1 /*
2 * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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24
25 #ifndef SHARE_VM_GC_G1_G1CONCURRENTMARK_HPP
26 #define SHARE_VM_GC_G1_G1CONCURRENTMARK_HPP
27
28 #include "classfile/javaClasses.hpp"
29 #include "gc/g1/g1RegionToSpaceMapper.hpp"
30 #include "gc/g1/heapRegionSet.hpp"
31 #include "gc/shared/taskqueue.hpp"
32
33 class G1CollectedHeap;
34 class G1CMBitMap;
35 class G1CMTask;
36 class G1ConcurrentMark;
37 class ConcurrentGCTimer;
38 class G1OldTracer;
39 class G1SurvivorRegions;
40 typedef GenericTaskQueue<oop, mtGC> G1CMTaskQueue;
41 typedef GenericTaskQueueSet<G1CMTaskQueue, mtGC> G1CMTaskQueueSet;
42
43 // Closure used by CM during concurrent reference discovery
44 // and reference processing (during remarking) to determine
45 // if a particular object is alive. It is primarily used
46 // to determine if referents of discovered reference objects
47 // are alive. An instance is also embedded into the
48 // reference processor as the _is_alive_non_header field
49 class G1CMIsAliveClosure: public BoolObjectClosure {
50 G1CollectedHeap* _g1;
51 public:
52 G1CMIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) { }
53
54 bool do_object_b(oop obj);
55 };
56
57 // A generic CM bit map. This is essentially a wrapper around the BitMap
58 // class, with one bit per (1<<_shifter) HeapWords.
59
60 class G1CMBitMapRO VALUE_OBJ_CLASS_SPEC {
61 protected:
62 HeapWord* _bmStartWord; // base address of range covered by map
63 size_t _bmWordSize; // map size (in #HeapWords covered)
64 const int _shifter; // map to char or bit
65 BitMapView _bm; // the bit map itself
66
67 public:
68 // constructor
69 G1CMBitMapRO(int shifter);
70
71 // inquiries
72 HeapWord* startWord() const { return _bmStartWord; }
73 // the following is one past the last word in space
74 HeapWord* endWord() const { return _bmStartWord + _bmWordSize; }
75
76 // read marks
77
78 bool isMarked(HeapWord* addr) const {
79 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
80 "outside underlying space?");
81 return _bm.at(heapWordToOffset(addr));
82 }
83
84 // iteration
85 inline bool iterate(BitMapClosure* cl, MemRegion mr);
86
87 // Return the address corresponding to the next marked bit at or after
88 // "addr", and before "limit", if "limit" is non-NULL. If there is no
89 // such bit, returns "limit" if that is non-NULL, or else "endWord()".
90 HeapWord* getNextMarkedWordAddress(const HeapWord* addr,
91 const HeapWord* limit = NULL) const;
92
93 // conversion utilities
94 HeapWord* offsetToHeapWord(size_t offset) const {
95 return _bmStartWord + (offset << _shifter);
96 }
97 size_t heapWordToOffset(const HeapWord* addr) const {
98 return pointer_delta(addr, _bmStartWord) >> _shifter;
99 }
100
101 // The argument addr should be the start address of a valid object
102 inline HeapWord* nextObject(HeapWord* addr);
103
104 void print_on_error(outputStream* st, const char* prefix) const;
105
106 // debugging
107 NOT_PRODUCT(bool covers(MemRegion rs) const;)
108 };
109
110 class G1CMBitMapMappingChangedListener : public G1MappingChangedListener {
111 private:
112 G1CMBitMap* _bm;
113 public:
114 G1CMBitMapMappingChangedListener() : _bm(NULL) {}
115
116 void set_bitmap(G1CMBitMap* bm) { _bm = bm; }
117
118 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
119 };
120
121 class G1CMBitMap : public G1CMBitMapRO {
122 private:
123 G1CMBitMapMappingChangedListener _listener;
124
125 public:
126 static size_t compute_size(size_t heap_size);
127 // Returns the amount of bytes on the heap between two marks in the bitmap.
128 static size_t mark_distance();
129 // Returns how many bytes (or bits) of the heap a single byte (or bit) of the
130 // mark bitmap corresponds to. This is the same as the mark distance above.
131 static size_t heap_map_factor() {
132 return mark_distance();
133 }
134
135 G1CMBitMap() : G1CMBitMapRO(LogMinObjAlignment), _listener() { _listener.set_bitmap(this); }
136
137 // Initializes the underlying BitMap to cover the given area.
138 void initialize(MemRegion heap, G1RegionToSpaceMapper* storage);
139
140 // Write marks.
141 inline void mark(HeapWord* addr);
142 inline void clear(HeapWord* addr);
143 inline bool parMark(HeapWord* addr);
144
145 void clear_range(MemRegion mr);
146 };
147
148 // Represents the overflow mark stack used by concurrent marking.
149 //
150 // Stores oops in a huge buffer in virtual memory that is always fully committed.
151 // Resizing may only happen during a STW pause when the stack is empty.
152 //
153 // Memory is allocated on a "chunk" basis, i.e. a set of oops. For this, the mark
154 // stack memory is split into evenly sized chunks of oops. Users can only
155 // add or remove entries on that basis.
156 // Chunks are filled in increasing address order. Not completely filled chunks
157 // have a NULL element as a terminating element.
158 //
159 // Every chunk has a header containing a single pointer element used for memory
160 // management. This wastes some space, but is negligible (< .1% with current sizing).
161 //
162 // Memory management is done using a mix of tracking a high water-mark indicating
163 // that all chunks at a lower address are valid chunks, and a singly linked free
164 // list connecting all empty chunks.
165 class G1CMMarkStack VALUE_OBJ_CLASS_SPEC {
166 public:
167 // Number of oops that can fit in a single chunk.
168 static const size_t OopsPerChunk = 1024 - 1 /* One reference for the next pointer */;
169 private:
170 struct OopChunk {
171 OopChunk* next;
172 oop data[OopsPerChunk];
173 };
174
175 size_t _max_chunk_capacity; // Maximum number of OopChunk elements on the stack.
176
177 OopChunk* _base; // Bottom address of allocated memory area.
178 size_t _chunk_capacity; // Current maximum number of OopChunk elements.
179
180 char _pad0[DEFAULT_CACHE_LINE_SIZE];
181 OopChunk* volatile _free_list; // Linked list of free chunks that can be allocated by users.
182 char _pad1[DEFAULT_CACHE_LINE_SIZE - sizeof(OopChunk*)];
183 OopChunk* volatile _chunk_list; // List of chunks currently containing data.
184 char _pad2[DEFAULT_CACHE_LINE_SIZE - sizeof(OopChunk*)];
185
186 volatile size_t _hwm; // High water mark within the reserved space.
187 char _pad4[DEFAULT_CACHE_LINE_SIZE - sizeof(size_t)];
188
189 // Allocate a new chunk from the reserved memory, using the high water mark. Returns
190 // NULL if out of memory.
191 OopChunk* allocate_new_chunk();
192
193 size_t volatile _chunks_in_chunk_list;
194
195 volatile bool _out_of_memory;
196
197 // Atomically add the given chunk to the list.
198 void add_chunk_to_list(OopChunk* volatile* list, OopChunk* elem);
199 // Atomically remove and return a chunk from the given list. Returns NULL if the
200 // list is empty.
201 OopChunk* remove_chunk_from_list(OopChunk* volatile* list);
202
203 bool _should_expand;
204
205 // Resizes the mark stack to the given new capacity. Releases any previous
206 // memory if successful.
207 bool resize(size_t new_capacity);
208
209 public:
210 G1CMMarkStack();
211 ~G1CMMarkStack();
212
213 // Alignment and minimum capacity of this mark stack in number of oops.
214 static size_t capacity_alignment();
215
216 // Allocate and initialize the mark stack with the given number of oops.
217 bool initialize(size_t initial_capacity, size_t max_capacity);
218
219 // Pushes the given buffer containing at most OopsPerChunk elements on the mark
220 // stack. If less than OopsPerChunk elements are to be pushed, the array must
221 // be terminated with a NULL.
222 // Returns whether the buffer contents were successfully pushed to the global mark
223 // stack.
224 bool par_push_chunk(oop* buffer);
225
226 // Pops a chunk from this mark stack, copying them into the given buffer. This
227 // chunk may contain up to OopsPerChunk elements. If there are less, the last
228 // element in the array is a NULL pointer.
229 bool par_pop_chunk(oop* buffer);
230
231 // Return whether the chunk list is empty. Racy due to unsynchronized access to
232 // _chunks_in_chunk_list.
233 bool is_empty() const { return _chunks_in_chunk_list == 0; }
234
235 size_t capacity() const { return _chunk_capacity; }
236
237 bool is_out_of_memory() const { return _out_of_memory; }
238 void clear_out_of_memory() { _out_of_memory = false; }
239
240 bool should_expand() const { return _should_expand; }
241 void set_should_expand(bool value) { _should_expand = value; }
242
243 // Expand the stack, typically in response to an overflow condition
244 void expand();
245
246 // Return the approximate number of oops on this mark stack. Racy due to
247 // unsynchronized access to _chunks_in_chunk_list.
248 size_t size() const { return _chunks_in_chunk_list * OopsPerChunk; }
249
250 void set_empty();
251
252 // Apply Fn to every oop on the mark stack. The mark stack must not
253 // be modified while iterating.
254 template<typename Fn> void iterate(Fn fn) const PRODUCT_RETURN;
255 };
256
257 // Root Regions are regions that are not empty at the beginning of a
258 // marking cycle and which we might collect during an evacuation pause
259 // while the cycle is active. Given that, during evacuation pauses, we
260 // do not copy objects that are explicitly marked, what we have to do
261 // for the root regions is to scan them and mark all objects reachable
262 // from them. According to the SATB assumptions, we only need to visit
263 // each object once during marking. So, as long as we finish this scan
264 // before the next evacuation pause, we can copy the objects from the
265 // root regions without having to mark them or do anything else to them.
266 //
267 // Currently, we only support root region scanning once (at the start
268 // of the marking cycle) and the root regions are all the survivor
269 // regions populated during the initial-mark pause.
270 class G1CMRootRegions VALUE_OBJ_CLASS_SPEC {
271 private:
272 const G1SurvivorRegions* _survivors;
273 G1ConcurrentMark* _cm;
274
275 volatile bool _scan_in_progress;
276 volatile bool _should_abort;
277 volatile int _claimed_survivor_index;
278
279 void notify_scan_done();
280
281 public:
282 G1CMRootRegions();
283 // We actually do most of the initialization in this method.
284 void init(const G1SurvivorRegions* survivors, G1ConcurrentMark* cm);
285
286 // Reset the claiming / scanning of the root regions.
287 void prepare_for_scan();
288
289 // Forces get_next() to return NULL so that the iteration aborts early.
290 void abort() { _should_abort = true; }
291
292 // Return true if the CM thread are actively scanning root regions,
293 // false otherwise.
294 bool scan_in_progress() { return _scan_in_progress; }
295
296 // Claim the next root region to scan atomically, or return NULL if
297 // all have been claimed.
298 HeapRegion* claim_next();
299
300 // The number of root regions to scan.
301 uint num_root_regions() const;
302
303 void cancel_scan();
304
305 // Flag that we're done with root region scanning and notify anyone
306 // who's waiting on it. If aborted is false, assume that all regions
307 // have been claimed.
308 void scan_finished();
309
310 // If CM threads are still scanning root regions, wait until they
311 // are done. Return true if we had to wait, false otherwise.
312 bool wait_until_scan_finished();
313 };
314
315 class ConcurrentMarkThread;
316
317 class G1ConcurrentMark: public CHeapObj<mtGC> {
318 friend class ConcurrentMarkThread;
319 friend class G1ParNoteEndTask;
320 friend class G1VerifyLiveDataClosure;
321 friend class G1CMRefProcTaskProxy;
322 friend class G1CMRefProcTaskExecutor;
323 friend class G1CMKeepAliveAndDrainClosure;
324 friend class G1CMDrainMarkingStackClosure;
325 friend class G1CMBitMapClosure;
326 friend class G1CMConcurrentMarkingTask;
327 friend class G1CMRemarkTask;
328 friend class G1CMTask;
329
330 protected:
331 ConcurrentMarkThread* _cmThread; // The thread doing the work
332 G1CollectedHeap* _g1h; // The heap
333 uint _parallel_marking_threads; // The number of marking
334 // threads we're using
335 uint _max_parallel_marking_threads; // Max number of marking
336 // threads we'll ever use
337 double _sleep_factor; // How much we have to sleep, with
338 // respect to the work we just did, to
339 // meet the marking overhead goal
340 double _marking_task_overhead; // Marking target overhead for
341 // a single task
342
343 FreeRegionList _cleanup_list;
344
345 // Concurrent marking support structures
346 G1CMBitMap _markBitMap1;
347 G1CMBitMap _markBitMap2;
348 G1CMBitMapRO* _prevMarkBitMap; // Completed mark bitmap
349 G1CMBitMap* _nextMarkBitMap; // Under-construction mark bitmap
350
351 // Heap bounds
352 HeapWord* _heap_start;
353 HeapWord* _heap_end;
354
355 // Root region tracking and claiming
356 G1CMRootRegions _root_regions;
357
358 // For gray objects
359 G1CMMarkStack _global_mark_stack; // Grey objects behind global finger
360 HeapWord* volatile _finger; // The global finger, region aligned,
361 // always points to the end of the
362 // last claimed region
363
364 // Marking tasks
365 uint _max_worker_id;// Maximum worker id
366 uint _active_tasks; // Task num currently active
367 G1CMTask** _tasks; // Task queue array (max_worker_id len)
368 G1CMTaskQueueSet* _task_queues; // Task queue set
369 ParallelTaskTerminator _terminator; // For termination
370
371 // Two sync barriers that are used to synchronize tasks when an
372 // overflow occurs. The algorithm is the following. All tasks enter
373 // the first one to ensure that they have all stopped manipulating
374 // the global data structures. After they exit it, they re-initialize
375 // their data structures and task 0 re-initializes the global data
376 // structures. Then, they enter the second sync barrier. This
377 // ensure, that no task starts doing work before all data
378 // structures (local and global) have been re-initialized. When they
379 // exit it, they are free to start working again.
380 WorkGangBarrierSync _first_overflow_barrier_sync;
381 WorkGangBarrierSync _second_overflow_barrier_sync;
382
383 // This is set by any task, when an overflow on the global data
384 // structures is detected
385 volatile bool _has_overflown;
386 // True: marking is concurrent, false: we're in remark
387 volatile bool _concurrent;
388 // Set at the end of a Full GC so that marking aborts
389 volatile bool _has_aborted;
390
391 // Used when remark aborts due to an overflow to indicate that
392 // another concurrent marking phase should start
393 volatile bool _restart_for_overflow;
394
395 // This is true from the very start of concurrent marking until the
396 // point when all the tasks complete their work. It is really used
397 // to determine the points between the end of concurrent marking and
398 // time of remark.
399 volatile bool _concurrent_marking_in_progress;
400
401 ConcurrentGCTimer* _gc_timer_cm;
402
403 G1OldTracer* _gc_tracer_cm;
404
405 // All of these times are in ms
406 NumberSeq _init_times;
407 NumberSeq _remark_times;
408 NumberSeq _remark_mark_times;
409 NumberSeq _remark_weak_ref_times;
410 NumberSeq _cleanup_times;
411 double _total_counting_time;
412 double _total_rs_scrub_time;
413
414 double* _accum_task_vtime; // Accumulated task vtime
415
416 WorkGang* _parallel_workers;
417
418 void weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes);
419 void weakRefsWork(bool clear_all_soft_refs);
420
421 void swapMarkBitMaps();
422
423 // It resets the global marking data structures, as well as the
424 // task local ones; should be called during initial mark.
425 void reset();
426
427 // Resets all the marking data structures. Called when we have to restart
428 // marking or when marking completes (via set_non_marking_state below).
429 void reset_marking_state(bool clear_overflow = true);
430
431 // We do this after we're done with marking so that the marking data
432 // structures are initialized to a sensible and predictable state.
433 void set_non_marking_state();
434
435 // Called to indicate how many threads are currently active.
436 void set_concurrency(uint active_tasks);
437
438 // It should be called to indicate which phase we're in (concurrent
439 // mark or remark) and how many threads are currently active.
440 void set_concurrency_and_phase(uint active_tasks, bool concurrent);
441
442 // Prints all gathered CM-related statistics
443 void print_stats();
444
445 bool cleanup_list_is_empty() {
446 return _cleanup_list.is_empty();
447 }
448
449 // Accessor methods
450 uint parallel_marking_threads() const { return _parallel_marking_threads; }
451 uint max_parallel_marking_threads() const { return _max_parallel_marking_threads;}
452 double sleep_factor() { return _sleep_factor; }
453 double marking_task_overhead() { return _marking_task_overhead;}
454
455 HeapWord* finger() { return _finger; }
456 bool concurrent() { return _concurrent; }
457 uint active_tasks() { return _active_tasks; }
458 ParallelTaskTerminator* terminator() { return &_terminator; }
459
460 // It claims the next available region to be scanned by a marking
461 // task/thread. It might return NULL if the next region is empty or
462 // we have run out of regions. In the latter case, out_of_regions()
463 // determines whether we've really run out of regions or the task
464 // should call claim_region() again. This might seem a bit
465 // awkward. Originally, the code was written so that claim_region()
466 // either successfully returned with a non-empty region or there
467 // were no more regions to be claimed. The problem with this was
468 // that, in certain circumstances, it iterated over large chunks of
469 // the heap finding only empty regions and, while it was working, it
470 // was preventing the calling task to call its regular clock
471 // method. So, this way, each task will spend very little time in
472 // claim_region() and is allowed to call the regular clock method
473 // frequently.
474 HeapRegion* claim_region(uint worker_id);
475
476 // It determines whether we've run out of regions to scan. Note that
477 // the finger can point past the heap end in case the heap was expanded
478 // to satisfy an allocation without doing a GC. This is fine, because all
479 // objects in those regions will be considered live anyway because of
480 // SATB guarantees (i.e. their TAMS will be equal to bottom).
481 bool out_of_regions() { return _finger >= _heap_end; }
482
483 // Returns the task with the given id
484 G1CMTask* task(int id) {
485 assert(0 <= id && id < (int) _active_tasks,
486 "task id not within active bounds");
487 return _tasks[id];
488 }
489
490 // Returns the task queue with the given id
491 G1CMTaskQueue* task_queue(int id) {
492 assert(0 <= id && id < (int) _active_tasks,
493 "task queue id not within active bounds");
494 return (G1CMTaskQueue*) _task_queues->queue(id);
495 }
496
497 // Returns the task queue set
498 G1CMTaskQueueSet* task_queues() { return _task_queues; }
499
500 // Access / manipulation of the overflow flag which is set to
501 // indicate that the global stack has overflown
502 bool has_overflown() { return _has_overflown; }
503 void set_has_overflown() { _has_overflown = true; }
504 void clear_has_overflown() { _has_overflown = false; }
505 bool restart_for_overflow() { return _restart_for_overflow; }
506
507 // Methods to enter the two overflow sync barriers
508 void enter_first_sync_barrier(uint worker_id);
509 void enter_second_sync_barrier(uint worker_id);
510
511 // Card index of the bottom of the G1 heap. Used for biasing indices into
512 // the card bitmaps.
513 intptr_t _heap_bottom_card_num;
514
515 // Set to true when initialization is complete
516 bool _completed_initialization;
517
518 // end_timer, true to end gc timer after ending concurrent phase.
519 void register_concurrent_phase_end_common(bool end_timer);
520
521 // Clear the given bitmap in parallel using the given WorkGang. If may_yield is
522 // true, periodically insert checks to see if this method should exit prematurely.
523 void clear_bitmap(G1CMBitMap* bitmap, WorkGang* workers, bool may_yield);
524 public:
525 // Manipulation of the global mark stack.
526 // The push and pop operations are used by tasks for transfers
527 // between task-local queues and the global mark stack.
528 bool mark_stack_push(oop* arr) {
529 if (!_global_mark_stack.par_push_chunk(arr)) {
530 set_has_overflown();
531 return false;
532 }
533 return true;
534 }
535 bool mark_stack_pop(oop* arr) {
536 return _global_mark_stack.par_pop_chunk(arr);
537 }
538 size_t mark_stack_size() { return _global_mark_stack.size(); }
539 size_t partial_mark_stack_size_target() { return _global_mark_stack.capacity()/3; }
540 bool mark_stack_overflow() { return _global_mark_stack.is_out_of_memory(); }
541 bool mark_stack_empty() { return _global_mark_stack.is_empty(); }
542
543 G1CMRootRegions* root_regions() { return &_root_regions; }
544
545 bool concurrent_marking_in_progress() {
546 return _concurrent_marking_in_progress;
547 }
548 void set_concurrent_marking_in_progress() {
549 _concurrent_marking_in_progress = true;
550 }
551 void clear_concurrent_marking_in_progress() {
552 _concurrent_marking_in_progress = false;
553 }
554
555 void concurrent_cycle_start();
556 void concurrent_cycle_end();
557
558 void update_accum_task_vtime(int i, double vtime) {
559 _accum_task_vtime[i] += vtime;
560 }
561
562 double all_task_accum_vtime() {
563 double ret = 0.0;
564 for (uint i = 0; i < _max_worker_id; ++i)
565 ret += _accum_task_vtime[i];
566 return ret;
567 }
568
569 // Attempts to steal an object from the task queues of other tasks
570 bool try_stealing(uint worker_id, int* hash_seed, oop& obj);
571
572 G1ConcurrentMark(G1CollectedHeap* g1h,
573 G1RegionToSpaceMapper* prev_bitmap_storage,
574 G1RegionToSpaceMapper* next_bitmap_storage);
575 ~G1ConcurrentMark();
576
577 ConcurrentMarkThread* cmThread() { return _cmThread; }
578
579 G1CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; }
580 G1CMBitMap* nextMarkBitMap() const { return _nextMarkBitMap; }
581
582 // Returns the number of GC threads to be used in a concurrent
583 // phase based on the number of GC threads being used in a STW
584 // phase.
585 uint scale_parallel_threads(uint n_par_threads);
586
587 // Calculates the number of GC threads to be used in a concurrent phase.
588 uint calc_parallel_marking_threads();
589
590 // The following three are interaction between CM and
591 // G1CollectedHeap
592
593 // This notifies CM that a root during initial-mark needs to be
594 // grayed. It is MT-safe. hr is the region that
595 // contains the object and it's passed optionally from callers who
596 // might already have it (no point in recalculating it).
597 inline void grayRoot(oop obj,
598 HeapRegion* hr = NULL);
599
600 // Prepare internal data structures for the next mark cycle. This includes clearing
601 // the next mark bitmap and some internal data structures. This method is intended
602 // to be called concurrently to the mutator. It will yield to safepoint requests.
603 void cleanup_for_next_mark();
604
605 // Clear the previous marking bitmap during safepoint.
606 void clear_prev_bitmap(WorkGang* workers);
607
608 // Return whether the next mark bitmap has no marks set. To be used for assertions
609 // only. Will not yield to pause requests.
610 bool nextMarkBitmapIsClear();
611
612 // These two do the work that needs to be done before and after the
613 // initial root checkpoint. Since this checkpoint can be done at two
614 // different points (i.e. an explicit pause or piggy-backed on a
615 // young collection), then it's nice to be able to easily share the
616 // pre/post code. It might be the case that we can put everything in
617 // the post method. TP
618 void checkpointRootsInitialPre();
619 void checkpointRootsInitialPost();
620
621 // Scan all the root regions and mark everything reachable from
622 // them.
623 void scan_root_regions();
624
625 // Scan a single root region and mark everything reachable from it.
626 void scanRootRegion(HeapRegion* hr);
627
628 // Do concurrent phase of marking, to a tentative transitive closure.
629 void mark_from_roots();
630
631 void checkpointRootsFinal(bool clear_all_soft_refs);
632 void checkpointRootsFinalWork();
633 void cleanup();
634 void complete_cleanup();
635
636 // Mark in the previous bitmap. NB: this is usually read-only, so use
637 // this carefully!
638 inline void markPrev(oop p);
639
640 // Clears marks for all objects in the given range, for the prev or
641 // next bitmaps. NB: the previous bitmap is usually
642 // read-only, so use this carefully!
643 void clearRangePrevBitmap(MemRegion mr);
644
645 // Verify that there are no CSet oops on the stacks (taskqueues /
646 // global mark stack) and fingers (global / per-task).
647 // If marking is not in progress, it's a no-op.
648 void verify_no_cset_oops() PRODUCT_RETURN;
649
650 inline bool isPrevMarked(oop p) const;
651
652 inline bool do_yield_check();
653
654 // Abandon current marking iteration due to a Full GC.
655 void abort();
656
657 bool has_aborted() { return _has_aborted; }
658
659 void print_summary_info();
660
661 void print_worker_threads_on(outputStream* st) const;
662 void threads_do(ThreadClosure* tc) const;
663
664 void print_on_error(outputStream* st) const;
665
666 // Attempts to mark the given object on the next mark bitmap.
667 inline bool par_mark(oop obj);
668
669 // Returns true if initialization was successfully completed.
670 bool completed_initialization() const {
671 return _completed_initialization;
672 }
673
674 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
675 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
676
677 private:
678 // Clear (Reset) all liveness count data.
679 void clear_live_data(WorkGang* workers);
680
681 #ifdef ASSERT
682 // Verify all of the above data structures that they are in initial state.
683 void verify_live_data_clear();
684 #endif
685
686 // Aggregates the per-card liveness data based on the current marking. Also sets
687 // the amount of marked bytes for each region.
688 void create_live_data();
689
690 void finalize_live_data();
691
692 void verify_live_data();
693 };
694
695 // A class representing a marking task.
696 class G1CMTask : public TerminatorTerminator {
697 private:
698 enum PrivateConstants {
699 // The regular clock call is called once the scanned words reaches
700 // this limit
701 words_scanned_period = 12*1024,
702 // The regular clock call is called once the number of visited
703 // references reaches this limit
704 refs_reached_period = 384,
705 // Initial value for the hash seed, used in the work stealing code
706 init_hash_seed = 17
707 };
708
709 uint _worker_id;
710 G1CollectedHeap* _g1h;
711 G1ConcurrentMark* _cm;
712 G1CMBitMap* _nextMarkBitMap;
713 // the task queue of this task
714 G1CMTaskQueue* _task_queue;
715 private:
716 // the task queue set---needed for stealing
717 G1CMTaskQueueSet* _task_queues;
718 // indicates whether the task has been claimed---this is only for
719 // debugging purposes
720 bool _claimed;
721
722 // number of calls to this task
723 int _calls;
724
725 // when the virtual timer reaches this time, the marking step should
726 // exit
727 double _time_target_ms;
728 // the start time of the current marking step
729 double _start_time_ms;
730
731 // the oop closure used for iterations over oops
732 G1CMOopClosure* _cm_oop_closure;
733
734 // the region this task is scanning, NULL if we're not scanning any
735 HeapRegion* _curr_region;
736 // the local finger of this task, NULL if we're not scanning a region
737 HeapWord* _finger;
738 // limit of the region this task is scanning, NULL if we're not scanning one
739 HeapWord* _region_limit;
740
741 // the number of words this task has scanned
742 size_t _words_scanned;
743 // When _words_scanned reaches this limit, the regular clock is
744 // called. Notice that this might be decreased under certain
745 // circumstances (i.e. when we believe that we did an expensive
746 // operation).
747 size_t _words_scanned_limit;
748 // the initial value of _words_scanned_limit (i.e. what it was
749 // before it was decreased).
750 size_t _real_words_scanned_limit;
751
752 // the number of references this task has visited
753 size_t _refs_reached;
754 // When _refs_reached reaches this limit, the regular clock is
755 // called. Notice this this might be decreased under certain
756 // circumstances (i.e. when we believe that we did an expensive
757 // operation).
758 size_t _refs_reached_limit;
759 // the initial value of _refs_reached_limit (i.e. what it was before
760 // it was decreased).
761 size_t _real_refs_reached_limit;
762
763 // used by the work stealing stuff
764 int _hash_seed;
765 // if this is true, then the task has aborted for some reason
766 bool _has_aborted;
767 // set when the task aborts because it has met its time quota
768 bool _has_timed_out;
769 // true when we're draining SATB buffers; this avoids the task
770 // aborting due to SATB buffers being available (as we're already
771 // dealing with them)
772 bool _draining_satb_buffers;
773
774 // number sequence of past step times
775 NumberSeq _step_times_ms;
776 // elapsed time of this task
777 double _elapsed_time_ms;
778 // termination time of this task
779 double _termination_time_ms;
780 // when this task got into the termination protocol
781 double _termination_start_time_ms;
782
783 // true when the task is during a concurrent phase, false when it is
784 // in the remark phase (so, in the latter case, we do not have to
785 // check all the things that we have to check during the concurrent
786 // phase, i.e. SATB buffer availability...)
787 bool _concurrent;
788
789 TruncatedSeq _marking_step_diffs_ms;
790
791 // it updates the local fields after this task has claimed
792 // a new region to scan
793 void setup_for_region(HeapRegion* hr);
794 // it brings up-to-date the limit of the region
795 void update_region_limit();
796
797 // called when either the words scanned or the refs visited limit
798 // has been reached
799 void reached_limit();
800 // recalculates the words scanned and refs visited limits
801 void recalculate_limits();
802 // decreases the words scanned and refs visited limits when we reach
803 // an expensive operation
804 void decrease_limits();
805 // it checks whether the words scanned or refs visited reached their
806 // respective limit and calls reached_limit() if they have
807 void check_limits() {
808 if (_words_scanned >= _words_scanned_limit ||
809 _refs_reached >= _refs_reached_limit) {
810 reached_limit();
811 }
812 }
813 // this is supposed to be called regularly during a marking step as
814 // it checks a bunch of conditions that might cause the marking step
815 // to abort
816 void regular_clock_call();
817 bool concurrent() { return _concurrent; }
818
819 // Test whether obj might have already been passed over by the
820 // mark bitmap scan, and so needs to be pushed onto the mark stack.
821 bool is_below_finger(oop obj, HeapWord* global_finger) const;
822
823 template<bool scan> void process_grey_object(oop obj);
824
825 public:
826 // It resets the task; it should be called right at the beginning of
827 // a marking phase.
828 void reset(G1CMBitMap* _nextMarkBitMap);
829 // it clears all the fields that correspond to a claimed region.
830 void clear_region_fields();
831
832 void set_concurrent(bool concurrent) { _concurrent = concurrent; }
833
834 // The main method of this class which performs a marking step
835 // trying not to exceed the given duration. However, it might exit
836 // prematurely, according to some conditions (i.e. SATB buffers are
837 // available for processing).
838 void do_marking_step(double target_ms,
839 bool do_termination,
840 bool is_serial);
841
842 // These two calls start and stop the timer
843 void record_start_time() {
844 _elapsed_time_ms = os::elapsedTime() * 1000.0;
845 }
846 void record_end_time() {
847 _elapsed_time_ms = os::elapsedTime() * 1000.0 - _elapsed_time_ms;
848 }
849
850 // returns the worker ID associated with this task.
851 uint worker_id() { return _worker_id; }
852
853 // From TerminatorTerminator. It determines whether this task should
854 // exit the termination protocol after it's entered it.
855 virtual bool should_exit_termination();
856
857 // Resets the local region fields after a task has finished scanning a
858 // region; or when they have become stale as a result of the region
859 // being evacuated.
860 void giveup_current_region();
861
862 HeapWord* finger() { return _finger; }
863
864 bool has_aborted() { return _has_aborted; }
865 void set_has_aborted() { _has_aborted = true; }
866 void clear_has_aborted() { _has_aborted = false; }
867 bool has_timed_out() { return _has_timed_out; }
868 bool claimed() { return _claimed; }
869
870 void set_cm_oop_closure(G1CMOopClosure* cm_oop_closure);
871
872 // Increment the number of references this task has visited.
873 void increment_refs_reached() { ++_refs_reached; }
874
875 // Grey the object by marking it. If not already marked, push it on
876 // the local queue if below the finger.
877 // obj is below its region's NTAMS.
878 inline void make_reference_grey(oop obj);
879
880 // Grey the object (by calling make_grey_reference) if required,
881 // e.g. obj is below its containing region's NTAMS.
882 // Precondition: obj is a valid heap object.
883 inline void deal_with_reference(oop obj);
884
885 // It scans an object and visits its children.
886 inline void scan_object(oop obj);
887
888 // It pushes an object on the local queue.
889 inline void push(oop obj);
890
891 // Move entries to the global stack.
892 void move_entries_to_global_stack();
893 // Move entries from the global stack, return true if we were successful to do so.
894 bool get_entries_from_global_stack();
895
896 // It pops and scans objects from the local queue. If partially is
897 // true, then it stops when the queue size is of a given limit. If
898 // partially is false, then it stops when the queue is empty.
899 void drain_local_queue(bool partially);
900 // It moves entries from the global stack to the local queue and
901 // drains the local queue. If partially is true, then it stops when
902 // both the global stack and the local queue reach a given size. If
903 // partially if false, it tries to empty them totally.
904 void drain_global_stack(bool partially);
905 // It keeps picking SATB buffers and processing them until no SATB
906 // buffers are available.
907 void drain_satb_buffers();
908
909 // moves the local finger to a new location
910 inline void move_finger_to(HeapWord* new_finger) {
911 assert(new_finger >= _finger && new_finger < _region_limit, "invariant");
912 _finger = new_finger;
913 }
914
915 G1CMTask(uint worker_id,
916 G1ConcurrentMark *cm,
917 G1CMTaskQueue* task_queue,
918 G1CMTaskQueueSet* task_queues);
919
920 // it prints statistics associated with this task
921 void print_stats();
922 };
923
924 // Class that's used to to print out per-region liveness
925 // information. It's currently used at the end of marking and also
926 // after we sort the old regions at the end of the cleanup operation.
927 class G1PrintRegionLivenessInfoClosure: public HeapRegionClosure {
928 private:
929 // Accumulators for these values.
930 size_t _total_used_bytes;
931 size_t _total_capacity_bytes;
932 size_t _total_prev_live_bytes;
933 size_t _total_next_live_bytes;
934
935 // Accumulator for the remembered set size
936 size_t _total_remset_bytes;
937
938 // Accumulator for strong code roots memory size
939 size_t _total_strong_code_roots_bytes;
940
941 static double perc(size_t val, size_t total) {
942 if (total == 0) {
943 return 0.0;
944 } else {
945 return 100.0 * ((double) val / (double) total);
946 }
947 }
948
949 static double bytes_to_mb(size_t val) {
950 return (double) val / (double) M;
951 }
952
953 public:
954 // The header and footer are printed in the constructor and
955 // destructor respectively.
956 G1PrintRegionLivenessInfoClosure(const char* phase_name);
957 virtual bool doHeapRegion(HeapRegion* r);
958 ~G1PrintRegionLivenessInfoClosure();
959 };
960
961 #endif // SHARE_VM_GC_G1_G1CONCURRENTMARK_HPP