first dequeues a finalizable object, and then finalizes it.
2412 * This means that just checking whether the queues are empty leaves the possibility that an
2413 * object might have been dequeued but not yet finalized. That's why we need the additional
2414 * flag `pending_unqueued_finalizer`.
2417 static volatile gboolean pending_unqueued_finalizer = FALSE;
2420 sgen_gc_invoke_finalizers (void)
2424 g_assert (!pending_unqueued_finalizer);
2426 /* FIXME: batch to reduce lock contention */
2427 while (sgen_have_pending_finalizers ()) {
2433 * We need to set `pending_unqueued_finalizer` before dequeing the
2434 * finalizable object.
2436 if (!sgen_pointer_queue_is_empty (&fin_ready_queue)) {
2437 pending_unqueued_finalizer = TRUE;
2438 mono_memory_write_barrier ();
2439 obj = (GCObject *)sgen_pointer_queue_pop (&fin_ready_queue);
2440 } else if (!sgen_pointer_queue_is_empty (&critical_fin_queue)) {
2441 pending_unqueued_finalizer = TRUE;
2442 mono_memory_write_barrier ();
2443 obj = (GCObject *)sgen_pointer_queue_pop (&critical_fin_queue);
2449 SGEN_LOG (7, "Finalizing object %p (%s)", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
2457 /* the object is on the stack so it is pinned */
2458 /*g_print ("Calling finalizer for object: %p (%s)\n", obj, sgen_client_object_safe_name (obj));*/
2459 sgen_client_run_finalize (obj);
2462 if (pending_unqueued_finalizer) {
2463 mono_memory_write_barrier ();
2464 pending_unqueued_finalizer = FALSE;
2471 sgen_have_pending_finalizers (void)
2473 return pending_unqueued_finalizer || !sgen_pointer_queue_is_empty (&fin_ready_queue) || !sgen_pointer_queue_is_empty (&critical_fin_queue);
2477 * ######################################################################
2478 * ######## registered roots support
2479 * ######################################################################
2483 * We do not coalesce roots.
2486 sgen_register_root (char *start, size_t size, SgenDescriptor descr, int root_type, int source, const char *msg)
2488 RootRecord new_root;
2491 for (i = 0; i < ROOT_TYPE_NUM; ++i) {
2492 RootRecord *root = (RootRecord *)sgen_hash_table_lookup (&roots_hash [i], start);
2493 /* we allow changing the size and the descriptor (for thread statics etc) */
2495 size_t old_size = root->end_root - start;
2496 root->end_root = start + size;
2497 SGEN_ASSERT (0, !!root->root_desc == !!descr, "Can't change whether a root is precise or conservative.");
2498 SGEN_ASSERT (0, root->source == source, "Can't change a root's source identifier.");
2499 SGEN_ASSERT (0, !!root->msg == !!msg, "Can't change a root's message.");
2500 root->root_desc = descr;
2502 roots_size -= old_size;
2508 new_root.end_root = start + size;
2509 new_root.root_desc = descr;
2510 new_root.source = source;
2513 sgen_hash_table_replace (&roots_hash [root_type], start, &new_root, NULL);
2516 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);
2523 sgen_deregister_root (char* addr)
2529 for (root_type = 0; root_type < ROOT_TYPE_NUM; ++root_type) {
2530 if (sgen_hash_table_remove (&roots_hash [root_type], addr, &root))
2531 roots_size -= (root.end_root - addr);
2537 * ######################################################################
2538 * ######## Thread handling (stop/start code)
2539 * ######################################################################
2543 sgen_get_current_collection_generation (void)
2545 return current_collection_generation;
2549 sgen_thread_register (SgenThreadInfo* info, void *stack_bottom_fallback)
2551 #ifndef HAVE_KW_THREAD
2552 info->tlab_start = info->tlab_next = info->tlab_temp_end = info->tlab_real_end = NULL;
2555 sgen_init_tlab_info (info);
2557 sgen_client_thread_register (info, stack_bottom_fallback);
2563 sgen_thread_unregister (SgenThreadInfo *p)
2565 sgen_client_thread_unregister (p);
2569 * ######################################################################
2570 * ######## Write barriers
2571 * ######################################################################
2575 * Note: the write barriers first do the needed GC work and then do the actual store:
2576 * this way the value is visible to the conservative GC scan after the write barrier
2577 * itself. If a GC interrupts the barrier in the middle, value will be kept alive by
2578 * the conservative scan, otherwise by the remembered set scan.
2582 mono_gc_wbarrier_arrayref_copy (gpointer dest_ptr, gpointer src_ptr, int count)
2584 HEAVY_STAT (++stat_wbarrier_arrayref_copy);
2585 /*This check can be done without taking a lock since dest_ptr array is pinned*/
2586 if (ptr_in_nursery (dest_ptr) || count <= 0) {
2587 mono_gc_memmove_aligned (dest_ptr, src_ptr, count * sizeof (gpointer));
2591 #ifdef SGEN_HEAVY_BINARY_PROTOCOL
2592 if (binary_protocol_is_heavy_enabled ()) {
2594 for (i = 0; i < count; ++i) {
2595 gpointer dest = (gpointer*)dest_ptr + i;
2596 gpointer obj = *((gpointer*)src_ptr + i);
2598 binary_protocol_wbarrier (dest, obj, (gpointer)LOAD_VTABLE (obj));
2603 remset.wbarrier_arrayref_copy (dest_ptr, src_ptr, count);
2607 mono_gc_wbarrier_generic_nostore (gpointer ptr)
2611 HEAVY_STAT (++stat_wbarrier_generic_store);
2613 sgen_client_wbarrier_generic_nostore_check (ptr);
2615 obj = *(gpointer*)ptr;
2617 binary_protocol_wbarrier (ptr, obj, (gpointer)LOAD_VTABLE (obj));
2620 * We need to record old->old pointer locations for the
2621 * concurrent collector.
2623 if (!ptr_in_nursery (obj) && !concurrent_collection_in_progress) {
2624 SGEN_LOG (8, "Skipping remset at %p", ptr);
2628 SGEN_LOG (8, "Adding remset at %p", ptr);
2630 remset.wbarrier_generic_nostore (ptr);
2634 mono_gc_wbarrier_generic_store (gpointer ptr, GCObject* value)
2636 SGEN_LOG (8, "Wbarrier store at %p to %p (%s)", ptr, value, value ? sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (value)) : "null");
2637 SGEN_UPDATE_REFERENCE_ALLOW_NULL (ptr, value);
2638 if (ptr_in_nursery (value) || concurrent_collection_in_progress)
2639 mono_gc_wbarrier_generic_nostore (ptr);
2640 sgen_dummy_use (value);
2643 /* Same as mono_gc_wbarrier_generic_store () but performs the store
2644 * as an atomic operation with release semantics.
2647 mono_gc_wbarrier_generic_store_atomic (gpointer ptr, GCObject *value)
2649 HEAVY_STAT (++stat_wbarrier_generic_store_atomic);
2651 SGEN_LOG (8, "Wbarrier atomic store at %p to %p (%s)", ptr, value, value ? sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (value)) : "null");
2653 InterlockedWritePointer ((volatile gpointer *)ptr, value);
2655 if (ptr_in_nursery (value) || concurrent_collection_in_progress)
2656 mono_gc_wbarrier_generic_nostore (ptr);
2658 sgen_dummy_use (value);
2662 sgen_wbarrier_value_copy_bitmap (gpointer _dest, gpointer _src, int size, unsigned bitmap)
2664 GCObject **dest = (GCObject **)_dest;
2665 GCObject **src = (GCObject **)_src;
2669 mono_gc_wbarrier_generic_store (dest, *src);
2674 size -= SIZEOF_VOID_P;
2680 * ######################################################################
2681 * ######## Other mono public interface functions.
2682 * ######################################################################
2686 sgen_gc_collect (int generation)
2691 sgen_perform_collection (0, generation, "user request", TRUE);
2696 sgen_gc_collection_count (int generation)
2698 if (generation == 0)
2699 return gc_stats.minor_gc_count;
2700 return gc_stats.major_gc_count;
2704 sgen_gc_get_used_size (void)
2708 tot = los_memory_usage;
2709 tot += nursery_section->next_data - nursery_section->data;
2710 tot += major_collector.get_used_size ();
2711 /* FIXME: account for pinned objects */
2717 sgen_env_var_error (const char *env_var, const char *fallback, const char *description_format, ...)
2721 va_start (ap, description_format);
2723 fprintf (stderr, "Warning: In environment variable `%s': ", env_var);
2724 vfprintf (stderr, description_format, ap);
2726 fprintf (stderr, " - %s", fallback);
2727 fprintf (stderr, "\n");
2733 parse_double_in_interval (const char *env_var, const char *opt_name, const char *opt, double min, double max, double *result)
2736 double val = strtod (opt, &endptr);
2737 if (endptr == opt) {
2738 sgen_env_var_error (env_var, "Using default value.", "`%s` must be a number.", opt_name);
2741 else if (val < min || val > max) {
2742 sgen_env_var_error (env_var, "Using default value.", "`%s` must be between %.2f - %.2f.", opt_name, min, max);
2754 char *major_collector_opt = NULL;
2755 char *minor_collector_opt = NULL;
2756 size_t max_heap = 0;
2757 size_t soft_limit = 0;
2759 gboolean debug_print_allowance = FALSE;
2760 double allowance_ratio = 0, save_target = 0;
2761 gboolean cement_enabled = TRUE;
2764 result = InterlockedCompareExchange (&gc_initialized, -1, 0);
2767 /* already inited */
2770 /* being inited by another thread */
2771 mono_thread_info_usleep (1000);
2774 /* we will init it */
2777 g_assert_not_reached ();
2779 } while (result != 0);
2781 SGEN_TV_GETTIME (sgen_init_timestamp);
2783 #ifdef SGEN_WITHOUT_MONO
2784 mono_thread_smr_init ();
2787 mono_coop_mutex_init (&gc_mutex);
2789 gc_debug_file = stderr;
2791 mono_coop_mutex_init (&sgen_interruption_mutex);
2793 if ((env = g_getenv (MONO_GC_PARAMS_NAME))) {
2794 opts = g_strsplit (env, ",", -1);
2795 for (ptr = opts; *ptr; ++ptr) {
2797 if (g_str_has_prefix (opt, "major=")) {
2798 opt = strchr (opt, '=') + 1;
2799 major_collector_opt = g_strdup (opt);
2800 } else if (g_str_has_prefix (opt, "minor=")) {
2801 opt = strchr (opt, '=') + 1;
2802 minor_collector_opt = g_strdup (opt);
2810 sgen_init_internal_allocator ();
2811 sgen_init_nursery_allocator ();
2812 sgen_init_fin_weak_hash ();
2813 sgen_init_hash_table ();
2814 sgen_init_descriptors ();
2815 sgen_init_gray_queues ();
2816 sgen_init_allocator ();
2817 sgen_init_gchandles ();
2819 sgen_register_fixed_internal_mem_type (INTERNAL_MEM_SECTION, SGEN_SIZEOF_GC_MEM_SECTION);
2820 sgen_register_fixed_internal_mem_type (INTERNAL_MEM_GRAY_QUEUE, sizeof (GrayQueueSection));
2822 sgen_client_init ();
2824 if (!minor_collector_opt) {
2825 sgen_simple_nursery_init (&sgen_minor_collector);
2827 if (!strcmp (minor_collector_opt, "simple")) {
2829 sgen_simple_nursery_init (&sgen_minor_collector);
2830 } else if (!strcmp (minor_collector_opt, "split")) {
2831 sgen_split_nursery_init (&sgen_minor_collector);
2833 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using `simple` instead.", "Unknown minor collector `%s'.", minor_collector_opt);
2834 goto use_simple_nursery;
2838 if (!major_collector_opt || !strcmp (major_collector_opt, "marksweep")) {
2839 use_marksweep_major:
2840 sgen_marksweep_init (&major_collector);
2841 } else if (!major_collector_opt || !strcmp (major_collector_opt, "marksweep-conc")) {
2842 sgen_marksweep_conc_init (&major_collector);
2844 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using `marksweep` instead.", "Unknown major collector `%s'.", major_collector_opt);
2845 goto use_marksweep_major;
2848 sgen_nursery_size = DEFAULT_NURSERY_SIZE;
2851 gboolean usage_printed = FALSE;
2853 for (ptr = opts; *ptr; ++ptr) {
2855 if (!strcmp (opt, ""))
2857 if (g_str_has_prefix (opt, "major="))
2859 if (g_str_has_prefix (opt, "minor="))
2861 if (g_str_has_prefix (opt, "max-heap-size=")) {
2862 size_t page_size = mono_pagesize ();
2863 size_t max_heap_candidate = 0;
2864 opt = strchr (opt, '=') + 1;
2865 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &max_heap_candidate)) {
2866 max_heap = (max_heap_candidate + page_size - 1) & ~(size_t)(page_size - 1);
2867 if (max_heap != max_heap_candidate)
2868 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Rounding up.", "`max-heap-size` size must be a multiple of %d.", page_size);
2870 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`max-heap-size` must be an integer.");
2874 if (g_str_has_prefix (opt, "soft-heap-limit=")) {
2875 opt = strchr (opt, '=') + 1;
2876 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &soft_limit)) {
2877 if (soft_limit <= 0) {
2878 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`soft-heap-limit` must be positive.");
2882 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`soft-heap-limit` must be an integer.");
2888 if (g_str_has_prefix (opt, "nursery-size=")) {
2890 opt = strchr (opt, '=') + 1;
2891 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &val)) {
2892 if ((val & (val - 1))) {
2893 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.", "`nursery-size` must be a power of two.");
2897 if (val < SGEN_MAX_NURSERY_WASTE) {
2898 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.",
2899 "`nursery-size` must be at least %d bytes.", SGEN_MAX_NURSERY_WASTE);
2903 sgen_nursery_size = val;
2904 sgen_nursery_bits = 0;
2905 while (ONE_P << (++ sgen_nursery_bits) != sgen_nursery_size)
2908 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.", "`nursery-size` must be an integer.");
2914 if (g_str_has_prefix (opt, "save-target-ratio=")) {
2916 opt = strchr (opt, '=') + 1;
2917 if (parse_double_in_interval (MONO_GC_PARAMS_NAME, "save-target-ratio", opt,
2918 SGEN_MIN_SAVE_TARGET_RATIO, SGEN_MAX_SAVE_TARGET_RATIO, &val)) {
2923 if (g_str_has_prefix (opt, "default-allowance-ratio=")) {
2925 opt = strchr (opt, '=') + 1;
2926 if (parse_double_in_interval (MONO_GC_PARAMS_NAME, "default-allowance-ratio", opt,
2927 SGEN_MIN_ALLOWANCE_NURSERY_SIZE_RATIO, SGEN_MIN_ALLOWANCE_NURSERY_SIZE_RATIO, &val)) {
2928 allowance_ratio = val;
2933 if (!strcmp (opt, "cementing")) {
2934 cement_enabled = TRUE;
2937 if (!strcmp (opt, "no-cementing")) {
2938 cement_enabled = FALSE;
2942 if (!strcmp (opt, "precleaning")) {
2943 precleaning_enabled = TRUE;
2946 if (!strcmp (opt, "no-precleaning")) {
2947 precleaning_enabled = FALSE;
2951 if (major_collector.handle_gc_param && major_collector.handle_gc_param (opt))
2954 if (sgen_minor_collector.handle_gc_param && sgen_minor_collector.handle_gc_param (opt))
2957 if (sgen_client_handle_gc_param (opt))
2960 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Ignoring.", "Unknown option `%s`.", opt);
2965 fprintf (stderr, "\n%s must be a comma-delimited list of one or more of the following:\n", MONO_GC_PARAMS_NAME);
2966 fprintf (stderr, " max-heap-size=N (where N is an integer, possibly with a k, m or a g suffix)\n");
2967 fprintf (stderr, " soft-heap-limit=n (where N is an integer, possibly with a k, m or a g suffix)\n");
2968 fprintf (stderr, " nursery-size=N (where N is an integer, possibly with a k, m or a g suffix)\n");
2969 fprintf (stderr, " major=COLLECTOR (where COLLECTOR is `marksweep', `marksweep-conc', `marksweep-par')\n");
2970 fprintf (stderr, " minor=COLLECTOR (where COLLECTOR is `simple' or `split')\n");
2971 fprintf (stderr, " wbarrier=WBARRIER (where WBARRIER is `remset' or `cardtable')\n");
2972 fprintf (stderr, " [no-]cementing\n");
2973 if (major_collector.print_gc_param_usage)
2974 major_collector.print_gc_param_usage ();
2975 if (sgen_minor_collector.print_gc_param_usage)
2976 sgen_minor_collector.print_gc_param_usage ();
2977 sgen_client_print_gc_params_usage ();
2978 fprintf (stderr, " Experimental options:\n");
2979 fprintf (stderr, " save-target-ratio=R (where R must be between %.2f - %.2f).\n", SGEN_MIN_SAVE_TARGET_RATIO, SGEN_MAX_SAVE_TARGET_RATIO);
2980 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);
2981 fprintf (stderr, "\n");
2983 usage_printed = TRUE;
2988 if (major_collector_opt)
2989 g_free (major_collector_opt);
2991 if (minor_collector_opt)
2992 g_free (minor_collector_opt);
2996 sgen_pinning_init ();
2997 sgen_cement_init (cement_enabled);
2999 if ((env = g_getenv (MONO_GC_DEBUG_NAME))) {
3000 gboolean usage_printed = FALSE;
3002 opts = g_strsplit (env, ",", -1);
3003 for (ptr = opts; ptr && *ptr; ptr ++) {
3005 if (!strcmp (opt, ""))
3007 if (opt [0] >= '0' && opt [0] <= '9') {
3008 gc_debug_level = atoi (opt);
3013 char *rf = g_strdup_printf ("%s.%d", opt, mono_process_current_pid ());
3014 gc_debug_file = fopen (rf, "wb");
3016 gc_debug_file = stderr;
3019 } else if (!strcmp (opt, "print-allowance")) {
3020 debug_print_allowance = TRUE;
3021 } else if (!strcmp (opt, "print-pinning")) {
3022 sgen_pin_stats_enable ();
3023 } else if (!strcmp (opt, "verify-before-allocs")) {
3024 verify_before_allocs = 1;
3025 has_per_allocation_action = TRUE;
3026 } else if (g_str_has_prefix (opt, "verify-before-allocs=")) {
3027 char *arg = strchr (opt, '=') + 1;
3028 verify_before_allocs = atoi (arg);
3029 has_per_allocation_action = TRUE;
3030 } else if (!strcmp (opt, "collect-before-allocs")) {
3031 collect_before_allocs = 1;
3032 has_per_allocation_action = TRUE;
3033 } else if (g_str_has_prefix (opt, "collect-before-allocs=")) {
3034 char *arg = strchr (opt, '=') + 1;
3035 has_per_allocation_action = TRUE;
3036 collect_before_allocs = atoi (arg);
3037 } else if (!strcmp (opt, "verify-before-collections")) {
3038 whole_heap_check_before_collection = TRUE;
3039 } else if (!strcmp (opt, "check-at-minor-collections")) {
3040 consistency_check_at_minor_collection = TRUE;
3041 nursery_clear_policy = CLEAR_AT_GC;
3042 } else if (!strcmp (opt, "mod-union-consistency-check")) {
3043 if (!major_collector.is_concurrent) {
3044 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "`mod-union-consistency-check` only works with concurrent major collector.");
3047 mod_union_consistency_check = TRUE;
3048 } else if (!strcmp (opt, "check-mark-bits")) {
3049 check_mark_bits_after_major_collection = TRUE;
3050 } else if (!strcmp (opt, "check-nursery-pinned")) {
3051 check_nursery_objects_pinned = TRUE;
3052 } else if (!strcmp (opt, "clear-at-gc")) {
3053 nursery_clear_policy = CLEAR_AT_GC;
3054 } else if (!strcmp (opt, "clear-nursery-at-gc")) {
3055 nursery_clear_policy = CLEAR_AT_GC;
3056 } else if (!strcmp (opt, "clear-at-tlab-creation")) {
3057 nursery_clear_policy = CLEAR_AT_TLAB_CREATION;
3058 } else if (!strcmp (opt, "debug-clear-at-tlab-creation")) {
3059 nursery_clear_policy = CLEAR_AT_TLAB_CREATION_DEBUG;
3060 } else if (!strcmp (opt, "check-scan-starts")) {
3061 do_scan_starts_check = TRUE;
3062 } else if (!strcmp (opt, "verify-nursery-at-minor-gc")) {
3063 do_verify_nursery = TRUE;
3064 } else if (!strcmp (opt, "check-concurrent")) {
3065 if (!major_collector.is_concurrent) {
3066 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "`check-concurrent` only works with concurrent major collectors.");
3069 nursery_clear_policy = CLEAR_AT_GC;
3070 do_concurrent_checks = TRUE;
3071 } else if (!strcmp (opt, "dump-nursery-at-minor-gc")) {
3072 do_dump_nursery_content = TRUE;
3073 } else if (!strcmp (opt, "disable-minor")) {
3074 disable_minor_collections = TRUE;
3075 } else if (!strcmp (opt, "disable-major")) {
3076 disable_major_collections = TRUE;
3077 } else if (g_str_has_prefix (opt, "heap-dump=")) {
3078 char *filename = strchr (opt, '=') + 1;
3079 nursery_clear_policy = CLEAR_AT_GC;
3080 sgen_debug_enable_heap_dump (filename);
3081 } else if (g_str_has_prefix (opt, "binary-protocol=")) {
3082 char *filename = strchr (opt, '=') + 1;
3083 char *colon = strrchr (filename, ':');
3086 if (!mono_gc_parse_environment_string_extract_number (colon + 1, &limit)) {
3087 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring limit.", "Binary protocol file size limit must be an integer.");
3092 binary_protocol_init (filename, (long long)limit);
3093 } else if (!strcmp (opt, "nursery-canaries")) {
3094 do_verify_nursery = TRUE;
3095 enable_nursery_canaries = TRUE;
3096 } else if (!sgen_client_handle_gc_debug (opt)) {
3097 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "Unknown option `%s`.", opt);
3102 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);
3103 fprintf (stderr, "Valid <option>s are:\n");
3104 fprintf (stderr, " collect-before-allocs[=<n>]\n");
3105 fprintf (stderr, " verify-before-allocs[=<n>]\n");
3106 fprintf (stderr, " check-at-minor-collections\n");
3107 fprintf (stderr, " check-mark-bits\n");
3108 fprintf (stderr, " check-nursery-pinned\n");
3109 fprintf (stderr, " verify-before-collections\n");
3110 fprintf (stderr, " verify-nursery-at-minor-gc\n");
3111 fprintf (stderr, " dump-nursery-at-minor-gc\n");
3112 fprintf (stderr, " disable-minor\n");
3113 fprintf (stderr, " disable-major\n");
3114 fprintf (stderr, " check-concurrent\n");
3115 fprintf (stderr, " clear-[nursery-]at-gc\n");
3116 fprintf (stderr, " clear-at-tlab-creation\n");
3117 fprintf (stderr, " debug-clear-at-tlab-creation\n");
3118 fprintf (stderr, " check-scan-starts\n");
3119 fprintf (stderr, " print-allowance\n");
3120 fprintf (stderr, " print-pinning\n");
3121 fprintf (stderr, " heap-dump=<filename>\n");
3122 fprintf (stderr, " binary-protocol=<filename>[:<file-size-limit>]\n");
3123 fprintf (stderr, " nursery-canaries\n");
3124 sgen_client_print_gc_debug_usage ();
3125 fprintf (stderr, "\n");
3127 usage_printed = TRUE;
3133 if (check_mark_bits_after_major_collection)
3134 nursery_clear_policy = CLEAR_AT_GC;
3136 if (major_collector.post_param_init)
3137 major_collector.post_param_init (&major_collector);
3139 if (major_collector.needs_thread_pool)
3140 sgen_workers_init (1);
3142 sgen_memgov_init (max_heap, soft_limit, debug_print_allowance, allowance_ratio, save_target);
3144 memset (&remset, 0, sizeof (remset));
3146 sgen_card_table_init (&remset);
3148 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");
3154 sgen_get_nursery_clear_policy (void)
3156 return nursery_clear_policy;
3162 mono_coop_mutex_lock (&gc_mutex);
3166 sgen_gc_unlock (void)
3168 mono_coop_mutex_unlock (&gc_mutex);
3172 sgen_major_collector_iterate_live_block_ranges (sgen_cardtable_block_callback callback)
3174 major_collector.iterate_live_block_ranges (callback);
3178 sgen_get_major_collector (void)
3180 return &major_collector;
3184 sgen_get_remset (void)
3190 count_cards (long long *major_total, long long *major_marked, long long *los_total, long long *los_marked)
3192 sgen_get_major_collector ()->count_cards (major_total, major_marked);
3193 sgen_los_count_cards (los_total, los_marked);
3196 static gboolean world_is_stopped = FALSE;
3198 /* LOCKING: assumes the GC lock is held */
3200 sgen_stop_world (int generation)
3202 long long major_total = -1, major_marked = -1, los_total = -1, los_marked = -1;
3204 SGEN_ASSERT (0, !world_is_stopped, "Why are we stopping a stopped world?");
3206 binary_protocol_world_stopping (generation, sgen_timestamp (), (gpointer) (gsize) mono_native_thread_id_get ());
3208 sgen_client_stop_world (generation);
3210 world_is_stopped = TRUE;
3212 if (binary_protocol_is_heavy_enabled ())
3213 count_cards (&major_total, &major_marked, &los_total, &los_marked);
3214 binary_protocol_world_stopped (generation, sgen_timestamp (), major_total, major_marked, los_total, los_marked);
3217 /* LOCKING: assumes the GC lock is held */
3219 sgen_restart_world (int generation, GGTimingInfo *timing)
3221 long long major_total = -1, major_marked = -1, los_total = -1, los_marked = -1;
3223 SGEN_ASSERT (0, world_is_stopped, "Why are we restarting a running world?");
3225 if (binary_protocol_is_heavy_enabled ())
3226 count_cards (&major_total, &major_marked, &los_total, &los_marked);
3227 binary_protocol_world_restarting (generation, sgen_timestamp (), major_total, major_marked, los_total, los_marked);
3229 world_is_stopped = FALSE;
3231 sgen_client_restart_world (generation, timing);
3233 binary_protocol_world_restarted (generation, sgen_timestamp ());
3235 if (sgen_client_bridge_need_processing ())
3236 sgen_client_bridge_processing_finish (generation);
3238 sgen_memgov_collection_end (generation, timing, timing ? 2 : 0);
3242 sgen_is_world_stopped (void)
3244 return world_is_stopped;
3248 sgen_check_whole_heap_stw (void)
3250 sgen_stop_world (0);
3251 sgen_clear_nursery_fragments ();
3252 sgen_check_whole_heap (FALSE);
3253 sgen_restart_world (0, NULL);
3257 sgen_timestamp (void)
3259 SGEN_TV_DECLARE (timestamp);
3260 SGEN_TV_GETTIME (timestamp);
3261 return SGEN_TV_ELAPSED (sgen_init_timestamp, timestamp);
3264 #endif /* HAVE_SGEN_GC */