1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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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 typedef GenericTaskQueue<oop, mtGC> G1CMTaskQueue;
40 typedef GenericTaskQueueSet<G1CMTaskQueue, mtGC> G1CMTaskQueueSet;
41
42 // Closure used by CM during concurrent reference discovery
43 // and reference processing (during remarking) to determine
44 // if a particular object is alive. It is primarily used
45 // to determine if referents of discovered reference objects
46 // are alive. An instance is also embedded into the
47 // reference processor as the _is_alive_non_header field
48 class G1CMIsAliveClosure: public BoolObjectClosure {
49 G1CollectedHeap* _g1;
50 public:
51 G1CMIsAliveClosure(G1CollectedHeap* g1) : _g1(g1) { }
52
53 bool do_object_b(oop obj);
54 };
55
56 // A generic CM bit map. This is essentially a wrapper around the BitMap
57 // class, with one bit per (1<<_shifter) HeapWords.
58
59 class G1CMBitMapRO VALUE_OBJ_CLASS_SPEC {
60 protected:
61 HeapWord* _bmStartWord; // base address of range covered by map
62 size_t _bmWordSize; // map size (in #HeapWords covered)
63 const int _shifter; // map to char or bit
64 BitMap _bm; // the bit map itself
65
66 public:
67 // constructor
68 G1CMBitMapRO(int shifter);
69
70 // inquiries
71 HeapWord* startWord() const { return _bmStartWord; }
72 // the following is one past the last word in space
73 HeapWord* endWord() const { return _bmStartWord + _bmWordSize; }
74
75 // read marks
76
77 bool isMarked(HeapWord* addr) const {
78 assert(_bmStartWord <= addr && addr < (_bmStartWord + _bmWordSize),
79 "outside underlying space?");
80 return _bm.at(heapWordToOffset(addr));
81 }
82
83 // iteration
84 inline bool iterate(BitMapClosure* cl, MemRegion mr);
85
86 // Return the address corresponding to the next marked bit at or after
87 // "addr", and before "limit", if "limit" is non-NULL. If there is no
88 // such bit, returns "limit" if that is non-NULL, or else "endWord()".
89 HeapWord* getNextMarkedWordAddress(const HeapWord* addr,
90 const HeapWord* limit = NULL) const;
91
92 // conversion utilities
93 HeapWord* offsetToHeapWord(size_t offset) const {
94 return _bmStartWord + (offset << _shifter);
95 }
96 size_t heapWordToOffset(const HeapWord* addr) const {
97 return pointer_delta(addr, _bmStartWord) >> _shifter;
98 }
99
100 // The argument addr should be the start address of a valid object
101 inline HeapWord* nextObject(HeapWord* addr);
102
103 void print_on_error(outputStream* st, const char* prefix) const;
104
105 // debugging
106 NOT_PRODUCT(bool covers(MemRegion rs) const;)
107 };
108
109 class G1CMBitMapMappingChangedListener : public G1MappingChangedListener {
110 private:
111 G1CMBitMap* _bm;
112 public:
113 G1CMBitMapMappingChangedListener() : _bm(NULL) {}
114
115 void set_bitmap(G1CMBitMap* bm) { _bm = bm; }
116
117 virtual void on_commit(uint start_idx, size_t num_regions, bool zero_filled);
118 };
119
120 class G1CMBitMap : public G1CMBitMapRO {
121 private:
122 G1CMBitMapMappingChangedListener _listener;
123
124 public:
125 static size_t compute_size(size_t heap_size);
126 // Returns the amount of bytes on the heap between two marks in the bitmap.
127 static size_t mark_distance();
128 // Returns how many bytes (or bits) of the heap a single byte (or bit) of the
129 // mark bitmap corresponds to. This is the same as the mark distance above.
130 static size_t heap_map_factor() {
131 return mark_distance();
132 }
133
134 G1CMBitMap() : G1CMBitMapRO(LogMinObjAlignment), _listener() { _listener.set_bitmap(this); }
135
136 // Initializes the underlying BitMap to cover the given area.
137 void initialize(MemRegion heap, G1RegionToSpaceMapper* storage);
138
139 // Write marks.
140 inline void mark(HeapWord* addr);
141 inline void clear(HeapWord* addr);
142 inline bool parMark(HeapWord* addr);
143
144 void clear_range(MemRegion mr);
145 };
146
147 // Represents a marking stack used by ConcurrentMarking in the G1 collector.
148 class G1CMMarkStack VALUE_OBJ_CLASS_SPEC {
149 VirtualSpace _virtual_space; // Underlying backing store for actual stack
150 G1ConcurrentMark* _cm;
151 oop* _base; // bottom of stack
152 jint _index; // one more than last occupied index
153 jint _capacity; // max #elements
154 jint _saved_index; // value of _index saved at start of GC
155
156 bool _overflow;
157 bool _should_expand;
158
159 public:
160 G1CMMarkStack(G1ConcurrentMark* cm);
161 ~G1CMMarkStack();
162
163 bool allocate(size_t capacity);
164
165 // Pushes the first "n" elements of "ptr_arr" on the stack.
166 // Locking impl: concurrency is allowed only with
167 // "par_push_arr" and/or "par_pop_arr" operations, which use the same
168 // locking strategy.
169 void par_push_arr(oop* ptr_arr, int n);
170
171 // If returns false, the array was empty. Otherwise, removes up to "max"
172 // elements from the stack, and transfers them to "ptr_arr" in an
173 // unspecified order. The actual number transferred is given in "n" ("n
174 // == 0" is deliberately redundant with the return value.) Locking impl:
175 // concurrency is allowed only with "par_push_arr" and/or "par_pop_arr"
176 // operations, which use the same locking strategy.
177 bool par_pop_arr(oop* ptr_arr, int max, int* n);
178
179 bool isEmpty() { return _index == 0; }
180 int maxElems() { return _capacity; }
181
182 bool overflow() { return _overflow; }
183 void clear_overflow() { _overflow = false; }
184
185 bool should_expand() const { return _should_expand; }
186 void set_should_expand();
187
188 // Expand the stack, typically in response to an overflow condition
189 void expand();
190
191 int size() { return _index; }
192
193 void setEmpty() { _index = 0; clear_overflow(); }
194
195 // Record the current index.
196 void note_start_of_gc();
197
198 // Make sure that we have not added any entries to the stack during GC.
199 void note_end_of_gc();
200
201 // Apply fn to each oop in the mark stack, up to the bound recorded
202 // via one of the above "note" functions. The mark stack must not
203 // be modified while iterating.
204 template<typename Fn> void iterate(Fn fn);
205 };
206
207 class YoungList;
208
209 // Root Regions are regions that are not empty at the beginning of a
210 // marking cycle and which we might collect during an evacuation pause
211 // while the cycle is active. Given that, during evacuation pauses, we
212 // do not copy objects that are explicitly marked, what we have to do
213 // for the root regions is to scan them and mark all objects reachable
214 // from them. According to the SATB assumptions, we only need to visit
215 // each object once during marking. So, as long as we finish this scan
216 // before the next evacuation pause, we can copy the objects from the
217 // root regions without having to mark them or do anything else to them.
218 //
219 // Currently, we only support root region scanning once (at the start
220 // of the marking cycle) and the root regions are all the survivor
221 // regions populated during the initial-mark pause.
222 class G1CMRootRegions VALUE_OBJ_CLASS_SPEC {
223 private:
224 YoungList* _young_list;
225 G1ConcurrentMark* _cm;
226
227 volatile bool _scan_in_progress;
228 volatile bool _should_abort;
229 HeapRegion* volatile _next_survivor;
230
231 void notify_scan_done();
232
233 public:
234 G1CMRootRegions();
235 // We actually do most of the initialization in this method.
236 void init(G1CollectedHeap* g1h, G1ConcurrentMark* cm);
237
238 // Reset the claiming / scanning of the root regions.
239 void prepare_for_scan();
240
241 // Forces get_next() to return NULL so that the iteration aborts early.
242 void abort() { _should_abort = true; }
243
244 // Return true if the CM thread are actively scanning root regions,
245 // false otherwise.
246 bool scan_in_progress() { return _scan_in_progress; }
247
248 // Claim the next root region to scan atomically, or return NULL if
249 // all have been claimed.
250 HeapRegion* claim_next();
251
252 void cancel_scan();
253
254 // Flag that we're done with root region scanning and notify anyone
255 // who's waiting on it. If aborted is false, assume that all regions
256 // have been claimed.
257 void scan_finished();
258
259 // If CM threads are still scanning root regions, wait until they
260 // are done. Return true if we had to wait, false otherwise.
261 bool wait_until_scan_finished();
262 };
263
264 class ConcurrentMarkThread;
265
266 class G1ConcurrentMark: public CHeapObj<mtGC> {
267 friend class ConcurrentMarkThread;
268 friend class G1ParNoteEndTask;
269 friend class CalcLiveObjectsClosure;
270 friend class G1CMRefProcTaskProxy;
271 friend class G1CMRefProcTaskExecutor;
272 friend class G1CMKeepAliveAndDrainClosure;
273 friend class G1CMDrainMarkingStackClosure;
274 friend class G1CMBitMapClosure;
275 friend class G1CMConcurrentMarkingTask;
276 friend class G1CMMarkStack;
277 friend class G1CMRemarkTask;
278 friend class G1CMTask;
279
280 protected:
281 ConcurrentMarkThread* _cmThread; // The thread doing the work
282 G1CollectedHeap* _g1h; // The heap
283 uint _parallel_marking_threads; // The number of marking
284 // threads we're using
285 uint _max_parallel_marking_threads; // Max number of marking
286 // threads we'll ever use
287 double _sleep_factor; // How much we have to sleep, with
288 // respect to the work we just did, to
289 // meet the marking overhead goal
290 double _marking_task_overhead; // Marking target overhead for
291 // a single task
292
293 FreeRegionList _cleanup_list;
294
295 // Concurrent marking support structures
296 G1CMBitMap _markBitMap1;
297 G1CMBitMap _markBitMap2;
298 G1CMBitMapRO* _prevMarkBitMap; // Completed mark bitmap
299 G1CMBitMap* _nextMarkBitMap; // Under-construction mark bitmap
300
301 BitMap _region_bm;
302 BitMap _card_bm;
303
304 // Heap bounds
305 HeapWord* _heap_start;
306 HeapWord* _heap_end;
307
308 // Root region tracking and claiming
309 G1CMRootRegions _root_regions;
310
311 // For gray objects
312 G1CMMarkStack _markStack; // Grey objects behind global finger
313 HeapWord* volatile _finger; // The global finger, region aligned,
314 // always points to the end of the
315 // last claimed region
316
317 // Marking tasks
318 uint _max_worker_id;// Maximum worker id
319 uint _active_tasks; // Task num currently active
320 G1CMTask** _tasks; // Task queue array (max_worker_id len)
321 G1CMTaskQueueSet* _task_queues; // Task queue set
322 ParallelTaskTerminator _terminator; // For termination
323
324 // Two sync barriers that are used to synchronize tasks when an
325 // overflow occurs. The algorithm is the following. All tasks enter
326 // the first one to ensure that they have all stopped manipulating
327 // the global data structures. After they exit it, they re-initialize
328 // their data structures and task 0 re-initializes the global data
329 // structures. Then, they enter the second sync barrier. This
330 // ensure, that no task starts doing work before all data
331 // structures (local and global) have been re-initialized. When they
332 // exit it, they are free to start working again.
333 WorkGangBarrierSync _first_overflow_barrier_sync;
334 WorkGangBarrierSync _second_overflow_barrier_sync;
335
336 // This is set by any task, when an overflow on the global data
337 // structures is detected
338 volatile bool _has_overflown;
339 // True: marking is concurrent, false: we're in remark
340 volatile bool _concurrent;
341 // Set at the end of a Full GC so that marking aborts
342 volatile bool _has_aborted;
343
344 // Used when remark aborts due to an overflow to indicate that
345 // another concurrent marking phase should start
346 volatile bool _restart_for_overflow;
347
348 // This is true from the very start of concurrent marking until the
349 // point when all the tasks complete their work. It is really used
350 // to determine the points between the end of concurrent marking and
351 // time of remark.
352 volatile bool _concurrent_marking_in_progress;
353
354 ConcurrentGCTimer* _gc_timer_cm;
355
356 G1OldTracer* _gc_tracer_cm;
357
358 // All of these times are in ms
359 NumberSeq _init_times;
360 NumberSeq _remark_times;
361 NumberSeq _remark_mark_times;
362 NumberSeq _remark_weak_ref_times;
363 NumberSeq _cleanup_times;
364 double _total_counting_time;
365 double _total_rs_scrub_time;
366
367 double* _accum_task_vtime; // Accumulated task vtime
368
369 WorkGang* _parallel_workers;
370
371 void weakRefsWorkParallelPart(BoolObjectClosure* is_alive, bool purged_classes);
372 void weakRefsWork(bool clear_all_soft_refs);
373
374 void swapMarkBitMaps();
375
376 // It resets the global marking data structures, as well as the
377 // task local ones; should be called during initial mark.
378 void reset();
379
380 // Resets all the marking data structures. Called when we have to restart
381 // marking or when marking completes (via set_non_marking_state below).
382 void reset_marking_state(bool clear_overflow = true);
383
384 // We do this after we're done with marking so that the marking data
385 // structures are initialized to a sensible and predictable state.
386 void set_non_marking_state();
387
388 // Called to indicate how many threads are currently active.
389 void set_concurrency(uint active_tasks);
390
391 // It should be called to indicate which phase we're in (concurrent
392 // mark or remark) and how many threads are currently active.
393 void set_concurrency_and_phase(uint active_tasks, bool concurrent);
394
395 // Prints all gathered CM-related statistics
396 void print_stats();
397
398 bool cleanup_list_is_empty() {
399 return _cleanup_list.is_empty();
400 }
401
402 // Accessor methods
403 uint parallel_marking_threads() const { return _parallel_marking_threads; }
404 uint max_parallel_marking_threads() const { return _max_parallel_marking_threads;}
405 double sleep_factor() { return _sleep_factor; }
406 double marking_task_overhead() { return _marking_task_overhead;}
407
408 HeapWord* finger() { return _finger; }
409 bool concurrent() { return _concurrent; }
410 uint active_tasks() { return _active_tasks; }
411 ParallelTaskTerminator* terminator() { return &_terminator; }
412
413 // It claims the next available region to be scanned by a marking
414 // task/thread. It might return NULL if the next region is empty or
415 // we have run out of regions. In the latter case, out_of_regions()
416 // determines whether we've really run out of regions or the task
417 // should call claim_region() again. This might seem a bit
418 // awkward. Originally, the code was written so that claim_region()
419 // either successfully returned with a non-empty region or there
420 // were no more regions to be claimed. The problem with this was
421 // that, in certain circumstances, it iterated over large chunks of
422 // the heap finding only empty regions and, while it was working, it
423 // was preventing the calling task to call its regular clock
424 // method. So, this way, each task will spend very little time in
425 // claim_region() and is allowed to call the regular clock method
426 // frequently.
427 HeapRegion* claim_region(uint worker_id);
428
429 // It determines whether we've run out of regions to scan. Note that
430 // the finger can point past the heap end in case the heap was expanded
431 // to satisfy an allocation without doing a GC. This is fine, because all
432 // objects in those regions will be considered live anyway because of
433 // SATB guarantees (i.e. their TAMS will be equal to bottom).
434 bool out_of_regions() { return _finger >= _heap_end; }
435
436 // Returns the task with the given id
437 G1CMTask* task(int id) {
438 assert(0 <= id && id < (int) _active_tasks,
439 "task id not within active bounds");
440 return _tasks[id];
441 }
442
443 // Returns the task queue with the given id
444 G1CMTaskQueue* task_queue(int id) {
445 assert(0 <= id && id < (int) _active_tasks,
446 "task queue id not within active bounds");
447 return (G1CMTaskQueue*) _task_queues->queue(id);
448 }
449
450 // Returns the task queue set
451 G1CMTaskQueueSet* task_queues() { return _task_queues; }
452
453 // Access / manipulation of the overflow flag which is set to
454 // indicate that the global stack has overflown
455 bool has_overflown() { return _has_overflown; }
456 void set_has_overflown() { _has_overflown = true; }
457 void clear_has_overflown() { _has_overflown = false; }
458 bool restart_for_overflow() { return _restart_for_overflow; }
459
460 // Methods to enter the two overflow sync barriers
461 void enter_first_sync_barrier(uint worker_id);
462 void enter_second_sync_barrier(uint worker_id);
463
464 // Live Data Counting data structures...
465 // These data structures are initialized at the start of
466 // marking. They are written to while marking is active.
467 // They are aggregated during remark; the aggregated values
468 // are then used to populate the _region_bm, _card_bm, and
469 // the total live bytes, which are then subsequently updated
470 // during cleanup.
471
472 // An array of bitmaps (one bit map per task). Each bitmap
473 // is used to record the cards spanned by the live objects
474 // marked by that task/worker.
475 BitMap* _count_card_bitmaps;
476
477 // Used to record the number of marked live bytes
478 // (for each region, by worker thread).
479 size_t** _count_marked_bytes;
480
481 // Card index of the bottom of the G1 heap. Used for biasing indices into
482 // the card bitmaps.
483 intptr_t _heap_bottom_card_num;
484
485 // Set to true when initialization is complete
486 bool _completed_initialization;
487
488 // end_timer, true to end gc timer after ending concurrent phase.
489 void register_concurrent_phase_end_common(bool end_timer);
490
491 // Clear the given bitmap in parallel using the given WorkGang. If may_yield is
492 // true, periodically insert checks to see if this method should exit prematurely.
493 void clear_bitmap(G1CMBitMap* bitmap, WorkGang* workers, bool may_yield);
494 public:
495 // Manipulation of the global mark stack.
496 // The push and pop operations are used by tasks for transfers
497 // between task-local queues and the global mark stack, and use
498 // locking for concurrency safety.
499 bool mark_stack_push(oop* arr, int n) {
500 _markStack.par_push_arr(arr, n);
501 if (_markStack.overflow()) {
502 set_has_overflown();
503 return false;
504 }
505 return true;
506 }
507 void mark_stack_pop(oop* arr, int max, int* n) {
508 _markStack.par_pop_arr(arr, max, n);
509 }
510 size_t mark_stack_size() { return _markStack.size(); }
511 size_t partial_mark_stack_size_target() { return _markStack.maxElems()/3; }
512 bool mark_stack_overflow() { return _markStack.overflow(); }
513 bool mark_stack_empty() { return _markStack.isEmpty(); }
514
515 G1CMRootRegions* root_regions() { return &_root_regions; }
516
517 bool concurrent_marking_in_progress() {
518 return _concurrent_marking_in_progress;
519 }
520 void set_concurrent_marking_in_progress() {
521 _concurrent_marking_in_progress = true;
522 }
523 void clear_concurrent_marking_in_progress() {
524 _concurrent_marking_in_progress = false;
525 }
526
527 void concurrent_cycle_start();
528 void concurrent_cycle_end();
529
530 void update_accum_task_vtime(int i, double vtime) {
531 _accum_task_vtime[i] += vtime;
532 }
533
534 double all_task_accum_vtime() {
535 double ret = 0.0;
536 for (uint i = 0; i < _max_worker_id; ++i)
537 ret += _accum_task_vtime[i];
538 return ret;
539 }
540
541 // Attempts to steal an object from the task queues of other tasks
542 bool try_stealing(uint worker_id, int* hash_seed, oop& obj);
543
544 G1ConcurrentMark(G1CollectedHeap* g1h,
545 G1RegionToSpaceMapper* prev_bitmap_storage,
546 G1RegionToSpaceMapper* next_bitmap_storage);
547 ~G1ConcurrentMark();
548
549 ConcurrentMarkThread* cmThread() { return _cmThread; }
550
551 G1CMBitMapRO* prevMarkBitMap() const { return _prevMarkBitMap; }
552 G1CMBitMap* nextMarkBitMap() const { return _nextMarkBitMap; }
553
554 // Returns the number of GC threads to be used in a concurrent
555 // phase based on the number of GC threads being used in a STW
556 // phase.
557 uint scale_parallel_threads(uint n_par_threads);
558
559 // Calculates the number of GC threads to be used in a concurrent phase.
560 uint calc_parallel_marking_threads();
561
562 // The following three are interaction between CM and
563 // G1CollectedHeap
564
565 // This notifies CM that a root during initial-mark needs to be
566 // grayed. It is MT-safe. word_size is the size of the object in
567 // words. It is passed explicitly as sometimes we cannot calculate
568 // it from the given object because it might be in an inconsistent
569 // state (e.g., in to-space and being copied). So the caller is
570 // responsible for dealing with this issue (e.g., get the size from
571 // the from-space image when the to-space image might be
572 // inconsistent) and always passing the size. hr is the region that
573 // contains the object and it's passed optionally from callers who
574 // might already have it (no point in recalculating it).
575 inline void grayRoot(oop obj,
576 size_t word_size,
577 uint worker_id,
578 HeapRegion* hr = NULL);
579
580 // Prepare internal data structures for the next mark cycle. This includes clearing
581 // the next mark bitmap and some internal data structures. This method is intended
582 // to be called concurrently to the mutator. It will yield to safepoint requests.
583 void cleanup_for_next_mark();
584
585 // Clear the previous marking bitmap during safepoint.
586 void clear_prev_bitmap(WorkGang* workers);
587
588 // Return whether the next mark bitmap has no marks set. To be used for assertions
589 // only. Will not yield to pause requests.
590 bool nextMarkBitmapIsClear();
591
592 // These two do the work that needs to be done before and after the
593 // initial root checkpoint. Since this checkpoint can be done at two
594 // different points (i.e. an explicit pause or piggy-backed on a
595 // young collection), then it's nice to be able to easily share the
596 // pre/post code. It might be the case that we can put everything in
597 // the post method. TP
598 void checkpointRootsInitialPre();
599 void checkpointRootsInitialPost();
600
601 // Scan all the root regions and mark everything reachable from
602 // them.
603 void scan_root_regions();
604
605 // Scan a single root region and mark everything reachable from it.
606 void scanRootRegion(HeapRegion* hr, uint worker_id);
607
608 // Do concurrent phase of marking, to a tentative transitive closure.
609 void mark_from_roots();
610
611 void checkpointRootsFinal(bool clear_all_soft_refs);
612 void checkpointRootsFinalWork();
613 void cleanup();
614 void complete_cleanup();
615
616 // Mark in the previous bitmap. NB: this is usually read-only, so use
617 // this carefully!
618 inline void markPrev(oop p);
619
620 // Clears marks for all objects in the given range, for the prev or
621 // next bitmaps. NB: the previous bitmap is usually
622 // read-only, so use this carefully!
623 void clearRangePrevBitmap(MemRegion mr);
624
625 // Notify data structures that a GC has started.
626 void note_start_of_gc() {
627 _markStack.note_start_of_gc();
628 }
629
630 // Notify data structures that a GC is finished.
631 void note_end_of_gc() {
632 _markStack.note_end_of_gc();
633 }
634
635 // Verify that there are no CSet oops on the stacks (taskqueues /
636 // global mark stack) and fingers (global / per-task).
637 // If marking is not in progress, it's a no-op.
638 void verify_no_cset_oops() PRODUCT_RETURN;
639
640 inline bool isPrevMarked(oop p) const;
641
642 inline bool do_yield_check(uint worker_i = 0);
643
644 // Called to abort the marking cycle after a Full GC takes place.
645 void abort();
646
647 bool has_aborted() { return _has_aborted; }
648
649 void print_summary_info();
650
651 void print_worker_threads_on(outputStream* st) const;
652
653 void print_on_error(outputStream* st) const;
654
655 // Liveness counting
656
657 // Utility routine to set an exclusive range of cards on the given
658 // card liveness bitmap
659 inline void set_card_bitmap_range(BitMap* card_bm,
660 BitMap::idx_t start_idx,
661 BitMap::idx_t end_idx,
662 bool is_par);
663
664 // Returns the card number of the bottom of the G1 heap.
665 // Used in biasing indices into accounting card bitmaps.
666 intptr_t heap_bottom_card_num() const {
667 return _heap_bottom_card_num;
668 }
669
670 // Returns the card bitmap for a given task or worker id.
671 BitMap* count_card_bitmap_for(uint worker_id) {
672 assert(worker_id < _max_worker_id, "oob");
673 assert(_count_card_bitmaps != NULL, "uninitialized");
674 BitMap* task_card_bm = &_count_card_bitmaps[worker_id];
675 assert(task_card_bm->size() == _card_bm.size(), "size mismatch");
676 return task_card_bm;
677 }
678
679 // Returns the array containing the marked bytes for each region,
680 // for the given worker or task id.
681 size_t* count_marked_bytes_array_for(uint worker_id) {
682 assert(worker_id < _max_worker_id, "oob");
683 assert(_count_marked_bytes != NULL, "uninitialized");
684 size_t* marked_bytes_array = _count_marked_bytes[worker_id];
685 assert(marked_bytes_array != NULL, "uninitialized");
686 return marked_bytes_array;
687 }
688
689 // Returns the index in the liveness accounting card table bitmap
690 // for the given address
691 inline BitMap::idx_t card_bitmap_index_for(HeapWord* addr);
692
693 // Counts the size of the given memory region in the the given
694 // marked_bytes array slot for the given HeapRegion.
695 // Sets the bits in the given card bitmap that are associated with the
696 // cards that are spanned by the memory region.
697 inline void count_region(MemRegion mr,
698 HeapRegion* hr,
699 size_t* marked_bytes_array,
700 BitMap* task_card_bm);
701
702 // Counts the given object in the given task/worker counting
703 // data structures.
704 inline void count_object(oop obj,
705 HeapRegion* hr,
706 size_t* marked_bytes_array,
707 BitMap* task_card_bm,
708 size_t word_size);
709
710 // Attempts to mark the given object and, if successful, counts
711 // the object in the given task/worker counting structures.
712 inline bool par_mark_and_count(oop obj,
713 HeapRegion* hr,
714 size_t* marked_bytes_array,
715 BitMap* task_card_bm);
716
717 // Attempts to mark the given object and, if successful, counts
718 // the object in the task/worker counting structures for the
719 // given worker id.
720 inline bool par_mark_and_count(oop obj,
721 size_t word_size,
722 HeapRegion* hr,
723 uint worker_id);
724
725 // Returns true if initialization was successfully completed.
726 bool completed_initialization() const {
727 return _completed_initialization;
728 }
729
730 ConcurrentGCTimer* gc_timer_cm() const { return _gc_timer_cm; }
731 G1OldTracer* gc_tracer_cm() const { return _gc_tracer_cm; }
732
733 protected:
734 // Clear all the per-task bitmaps and arrays used to store the
735 // counting data.
736 void clear_all_count_data();
737
738 // Aggregates the counting data for each worker/task
739 // that was constructed while marking. Also sets
740 // the amount of marked bytes for each region and
741 // the top at concurrent mark count.
742 void aggregate_count_data();
743
744 // Verification routine
745 void verify_count_data();
746 };
747
748 // A class representing a marking task.
749 class G1CMTask : public TerminatorTerminator {
750 private:
751 enum PrivateConstants {
752 // the regular clock call is called once the scanned words reaches
753 // this limit
754 words_scanned_period = 12*1024,
755 // the regular clock call is called once the number of visited
756 // references reaches this limit
757 refs_reached_period = 384,
758 // initial value for the hash seed, used in the work stealing code
759 init_hash_seed = 17,
760 // how many entries will be transferred between global stack and
761 // local queues
762 global_stack_transfer_size = 16
763 };
764
765 uint _worker_id;
766 G1CollectedHeap* _g1h;
767 G1ConcurrentMark* _cm;
768 G1CMBitMap* _nextMarkBitMap;
769 // the task queue of this task
770 G1CMTaskQueue* _task_queue;
771 private:
772 // the task queue set---needed for stealing
773 G1CMTaskQueueSet* _task_queues;
774 // indicates whether the task has been claimed---this is only for
775 // debugging purposes
776 bool _claimed;
777
778 // number of calls to this task
779 int _calls;
780
781 // when the virtual timer reaches this time, the marking step should
782 // exit
783 double _time_target_ms;
784 // the start time of the current marking step
785 double _start_time_ms;
786
787 // the oop closure used for iterations over oops
788 G1CMOopClosure* _cm_oop_closure;
789
790 // the region this task is scanning, NULL if we're not scanning any
791 HeapRegion* _curr_region;
792 // the local finger of this task, NULL if we're not scanning a region
793 HeapWord* _finger;
794 // limit of the region this task is scanning, NULL if we're not scanning one
795 HeapWord* _region_limit;
796
797 // the number of words this task has scanned
798 size_t _words_scanned;
799 // When _words_scanned reaches this limit, the regular clock is
800 // called. Notice that this might be decreased under certain
801 // circumstances (i.e. when we believe that we did an expensive
802 // operation).
803 size_t _words_scanned_limit;
804 // the initial value of _words_scanned_limit (i.e. what it was
805 // before it was decreased).
806 size_t _real_words_scanned_limit;
807
808 // the number of references this task has visited
809 size_t _refs_reached;
810 // When _refs_reached reaches this limit, the regular clock is
811 // called. Notice this this might be decreased under certain
812 // circumstances (i.e. when we believe that we did an expensive
813 // operation).
814 size_t _refs_reached_limit;
815 // the initial value of _refs_reached_limit (i.e. what it was before
816 // it was decreased).
817 size_t _real_refs_reached_limit;
818
819 // used by the work stealing stuff
820 int _hash_seed;
821 // if this is true, then the task has aborted for some reason
822 bool _has_aborted;
823 // set when the task aborts because it has met its time quota
824 bool _has_timed_out;
825 // true when we're draining SATB buffers; this avoids the task
826 // aborting due to SATB buffers being available (as we're already
827 // dealing with them)
828 bool _draining_satb_buffers;
829
830 // number sequence of past step times
831 NumberSeq _step_times_ms;
832 // elapsed time of this task
833 double _elapsed_time_ms;
834 // termination time of this task
835 double _termination_time_ms;
836 // when this task got into the termination protocol
837 double _termination_start_time_ms;
838
839 // true when the task is during a concurrent phase, false when it is
840 // in the remark phase (so, in the latter case, we do not have to
841 // check all the things that we have to check during the concurrent
842 // phase, i.e. SATB buffer availability...)
843 bool _concurrent;
844
845 TruncatedSeq _marking_step_diffs_ms;
846
847 // Counting data structures. Embedding the task's marked_bytes_array
848 // and card bitmap into the actual task saves having to go through
849 // the ConcurrentMark object.
850 size_t* _marked_bytes_array;
851 BitMap* _card_bm;
852
853 // it updates the local fields after this task has claimed
854 // a new region to scan
855 void setup_for_region(HeapRegion* hr);
856 // it brings up-to-date the limit of the region
857 void update_region_limit();
858
859 // called when either the words scanned or the refs visited limit
860 // has been reached
861 void reached_limit();
862 // recalculates the words scanned and refs visited limits
863 void recalculate_limits();
864 // decreases the words scanned and refs visited limits when we reach
865 // an expensive operation
866 void decrease_limits();
867 // it checks whether the words scanned or refs visited reached their
868 // respective limit and calls reached_limit() if they have
869 void check_limits() {
870 if (_words_scanned >= _words_scanned_limit ||
871 _refs_reached >= _refs_reached_limit) {
872 reached_limit();
873 }
874 }
875 // this is supposed to be called regularly during a marking step as
876 // it checks a bunch of conditions that might cause the marking step
877 // to abort
878 void regular_clock_call();
879 bool concurrent() { return _concurrent; }
880
881 // Test whether obj might have already been passed over by the
882 // mark bitmap scan, and so needs to be pushed onto the mark stack.
883 bool is_below_finger(oop obj, HeapWord* global_finger) const;
884
885 template<bool scan> void process_grey_object(oop obj);
886
887 public:
888 // It resets the task; it should be called right at the beginning of
889 // a marking phase.
890 void reset(G1CMBitMap* _nextMarkBitMap);
891 // it clears all the fields that correspond to a claimed region.
892 void clear_region_fields();
893
894 void set_concurrent(bool concurrent) { _concurrent = concurrent; }
895
896 // The main method of this class which performs a marking step
897 // trying not to exceed the given duration. However, it might exit
898 // prematurely, according to some conditions (i.e. SATB buffers are
899 // available for processing).
900 void do_marking_step(double target_ms,
901 bool do_termination,
902 bool is_serial);
903
904 // These two calls start and stop the timer
905 void record_start_time() {
906 _elapsed_time_ms = os::elapsedTime() * 1000.0;
907 }
908 void record_end_time() {
909 _elapsed_time_ms = os::elapsedTime() * 1000.0 - _elapsed_time_ms;
910 }
911
912 // returns the worker ID associated with this task.
913 uint worker_id() { return _worker_id; }
914
915 // From TerminatorTerminator. It determines whether this task should
916 // exit the termination protocol after it's entered it.
917 virtual bool should_exit_termination();
918
919 // Resets the local region fields after a task has finished scanning a
920 // region; or when they have become stale as a result of the region
921 // being evacuated.
922 void giveup_current_region();
923
924 HeapWord* finger() { return _finger; }
925
926 bool has_aborted() { return _has_aborted; }
927 void set_has_aborted() { _has_aborted = true; }
928 void clear_has_aborted() { _has_aborted = false; }
929 bool has_timed_out() { return _has_timed_out; }
930 bool claimed() { return _claimed; }
931
932 void set_cm_oop_closure(G1CMOopClosure* cm_oop_closure);
933
934 // Increment the number of references this task has visited.
935 void increment_refs_reached() { ++_refs_reached; }
936
937 // Grey the object by marking it. If not already marked, push it on
938 // the local queue if below the finger.
939 // Precondition: obj is in region.
940 // Precondition: obj is below region's NTAMS.
941 inline void make_reference_grey(oop obj, HeapRegion* region);
942
943 // Grey the object (by calling make_grey_reference) if required,
944 // e.g. obj is below its containing region's NTAMS.
945 // Precondition: obj is a valid heap object.
946 inline void deal_with_reference(oop obj);
947
948 // It scans an object and visits its children.
949 inline void scan_object(oop obj);
950
951 // It pushes an object on the local queue.
952 inline void push(oop obj);
953
954 // These two move entries to/from the global stack.
955 void move_entries_to_global_stack();
956 void get_entries_from_global_stack();
957
958 // It pops and scans objects from the local queue. If partially is
959 // true, then it stops when the queue size is of a given limit. If
960 // partially is false, then it stops when the queue is empty.
961 void drain_local_queue(bool partially);
962 // It moves entries from the global stack to the local queue and
963 // drains the local queue. If partially is true, then it stops when
964 // both the global stack and the local queue reach a given size. If
965 // partially if false, it tries to empty them totally.
966 void drain_global_stack(bool partially);
967 // It keeps picking SATB buffers and processing them until no SATB
968 // buffers are available.
969 void drain_satb_buffers();
970
971 // moves the local finger to a new location
972 inline void move_finger_to(HeapWord* new_finger) {
973 assert(new_finger >= _finger && new_finger < _region_limit, "invariant");
974 _finger = new_finger;
975 }
976
977 G1CMTask(uint worker_id,
978 G1ConcurrentMark *cm,
979 size_t* marked_bytes,
980 BitMap* card_bm,
981 G1CMTaskQueue* task_queue,
982 G1CMTaskQueueSet* task_queues);
983
984 // it prints statistics associated with this task
985 void print_stats();
986 };
987
988 // Class that's used to to print out per-region liveness
989 // information. It's currently used at the end of marking and also
990 // after we sort the old regions at the end of the cleanup operation.
991 class G1PrintRegionLivenessInfoClosure: public HeapRegionClosure {
992 private:
993 // Accumulators for these values.
994 size_t _total_used_bytes;
995 size_t _total_capacity_bytes;
996 size_t _total_prev_live_bytes;
997 size_t _total_next_live_bytes;
998
999 // Accumulator for the remembered set size
1000 size_t _total_remset_bytes;
1001
1002 // Accumulator for strong code roots memory size
1003 size_t _total_strong_code_roots_bytes;
1004
1005 static double perc(size_t val, size_t total) {
1006 if (total == 0) {
1007 return 0.0;
1008 } else {
1009 return 100.0 * ((double) val / (double) total);
1010 }
1011 }
1012
1013 static double bytes_to_mb(size_t val) {
1014 return (double) val / (double) M;
1015 }
1016
1017 public:
1018 // The header and footer are printed in the constructor and
1019 // destructor respectively.
1020 G1PrintRegionLivenessInfoClosure(const char* phase_name);
1021 virtual bool doHeapRegion(HeapRegion* r);
1022 ~G1PrintRegionLivenessInfoClosure();
1023 };
1024
1025 #endif // SHARE_VM_GC_G1_G1CONCURRENTMARK_HPP