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;
335 gboolean sgen_try_free_some_memory;
337 #define SCAN_START_SIZE SGEN_SCAN_START_SIZE
339 size_t degraded_mode = 0;
341 static mword bytes_pinned_from_failed_allocation = 0;
343 GCMemSection *nursery_section = NULL;
344 static volatile mword lowest_heap_address = ~(mword)0;
345 static volatile mword highest_heap_address = 0;
347 MonoCoopMutex sgen_interruption_mutex;
349 int current_collection_generation = -1;
350 static volatile gboolean concurrent_collection_in_progress = FALSE;
352 /* objects that are ready to be finalized */
353 static SgenPointerQueue fin_ready_queue = SGEN_POINTER_QUEUE_INIT (INTERNAL_MEM_FINALIZE_READY);
354 static SgenPointerQueue critical_fin_queue = SGEN_POINTER_QUEUE_INIT (INTERNAL_MEM_FINALIZE_READY);
356 /* registered roots: the key to the hash is the root start address */
358 * Different kinds of roots are kept separate to speed up pin_from_roots () for example.
360 SgenHashTable roots_hash [ROOT_TYPE_NUM] = {
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),
363 SGEN_HASH_TABLE_INIT (INTERNAL_MEM_ROOTS_TABLE, INTERNAL_MEM_ROOT_RECORD, sizeof (RootRecord), sgen_aligned_addr_hash, NULL)
365 static mword roots_size = 0; /* amount of memory in the root set */
367 /* The size of a TLAB */
368 /* The bigger the value, the less often we have to go to the slow path to allocate a new
369 * one, but the more space is wasted by threads not allocating much memory.
371 * FIXME: Make this self-tuning for each thread.
373 guint32 tlab_size = (1024 * 4);
375 #define MAX_SMALL_OBJ_SIZE SGEN_MAX_SMALL_OBJ_SIZE
377 #define ALLOC_ALIGN SGEN_ALLOC_ALIGN
379 #define ALIGN_UP SGEN_ALIGN_UP
381 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
382 MonoNativeThreadId main_gc_thread = NULL;
385 /*Object was pinned during the current collection*/
386 static mword objects_pinned;
389 * ######################################################################
390 * ######## Macros and function declarations.
391 * ######################################################################
394 typedef SgenGrayQueue GrayQueue;
396 /* forward declarations */
397 static void scan_from_registered_roots (char *addr_start, char *addr_end, int root_type, ScanCopyContext ctx);
399 static void pin_from_roots (void *start_nursery, void *end_nursery, ScanCopyContext ctx);
400 static void finish_gray_stack (int generation, ScanCopyContext ctx);
403 SgenMajorCollector major_collector;
404 SgenMinorCollector sgen_minor_collector;
405 /* FIXME: get rid of this */
406 static GrayQueue gray_queue;
408 static SgenRememberedSet remset;
410 /* The gray queue to use from the main collection thread. */
411 #define WORKERS_DISTRIBUTE_GRAY_QUEUE (&gray_queue)
414 * The gray queue a worker job must use. If we're not parallel or
415 * concurrent, we use the main gray queue.
417 static SgenGrayQueue*
418 sgen_workers_get_job_gray_queue (WorkerData *worker_data)
420 return worker_data ? &worker_data->private_gray_queue : WORKERS_DISTRIBUTE_GRAY_QUEUE;
424 gray_queue_redirect (SgenGrayQueue *queue)
426 gboolean wake = FALSE;
429 GrayQueueSection *section = sgen_gray_object_dequeue_section (queue);
432 sgen_section_gray_queue_enqueue ((SgenSectionGrayQueue *)queue->alloc_prepare_data, section);
437 g_assert (concurrent_collection_in_progress);
438 sgen_workers_ensure_awake ();
443 gray_queue_enable_redirect (SgenGrayQueue *queue)
445 if (!concurrent_collection_in_progress)
448 sgen_gray_queue_set_alloc_prepare (queue, gray_queue_redirect, sgen_workers_get_distribute_section_gray_queue ());
449 gray_queue_redirect (queue);
453 sgen_scan_area_with_callback (char *start, char *end, IterateObjectCallbackFunc callback, void *data, gboolean allow_flags, gboolean fail_on_canaries)
455 while (start < end) {
459 if (!*(void**)start) {
460 start += sizeof (void*); /* should be ALLOC_ALIGN, really */
465 if (!(obj = (char *)SGEN_OBJECT_IS_FORWARDED (start)))
471 if (!sgen_client_object_is_array_fill ((GCObject*)obj)) {
472 CHECK_CANARY_FOR_OBJECT ((GCObject*)obj, fail_on_canaries);
473 size = ALIGN_UP (safe_object_get_size ((GCObject*)obj));
474 callback ((GCObject*)obj, size, data);
475 CANARIFY_SIZE (size);
477 size = ALIGN_UP (safe_object_get_size ((GCObject*)obj));
485 * sgen_add_to_global_remset:
487 * The global remset contains locations which point into newspace after
488 * a minor collection. This can happen if the objects they point to are pinned.
490 * LOCKING: If called from a parallel collector, the global remset
491 * lock must be held. For serial collectors that is not necessary.
494 sgen_add_to_global_remset (gpointer ptr, GCObject *obj)
496 SGEN_ASSERT (5, sgen_ptr_in_nursery (obj), "Target pointer of global remset must be in the nursery");
498 HEAVY_STAT (++stat_wbarrier_add_to_global_remset);
500 if (!major_collector.is_concurrent) {
501 SGEN_ASSERT (5, current_collection_generation != -1, "Global remsets can only be added during collections");
503 if (current_collection_generation == -1)
504 SGEN_ASSERT (5, sgen_concurrent_collection_in_progress (), "Global remsets outside of collection pauses can only be added by the concurrent collector");
507 if (!object_is_pinned (obj))
508 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");
509 else if (sgen_cement_lookup_or_register (obj))
512 remset.record_pointer (ptr);
514 sgen_pin_stats_register_global_remset (obj);
516 SGEN_LOG (8, "Adding global remset for %p", ptr);
517 binary_protocol_global_remset (ptr, obj, (gpointer)SGEN_LOAD_VTABLE (obj));
521 * sgen_drain_gray_stack:
523 * Scan objects in the gray stack until the stack is empty. This should be called
524 * frequently after each object is copied, to achieve better locality and cache
529 sgen_drain_gray_stack (ScanCopyContext ctx)
531 ScanObjectFunc scan_func = ctx.ops->scan_object;
532 GrayQueue *queue = ctx.queue;
534 if (ctx.ops->drain_gray_stack)
535 return ctx.ops->drain_gray_stack (queue);
540 GRAY_OBJECT_DEQUEUE (queue, &obj, &desc);
543 SGEN_LOG (9, "Precise gray object scan %p (%s)", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
544 scan_func (obj, desc, queue);
550 * Addresses in the pin queue are already sorted. This function finds
551 * the object header for each address and pins the object. The
552 * addresses must be inside the nursery section. The (start of the)
553 * address array is overwritten with the addresses of the actually
554 * pinned objects. Return the number of pinned objects.
557 pin_objects_from_nursery_pin_queue (gboolean do_scan_objects, ScanCopyContext ctx)
559 GCMemSection *section = nursery_section;
560 void **start = sgen_pinning_get_entry (section->pin_queue_first_entry);
561 void **end = sgen_pinning_get_entry (section->pin_queue_last_entry);
562 void *start_nursery = section->data;
563 void *end_nursery = section->next_data;
568 void *pinning_front = start_nursery;
570 void **definitely_pinned = start;
571 ScanObjectFunc scan_func = ctx.ops->scan_object;
572 SgenGrayQueue *queue = ctx.queue;
574 sgen_nursery_allocator_prepare_for_pinning ();
576 while (start < end) {
577 GCObject *obj_to_pin = NULL;
578 size_t obj_to_pin_size = 0;
583 SGEN_ASSERT (0, addr >= start_nursery && addr < end_nursery, "Potential pinning address out of range");
584 SGEN_ASSERT (0, addr >= last, "Pin queue not sorted");
591 SGEN_LOG (5, "Considering pinning addr %p", addr);
592 /* We've already processed everything up to pinning_front. */
593 if (addr < pinning_front) {
599 * Find the closest scan start <= addr. We might search backward in the
600 * scan_starts array because entries might be NULL. In the worst case we
601 * start at start_nursery.
603 idx = ((char*)addr - (char*)section->data) / SCAN_START_SIZE;
604 SGEN_ASSERT (0, idx < section->num_scan_start, "Scan start index out of range");
605 search_start = (void*)section->scan_starts [idx];
606 if (!search_start || search_start > addr) {
609 search_start = section->scan_starts [idx];
610 if (search_start && search_start <= addr)
613 if (!search_start || search_start > addr)
614 search_start = start_nursery;
618 * If the pinning front is closer than the scan start we found, start
619 * searching at the front.
621 if (search_start < pinning_front)
622 search_start = pinning_front;
625 * Now addr should be in an object a short distance from search_start.
627 * search_start must point to zeroed mem or point to an object.
630 size_t obj_size, canarified_obj_size;
633 if (!*(void**)search_start) {
634 search_start = (void*)ALIGN_UP ((mword)search_start + sizeof (gpointer));
635 /* The loop condition makes sure we don't overrun addr. */
639 canarified_obj_size = obj_size = ALIGN_UP (safe_object_get_size ((GCObject*)search_start));
642 * Filler arrays are marked by an invalid sync word. We don't
643 * consider them for pinning. They are not delimited by canaries,
646 if (!sgen_client_object_is_array_fill ((GCObject*)search_start)) {
647 CHECK_CANARY_FOR_OBJECT (search_start, TRUE);
648 CANARIFY_SIZE (canarified_obj_size);
650 if (addr >= search_start && (char*)addr < (char*)search_start + obj_size) {
651 /* This is the object we're looking for. */
652 obj_to_pin = (GCObject*)search_start;
653 obj_to_pin_size = canarified_obj_size;
658 /* Skip to the next object */
659 search_start = (void*)((char*)search_start + canarified_obj_size);
660 } while (search_start <= addr);
662 /* We've searched past the address we were looking for. */
664 pinning_front = search_start;
665 goto next_pin_queue_entry;
669 * We've found an object to pin. It might still be a dummy array, but we
670 * can advance the pinning front in any case.
672 pinning_front = (char*)obj_to_pin + obj_to_pin_size;
675 * If this is a dummy array marking the beginning of a nursery
676 * fragment, we don't pin it.
678 if (sgen_client_object_is_array_fill (obj_to_pin))
679 goto next_pin_queue_entry;
682 * Finally - pin the object!
684 desc = sgen_obj_get_descriptor_safe (obj_to_pin);
685 if (do_scan_objects) {
686 scan_func (obj_to_pin, desc, queue);
688 SGEN_LOG (4, "Pinned object %p, vtable %p (%s), count %d\n",
689 obj_to_pin, *(void**)obj_to_pin, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj_to_pin)), count);
690 binary_protocol_pin (obj_to_pin,
691 (gpointer)LOAD_VTABLE (obj_to_pin),
692 safe_object_get_size (obj_to_pin));
694 pin_object (obj_to_pin);
695 GRAY_OBJECT_ENQUEUE (queue, obj_to_pin, desc);
696 sgen_pin_stats_register_object (obj_to_pin, obj_to_pin_size);
697 definitely_pinned [count] = obj_to_pin;
701 next_pin_queue_entry:
705 sgen_client_nursery_objects_pinned (definitely_pinned, count);
706 stat_pinned_objects += count;
711 pin_objects_in_nursery (gboolean do_scan_objects, ScanCopyContext ctx)
715 if (nursery_section->pin_queue_first_entry == nursery_section->pin_queue_last_entry)
718 reduced_to = pin_objects_from_nursery_pin_queue (do_scan_objects, ctx);
719 nursery_section->pin_queue_last_entry = nursery_section->pin_queue_first_entry + reduced_to;
723 * This function is only ever called (via `collector_pin_object()` in `sgen-copy-object.h`)
724 * when we can't promote an object because we're out of memory.
727 sgen_pin_object (GCObject *object, GrayQueue *queue)
730 * All pinned objects are assumed to have been staged, so we need to stage as well.
731 * Also, the count of staged objects shows that "late pinning" happened.
733 sgen_pin_stage_ptr (object);
735 SGEN_PIN_OBJECT (object);
736 binary_protocol_pin (object, (gpointer)LOAD_VTABLE (object), safe_object_get_size (object));
739 sgen_pin_stats_register_object (object, safe_object_get_size (object));
741 GRAY_OBJECT_ENQUEUE (queue, object, sgen_obj_get_descriptor_safe (object));
744 /* Sort the addresses in array in increasing order.
745 * Done using a by-the book heap sort. Which has decent and stable performance, is pretty cache efficient.
748 sgen_sort_addresses (void **array, size_t size)
753 for (i = 1; i < size; ++i) {
756 size_t parent = (child - 1) / 2;
758 if (array [parent] >= array [child])
761 tmp = array [parent];
762 array [parent] = array [child];
769 for (i = size - 1; i > 0; --i) {
772 array [i] = array [0];
778 while (root * 2 + 1 <= end) {
779 size_t child = root * 2 + 1;
781 if (child < end && array [child] < array [child + 1])
783 if (array [root] >= array [child])
787 array [root] = array [child];
796 * Scan the memory between start and end and queue values which could be pointers
797 * to the area between start_nursery and end_nursery for later consideration.
798 * Typically used for thread stacks.
801 sgen_conservatively_pin_objects_from (void **start, void **end, void *start_nursery, void *end_nursery, int pin_type)
805 SGEN_ASSERT (0, ((mword)start & (SIZEOF_VOID_P - 1)) == 0, "Why are we scanning for references in unaligned memory ?");
807 #if defined(VALGRIND_MAKE_MEM_DEFINED_IF_ADDRESSABLE) && !defined(_WIN64)
808 VALGRIND_MAKE_MEM_DEFINED_IF_ADDRESSABLE (start, (char*)end - (char*)start);
811 while (start < end) {
813 * *start can point to the middle of an object
814 * note: should we handle pointing at the end of an object?
815 * pinning in C# code disallows pointing at the end of an object
816 * but there is some small chance that an optimizing C compiler
817 * may keep the only reference to an object by pointing
818 * at the end of it. We ignore this small chance for now.
819 * Pointers to the end of an object are indistinguishable
820 * from pointers to the start of the next object in memory
821 * so if we allow that we'd need to pin two objects...
822 * We queue the pointer in an array, the
823 * array will then be sorted and uniqued. This way
824 * we can coalesce several pinning pointers and it should
825 * be faster since we'd do a memory scan with increasing
826 * addresses. Note: we can align the address to the allocation
827 * alignment, so the unique process is more effective.
829 mword addr = (mword)*start;
830 addr &= ~(ALLOC_ALIGN - 1);
831 if (addr >= (mword)start_nursery && addr < (mword)end_nursery) {
832 SGEN_LOG (6, "Pinning address %p from %p", (void*)addr, start);
833 sgen_pin_stage_ptr ((void*)addr);
834 binary_protocol_pin_stage (start, (void*)addr);
835 sgen_pin_stats_register_address ((char*)addr, pin_type);
841 SGEN_LOG (7, "found %d potential pinned heap pointers", count);
845 * The first thing we do in a collection is to identify pinned objects.
846 * This function considers all the areas of memory that need to be
847 * conservatively scanned.
850 pin_from_roots (void *start_nursery, void *end_nursery, ScanCopyContext ctx)
854 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);
855 /* objects pinned from the API are inside these roots */
856 SGEN_HASH_TABLE_FOREACH (&roots_hash [ROOT_TYPE_PINNED], void **, start_root, RootRecord *, root) {
857 SGEN_LOG (6, "Pinned roots %p-%p", start_root, root->end_root);
858 sgen_conservatively_pin_objects_from (start_root, (void**)root->end_root, start_nursery, end_nursery, PIN_TYPE_OTHER);
859 } SGEN_HASH_TABLE_FOREACH_END;
860 /* now deal with the thread stacks
861 * in the future we should be able to conservatively scan only:
862 * *) the cpu registers
863 * *) the unmanaged stack frames
864 * *) the _last_ managed stack frame
865 * *) pointers slots in managed frames
867 sgen_client_scan_thread_data (start_nursery, end_nursery, FALSE, ctx);
871 single_arg_user_copy_or_mark (GCObject **obj, void *gc_data)
873 ScanCopyContext *ctx = (ScanCopyContext *)gc_data;
874 ctx->ops->copy_or_mark_object (obj, ctx->queue);
878 * The memory area from start_root to end_root contains pointers to objects.
879 * Their position is precisely described by @desc (this means that the pointer
880 * can be either NULL or the pointer to the start of an object).
881 * This functions copies them to to_space updates them.
883 * This function is not thread-safe!
886 precisely_scan_objects_from (void** start_root, void** end_root, char* n_start, char *n_end, SgenDescriptor desc, ScanCopyContext ctx)
888 CopyOrMarkObjectFunc copy_func = ctx.ops->copy_or_mark_object;
889 SgenGrayQueue *queue = ctx.queue;
891 switch (desc & ROOT_DESC_TYPE_MASK) {
892 case ROOT_DESC_BITMAP:
893 desc >>= ROOT_DESC_TYPE_SHIFT;
895 if ((desc & 1) && *start_root) {
896 copy_func ((GCObject**)start_root, queue);
897 SGEN_LOG (9, "Overwrote root at %p with %p", start_root, *start_root);
903 case ROOT_DESC_COMPLEX: {
904 gsize *bitmap_data = (gsize *)sgen_get_complex_descriptor_bitmap (desc);
905 gsize bwords = (*bitmap_data) - 1;
906 void **start_run = start_root;
908 while (bwords-- > 0) {
909 gsize bmap = *bitmap_data++;
910 void **objptr = start_run;
912 if ((bmap & 1) && *objptr) {
913 copy_func ((GCObject**)objptr, queue);
914 SGEN_LOG (9, "Overwrote root at %p with %p", objptr, *objptr);
919 start_run += GC_BITS_PER_WORD;
923 case ROOT_DESC_USER: {
924 SgenUserRootMarkFunc marker = sgen_get_user_descriptor_func (desc);
925 marker (start_root, single_arg_user_copy_or_mark, &ctx);
928 case ROOT_DESC_RUN_LEN:
929 g_assert_not_reached ();
931 g_assert_not_reached ();
936 reset_heap_boundaries (void)
938 lowest_heap_address = ~(mword)0;
939 highest_heap_address = 0;
943 sgen_update_heap_boundaries (mword low, mword high)
948 old = lowest_heap_address;
951 } while (SGEN_CAS_PTR ((gpointer*)&lowest_heap_address, (gpointer)low, (gpointer)old) != (gpointer)old);
954 old = highest_heap_address;
957 } while (SGEN_CAS_PTR ((gpointer*)&highest_heap_address, (gpointer)high, (gpointer)old) != (gpointer)old);
961 * Allocate and setup the data structures needed to be able to allocate objects
962 * in the nursery. The nursery is stored in nursery_section.
967 GCMemSection *section;
974 SGEN_LOG (2, "Allocating nursery size: %zu", (size_t)sgen_nursery_size);
975 /* later we will alloc a larger area for the nursery but only activate
976 * what we need. The rest will be used as expansion if we have too many pinned
977 * objects in the existing nursery.
979 /* FIXME: handle OOM */
980 section = (GCMemSection *)sgen_alloc_internal (INTERNAL_MEM_SECTION);
982 alloc_size = sgen_nursery_size;
984 /* If there isn't enough space even for the nursery we should simply abort. */
985 g_assert (sgen_memgov_try_alloc_space (alloc_size, SPACE_NURSERY));
987 data = (char *)major_collector.alloc_heap (alloc_size, alloc_size, DEFAULT_NURSERY_BITS);
988 sgen_update_heap_boundaries ((mword)data, (mword)(data + sgen_nursery_size));
989 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 ());
990 section->data = section->next_data = data;
991 section->size = alloc_size;
992 section->end_data = data + sgen_nursery_size;
993 scan_starts = (alloc_size + SCAN_START_SIZE - 1) / SCAN_START_SIZE;
994 section->scan_starts = (char **)sgen_alloc_internal_dynamic (sizeof (char*) * scan_starts, INTERNAL_MEM_SCAN_STARTS, TRUE);
995 section->num_scan_start = scan_starts;
997 nursery_section = section;
999 sgen_nursery_allocator_set_nursery_bounds (data, data + sgen_nursery_size);
1003 mono_gc_get_logfile (void)
1005 return gc_debug_file;
1009 scan_finalizer_entries (SgenPointerQueue *fin_queue, ScanCopyContext ctx)
1011 CopyOrMarkObjectFunc copy_func = ctx.ops->copy_or_mark_object;
1012 SgenGrayQueue *queue = ctx.queue;
1015 for (i = 0; i < fin_queue->next_slot; ++i) {
1016 GCObject *obj = (GCObject *)fin_queue->data [i];
1019 SGEN_LOG (5, "Scan of fin ready object: %p (%s)\n", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
1020 copy_func ((GCObject**)&fin_queue->data [i], queue);
1025 generation_name (int generation)
1027 switch (generation) {
1028 case GENERATION_NURSERY: return "nursery";
1029 case GENERATION_OLD: return "old";
1030 default: g_assert_not_reached ();
1035 sgen_generation_name (int generation)
1037 return generation_name (generation);
1041 finish_gray_stack (int generation, ScanCopyContext ctx)
1045 int done_with_ephemerons, ephemeron_rounds = 0;
1046 char *start_addr = generation == GENERATION_NURSERY ? sgen_get_nursery_start () : NULL;
1047 char *end_addr = generation == GENERATION_NURSERY ? sgen_get_nursery_end () : (char*)-1;
1048 SgenGrayQueue *queue = ctx.queue;
1050 binary_protocol_finish_gray_stack_start (sgen_timestamp (), generation);
1052 * We copied all the reachable objects. Now it's the time to copy
1053 * the objects that were not referenced by the roots, but by the copied objects.
1054 * we built a stack of objects pointed to by gray_start: they are
1055 * additional roots and we may add more items as we go.
1056 * We loop until gray_start == gray_objects which means no more objects have
1057 * been added. Note this is iterative: no recursion is involved.
1058 * We need to walk the LO list as well in search of marked big objects
1059 * (use a flag since this is needed only on major collections). We need to loop
1060 * here as well, so keep a counter of marked LO (increasing it in copy_object).
1061 * To achieve better cache locality and cache usage, we drain the gray stack
1062 * frequently, after each object is copied, and just finish the work here.
1064 sgen_drain_gray_stack (ctx);
1066 SGEN_LOG (2, "%s generation done", generation_name (generation));
1069 Reset bridge data, we might have lingering data from a previous collection if this is a major
1070 collection trigged by minor overflow.
1072 We must reset the gathered bridges since their original block might be evacuated due to major
1073 fragmentation in the meanwhile and the bridge code should not have to deal with that.
1075 if (sgen_client_bridge_need_processing ())
1076 sgen_client_bridge_reset_data ();
1079 * Walk the ephemeron tables marking all values with reachable keys. This must be completely done
1080 * before processing finalizable objects and non-tracking weak links to avoid finalizing/clearing
1081 * objects that are in fact reachable.
1083 done_with_ephemerons = 0;
1085 done_with_ephemerons = sgen_client_mark_ephemerons (ctx);
1086 sgen_drain_gray_stack (ctx);
1088 } while (!done_with_ephemerons);
1090 sgen_client_mark_togglerefs (start_addr, end_addr, ctx);
1092 if (sgen_client_bridge_need_processing ()) {
1093 /*Make sure the gray stack is empty before we process bridge objects so we get liveness right*/
1094 sgen_drain_gray_stack (ctx);
1095 sgen_collect_bridge_objects (generation, ctx);
1096 if (generation == GENERATION_OLD)
1097 sgen_collect_bridge_objects (GENERATION_NURSERY, ctx);
1100 Do the first bridge step here, as the collector liveness state will become useless after that.
1102 An important optimization is to only proccess the possibly dead part of the object graph and skip
1103 over all live objects as we transitively know everything they point must be alive too.
1105 The above invariant is completely wrong if we let the gray queue be drained and mark/copy everything.
1107 This has the unfortunate side effect of making overflow collections perform the first step twice, but
1108 given we now have heuristics that perform major GC in anticipation of minor overflows this should not
1111 sgen_client_bridge_processing_stw_step ();
1115 Make sure we drain the gray stack before processing disappearing links and finalizers.
1116 If we don't make sure it is empty we might wrongly see a live object as dead.
1118 sgen_drain_gray_stack (ctx);
1121 We must clear weak links that don't track resurrection before processing object ready for
1122 finalization so they can be cleared before that.
1124 sgen_null_link_in_range (generation, ctx, FALSE);
1125 if (generation == GENERATION_OLD)
1126 sgen_null_link_in_range (GENERATION_NURSERY, ctx, FALSE);
1129 /* walk the finalization queue and move also the objects that need to be
1130 * finalized: use the finalized objects as new roots so the objects they depend
1131 * on are also not reclaimed. As with the roots above, only objects in the nursery
1132 * are marked/copied.
1134 sgen_finalize_in_range (generation, ctx);
1135 if (generation == GENERATION_OLD)
1136 sgen_finalize_in_range (GENERATION_NURSERY, ctx);
1137 /* drain the new stack that might have been created */
1138 SGEN_LOG (6, "Precise scan of gray area post fin");
1139 sgen_drain_gray_stack (ctx);
1142 * This must be done again after processing finalizable objects since CWL slots are cleared only after the key is finalized.
1144 done_with_ephemerons = 0;
1146 done_with_ephemerons = sgen_client_mark_ephemerons (ctx);
1147 sgen_drain_gray_stack (ctx);
1149 } while (!done_with_ephemerons);
1151 sgen_client_clear_unreachable_ephemerons (ctx);
1154 * We clear togglerefs only after all possible chances of revival are done.
1155 * This is semantically more inline with what users expect and it allows for
1156 * user finalizers to correctly interact with TR objects.
1158 sgen_client_clear_togglerefs (start_addr, end_addr, ctx);
1161 SGEN_LOG (2, "Finalize queue handling scan for %s generation: %lld usecs %d ephemeron rounds", generation_name (generation), TV_ELAPSED (atv, btv), ephemeron_rounds);
1164 * handle disappearing links
1165 * Note we do this after checking the finalization queue because if an object
1166 * survives (at least long enough to be finalized) we don't clear the link.
1167 * This also deals with a possible issue with the monitor reclamation: with the Boehm
1168 * GC a finalized object my lose the monitor because it is cleared before the finalizer is
1171 g_assert (sgen_gray_object_queue_is_empty (queue));
1173 sgen_null_link_in_range (generation, ctx, TRUE);
1174 if (generation == GENERATION_OLD)
1175 sgen_null_link_in_range (GENERATION_NURSERY, ctx, TRUE);
1176 if (sgen_gray_object_queue_is_empty (queue))
1178 sgen_drain_gray_stack (ctx);
1181 g_assert (sgen_gray_object_queue_is_empty (queue));
1183 sgen_gray_object_queue_trim_free_list (queue);
1184 binary_protocol_finish_gray_stack_end (sgen_timestamp (), generation);
1188 sgen_check_section_scan_starts (GCMemSection *section)
1191 for (i = 0; i < section->num_scan_start; ++i) {
1192 if (section->scan_starts [i]) {
1193 mword size = safe_object_get_size ((GCObject*) section->scan_starts [i]);
1194 SGEN_ASSERT (0, size >= SGEN_CLIENT_MINIMUM_OBJECT_SIZE && size <= MAX_SMALL_OBJ_SIZE, "Weird object size at scan starts.");
1200 check_scan_starts (void)
1202 if (!do_scan_starts_check)
1204 sgen_check_section_scan_starts (nursery_section);
1205 major_collector.check_scan_starts ();
1209 scan_from_registered_roots (char *addr_start, char *addr_end, int root_type, ScanCopyContext ctx)
1213 SGEN_HASH_TABLE_FOREACH (&roots_hash [root_type], void **, start_root, RootRecord *, root) {
1214 SGEN_LOG (6, "Precise root scan %p-%p (desc: %p)", start_root, root->end_root, (void*)root->root_desc);
1215 precisely_scan_objects_from (start_root, (void**)root->end_root, addr_start, addr_end, root->root_desc, ctx);
1216 } SGEN_HASH_TABLE_FOREACH_END;
1222 static gboolean inited = FALSE;
1227 mono_counters_register ("Collection max time", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME | MONO_COUNTER_MONOTONIC, &time_max);
1229 mono_counters_register ("Minor fragment clear", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_pre_collection_fragment_clear);
1230 mono_counters_register ("Minor pinning", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_pinning);
1231 mono_counters_register ("Minor scan remembered set", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_remsets);
1232 mono_counters_register ("Minor scan pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_pinned);
1233 mono_counters_register ("Minor scan roots", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_scan_roots);
1234 mono_counters_register ("Minor fragment creation", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_minor_fragment_creation);
1236 mono_counters_register ("Major fragment clear", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_pre_collection_fragment_clear);
1237 mono_counters_register ("Major pinning", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_pinning);
1238 mono_counters_register ("Major scan pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_pinned);
1239 mono_counters_register ("Major scan roots", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_roots);
1240 mono_counters_register ("Major scan mod union", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_scan_mod_union);
1241 mono_counters_register ("Major finish gray stack", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_finish_gray_stack);
1242 mono_counters_register ("Major free big objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_free_bigobjs);
1243 mono_counters_register ("Major LOS sweep", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_los_sweep);
1244 mono_counters_register ("Major sweep", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_sweep);
1245 mono_counters_register ("Major fragment creation", MONO_COUNTER_GC | MONO_COUNTER_ULONG | MONO_COUNTER_TIME, &time_major_fragment_creation);
1247 mono_counters_register ("Number of pinned objects", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_pinned_objects);
1249 #ifdef HEAVY_STATISTICS
1250 mono_counters_register ("WBarrier remember pointer", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_add_to_global_remset);
1251 mono_counters_register ("WBarrier arrayref copy", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_arrayref_copy);
1252 mono_counters_register ("WBarrier generic store called", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_generic_store);
1253 mono_counters_register ("WBarrier generic atomic store called", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_generic_store_atomic);
1254 mono_counters_register ("WBarrier set root", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_wbarrier_set_root);
1256 mono_counters_register ("# objects allocated degraded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_alloced_degraded);
1257 mono_counters_register ("bytes allocated degraded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_bytes_alloced_degraded);
1259 mono_counters_register ("# copy_object() called (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_copy_object_called_nursery);
1260 mono_counters_register ("# objects copied (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_copied_nursery);
1261 mono_counters_register ("# copy_object() called (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_copy_object_called_major);
1262 mono_counters_register ("# objects copied (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_objects_copied_major);
1264 mono_counters_register ("# scan_object() called (nursery)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_scan_object_called_nursery);
1265 mono_counters_register ("# scan_object() called (major)", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_scan_object_called_major);
1267 mono_counters_register ("Slots allocated in vain", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_slots_allocated_in_vain);
1269 mono_counters_register ("# nursery copy_object() failed from space", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_from_space);
1270 mono_counters_register ("# nursery copy_object() failed forwarded", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_forwarded);
1271 mono_counters_register ("# nursery copy_object() failed pinned", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_pinned);
1272 mono_counters_register ("# nursery copy_object() failed to space", MONO_COUNTER_GC | MONO_COUNTER_ULONG, &stat_nursery_copy_object_failed_to_space);
1274 sgen_nursery_allocator_init_heavy_stats ();
1282 reset_pinned_from_failed_allocation (void)
1284 bytes_pinned_from_failed_allocation = 0;
1288 sgen_set_pinned_from_failed_allocation (mword objsize)
1290 bytes_pinned_from_failed_allocation += objsize;
1294 sgen_collection_is_concurrent (void)
1296 switch (current_collection_generation) {
1297 case GENERATION_NURSERY:
1299 case GENERATION_OLD:
1300 return concurrent_collection_in_progress;
1302 g_error ("Invalid current generation %d", current_collection_generation);
1308 sgen_concurrent_collection_in_progress (void)
1310 return concurrent_collection_in_progress;
1314 SgenThreadPoolJob job;
1315 SgenObjectOperations *ops;
1319 job_remembered_set_scan (void *worker_data_untyped, SgenThreadPoolJob *job)
1321 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1322 ScanJob *job_data = (ScanJob*)job;
1323 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1324 remset.scan_remsets (ctx);
1328 SgenThreadPoolJob job;
1329 SgenObjectOperations *ops;
1333 } ScanFromRegisteredRootsJob;
1336 job_scan_from_registered_roots (void *worker_data_untyped, SgenThreadPoolJob *job)
1338 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1339 ScanFromRegisteredRootsJob *job_data = (ScanFromRegisteredRootsJob*)job;
1340 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1342 scan_from_registered_roots (job_data->heap_start, job_data->heap_end, job_data->root_type, ctx);
1346 SgenThreadPoolJob job;
1347 SgenObjectOperations *ops;
1350 } ScanThreadDataJob;
1353 job_scan_thread_data (void *worker_data_untyped, SgenThreadPoolJob *job)
1355 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1356 ScanThreadDataJob *job_data = (ScanThreadDataJob*)job;
1357 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1359 sgen_client_scan_thread_data (job_data->heap_start, job_data->heap_end, TRUE, ctx);
1363 SgenThreadPoolJob job;
1364 SgenObjectOperations *ops;
1365 SgenPointerQueue *queue;
1366 } ScanFinalizerEntriesJob;
1369 job_scan_finalizer_entries (void *worker_data_untyped, SgenThreadPoolJob *job)
1371 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1372 ScanFinalizerEntriesJob *job_data = (ScanFinalizerEntriesJob*)job;
1373 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1375 scan_finalizer_entries (job_data->queue, ctx);
1379 job_scan_major_mod_union_card_table (void *worker_data_untyped, SgenThreadPoolJob *job)
1381 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1382 ScanJob *job_data = (ScanJob*)job;
1383 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1385 g_assert (concurrent_collection_in_progress);
1386 major_collector.scan_card_table (CARDTABLE_SCAN_MOD_UNION, ctx);
1390 job_scan_los_mod_union_card_table (void *worker_data_untyped, SgenThreadPoolJob *job)
1392 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1393 ScanJob *job_data = (ScanJob*)job;
1394 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1396 g_assert (concurrent_collection_in_progress);
1397 sgen_los_scan_card_table (CARDTABLE_SCAN_MOD_UNION, ctx);
1401 job_mod_union_preclean (void *worker_data_untyped, SgenThreadPoolJob *job)
1403 WorkerData *worker_data = (WorkerData *)worker_data_untyped;
1404 ScanJob *job_data = (ScanJob*)job;
1405 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (job_data->ops, sgen_workers_get_job_gray_queue (worker_data));
1407 g_assert (concurrent_collection_in_progress);
1409 major_collector.scan_card_table (CARDTABLE_SCAN_MOD_UNION_PRECLEAN, ctx);
1410 sgen_los_scan_card_table (CARDTABLE_SCAN_MOD_UNION_PRECLEAN, ctx);
1414 init_gray_queue (gboolean use_workers)
1417 sgen_workers_init_distribute_gray_queue ();
1418 sgen_gray_object_queue_init (&gray_queue, NULL);
1422 enqueue_scan_from_roots_jobs (char *heap_start, char *heap_end, SgenObjectOperations *ops, gboolean enqueue)
1424 ScanFromRegisteredRootsJob *scrrj;
1425 ScanThreadDataJob *stdj;
1426 ScanFinalizerEntriesJob *sfej;
1428 /* registered roots, this includes static fields */
1430 scrrj = (ScanFromRegisteredRootsJob*)sgen_thread_pool_job_alloc ("scan from registered roots normal", job_scan_from_registered_roots, sizeof (ScanFromRegisteredRootsJob));
1432 scrrj->heap_start = heap_start;
1433 scrrj->heap_end = heap_end;
1434 scrrj->root_type = ROOT_TYPE_NORMAL;
1435 sgen_workers_enqueue_job (&scrrj->job, enqueue);
1437 scrrj = (ScanFromRegisteredRootsJob*)sgen_thread_pool_job_alloc ("scan from registered roots wbarrier", job_scan_from_registered_roots, sizeof (ScanFromRegisteredRootsJob));
1439 scrrj->heap_start = heap_start;
1440 scrrj->heap_end = heap_end;
1441 scrrj->root_type = ROOT_TYPE_WBARRIER;
1442 sgen_workers_enqueue_job (&scrrj->job, enqueue);
1446 stdj = (ScanThreadDataJob*)sgen_thread_pool_job_alloc ("scan thread data", job_scan_thread_data, sizeof (ScanThreadDataJob));
1447 stdj->heap_start = heap_start;
1448 stdj->heap_end = heap_end;
1449 sgen_workers_enqueue_job (&stdj->job, enqueue);
1451 /* Scan the list of objects ready for finalization. */
1453 sfej = (ScanFinalizerEntriesJob*)sgen_thread_pool_job_alloc ("scan finalizer entries", job_scan_finalizer_entries, sizeof (ScanFinalizerEntriesJob));
1454 sfej->queue = &fin_ready_queue;
1456 sgen_workers_enqueue_job (&sfej->job, enqueue);
1458 sfej = (ScanFinalizerEntriesJob*)sgen_thread_pool_job_alloc ("scan critical finalizer entries", job_scan_finalizer_entries, sizeof (ScanFinalizerEntriesJob));
1459 sfej->queue = &critical_fin_queue;
1461 sgen_workers_enqueue_job (&sfej->job, enqueue);
1465 * Perform a nursery collection.
1467 * Return whether any objects were late-pinned due to being out of memory.
1470 collect_nursery (SgenGrayQueue *unpin_queue, gboolean finish_up_concurrent_mark)
1472 gboolean needs_major;
1473 size_t max_garbage_amount;
1475 mword fragment_total;
1477 SgenObjectOperations *object_ops = &sgen_minor_collector.serial_ops;
1478 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, &gray_queue);
1482 if (disable_minor_collections)
1485 TV_GETTIME (last_minor_collection_start_tv);
1486 atv = last_minor_collection_start_tv;
1488 binary_protocol_collection_begin (gc_stats.minor_gc_count, GENERATION_NURSERY);
1490 if (do_verify_nursery || do_dump_nursery_content)
1491 sgen_debug_verify_nursery (do_dump_nursery_content);
1493 current_collection_generation = GENERATION_NURSERY;
1495 SGEN_ASSERT (0, !sgen_collection_is_concurrent (), "Why is the nursery collection concurrent?");
1497 reset_pinned_from_failed_allocation ();
1499 check_scan_starts ();
1501 sgen_nursery_alloc_prepare_for_minor ();
1505 nursery_next = sgen_nursery_alloc_get_upper_alloc_bound ();
1506 /* FIXME: optimize later to use the higher address where an object can be present */
1507 nursery_next = MAX (nursery_next, sgen_get_nursery_end ());
1509 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 ()));
1510 max_garbage_amount = nursery_next - sgen_get_nursery_start ();
1511 g_assert (nursery_section->size >= max_garbage_amount);
1513 /* world must be stopped already */
1515 time_minor_pre_collection_fragment_clear += TV_ELAPSED (atv, btv);
1517 sgen_client_pre_collection_checks ();
1519 nursery_section->next_data = nursery_next;
1521 major_collector.start_nursery_collection ();
1523 sgen_memgov_minor_collection_start ();
1525 init_gray_queue (FALSE);
1527 gc_stats.minor_gc_count ++;
1529 if (whole_heap_check_before_collection) {
1530 sgen_clear_nursery_fragments ();
1531 sgen_check_whole_heap (finish_up_concurrent_mark);
1533 if (consistency_check_at_minor_collection)
1534 sgen_check_consistency ();
1536 sgen_process_fin_stage_entries ();
1538 /* pin from pinned handles */
1539 sgen_init_pinning ();
1540 sgen_client_binary_protocol_mark_start (GENERATION_NURSERY);
1541 pin_from_roots (sgen_get_nursery_start (), nursery_next, ctx);
1542 /* pin cemented objects */
1543 sgen_pin_cemented_objects ();
1544 /* identify pinned objects */
1545 sgen_optimize_pin_queue ();
1546 sgen_pinning_setup_section (nursery_section);
1548 pin_objects_in_nursery (FALSE, ctx);
1549 sgen_pinning_trim_queue_to_section (nursery_section);
1552 time_minor_pinning += TV_ELAPSED (btv, atv);
1553 SGEN_LOG (2, "Finding pinned pointers: %zd in %lld usecs", sgen_get_pinned_count (), TV_ELAPSED (btv, atv));
1554 SGEN_LOG (4, "Start scan with %zd pinned objects", sgen_get_pinned_count ());
1556 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan remset", job_remembered_set_scan, sizeof (ScanJob));
1557 sj->ops = object_ops;
1558 sgen_workers_enqueue_job (&sj->job, FALSE);
1560 /* we don't have complete write barrier yet, so we scan all the old generation sections */
1562 time_minor_scan_remsets += TV_ELAPSED (atv, btv);
1563 SGEN_LOG (2, "Old generation scan: %lld usecs", TV_ELAPSED (atv, btv));
1565 sgen_pin_stats_print_class_stats ();
1567 /* FIXME: Why do we do this at this specific, seemingly random, point? */
1568 sgen_client_collecting_minor (&fin_ready_queue, &critical_fin_queue);
1571 time_minor_scan_pinned += TV_ELAPSED (btv, atv);
1573 enqueue_scan_from_roots_jobs (sgen_get_nursery_start (), nursery_next, object_ops, FALSE);
1576 time_minor_scan_roots += TV_ELAPSED (atv, btv);
1578 finish_gray_stack (GENERATION_NURSERY, ctx);
1581 time_minor_finish_gray_stack += TV_ELAPSED (btv, atv);
1582 sgen_client_binary_protocol_mark_end (GENERATION_NURSERY);
1584 if (objects_pinned) {
1585 sgen_optimize_pin_queue ();
1586 sgen_pinning_setup_section (nursery_section);
1589 /* walk the pin_queue, build up the fragment list of free memory, unmark
1590 * pinned objects as we go, memzero() the empty fragments so they are ready for the
1593 sgen_client_binary_protocol_reclaim_start (GENERATION_NURSERY);
1594 fragment_total = sgen_build_nursery_fragments (nursery_section, unpin_queue);
1595 if (!fragment_total)
1598 /* Clear TLABs for all threads */
1599 sgen_clear_tlabs ();
1601 sgen_client_binary_protocol_reclaim_end (GENERATION_NURSERY);
1603 time_minor_fragment_creation += TV_ELAPSED (atv, btv);
1604 SGEN_LOG (2, "Fragment creation: %lld usecs, %lu bytes available", TV_ELAPSED (atv, btv), (unsigned long)fragment_total);
1606 if (consistency_check_at_minor_collection)
1607 sgen_check_major_refs ();
1609 major_collector.finish_nursery_collection ();
1611 TV_GETTIME (last_minor_collection_end_tv);
1612 gc_stats.minor_gc_time += TV_ELAPSED (last_minor_collection_start_tv, last_minor_collection_end_tv);
1614 sgen_debug_dump_heap ("minor", gc_stats.minor_gc_count - 1, NULL);
1616 /* prepare the pin queue for the next collection */
1617 sgen_finish_pinning ();
1618 if (sgen_have_pending_finalizers ()) {
1619 SGEN_LOG (4, "Finalizer-thread wakeup");
1620 sgen_client_finalize_notify ();
1622 sgen_pin_stats_reset ();
1623 /* clear cemented hash */
1624 sgen_cement_clear_below_threshold ();
1626 g_assert (sgen_gray_object_queue_is_empty (&gray_queue));
1628 remset.finish_minor_collection ();
1630 check_scan_starts ();
1632 binary_protocol_flush_buffers (FALSE);
1634 sgen_memgov_minor_collection_end ();
1636 /*objects are late pinned because of lack of memory, so a major is a good call*/
1637 needs_major = objects_pinned > 0;
1638 current_collection_generation = -1;
1641 binary_protocol_collection_end (gc_stats.minor_gc_count - 1, GENERATION_NURSERY, 0, 0);
1643 if (check_nursery_objects_pinned && !sgen_minor_collector.is_split)
1644 sgen_check_nursery_objects_pinned (unpin_queue != NULL);
1650 COPY_OR_MARK_FROM_ROOTS_SERIAL,
1651 COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT,
1652 COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT
1653 } CopyOrMarkFromRootsMode;
1656 major_copy_or_mark_from_roots (size_t *old_next_pin_slot, CopyOrMarkFromRootsMode mode, SgenObjectOperations *object_ops)
1661 /* FIXME: only use these values for the precise scan
1662 * note that to_space pointers should be excluded anyway...
1664 char *heap_start = NULL;
1665 char *heap_end = (char*)-1;
1666 ScanCopyContext ctx = CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, WORKERS_DISTRIBUTE_GRAY_QUEUE);
1667 gboolean concurrent = mode != COPY_OR_MARK_FROM_ROOTS_SERIAL;
1669 SGEN_ASSERT (0, !!concurrent == !!concurrent_collection_in_progress, "We've been called with the wrong mode.");
1671 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1672 /*This cleans up unused fragments */
1673 sgen_nursery_allocator_prepare_for_pinning ();
1675 if (do_concurrent_checks)
1676 sgen_debug_check_nursery_is_clean ();
1678 /* The concurrent collector doesn't touch the nursery. */
1679 sgen_nursery_alloc_prepare_for_major ();
1682 init_gray_queue (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT);
1686 /* Pinning depends on this */
1687 sgen_clear_nursery_fragments ();
1689 if (whole_heap_check_before_collection)
1690 sgen_check_whole_heap (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT);
1693 time_major_pre_collection_fragment_clear += TV_ELAPSED (atv, btv);
1695 if (!sgen_collection_is_concurrent ())
1696 nursery_section->next_data = sgen_get_nursery_end ();
1697 /* we should also coalesce scanning from sections close to each other
1698 * and deal with pointers outside of the sections later.
1703 sgen_client_pre_collection_checks ();
1705 if (mode != COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1706 /* Remsets are not useful for a major collection */
1707 remset.clear_cards ();
1710 sgen_process_fin_stage_entries ();
1713 sgen_init_pinning ();
1714 SGEN_LOG (6, "Collecting pinned addresses");
1715 pin_from_roots ((void*)lowest_heap_address, (void*)highest_heap_address, ctx);
1716 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1717 /* Pin cemented objects that were forced */
1718 sgen_pin_cemented_objects ();
1720 sgen_optimize_pin_queue ();
1721 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1723 * Cemented objects that are in the pinned list will be marked. When
1724 * marking concurrently we won't mark mod-union cards for these objects.
1725 * Instead they will remain cemented until the next major collection,
1726 * when we will recheck if they are still pinned in the roots.
1728 sgen_cement_force_pinned ();
1731 sgen_client_collecting_major_1 ();
1734 * pin_queue now contains all candidate pointers, sorted and
1735 * uniqued. We must do two passes now to figure out which
1736 * objects are pinned.
1738 * The first is to find within the pin_queue the area for each
1739 * section. This requires that the pin_queue be sorted. We
1740 * also process the LOS objects and pinned chunks here.
1742 * The second, destructive, pass is to reduce the section
1743 * areas to pointers to the actually pinned objects.
1745 SGEN_LOG (6, "Pinning from sections");
1746 /* first pass for the sections */
1747 sgen_find_section_pin_queue_start_end (nursery_section);
1748 /* identify possible pointers to the insize of large objects */
1749 SGEN_LOG (6, "Pinning from large objects");
1750 for (bigobj = los_object_list; bigobj; bigobj = bigobj->next) {
1752 if (sgen_find_optimized_pin_queue_area ((char*)bigobj->data, (char*)bigobj->data + sgen_los_object_size (bigobj), &dummy, &dummy)) {
1753 binary_protocol_pin (bigobj->data, (gpointer)LOAD_VTABLE (bigobj->data), safe_object_get_size (bigobj->data));
1755 if (sgen_los_object_is_pinned (bigobj->data)) {
1756 SGEN_ASSERT (0, mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT, "LOS objects can only be pinned here after concurrent marking.");
1759 sgen_los_pin_object (bigobj->data);
1760 if (SGEN_OBJECT_HAS_REFERENCES (bigobj->data))
1761 GRAY_OBJECT_ENQUEUE (WORKERS_DISTRIBUTE_GRAY_QUEUE, bigobj->data, sgen_obj_get_descriptor ((GCObject*)bigobj->data));
1762 sgen_pin_stats_register_object (bigobj->data, safe_object_get_size (bigobj->data));
1763 SGEN_LOG (6, "Marked large object %p (%s) size: %lu from roots", bigobj->data,
1764 sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (bigobj->data)),
1765 (unsigned long)sgen_los_object_size (bigobj));
1767 sgen_client_pinned_los_object (bigobj->data);
1771 pin_objects_in_nursery (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT, ctx);
1772 if (check_nursery_objects_pinned && !sgen_minor_collector.is_split)
1773 sgen_check_nursery_objects_pinned (mode != COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT);
1775 major_collector.pin_objects (WORKERS_DISTRIBUTE_GRAY_QUEUE);
1776 if (old_next_pin_slot)
1777 *old_next_pin_slot = sgen_get_pinned_count ();
1780 time_major_pinning += TV_ELAPSED (atv, btv);
1781 SGEN_LOG (2, "Finding pinned pointers: %zd in %lld usecs", sgen_get_pinned_count (), TV_ELAPSED (atv, btv));
1782 SGEN_LOG (4, "Start scan with %zd pinned objects", sgen_get_pinned_count ());
1784 major_collector.init_to_space ();
1786 SGEN_ASSERT (0, sgen_workers_all_done (), "Why are the workers not done when we start or finish a major collection?");
1787 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1788 if (sgen_workers_have_idle_work ()) {
1790 * We force the finish of the worker with the new object ops context
1791 * which can also do copying. We need to have finished pinning.
1793 sgen_workers_start_all_workers (object_ops, NULL);
1794 sgen_workers_join ();
1798 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
1799 main_gc_thread = mono_native_thread_self ();
1802 sgen_client_collecting_major_2 ();
1805 time_major_scan_pinned += TV_ELAPSED (btv, atv);
1807 sgen_client_collecting_major_3 (&fin_ready_queue, &critical_fin_queue);
1809 enqueue_scan_from_roots_jobs (heap_start, heap_end, object_ops, FALSE);
1812 time_major_scan_roots += TV_ELAPSED (atv, btv);
1815 * We start the concurrent worker after pinning and after we scanned the roots
1816 * in order to make sure that the worker does not finish before handling all
1819 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1820 if (precleaning_enabled) {
1822 /* Mod union preclean job */
1823 sj = (ScanJob*)sgen_thread_pool_job_alloc ("preclean mod union cardtable", job_mod_union_preclean, sizeof (ScanJob));
1824 sj->ops = object_ops;
1825 sgen_workers_start_all_workers (object_ops, &sj->job);
1827 sgen_workers_start_all_workers (object_ops, NULL);
1829 gray_queue_enable_redirect (WORKERS_DISTRIBUTE_GRAY_QUEUE);
1832 if (mode == COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT) {
1835 /* Mod union card table */
1836 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan mod union cardtable", job_scan_major_mod_union_card_table, sizeof (ScanJob));
1837 sj->ops = object_ops;
1838 sgen_workers_enqueue_job (&sj->job, FALSE);
1840 sj = (ScanJob*)sgen_thread_pool_job_alloc ("scan LOS mod union cardtable", job_scan_los_mod_union_card_table, sizeof (ScanJob));
1841 sj->ops = object_ops;
1842 sgen_workers_enqueue_job (&sj->job, FALSE);
1845 time_major_scan_mod_union += TV_ELAPSED (btv, atv);
1848 sgen_pin_stats_print_class_stats ();
1852 major_finish_copy_or_mark (CopyOrMarkFromRootsMode mode)
1854 if (mode == COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT) {
1855 sgen_finish_pinning ();
1857 sgen_pin_stats_reset ();
1859 if (do_concurrent_checks)
1860 sgen_debug_check_nursery_is_clean ();
1865 major_start_collection (gboolean concurrent, size_t *old_next_pin_slot)
1867 SgenObjectOperations *object_ops;
1869 binary_protocol_collection_begin (gc_stats.major_gc_count, GENERATION_OLD);
1871 current_collection_generation = GENERATION_OLD;
1873 g_assert (sgen_section_gray_queue_is_empty (sgen_workers_get_distribute_section_gray_queue ()));
1876 sgen_cement_reset ();
1879 g_assert (major_collector.is_concurrent);
1880 concurrent_collection_in_progress = TRUE;
1882 object_ops = &major_collector.major_ops_concurrent_start;
1884 object_ops = &major_collector.major_ops_serial;
1887 reset_pinned_from_failed_allocation ();
1889 sgen_memgov_major_collection_start ();
1891 //count_ref_nonref_objs ();
1892 //consistency_check ();
1894 check_scan_starts ();
1897 SGEN_LOG (1, "Start major collection %d", gc_stats.major_gc_count);
1898 gc_stats.major_gc_count ++;
1900 if (major_collector.start_major_collection)
1901 major_collector.start_major_collection ();
1903 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);
1904 major_finish_copy_or_mark (concurrent ? COPY_OR_MARK_FROM_ROOTS_START_CONCURRENT : COPY_OR_MARK_FROM_ROOTS_SERIAL);
1908 major_finish_collection (const char *reason, size_t old_next_pin_slot, gboolean forced)
1910 ScannedObjectCounts counts;
1911 SgenObjectOperations *object_ops;
1912 mword fragment_total;
1918 if (concurrent_collection_in_progress) {
1919 object_ops = &major_collector.major_ops_concurrent_finish;
1921 major_copy_or_mark_from_roots (NULL, COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT, object_ops);
1923 major_finish_copy_or_mark (COPY_OR_MARK_FROM_ROOTS_FINISH_CONCURRENT);
1925 #ifdef SGEN_DEBUG_INTERNAL_ALLOC
1926 main_gc_thread = NULL;
1929 object_ops = &major_collector.major_ops_serial;
1932 g_assert (sgen_section_gray_queue_is_empty (sgen_workers_get_distribute_section_gray_queue ()));
1934 /* all the objects in the heap */
1935 finish_gray_stack (GENERATION_OLD, CONTEXT_FROM_OBJECT_OPERATIONS (object_ops, &gray_queue));
1937 time_major_finish_gray_stack += TV_ELAPSED (btv, atv);
1939 SGEN_ASSERT (0, sgen_workers_all_done (), "Can't have workers working after joining");
1941 if (objects_pinned) {
1942 g_assert (!concurrent_collection_in_progress);
1945 * This is slow, but we just OOM'd.
1947 * See comment at `sgen_pin_queue_clear_discarded_entries` for how the pin
1948 * queue is laid out at this point.
1950 sgen_pin_queue_clear_discarded_entries (nursery_section, old_next_pin_slot);
1952 * We need to reestablish all pinned nursery objects in the pin queue
1953 * because they're needed for fragment creation. Unpinning happens by
1954 * walking the whole queue, so it's not necessary to reestablish where major
1955 * heap block pins are - all we care is that they're still in there
1958 sgen_optimize_pin_queue ();
1959 sgen_find_section_pin_queue_start_end (nursery_section);
1963 reset_heap_boundaries ();
1964 sgen_update_heap_boundaries ((mword)sgen_get_nursery_start (), (mword)sgen_get_nursery_end ());
1966 /* walk the pin_queue, build up the fragment list of free memory, unmark
1967 * pinned objects as we go, memzero() the empty fragments so they are ready for the
1970 fragment_total = sgen_build_nursery_fragments (nursery_section, NULL);
1971 if (!fragment_total)
1973 SGEN_LOG (4, "Free space in nursery after major %ld", (long)fragment_total);
1975 if (do_concurrent_checks && concurrent_collection_in_progress)
1976 sgen_debug_check_nursery_is_clean ();
1978 /* prepare the pin queue for the next collection */
1979 sgen_finish_pinning ();
1981 /* Clear TLABs for all threads */
1982 sgen_clear_tlabs ();
1984 sgen_pin_stats_reset ();
1986 sgen_cement_clear_below_threshold ();
1988 if (check_mark_bits_after_major_collection)
1989 sgen_check_heap_marked (concurrent_collection_in_progress);
1992 time_major_fragment_creation += TV_ELAPSED (atv, btv);
1994 binary_protocol_sweep_begin (GENERATION_OLD, !major_collector.sweeps_lazily);
1995 sgen_memgov_major_pre_sweep ();
1998 time_major_free_bigobjs += TV_ELAPSED (btv, atv);
2003 time_major_los_sweep += TV_ELAPSED (atv, btv);
2005 major_collector.sweep ();
2007 binary_protocol_sweep_end (GENERATION_OLD, !major_collector.sweeps_lazily);
2010 time_major_sweep += TV_ELAPSED (btv, atv);
2012 sgen_debug_dump_heap ("major", gc_stats.major_gc_count - 1, reason);
2014 if (sgen_have_pending_finalizers ()) {
2015 SGEN_LOG (4, "Finalizer-thread wakeup");
2016 sgen_client_finalize_notify ();
2019 g_assert (sgen_gray_object_queue_is_empty (&gray_queue));
2021 sgen_memgov_major_collection_end (forced);
2022 current_collection_generation = -1;
2024 memset (&counts, 0, sizeof (ScannedObjectCounts));
2025 major_collector.finish_major_collection (&counts);
2027 g_assert (sgen_section_gray_queue_is_empty (sgen_workers_get_distribute_section_gray_queue ()));
2029 SGEN_ASSERT (0, sgen_workers_all_done (), "Can't have workers working after major collection has finished");
2030 if (concurrent_collection_in_progress)
2031 concurrent_collection_in_progress = FALSE;
2033 check_scan_starts ();
2035 binary_protocol_flush_buffers (FALSE);
2037 //consistency_check ();
2039 binary_protocol_collection_end (gc_stats.major_gc_count - 1, GENERATION_OLD, counts.num_scanned_objects, counts.num_unique_scanned_objects);
2043 major_do_collection (const char *reason, gboolean forced)
2045 TV_DECLARE (time_start);
2046 TV_DECLARE (time_end);
2047 size_t old_next_pin_slot;
2049 if (disable_major_collections)
2052 if (major_collector.get_and_reset_num_major_objects_marked) {
2053 long long num_marked = major_collector.get_and_reset_num_major_objects_marked ();
2054 g_assert (!num_marked);
2057 /* world must be stopped already */
2058 TV_GETTIME (time_start);
2060 major_start_collection (FALSE, &old_next_pin_slot);
2061 major_finish_collection (reason, old_next_pin_slot, forced);
2063 TV_GETTIME (time_end);
2064 gc_stats.major_gc_time += TV_ELAPSED (time_start, time_end);
2066 /* FIXME: also report this to the user, preferably in gc-end. */
2067 if (major_collector.get_and_reset_num_major_objects_marked)
2068 major_collector.get_and_reset_num_major_objects_marked ();
2070 return bytes_pinned_from_failed_allocation > 0;
2074 major_start_concurrent_collection (const char *reason)
2076 TV_DECLARE (time_start);
2077 TV_DECLARE (time_end);
2078 long long num_objects_marked;
2080 if (disable_major_collections)
2083 TV_GETTIME (time_start);
2084 SGEN_TV_GETTIME (time_major_conc_collection_start);
2086 num_objects_marked = major_collector.get_and_reset_num_major_objects_marked ();
2087 g_assert (num_objects_marked == 0);
2089 binary_protocol_concurrent_start ();
2091 // FIXME: store reason and pass it when finishing
2092 major_start_collection (TRUE, NULL);
2094 gray_queue_redirect (&gray_queue);
2096 num_objects_marked = major_collector.get_and_reset_num_major_objects_marked ();
2098 TV_GETTIME (time_end);
2099 gc_stats.major_gc_time += TV_ELAPSED (time_start, time_end);
2101 current_collection_generation = -1;
2105 * Returns whether the major collection has finished.
2108 major_should_finish_concurrent_collection (void)
2110 SGEN_ASSERT (0, sgen_gray_object_queue_is_empty (&gray_queue), "Why is the gray queue not empty before we have started doing anything?");
2111 return sgen_workers_all_done ();
2115 major_update_concurrent_collection (void)
2117 TV_DECLARE (total_start);
2118 TV_DECLARE (total_end);
2120 TV_GETTIME (total_start);
2122 binary_protocol_concurrent_update ();
2124 major_collector.update_cardtable_mod_union ();
2125 sgen_los_update_cardtable_mod_union ();
2127 TV_GETTIME (total_end);
2128 gc_stats.major_gc_time += TV_ELAPSED (total_start, total_end);
2132 major_finish_concurrent_collection (gboolean forced)
2134 TV_DECLARE (total_start);
2135 TV_DECLARE (total_end);
2137 TV_GETTIME (total_start);
2139 binary_protocol_concurrent_finish ();
2142 * We need to stop all workers since we're updating the cardtable below.
2143 * The workers will be resumed with a finishing pause context to avoid
2144 * additional cardtable and object scanning.
2146 sgen_workers_stop_all_workers ();
2148 SGEN_TV_GETTIME (time_major_conc_collection_end);
2149 gc_stats.major_gc_time_concurrent += SGEN_TV_ELAPSED (time_major_conc_collection_start, time_major_conc_collection_end);
2151 major_collector.update_cardtable_mod_union ();
2152 sgen_los_update_cardtable_mod_union ();
2154 if (mod_union_consistency_check)
2155 sgen_check_mod_union_consistency ();
2157 current_collection_generation = GENERATION_OLD;
2158 sgen_cement_reset ();
2159 major_finish_collection ("finishing", -1, forced);
2161 if (whole_heap_check_before_collection)
2162 sgen_check_whole_heap (FALSE);
2164 TV_GETTIME (total_end);
2165 gc_stats.major_gc_time += TV_ELAPSED (total_start, total_end) - TV_ELAPSED (last_minor_collection_start_tv, last_minor_collection_end_tv);
2167 current_collection_generation = -1;
2171 * Ensure an allocation request for @size will succeed by freeing enough memory.
2173 * LOCKING: The GC lock MUST be held.
2176 sgen_ensure_free_space (size_t size, int generation)
2178 int generation_to_collect = -1;
2179 const char *reason = NULL;
2181 if (generation == GENERATION_OLD) {
2182 if (sgen_need_major_collection (size)) {
2183 reason = "LOS overflow";
2184 generation_to_collect = GENERATION_OLD;
2187 if (degraded_mode) {
2188 if (sgen_need_major_collection (size)) {
2189 reason = "Degraded mode overflow";
2190 generation_to_collect = GENERATION_OLD;
2192 } else if (sgen_need_major_collection (size)) {
2193 reason = concurrent_collection_in_progress ? "Forced finish concurrent collection" : "Minor allowance";
2194 generation_to_collect = GENERATION_OLD;
2196 generation_to_collect = GENERATION_NURSERY;
2197 reason = "Nursery full";
2201 if (generation_to_collect == -1) {
2202 if (concurrent_collection_in_progress && sgen_workers_all_done ()) {
2203 generation_to_collect = GENERATION_OLD;
2204 reason = "Finish concurrent collection";
2208 if (generation_to_collect == -1)
2210 sgen_perform_collection (size, generation_to_collect, reason, FALSE);
2214 * LOCKING: Assumes the GC lock is held.
2217 sgen_perform_collection (size_t requested_size, int generation_to_collect, const char *reason, gboolean wait_to_finish)
2219 TV_DECLARE (gc_start);
2220 TV_DECLARE (gc_end);
2221 TV_DECLARE (gc_total_start);
2222 TV_DECLARE (gc_total_end);
2223 GGTimingInfo infos [2];
2224 int overflow_generation_to_collect = -1;
2225 int oldest_generation_collected = generation_to_collect;
2226 const char *overflow_reason = NULL;
2228 binary_protocol_collection_requested (generation_to_collect, requested_size, wait_to_finish ? 1 : 0);
2230 SGEN_ASSERT (0, generation_to_collect == GENERATION_NURSERY || generation_to_collect == GENERATION_OLD, "What generation is this?");
2232 TV_GETTIME (gc_start);
2234 sgen_stop_world (generation_to_collect);
2236 TV_GETTIME (gc_total_start);
2238 if (concurrent_collection_in_progress) {
2240 * If the concurrent worker is finished or we are asked to do a major collection
2241 * then we finish the concurrent collection.
2243 gboolean finish = major_should_finish_concurrent_collection () || generation_to_collect == GENERATION_OLD;
2246 major_finish_concurrent_collection (wait_to_finish);
2247 oldest_generation_collected = GENERATION_OLD;
2249 SGEN_ASSERT (0, generation_to_collect == GENERATION_NURSERY, "Why aren't we finishing the concurrent collection?");
2250 major_update_concurrent_collection ();
2251 collect_nursery (NULL, FALSE);
2257 SGEN_ASSERT (0, !concurrent_collection_in_progress, "Why did this not get handled above?");
2260 * There's no concurrent collection in progress. Collect the generation we're asked
2261 * to collect. If the major collector is concurrent and we're not forced to wait,
2262 * start a concurrent collection.
2264 // FIXME: extract overflow reason
2265 if (generation_to_collect == GENERATION_NURSERY) {
2266 if (collect_nursery (NULL, FALSE)) {
2267 overflow_generation_to_collect = GENERATION_OLD;
2268 overflow_reason = "Minor overflow";
2271 if (major_collector.is_concurrent && !wait_to_finish) {
2272 collect_nursery (NULL, FALSE);
2273 major_start_concurrent_collection (reason);
2274 // FIXME: set infos[0] properly
2278 if (major_do_collection (reason, wait_to_finish)) {
2279 overflow_generation_to_collect = GENERATION_NURSERY;
2280 overflow_reason = "Excessive pinning";
2284 TV_GETTIME (gc_end);
2286 memset (infos, 0, sizeof (infos));
2287 infos [0].generation = generation_to_collect;
2288 infos [0].reason = reason;
2289 infos [0].is_overflow = FALSE;
2290 infos [1].generation = -1;
2291 infos [0].total_time = SGEN_TV_ELAPSED (gc_start, gc_end);
2293 SGEN_ASSERT (0, !concurrent_collection_in_progress, "Why did this not get handled above?");
2295 if (overflow_generation_to_collect != -1) {
2297 * We need to do an overflow collection, either because we ran out of memory
2298 * or the nursery is fully pinned.
2301 infos [1].generation = overflow_generation_to_collect;
2302 infos [1].reason = overflow_reason;
2303 infos [1].is_overflow = TRUE;
2306 if (overflow_generation_to_collect == GENERATION_NURSERY)
2307 collect_nursery (NULL, FALSE);
2309 major_do_collection (overflow_reason, wait_to_finish);
2311 TV_GETTIME (gc_end);
2312 infos [1].total_time = SGEN_TV_ELAPSED (gc_start, gc_end);
2314 oldest_generation_collected = MAX (oldest_generation_collected, overflow_generation_to_collect);
2317 SGEN_LOG (2, "Heap size: %lu, LOS size: %lu", (unsigned long)sgen_gc_get_total_heap_allocation (), (unsigned long)los_memory_usage);
2319 /* this also sets the proper pointers for the next allocation */
2320 if (generation_to_collect == GENERATION_NURSERY && !sgen_can_alloc_size (requested_size)) {
2321 /* TypeBuilder and MonoMethod are killing mcs with fragmentation */
2322 SGEN_LOG (1, "nursery collection didn't find enough room for %zd alloc (%zd pinned)", requested_size, sgen_get_pinned_count ());
2323 sgen_dump_pin_queue ();
2328 g_assert (sgen_gray_object_queue_is_empty (&gray_queue));
2330 TV_GETTIME (gc_total_end);
2331 time_max = MAX (time_max, TV_ELAPSED (gc_total_start, gc_total_end));
2333 sgen_restart_world (oldest_generation_collected, infos);
2337 * ######################################################################
2338 * ######## Memory allocation from the OS
2339 * ######################################################################
2340 * This section of code deals with getting memory from the OS and
2341 * allocating memory for GC-internal data structures.
2342 * Internal memory can be handled with a freelist for small objects.
2348 G_GNUC_UNUSED static void
2349 report_internal_mem_usage (void)
2351 printf ("Internal memory usage:\n");
2352 sgen_report_internal_mem_usage ();
2353 printf ("Pinned memory usage:\n");
2354 major_collector.report_pinned_memory_usage ();
2358 * ######################################################################
2359 * ######## Finalization support
2360 * ######################################################################
2364 * If the object has been forwarded it means it's still referenced from a root.
2365 * If it is pinned it's still alive as well.
2366 * A LOS object is only alive if we have pinned it.
2367 * Return TRUE if @obj is ready to be finalized.
2369 static inline gboolean
2370 sgen_is_object_alive (GCObject *object)
2372 if (ptr_in_nursery (object))
2373 return sgen_nursery_is_object_alive (object);
2375 return sgen_major_is_object_alive (object);
2379 * This function returns true if @object is either alive and belongs to the
2380 * current collection - major collections are full heap, so old gen objects
2381 * are never alive during a minor collection.
2384 sgen_is_object_alive_and_on_current_collection (GCObject *object)
2386 if (ptr_in_nursery (object))
2387 return sgen_nursery_is_object_alive (object);
2389 if (current_collection_generation == GENERATION_NURSERY)
2392 return sgen_major_is_object_alive (object);
2397 sgen_gc_is_object_ready_for_finalization (GCObject *object)
2399 return !sgen_is_object_alive (object);
2403 sgen_queue_finalization_entry (GCObject *obj)
2405 gboolean critical = sgen_client_object_has_critical_finalizer (obj);
2407 sgen_pointer_queue_add (critical ? &critical_fin_queue : &fin_ready_queue, obj);
2409 sgen_client_object_queued_for_finalization (obj);
2413 sgen_object_is_live (GCObject *obj)
2415 return sgen_is_object_alive_and_on_current_collection (obj);
2419 * `System.GC.WaitForPendingFinalizers` first checks `sgen_have_pending_finalizers()` to
2420 * determine whether it can exit quickly. The latter must therefore only return FALSE if
2421 * all finalizers have really finished running.
2423 * `sgen_gc_invoke_finalizers()` first dequeues a finalizable object, and then finalizes it.
2424 * This means that just checking whether the queues are empty leaves the possibility that an
2425 * object might have been dequeued but not yet finalized. That's why we need the additional
2426 * flag `pending_unqueued_finalizer`.
2429 static volatile gboolean pending_unqueued_finalizer = FALSE;
2432 sgen_gc_invoke_finalizers (void)
2436 g_assert (!pending_unqueued_finalizer);
2438 /* FIXME: batch to reduce lock contention */
2439 while (sgen_have_pending_finalizers ()) {
2445 * We need to set `pending_unqueued_finalizer` before dequeing the
2446 * finalizable object.
2448 if (!sgen_pointer_queue_is_empty (&fin_ready_queue)) {
2449 pending_unqueued_finalizer = TRUE;
2450 mono_memory_write_barrier ();
2451 obj = (GCObject *)sgen_pointer_queue_pop (&fin_ready_queue);
2452 } else if (!sgen_pointer_queue_is_empty (&critical_fin_queue)) {
2453 pending_unqueued_finalizer = TRUE;
2454 mono_memory_write_barrier ();
2455 obj = (GCObject *)sgen_pointer_queue_pop (&critical_fin_queue);
2461 SGEN_LOG (7, "Finalizing object %p (%s)", obj, sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (obj)));
2469 /* the object is on the stack so it is pinned */
2470 /*g_print ("Calling finalizer for object: %p (%s)\n", obj, sgen_client_object_safe_name (obj));*/
2471 sgen_client_run_finalize (obj);
2474 if (pending_unqueued_finalizer) {
2475 mono_memory_write_barrier ();
2476 pending_unqueued_finalizer = FALSE;
2483 sgen_have_pending_finalizers (void)
2485 return pending_unqueued_finalizer || !sgen_pointer_queue_is_empty (&fin_ready_queue) || !sgen_pointer_queue_is_empty (&critical_fin_queue);
2489 * ######################################################################
2490 * ######## registered roots support
2491 * ######################################################################
2495 * We do not coalesce roots.
2498 sgen_register_root (char *start, size_t size, SgenDescriptor descr, int root_type, int source, const char *msg)
2500 RootRecord new_root;
2503 for (i = 0; i < ROOT_TYPE_NUM; ++i) {
2504 RootRecord *root = (RootRecord *)sgen_hash_table_lookup (&roots_hash [i], start);
2505 /* we allow changing the size and the descriptor (for thread statics etc) */
2507 size_t old_size = root->end_root - start;
2508 root->end_root = start + size;
2509 SGEN_ASSERT (0, !!root->root_desc == !!descr, "Can't change whether a root is precise or conservative.");
2510 SGEN_ASSERT (0, root->source == source, "Can't change a root's source identifier.");
2511 SGEN_ASSERT (0, !!root->msg == !!msg, "Can't change a root's message.");
2512 root->root_desc = descr;
2514 roots_size -= old_size;
2520 new_root.end_root = start + size;
2521 new_root.root_desc = descr;
2522 new_root.source = source;
2525 sgen_hash_table_replace (&roots_hash [root_type], start, &new_root, NULL);
2528 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);
2535 sgen_deregister_root (char* addr)
2541 for (root_type = 0; root_type < ROOT_TYPE_NUM; ++root_type) {
2542 if (sgen_hash_table_remove (&roots_hash [root_type], addr, &root))
2543 roots_size -= (root.end_root - addr);
2549 * ######################################################################
2550 * ######## Thread handling (stop/start code)
2551 * ######################################################################
2555 sgen_get_current_collection_generation (void)
2557 return current_collection_generation;
2561 sgen_thread_register (SgenThreadInfo* info, void *stack_bottom_fallback)
2563 #ifndef HAVE_KW_THREAD
2564 info->tlab_start = info->tlab_next = info->tlab_temp_end = info->tlab_real_end = NULL;
2567 sgen_init_tlab_info (info);
2569 sgen_client_thread_register (info, stack_bottom_fallback);
2575 sgen_thread_unregister (SgenThreadInfo *p)
2577 sgen_client_thread_unregister (p);
2581 * ######################################################################
2582 * ######## Write barriers
2583 * ######################################################################
2587 * Note: the write barriers first do the needed GC work and then do the actual store:
2588 * this way the value is visible to the conservative GC scan after the write barrier
2589 * itself. If a GC interrupts the barrier in the middle, value will be kept alive by
2590 * the conservative scan, otherwise by the remembered set scan.
2594 mono_gc_wbarrier_arrayref_copy (gpointer dest_ptr, gpointer src_ptr, int count)
2596 HEAVY_STAT (++stat_wbarrier_arrayref_copy);
2597 /*This check can be done without taking a lock since dest_ptr array is pinned*/
2598 if (ptr_in_nursery (dest_ptr) || count <= 0) {
2599 mono_gc_memmove_aligned (dest_ptr, src_ptr, count * sizeof (gpointer));
2603 #ifdef SGEN_HEAVY_BINARY_PROTOCOL
2604 if (binary_protocol_is_heavy_enabled ()) {
2606 for (i = 0; i < count; ++i) {
2607 gpointer dest = (gpointer*)dest_ptr + i;
2608 gpointer obj = *((gpointer*)src_ptr + i);
2610 binary_protocol_wbarrier (dest, obj, (gpointer)LOAD_VTABLE (obj));
2615 remset.wbarrier_arrayref_copy (dest_ptr, src_ptr, count);
2619 mono_gc_wbarrier_generic_nostore (gpointer ptr)
2623 HEAVY_STAT (++stat_wbarrier_generic_store);
2625 sgen_client_wbarrier_generic_nostore_check (ptr);
2627 obj = *(gpointer*)ptr;
2629 binary_protocol_wbarrier (ptr, obj, (gpointer)LOAD_VTABLE (obj));
2632 * We need to record old->old pointer locations for the
2633 * concurrent collector.
2635 if (!ptr_in_nursery (obj) && !concurrent_collection_in_progress) {
2636 SGEN_LOG (8, "Skipping remset at %p", ptr);
2640 SGEN_LOG (8, "Adding remset at %p", ptr);
2642 remset.wbarrier_generic_nostore (ptr);
2646 mono_gc_wbarrier_generic_store (gpointer ptr, GCObject* value)
2648 SGEN_LOG (8, "Wbarrier store at %p to %p (%s)", ptr, value, value ? sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (value)) : "null");
2649 SGEN_UPDATE_REFERENCE_ALLOW_NULL (ptr, value);
2650 if (ptr_in_nursery (value) || concurrent_collection_in_progress)
2651 mono_gc_wbarrier_generic_nostore (ptr);
2652 sgen_dummy_use (value);
2655 /* Same as mono_gc_wbarrier_generic_store () but performs the store
2656 * as an atomic operation with release semantics.
2659 mono_gc_wbarrier_generic_store_atomic (gpointer ptr, GCObject *value)
2661 HEAVY_STAT (++stat_wbarrier_generic_store_atomic);
2663 SGEN_LOG (8, "Wbarrier atomic store at %p to %p (%s)", ptr, value, value ? sgen_client_vtable_get_name (SGEN_LOAD_VTABLE (value)) : "null");
2665 InterlockedWritePointer ((volatile gpointer *)ptr, value);
2667 if (ptr_in_nursery (value) || concurrent_collection_in_progress)
2668 mono_gc_wbarrier_generic_nostore (ptr);
2670 sgen_dummy_use (value);
2674 sgen_wbarrier_value_copy_bitmap (gpointer _dest, gpointer _src, int size, unsigned bitmap)
2676 GCObject **dest = (GCObject **)_dest;
2677 GCObject **src = (GCObject **)_src;
2681 mono_gc_wbarrier_generic_store (dest, *src);
2686 size -= SIZEOF_VOID_P;
2692 * ######################################################################
2693 * ######## Other mono public interface functions.
2694 * ######################################################################
2698 sgen_gc_collect (int generation)
2703 sgen_perform_collection (0, generation, "user request", TRUE);
2708 sgen_gc_collection_count (int generation)
2710 if (generation == 0)
2711 return gc_stats.minor_gc_count;
2712 return gc_stats.major_gc_count;
2716 sgen_gc_get_used_size (void)
2720 tot = los_memory_usage;
2721 tot += nursery_section->next_data - nursery_section->data;
2722 tot += major_collector.get_used_size ();
2723 /* FIXME: account for pinned objects */
2729 sgen_env_var_error (const char *env_var, const char *fallback, const char *description_format, ...)
2733 va_start (ap, description_format);
2735 fprintf (stderr, "Warning: In environment variable `%s': ", env_var);
2736 vfprintf (stderr, description_format, ap);
2738 fprintf (stderr, " - %s", fallback);
2739 fprintf (stderr, "\n");
2745 parse_double_in_interval (const char *env_var, const char *opt_name, const char *opt, double min, double max, double *result)
2748 double val = strtod (opt, &endptr);
2749 if (endptr == opt) {
2750 sgen_env_var_error (env_var, "Using default value.", "`%s` must be a number.", opt_name);
2753 else if (val < min || val > max) {
2754 sgen_env_var_error (env_var, "Using default value.", "`%s` must be between %.2f - %.2f.", opt_name, min, max);
2766 char *major_collector_opt = NULL;
2767 char *minor_collector_opt = NULL;
2768 size_t max_heap = 0;
2769 size_t soft_limit = 0;
2771 gboolean debug_print_allowance = FALSE;
2772 double allowance_ratio = 0, save_target = 0;
2773 gboolean cement_enabled = TRUE;
2776 result = InterlockedCompareExchange (&gc_initialized, -1, 0);
2779 /* already inited */
2782 /* being inited by another thread */
2783 mono_thread_info_usleep (1000);
2786 /* we will init it */
2789 g_assert_not_reached ();
2791 } while (result != 0);
2793 SGEN_TV_GETTIME (sgen_init_timestamp);
2795 #ifdef SGEN_WITHOUT_MONO
2796 mono_thread_smr_init ();
2799 mono_coop_mutex_init (&gc_mutex);
2801 gc_debug_file = stderr;
2803 mono_coop_mutex_init (&sgen_interruption_mutex);
2805 if ((env = g_getenv (MONO_GC_PARAMS_NAME))) {
2806 opts = g_strsplit (env, ",", -1);
2807 for (ptr = opts; *ptr; ++ptr) {
2809 if (g_str_has_prefix (opt, "major=")) {
2810 opt = strchr (opt, '=') + 1;
2811 major_collector_opt = g_strdup (opt);
2812 } else if (g_str_has_prefix (opt, "minor=")) {
2813 opt = strchr (opt, '=') + 1;
2814 minor_collector_opt = g_strdup (opt);
2822 sgen_init_internal_allocator ();
2823 sgen_init_nursery_allocator ();
2824 sgen_init_fin_weak_hash ();
2825 sgen_init_hash_table ();
2826 sgen_init_descriptors ();
2827 sgen_init_gray_queues ();
2828 sgen_init_allocator ();
2829 sgen_init_gchandles ();
2831 sgen_register_fixed_internal_mem_type (INTERNAL_MEM_SECTION, SGEN_SIZEOF_GC_MEM_SECTION);
2832 sgen_register_fixed_internal_mem_type (INTERNAL_MEM_GRAY_QUEUE, sizeof (GrayQueueSection));
2834 sgen_client_init ();
2836 if (!minor_collector_opt) {
2837 sgen_simple_nursery_init (&sgen_minor_collector);
2839 if (!strcmp (minor_collector_opt, "simple")) {
2841 sgen_simple_nursery_init (&sgen_minor_collector);
2842 } else if (!strcmp (minor_collector_opt, "split")) {
2843 sgen_split_nursery_init (&sgen_minor_collector);
2845 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using `simple` instead.", "Unknown minor collector `%s'.", minor_collector_opt);
2846 goto use_simple_nursery;
2850 if (!major_collector_opt || !strcmp (major_collector_opt, "marksweep")) {
2851 use_marksweep_major:
2852 sgen_marksweep_init (&major_collector);
2853 } else if (!major_collector_opt || !strcmp (major_collector_opt, "marksweep-conc")) {
2854 sgen_marksweep_conc_init (&major_collector);
2856 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using `marksweep` instead.", "Unknown major collector `%s'.", major_collector_opt);
2857 goto use_marksweep_major;
2860 sgen_nursery_size = DEFAULT_NURSERY_SIZE;
2863 gboolean usage_printed = FALSE;
2865 for (ptr = opts; *ptr; ++ptr) {
2867 if (!strcmp (opt, ""))
2869 if (g_str_has_prefix (opt, "major="))
2871 if (g_str_has_prefix (opt, "minor="))
2873 if (g_str_has_prefix (opt, "max-heap-size=")) {
2874 size_t page_size = mono_pagesize ();
2875 size_t max_heap_candidate = 0;
2876 opt = strchr (opt, '=') + 1;
2877 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &max_heap_candidate)) {
2878 max_heap = (max_heap_candidate + page_size - 1) & ~(size_t)(page_size - 1);
2879 if (max_heap != max_heap_candidate)
2880 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Rounding up.", "`max-heap-size` size must be a multiple of %d.", page_size);
2882 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`max-heap-size` must be an integer.");
2886 if (g_str_has_prefix (opt, "soft-heap-limit=")) {
2887 opt = strchr (opt, '=') + 1;
2888 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &soft_limit)) {
2889 if (soft_limit <= 0) {
2890 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`soft-heap-limit` must be positive.");
2894 sgen_env_var_error (MONO_GC_PARAMS_NAME, NULL, "`soft-heap-limit` must be an integer.");
2900 if (g_str_has_prefix (opt, "nursery-size=")) {
2902 opt = strchr (opt, '=') + 1;
2903 if (*opt && mono_gc_parse_environment_string_extract_number (opt, &val)) {
2904 if ((val & (val - 1))) {
2905 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.", "`nursery-size` must be a power of two.");
2909 if (val < SGEN_MAX_NURSERY_WASTE) {
2910 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.",
2911 "`nursery-size` must be at least %d bytes.", SGEN_MAX_NURSERY_WASTE);
2915 sgen_nursery_size = val;
2916 sgen_nursery_bits = 0;
2917 while (ONE_P << (++ sgen_nursery_bits) != sgen_nursery_size)
2920 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Using default value.", "`nursery-size` must be an integer.");
2926 if (g_str_has_prefix (opt, "save-target-ratio=")) {
2928 opt = strchr (opt, '=') + 1;
2929 if (parse_double_in_interval (MONO_GC_PARAMS_NAME, "save-target-ratio", opt,
2930 SGEN_MIN_SAVE_TARGET_RATIO, SGEN_MAX_SAVE_TARGET_RATIO, &val)) {
2935 if (g_str_has_prefix (opt, "default-allowance-ratio=")) {
2937 opt = strchr (opt, '=') + 1;
2938 if (parse_double_in_interval (MONO_GC_PARAMS_NAME, "default-allowance-ratio", opt,
2939 SGEN_MIN_ALLOWANCE_NURSERY_SIZE_RATIO, SGEN_MIN_ALLOWANCE_NURSERY_SIZE_RATIO, &val)) {
2940 allowance_ratio = val;
2945 if (!strcmp (opt, "cementing")) {
2946 cement_enabled = TRUE;
2949 if (!strcmp (opt, "no-cementing")) {
2950 cement_enabled = FALSE;
2954 if (!strcmp (opt, "precleaning")) {
2955 precleaning_enabled = TRUE;
2958 if (!strcmp (opt, "no-precleaning")) {
2959 precleaning_enabled = FALSE;
2963 if (major_collector.handle_gc_param && major_collector.handle_gc_param (opt))
2966 if (sgen_minor_collector.handle_gc_param && sgen_minor_collector.handle_gc_param (opt))
2969 if (sgen_client_handle_gc_param (opt))
2972 sgen_env_var_error (MONO_GC_PARAMS_NAME, "Ignoring.", "Unknown option `%s`.", opt);
2977 fprintf (stderr, "\n%s must be a comma-delimited list of one or more of the following:\n", MONO_GC_PARAMS_NAME);
2978 fprintf (stderr, " max-heap-size=N (where N is an integer, possibly with a k, m or a g suffix)\n");
2979 fprintf (stderr, " soft-heap-limit=n (where N is an integer, possibly with a k, m or a g suffix)\n");
2980 fprintf (stderr, " nursery-size=N (where N is an integer, possibly with a k, m or a g suffix)\n");
2981 fprintf (stderr, " major=COLLECTOR (where COLLECTOR is `marksweep', `marksweep-conc', `marksweep-par')\n");
2982 fprintf (stderr, " minor=COLLECTOR (where COLLECTOR is `simple' or `split')\n");
2983 fprintf (stderr, " wbarrier=WBARRIER (where WBARRIER is `remset' or `cardtable')\n");
2984 fprintf (stderr, " [no-]cementing\n");
2985 if (major_collector.print_gc_param_usage)
2986 major_collector.print_gc_param_usage ();
2987 if (sgen_minor_collector.print_gc_param_usage)
2988 sgen_minor_collector.print_gc_param_usage ();
2989 sgen_client_print_gc_params_usage ();
2990 fprintf (stderr, " Experimental options:\n");
2991 fprintf (stderr, " save-target-ratio=R (where R must be between %.2f - %.2f).\n", SGEN_MIN_SAVE_TARGET_RATIO, SGEN_MAX_SAVE_TARGET_RATIO);
2992 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);
2993 fprintf (stderr, "\n");
2995 usage_printed = TRUE;
3000 if (major_collector_opt)
3001 g_free (major_collector_opt);
3003 if (minor_collector_opt)
3004 g_free (minor_collector_opt);
3008 sgen_cement_init (cement_enabled);
3010 if ((env = g_getenv (MONO_GC_DEBUG_NAME))) {
3011 gboolean usage_printed = FALSE;
3013 opts = g_strsplit (env, ",", -1);
3014 for (ptr = opts; ptr && *ptr; ptr ++) {
3016 if (!strcmp (opt, ""))
3018 if (opt [0] >= '0' && opt [0] <= '9') {
3019 gc_debug_level = atoi (opt);
3024 char *rf = g_strdup_printf ("%s.%d", opt, mono_process_current_pid ());
3025 gc_debug_file = fopen (rf, "wb");
3027 gc_debug_file = stderr;
3030 } else if (!strcmp (opt, "print-allowance")) {
3031 debug_print_allowance = TRUE;
3032 } else if (!strcmp (opt, "print-pinning")) {
3033 sgen_pin_stats_enable ();
3034 } else if (!strcmp (opt, "verify-before-allocs")) {
3035 verify_before_allocs = 1;
3036 has_per_allocation_action = TRUE;
3037 } else if (g_str_has_prefix (opt, "verify-before-allocs=")) {
3038 char *arg = strchr (opt, '=') + 1;
3039 verify_before_allocs = atoi (arg);
3040 has_per_allocation_action = TRUE;
3041 } else if (!strcmp (opt, "collect-before-allocs")) {
3042 collect_before_allocs = 1;
3043 has_per_allocation_action = TRUE;
3044 } else if (g_str_has_prefix (opt, "collect-before-allocs=")) {
3045 char *arg = strchr (opt, '=') + 1;
3046 has_per_allocation_action = TRUE;
3047 collect_before_allocs = atoi (arg);
3048 } else if (!strcmp (opt, "verify-before-collections")) {
3049 whole_heap_check_before_collection = TRUE;
3050 } else if (!strcmp (opt, "check-at-minor-collections")) {
3051 consistency_check_at_minor_collection = TRUE;
3052 nursery_clear_policy = CLEAR_AT_GC;
3053 } else if (!strcmp (opt, "mod-union-consistency-check")) {
3054 if (!major_collector.is_concurrent) {
3055 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "`mod-union-consistency-check` only works with concurrent major collector.");
3058 mod_union_consistency_check = TRUE;
3059 } else if (!strcmp (opt, "check-mark-bits")) {
3060 check_mark_bits_after_major_collection = TRUE;
3061 } else if (!strcmp (opt, "check-nursery-pinned")) {
3062 check_nursery_objects_pinned = TRUE;
3063 } else if (!strcmp (opt, "clear-at-gc")) {
3064 nursery_clear_policy = CLEAR_AT_GC;
3065 } else if (!strcmp (opt, "clear-nursery-at-gc")) {
3066 nursery_clear_policy = CLEAR_AT_GC;
3067 } else if (!strcmp (opt, "clear-at-tlab-creation")) {
3068 nursery_clear_policy = CLEAR_AT_TLAB_CREATION;
3069 } else if (!strcmp (opt, "debug-clear-at-tlab-creation")) {
3070 nursery_clear_policy = CLEAR_AT_TLAB_CREATION_DEBUG;
3071 } else if (!strcmp (opt, "check-scan-starts")) {
3072 do_scan_starts_check = TRUE;
3073 } else if (!strcmp (opt, "verify-nursery-at-minor-gc")) {
3074 do_verify_nursery = TRUE;
3075 } else if (!strcmp (opt, "check-concurrent")) {
3076 if (!major_collector.is_concurrent) {
3077 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "`check-concurrent` only works with concurrent major collectors.");
3080 nursery_clear_policy = CLEAR_AT_GC;
3081 do_concurrent_checks = TRUE;
3082 } else if (!strcmp (opt, "dump-nursery-at-minor-gc")) {
3083 do_dump_nursery_content = TRUE;
3084 } else if (!strcmp (opt, "disable-minor")) {
3085 disable_minor_collections = TRUE;
3086 } else if (!strcmp (opt, "disable-major")) {
3087 disable_major_collections = TRUE;
3088 } else if (g_str_has_prefix (opt, "heap-dump=")) {
3089 char *filename = strchr (opt, '=') + 1;
3090 nursery_clear_policy = CLEAR_AT_GC;
3091 sgen_debug_enable_heap_dump (filename);
3092 } else if (g_str_has_prefix (opt, "binary-protocol=")) {
3093 char *filename = strchr (opt, '=') + 1;
3094 char *colon = strrchr (filename, ':');
3097 if (!mono_gc_parse_environment_string_extract_number (colon + 1, &limit)) {
3098 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring limit.", "Binary protocol file size limit must be an integer.");
3103 binary_protocol_init (filename, (long long)limit);
3104 } else if (!strcmp (opt, "nursery-canaries")) {
3105 do_verify_nursery = TRUE;
3106 enable_nursery_canaries = TRUE;
3107 } else if (!sgen_client_handle_gc_debug (opt)) {
3108 sgen_env_var_error (MONO_GC_DEBUG_NAME, "Ignoring.", "Unknown option `%s`.", opt);
3113 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);
3114 fprintf (stderr, "Valid <option>s are:\n");
3115 fprintf (stderr, " collect-before-allocs[=<n>]\n");
3116 fprintf (stderr, " verify-before-allocs[=<n>]\n");
3117 fprintf (stderr, " check-at-minor-collections\n");
3118 fprintf (stderr, " check-mark-bits\n");
3119 fprintf (stderr, " check-nursery-pinned\n");
3120 fprintf (stderr, " verify-before-collections\n");
3121 fprintf (stderr, " verify-nursery-at-minor-gc\n");
3122 fprintf (stderr, " dump-nursery-at-minor-gc\n");
3123 fprintf (stderr, " disable-minor\n");
3124 fprintf (stderr, " disable-major\n");
3125 fprintf (stderr, " check-concurrent\n");
3126 fprintf (stderr, " clear-[nursery-]at-gc\n");
3127 fprintf (stderr, " clear-at-tlab-creation\n");
3128 fprintf (stderr, " debug-clear-at-tlab-creation\n");
3129 fprintf (stderr, " check-scan-starts\n");
3130 fprintf (stderr, " print-allowance\n");
3131 fprintf (stderr, " print-pinning\n");
3132 fprintf (stderr, " heap-dump=<filename>\n");
3133 fprintf (stderr, " binary-protocol=<filename>[:<file-size-limit>]\n");
3134 fprintf (stderr, " nursery-canaries\n");
3135 sgen_client_print_gc_debug_usage ();
3136 fprintf (stderr, "\n");
3138 usage_printed = TRUE;
3144 if (check_mark_bits_after_major_collection)
3145 nursery_clear_policy = CLEAR_AT_GC;
3147 if (major_collector.post_param_init)
3148 major_collector.post_param_init (&major_collector);
3150 if (major_collector.needs_thread_pool)
3151 sgen_workers_init (1);
3153 sgen_memgov_init (max_heap, soft_limit, debug_print_allowance, allowance_ratio, save_target);
3155 memset (&remset, 0, sizeof (remset));
3157 sgen_card_table_init (&remset);
3159 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");
3165 sgen_get_nursery_clear_policy (void)
3167 return nursery_clear_policy;
3173 mono_coop_mutex_lock (&gc_mutex);
3177 sgen_gc_unlock (void)
3179 gboolean try_free = sgen_try_free_some_memory;
3180 sgen_try_free_some_memory = FALSE;
3181 mono_coop_mutex_unlock (&gc_mutex);
3183 mono_thread_hazardous_try_free_some ();
3187 sgen_major_collector_iterate_live_block_ranges (sgen_cardtable_block_callback callback)
3189 major_collector.iterate_live_block_ranges (callback);
3193 sgen_get_major_collector (void)
3195 return &major_collector;
3199 sgen_get_remset (void)
3205 count_cards (long long *major_total, long long *major_marked, long long *los_total, long long *los_marked)
3207 sgen_get_major_collector ()->count_cards (major_total, major_marked);
3208 sgen_los_count_cards (los_total, los_marked);
3211 static gboolean world_is_stopped = FALSE;
3213 /* LOCKING: assumes the GC lock is held */
3215 sgen_stop_world (int generation)
3217 long long major_total = -1, major_marked = -1, los_total = -1, los_marked = -1;
3219 SGEN_ASSERT (0, !world_is_stopped, "Why are we stopping a stopped world?");
3221 binary_protocol_world_stopping (generation, sgen_timestamp (), (gpointer) (gsize) mono_native_thread_id_get ());
3223 sgen_client_stop_world (generation);
3225 world_is_stopped = TRUE;
3227 if (binary_protocol_is_heavy_enabled ())
3228 count_cards (&major_total, &major_marked, &los_total, &los_marked);
3229 binary_protocol_world_stopped (generation, sgen_timestamp (), major_total, major_marked, los_total, los_marked);
3232 /* LOCKING: assumes the GC lock is held */
3234 sgen_restart_world (int generation, GGTimingInfo *timing)
3236 long long major_total = -1, major_marked = -1, los_total = -1, los_marked = -1;
3238 SGEN_ASSERT (0, world_is_stopped, "Why are we restarting a running world?");
3240 if (binary_protocol_is_heavy_enabled ())
3241 count_cards (&major_total, &major_marked, &los_total, &los_marked);
3242 binary_protocol_world_restarting (generation, sgen_timestamp (), major_total, major_marked, los_total, los_marked);
3244 sgen_client_restart_world (generation, timing);
3246 world_is_stopped = FALSE;
3248 binary_protocol_world_restarted (generation, sgen_timestamp ());
3250 sgen_try_free_some_memory = TRUE;
3252 if (sgen_client_bridge_need_processing ())
3253 sgen_client_bridge_processing_finish (generation);
3255 sgen_memgov_collection_end (generation, timing, timing ? 2 : 0);
3259 sgen_is_world_stopped (void)
3261 return world_is_stopped;
3265 sgen_check_whole_heap_stw (void)
3267 sgen_stop_world (0);
3268 sgen_clear_nursery_fragments ();
3269 sgen_check_whole_heap (FALSE);
3270 sgen_restart_world (0, NULL);
3274 sgen_timestamp (void)
3276 SGEN_TV_DECLARE (timestamp);
3277 SGEN_TV_GETTIME (timestamp);
3278 return SGEN_TV_ELAPSED (sgen_init_timestamp, timestamp);
3281 #endif /* HAVE_SGEN_GC */