Mon, 24 Mar 2014 15:30:36 +0100
8027295: Free CSet takes ~50% of young pause time
Summary: Improve fast card cache iteration and avoid taking locks when freeing the collection set.
Reviewed-by: brutisso
1 /*
2 * Copyright (c) 2001, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP
28 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
29 #include "gc_implementation/g1/g1_specialized_oop_closures.hpp"
30 #include "gc_implementation/g1/survRateGroup.hpp"
31 #include "gc_implementation/shared/ageTable.hpp"
32 #include "gc_implementation/shared/spaceDecorator.hpp"
33 #include "memory/space.inline.hpp"
34 #include "memory/watermark.hpp"
35 #include "utilities/macros.hpp"
37 #if INCLUDE_ALL_GCS
39 // A HeapRegion is the smallest piece of a G1CollectedHeap that
40 // can be collected independently.
42 // NOTE: Although a HeapRegion is a Space, its
43 // Space::initDirtyCardClosure method must not be called.
44 // The problem is that the existence of this method breaks
45 // the independence of barrier sets from remembered sets.
46 // The solution is to remove this method from the definition
47 // of a Space.
49 class CompactibleSpace;
50 class ContiguousSpace;
51 class HeapRegionRemSet;
52 class HeapRegionRemSetIterator;
53 class HeapRegion;
54 class HeapRegionSetBase;
55 class nmethod;
57 #define HR_FORMAT "%u:(%s)["PTR_FORMAT","PTR_FORMAT","PTR_FORMAT"]"
58 #define HR_FORMAT_PARAMS(_hr_) \
59 (_hr_)->hrs_index(), \
60 (_hr_)->is_survivor() ? "S" : (_hr_)->is_young() ? "E" : \
61 (_hr_)->startsHumongous() ? "HS" : \
62 (_hr_)->continuesHumongous() ? "HC" : \
63 !(_hr_)->is_empty() ? "O" : "F", \
64 (_hr_)->bottom(), (_hr_)->top(), (_hr_)->end()
66 // sentinel value for hrs_index
67 #define G1_NULL_HRS_INDEX ((uint) -1)
69 // A dirty card to oop closure for heap regions. It
70 // knows how to get the G1 heap and how to use the bitmap
71 // in the concurrent marker used by G1 to filter remembered
72 // sets.
74 class HeapRegionDCTOC : public ContiguousSpaceDCTOC {
75 public:
76 // Specification of possible DirtyCardToOopClosure filtering.
77 enum FilterKind {
78 NoFilterKind,
79 IntoCSFilterKind,
80 OutOfRegionFilterKind
81 };
83 protected:
84 HeapRegion* _hr;
85 FilterKind _fk;
86 G1CollectedHeap* _g1;
88 void walk_mem_region_with_cl(MemRegion mr,
89 HeapWord* bottom, HeapWord* top,
90 ExtendedOopClosure* cl);
92 // We don't specialize this for FilteringClosure; filtering is handled by
93 // the "FilterKind" mechanism. But we provide this to avoid a compiler
94 // warning.
95 void walk_mem_region_with_cl(MemRegion mr,
96 HeapWord* bottom, HeapWord* top,
97 FilteringClosure* cl) {
98 HeapRegionDCTOC::walk_mem_region_with_cl(mr, bottom, top,
99 (ExtendedOopClosure*)cl);
100 }
102 // Get the actual top of the area on which the closure will
103 // operate, given where the top is assumed to be (the end of the
104 // memory region passed to do_MemRegion) and where the object
105 // at the top is assumed to start. For example, an object may
106 // start at the top but actually extend past the assumed top,
107 // in which case the top becomes the end of the object.
108 HeapWord* get_actual_top(HeapWord* top, HeapWord* top_obj) {
109 return ContiguousSpaceDCTOC::get_actual_top(top, top_obj);
110 }
112 // Walk the given memory region from bottom to (actual) top
113 // looking for objects and applying the oop closure (_cl) to
114 // them. The base implementation of this treats the area as
115 // blocks, where a block may or may not be an object. Sub-
116 // classes should override this to provide more accurate
117 // or possibly more efficient walking.
118 void walk_mem_region(MemRegion mr, HeapWord* bottom, HeapWord* top) {
119 Filtering_DCTOC::walk_mem_region(mr, bottom, top);
120 }
122 public:
123 HeapRegionDCTOC(G1CollectedHeap* g1,
124 HeapRegion* hr, ExtendedOopClosure* cl,
125 CardTableModRefBS::PrecisionStyle precision,
126 FilterKind fk);
127 };
129 // The complicating factor is that BlockOffsetTable diverged
130 // significantly, and we need functionality that is only in the G1 version.
131 // So I copied that code, which led to an alternate G1 version of
132 // OffsetTableContigSpace. If the two versions of BlockOffsetTable could
133 // be reconciled, then G1OffsetTableContigSpace could go away.
135 // The idea behind time stamps is the following. Doing a save_marks on
136 // all regions at every GC pause is time consuming (if I remember
137 // well, 10ms or so). So, we would like to do that only for regions
138 // that are GC alloc regions. To achieve this, we use time
139 // stamps. For every evacuation pause, G1CollectedHeap generates a
140 // unique time stamp (essentially a counter that gets
141 // incremented). Every time we want to call save_marks on a region,
142 // we set the saved_mark_word to top and also copy the current GC
143 // time stamp to the time stamp field of the space. Reading the
144 // saved_mark_word involves checking the time stamp of the
145 // region. If it is the same as the current GC time stamp, then we
146 // can safely read the saved_mark_word field, as it is valid. If the
147 // time stamp of the region is not the same as the current GC time
148 // stamp, then we instead read top, as the saved_mark_word field is
149 // invalid. Time stamps (on the regions and also on the
150 // G1CollectedHeap) are reset at every cleanup (we iterate over
151 // the regions anyway) and at the end of a Full GC. The current scheme
152 // that uses sequential unsigned ints will fail only if we have 4b
153 // evacuation pauses between two cleanups, which is _highly_ unlikely.
155 class G1OffsetTableContigSpace: public ContiguousSpace {
156 friend class VMStructs;
157 protected:
158 G1BlockOffsetArrayContigSpace _offsets;
159 Mutex _par_alloc_lock;
160 volatile unsigned _gc_time_stamp;
161 // When we need to retire an allocation region, while other threads
162 // are also concurrently trying to allocate into it, we typically
163 // allocate a dummy object at the end of the region to ensure that
164 // no more allocations can take place in it. However, sometimes we
165 // want to know where the end of the last "real" object we allocated
166 // into the region was and this is what this keeps track.
167 HeapWord* _pre_dummy_top;
169 public:
170 G1OffsetTableContigSpace(G1BlockOffsetSharedArray* sharedOffsetArray,
171 MemRegion mr);
173 void set_bottom(HeapWord* value);
174 void set_end(HeapWord* value);
176 virtual HeapWord* saved_mark_word() const;
177 virtual void set_saved_mark();
178 void reset_gc_time_stamp() { _gc_time_stamp = 0; }
179 unsigned get_gc_time_stamp() { return _gc_time_stamp; }
181 // See the comment above in the declaration of _pre_dummy_top for an
182 // explanation of what it is.
183 void set_pre_dummy_top(HeapWord* pre_dummy_top) {
184 assert(is_in(pre_dummy_top) && pre_dummy_top <= top(), "pre-condition");
185 _pre_dummy_top = pre_dummy_top;
186 }
187 HeapWord* pre_dummy_top() {
188 return (_pre_dummy_top == NULL) ? top() : _pre_dummy_top;
189 }
190 void reset_pre_dummy_top() { _pre_dummy_top = NULL; }
192 virtual void clear(bool mangle_space);
194 HeapWord* block_start(const void* p);
195 HeapWord* block_start_const(const void* p) const;
197 // Add offset table update.
198 virtual HeapWord* allocate(size_t word_size);
199 HeapWord* par_allocate(size_t word_size);
201 // MarkSweep support phase3
202 virtual HeapWord* initialize_threshold();
203 virtual HeapWord* cross_threshold(HeapWord* start, HeapWord* end);
205 virtual void print() const;
207 void reset_bot() {
208 _offsets.zero_bottom_entry();
209 _offsets.initialize_threshold();
210 }
212 void update_bot_for_object(HeapWord* start, size_t word_size) {
213 _offsets.alloc_block(start, word_size);
214 }
216 void print_bot_on(outputStream* out) {
217 _offsets.print_on(out);
218 }
219 };
221 class HeapRegion: public G1OffsetTableContigSpace {
222 friend class VMStructs;
223 private:
225 enum HumongousType {
226 NotHumongous = 0,
227 StartsHumongous,
228 ContinuesHumongous
229 };
231 // Requires that the region "mr" be dense with objects, and begin and end
232 // with an object.
233 void oops_in_mr_iterate(MemRegion mr, ExtendedOopClosure* cl);
235 // The remembered set for this region.
236 // (Might want to make this "inline" later, to avoid some alloc failure
237 // issues.)
238 HeapRegionRemSet* _rem_set;
240 G1BlockOffsetArrayContigSpace* offsets() { return &_offsets; }
242 protected:
243 // The index of this region in the heap region sequence.
244 uint _hrs_index;
246 HumongousType _humongous_type;
247 // For a humongous region, region in which it starts.
248 HeapRegion* _humongous_start_region;
249 // For the start region of a humongous sequence, it's original end().
250 HeapWord* _orig_end;
252 // True iff the region is in current collection_set.
253 bool _in_collection_set;
255 // True iff an attempt to evacuate an object in the region failed.
256 bool _evacuation_failed;
258 // A heap region may be a member one of a number of special subsets, each
259 // represented as linked lists through the field below. Currently, these
260 // sets include:
261 // The collection set.
262 // The set of allocation regions used in a collection pause.
263 // Spaces that may contain gray objects.
264 HeapRegion* _next_in_special_set;
266 // next region in the young "generation" region set
267 HeapRegion* _next_young_region;
269 // Next region whose cards need cleaning
270 HeapRegion* _next_dirty_cards_region;
272 // Fields used by the HeapRegionSetBase class and subclasses.
273 HeapRegion* _next;
274 #ifdef ASSERT
275 HeapRegionSetBase* _containing_set;
276 #endif // ASSERT
277 bool _pending_removal;
279 // For parallel heapRegion traversal.
280 jint _claimed;
282 // We use concurrent marking to determine the amount of live data
283 // in each heap region.
284 size_t _prev_marked_bytes; // Bytes known to be live via last completed marking.
285 size_t _next_marked_bytes; // Bytes known to be live via in-progress marking.
287 // The calculated GC efficiency of the region.
288 double _gc_efficiency;
290 enum YoungType {
291 NotYoung, // a region is not young
292 Young, // a region is young
293 Survivor // a region is young and it contains survivors
294 };
296 volatile YoungType _young_type;
297 int _young_index_in_cset;
298 SurvRateGroup* _surv_rate_group;
299 int _age_index;
301 // The start of the unmarked area. The unmarked area extends from this
302 // word until the top and/or end of the region, and is the part
303 // of the region for which no marking was done, i.e. objects may
304 // have been allocated in this part since the last mark phase.
305 // "prev" is the top at the start of the last completed marking.
306 // "next" is the top at the start of the in-progress marking (if any.)
307 HeapWord* _prev_top_at_mark_start;
308 HeapWord* _next_top_at_mark_start;
309 // If a collection pause is in progress, this is the top at the start
310 // of that pause.
312 void init_top_at_mark_start() {
313 assert(_prev_marked_bytes == 0 &&
314 _next_marked_bytes == 0,
315 "Must be called after zero_marked_bytes.");
316 HeapWord* bot = bottom();
317 _prev_top_at_mark_start = bot;
318 _next_top_at_mark_start = bot;
319 }
321 void set_young_type(YoungType new_type) {
322 //assert(_young_type != new_type, "setting the same type" );
323 // TODO: add more assertions here
324 _young_type = new_type;
325 }
327 // Cached attributes used in the collection set policy information
329 // The RSet length that was added to the total value
330 // for the collection set.
331 size_t _recorded_rs_length;
333 // The predicted elapsed time that was added to total value
334 // for the collection set.
335 double _predicted_elapsed_time_ms;
337 // The predicted number of bytes to copy that was added to
338 // the total value for the collection set.
339 size_t _predicted_bytes_to_copy;
341 public:
342 HeapRegion(uint hrs_index,
343 G1BlockOffsetSharedArray* sharedOffsetArray,
344 MemRegion mr);
346 static int LogOfHRGrainBytes;
347 static int LogOfHRGrainWords;
349 static size_t GrainBytes;
350 static size_t GrainWords;
351 static size_t CardsPerRegion;
353 static size_t align_up_to_region_byte_size(size_t sz) {
354 return (sz + (size_t) GrainBytes - 1) &
355 ~((1 << (size_t) LogOfHRGrainBytes) - 1);
356 }
358 static size_t max_region_size();
360 // It sets up the heap region size (GrainBytes / GrainWords), as
361 // well as other related fields that are based on the heap region
362 // size (LogOfHRGrainBytes / LogOfHRGrainWords /
363 // CardsPerRegion). All those fields are considered constant
364 // throughout the JVM's execution, therefore they should only be set
365 // up once during initialization time.
366 static void setup_heap_region_size(size_t initial_heap_size, size_t max_heap_size);
368 enum ClaimValues {
369 InitialClaimValue = 0,
370 FinalCountClaimValue = 1,
371 NoteEndClaimValue = 2,
372 ScrubRemSetClaimValue = 3,
373 ParVerifyClaimValue = 4,
374 RebuildRSClaimValue = 5,
375 ParEvacFailureClaimValue = 6,
376 AggregateCountClaimValue = 7,
377 VerifyCountClaimValue = 8,
378 ParMarkRootClaimValue = 9
379 };
381 inline HeapWord* par_allocate_no_bot_updates(size_t word_size) {
382 assert(is_young(), "we can only skip BOT updates on young regions");
383 return ContiguousSpace::par_allocate(word_size);
384 }
385 inline HeapWord* allocate_no_bot_updates(size_t word_size) {
386 assert(is_young(), "we can only skip BOT updates on young regions");
387 return ContiguousSpace::allocate(word_size);
388 }
390 // If this region is a member of a HeapRegionSeq, the index in that
391 // sequence, otherwise -1.
392 uint hrs_index() const { return _hrs_index; }
394 // The number of bytes marked live in the region in the last marking phase.
395 size_t marked_bytes() { return _prev_marked_bytes; }
396 size_t live_bytes() {
397 return (top() - prev_top_at_mark_start()) * HeapWordSize + marked_bytes();
398 }
400 // The number of bytes counted in the next marking.
401 size_t next_marked_bytes() { return _next_marked_bytes; }
402 // The number of bytes live wrt the next marking.
403 size_t next_live_bytes() {
404 return
405 (top() - next_top_at_mark_start()) * HeapWordSize + next_marked_bytes();
406 }
408 // A lower bound on the amount of garbage bytes in the region.
409 size_t garbage_bytes() {
410 size_t used_at_mark_start_bytes =
411 (prev_top_at_mark_start() - bottom()) * HeapWordSize;
412 assert(used_at_mark_start_bytes >= marked_bytes(),
413 "Can't mark more than we have.");
414 return used_at_mark_start_bytes - marked_bytes();
415 }
417 // Return the amount of bytes we'll reclaim if we collect this
418 // region. This includes not only the known garbage bytes in the
419 // region but also any unallocated space in it, i.e., [top, end),
420 // since it will also be reclaimed if we collect the region.
421 size_t reclaimable_bytes() {
422 size_t known_live_bytes = live_bytes();
423 assert(known_live_bytes <= capacity(), "sanity");
424 return capacity() - known_live_bytes;
425 }
427 // An upper bound on the number of live bytes in the region.
428 size_t max_live_bytes() { return used() - garbage_bytes(); }
430 void add_to_marked_bytes(size_t incr_bytes) {
431 _next_marked_bytes = _next_marked_bytes + incr_bytes;
432 assert(_next_marked_bytes <= used(), "invariant" );
433 }
435 void zero_marked_bytes() {
436 _prev_marked_bytes = _next_marked_bytes = 0;
437 }
439 bool isHumongous() const { return _humongous_type != NotHumongous; }
440 bool startsHumongous() const { return _humongous_type == StartsHumongous; }
441 bool continuesHumongous() const { return _humongous_type == ContinuesHumongous; }
442 // For a humongous region, region in which it starts.
443 HeapRegion* humongous_start_region() const {
444 return _humongous_start_region;
445 }
447 // Return the number of distinct regions that are covered by this region:
448 // 1 if the region is not humongous, >= 1 if the region is humongous.
449 uint region_num() const {
450 if (!isHumongous()) {
451 return 1U;
452 } else {
453 assert(startsHumongous(), "doesn't make sense on HC regions");
454 assert(capacity() % HeapRegion::GrainBytes == 0, "sanity");
455 return (uint) (capacity() >> HeapRegion::LogOfHRGrainBytes);
456 }
457 }
459 // Return the index + 1 of the last HC regions that's associated
460 // with this HS region.
461 uint last_hc_index() const {
462 assert(startsHumongous(), "don't call this otherwise");
463 return hrs_index() + region_num();
464 }
466 // Same as Space::is_in_reserved, but will use the original size of the region.
467 // The original size is different only for start humongous regions. They get
468 // their _end set up to be the end of the last continues region of the
469 // corresponding humongous object.
470 bool is_in_reserved_raw(const void* p) const {
471 return _bottom <= p && p < _orig_end;
472 }
474 // Makes the current region be a "starts humongous" region, i.e.,
475 // the first region in a series of one or more contiguous regions
476 // that will contain a single "humongous" object. The two parameters
477 // are as follows:
478 //
479 // new_top : The new value of the top field of this region which
480 // points to the end of the humongous object that's being
481 // allocated. If there is more than one region in the series, top
482 // will lie beyond this region's original end field and on the last
483 // region in the series.
484 //
485 // new_end : The new value of the end field of this region which
486 // points to the end of the last region in the series. If there is
487 // one region in the series (namely: this one) end will be the same
488 // as the original end of this region.
489 //
490 // Updating top and end as described above makes this region look as
491 // if it spans the entire space taken up by all the regions in the
492 // series and an single allocation moved its top to new_top. This
493 // ensures that the space (capacity / allocated) taken up by all
494 // humongous regions can be calculated by just looking at the
495 // "starts humongous" regions and by ignoring the "continues
496 // humongous" regions.
497 void set_startsHumongous(HeapWord* new_top, HeapWord* new_end);
499 // Makes the current region be a "continues humongous'
500 // region. first_hr is the "start humongous" region of the series
501 // which this region will be part of.
502 void set_continuesHumongous(HeapRegion* first_hr);
504 // Unsets the humongous-related fields on the region.
505 void set_notHumongous();
507 // If the region has a remembered set, return a pointer to it.
508 HeapRegionRemSet* rem_set() const {
509 return _rem_set;
510 }
512 // True iff the region is in current collection_set.
513 bool in_collection_set() const {
514 return _in_collection_set;
515 }
516 void set_in_collection_set(bool b) {
517 _in_collection_set = b;
518 }
519 HeapRegion* next_in_collection_set() {
520 assert(in_collection_set(), "should only invoke on member of CS.");
521 assert(_next_in_special_set == NULL ||
522 _next_in_special_set->in_collection_set(),
523 "Malformed CS.");
524 return _next_in_special_set;
525 }
526 void set_next_in_collection_set(HeapRegion* r) {
527 assert(in_collection_set(), "should only invoke on member of CS.");
528 assert(r == NULL || r->in_collection_set(), "Malformed CS.");
529 _next_in_special_set = r;
530 }
532 // Methods used by the HeapRegionSetBase class and subclasses.
534 // Getter and setter for the next field used to link regions into
535 // linked lists.
536 HeapRegion* next() { return _next; }
538 void set_next(HeapRegion* next) { _next = next; }
540 // Every region added to a set is tagged with a reference to that
541 // set. This is used for doing consistency checking to make sure that
542 // the contents of a set are as they should be and it's only
543 // available in non-product builds.
544 #ifdef ASSERT
545 void set_containing_set(HeapRegionSetBase* containing_set) {
546 assert((containing_set == NULL && _containing_set != NULL) ||
547 (containing_set != NULL && _containing_set == NULL),
548 err_msg("containing_set: "PTR_FORMAT" "
549 "_containing_set: "PTR_FORMAT,
550 containing_set, _containing_set));
552 _containing_set = containing_set;
553 }
555 HeapRegionSetBase* containing_set() { return _containing_set; }
556 #else // ASSERT
557 void set_containing_set(HeapRegionSetBase* containing_set) { }
559 // containing_set() is only used in asserts so there's no reason
560 // to provide a dummy version of it.
561 #endif // ASSERT
563 // If we want to remove regions from a list in bulk we can simply tag
564 // them with the pending_removal tag and call the
565 // remove_all_pending() method on the list.
567 bool pending_removal() { return _pending_removal; }
569 void set_pending_removal(bool pending_removal) {
570 if (pending_removal) {
571 assert(!_pending_removal && containing_set() != NULL,
572 "can only set pending removal to true if it's false and "
573 "the region belongs to a region set");
574 } else {
575 assert( _pending_removal && containing_set() == NULL,
576 "can only set pending removal to false if it's true and "
577 "the region does not belong to a region set");
578 }
580 _pending_removal = pending_removal;
581 }
583 HeapRegion* get_next_young_region() { return _next_young_region; }
584 void set_next_young_region(HeapRegion* hr) {
585 _next_young_region = hr;
586 }
588 HeapRegion* get_next_dirty_cards_region() const { return _next_dirty_cards_region; }
589 HeapRegion** next_dirty_cards_region_addr() { return &_next_dirty_cards_region; }
590 void set_next_dirty_cards_region(HeapRegion* hr) { _next_dirty_cards_region = hr; }
591 bool is_on_dirty_cards_region_list() const { return get_next_dirty_cards_region() != NULL; }
593 HeapWord* orig_end() { return _orig_end; }
595 // Allows logical separation between objects allocated before and after.
596 void save_marks();
598 // Reset HR stuff to default values.
599 void hr_clear(bool par, bool clear_space, bool locked = false);
600 void par_clear();
602 // Get the start of the unmarked area in this region.
603 HeapWord* prev_top_at_mark_start() const { return _prev_top_at_mark_start; }
604 HeapWord* next_top_at_mark_start() const { return _next_top_at_mark_start; }
606 // Apply "cl->do_oop" to (the addresses of) all reference fields in objects
607 // allocated in the current region before the last call to "save_mark".
608 void oop_before_save_marks_iterate(ExtendedOopClosure* cl);
610 // Note the start or end of marking. This tells the heap region
611 // that the collector is about to start or has finished (concurrently)
612 // marking the heap.
614 // Notify the region that concurrent marking is starting. Initialize
615 // all fields related to the next marking info.
616 inline void note_start_of_marking();
618 // Notify the region that concurrent marking has finished. Copy the
619 // (now finalized) next marking info fields into the prev marking
620 // info fields.
621 inline void note_end_of_marking();
623 // Notify the region that it will be used as to-space during a GC
624 // and we are about to start copying objects into it.
625 inline void note_start_of_copying(bool during_initial_mark);
627 // Notify the region that it ceases being to-space during a GC and
628 // we will not copy objects into it any more.
629 inline void note_end_of_copying(bool during_initial_mark);
631 // Notify the region that we are about to start processing
632 // self-forwarded objects during evac failure handling.
633 void note_self_forwarding_removal_start(bool during_initial_mark,
634 bool during_conc_mark);
636 // Notify the region that we have finished processing self-forwarded
637 // objects during evac failure handling.
638 void note_self_forwarding_removal_end(bool during_initial_mark,
639 bool during_conc_mark,
640 size_t marked_bytes);
642 // Returns "false" iff no object in the region was allocated when the
643 // last mark phase ended.
644 bool is_marked() { return _prev_top_at_mark_start != bottom(); }
646 void reset_during_compaction() {
647 assert(isHumongous() && startsHumongous(),
648 "should only be called for starts humongous regions");
650 zero_marked_bytes();
651 init_top_at_mark_start();
652 }
654 void calc_gc_efficiency(void);
655 double gc_efficiency() { return _gc_efficiency;}
657 bool is_young() const { return _young_type != NotYoung; }
658 bool is_survivor() const { return _young_type == Survivor; }
660 int young_index_in_cset() const { return _young_index_in_cset; }
661 void set_young_index_in_cset(int index) {
662 assert( (index == -1) || is_young(), "pre-condition" );
663 _young_index_in_cset = index;
664 }
666 int age_in_surv_rate_group() {
667 assert( _surv_rate_group != NULL, "pre-condition" );
668 assert( _age_index > -1, "pre-condition" );
669 return _surv_rate_group->age_in_group(_age_index);
670 }
672 void record_surv_words_in_group(size_t words_survived) {
673 assert( _surv_rate_group != NULL, "pre-condition" );
674 assert( _age_index > -1, "pre-condition" );
675 int age_in_group = age_in_surv_rate_group();
676 _surv_rate_group->record_surviving_words(age_in_group, words_survived);
677 }
679 int age_in_surv_rate_group_cond() {
680 if (_surv_rate_group != NULL)
681 return age_in_surv_rate_group();
682 else
683 return -1;
684 }
686 SurvRateGroup* surv_rate_group() {
687 return _surv_rate_group;
688 }
690 void install_surv_rate_group(SurvRateGroup* surv_rate_group) {
691 assert( surv_rate_group != NULL, "pre-condition" );
692 assert( _surv_rate_group == NULL, "pre-condition" );
693 assert( is_young(), "pre-condition" );
695 _surv_rate_group = surv_rate_group;
696 _age_index = surv_rate_group->next_age_index();
697 }
699 void uninstall_surv_rate_group() {
700 if (_surv_rate_group != NULL) {
701 assert( _age_index > -1, "pre-condition" );
702 assert( is_young(), "pre-condition" );
704 _surv_rate_group = NULL;
705 _age_index = -1;
706 } else {
707 assert( _age_index == -1, "pre-condition" );
708 }
709 }
711 void set_young() { set_young_type(Young); }
713 void set_survivor() { set_young_type(Survivor); }
715 void set_not_young() { set_young_type(NotYoung); }
717 // Determine if an object has been allocated since the last
718 // mark performed by the collector. This returns true iff the object
719 // is within the unmarked area of the region.
720 bool obj_allocated_since_prev_marking(oop obj) const {
721 return (HeapWord *) obj >= prev_top_at_mark_start();
722 }
723 bool obj_allocated_since_next_marking(oop obj) const {
724 return (HeapWord *) obj >= next_top_at_mark_start();
725 }
727 // For parallel heapRegion traversal.
728 bool claimHeapRegion(int claimValue);
729 jint claim_value() { return _claimed; }
730 // Use this carefully: only when you're sure no one is claiming...
731 void set_claim_value(int claimValue) { _claimed = claimValue; }
733 // Returns the "evacuation_failed" property of the region.
734 bool evacuation_failed() { return _evacuation_failed; }
736 // Sets the "evacuation_failed" property of the region.
737 void set_evacuation_failed(bool b) {
738 _evacuation_failed = b;
740 if (b) {
741 _next_marked_bytes = 0;
742 }
743 }
745 // Requires that "mr" be entirely within the region.
746 // Apply "cl->do_object" to all objects that intersect with "mr".
747 // If the iteration encounters an unparseable portion of the region,
748 // or if "cl->abort()" is true after a closure application,
749 // terminate the iteration and return the address of the start of the
750 // subregion that isn't done. (The two can be distinguished by querying
751 // "cl->abort()".) Return of "NULL" indicates that the iteration
752 // completed.
753 HeapWord*
754 object_iterate_mem_careful(MemRegion mr, ObjectClosure* cl);
756 // filter_young: if true and the region is a young region then we
757 // skip the iteration.
758 // card_ptr: if not NULL, and we decide that the card is not young
759 // and we iterate over it, we'll clean the card before we start the
760 // iteration.
761 HeapWord*
762 oops_on_card_seq_iterate_careful(MemRegion mr,
763 FilterOutOfRegionClosure* cl,
764 bool filter_young,
765 jbyte* card_ptr);
767 // A version of block start that is guaranteed to find *some* block
768 // boundary at or before "p", but does not object iteration, and may
769 // therefore be used safely when the heap is unparseable.
770 HeapWord* block_start_careful(const void* p) const {
771 return _offsets.block_start_careful(p);
772 }
774 // Requires that "addr" is within the region. Returns the start of the
775 // first ("careful") block that starts at or after "addr", or else the
776 // "end" of the region if there is no such block.
777 HeapWord* next_block_start_careful(HeapWord* addr);
779 size_t recorded_rs_length() const { return _recorded_rs_length; }
780 double predicted_elapsed_time_ms() const { return _predicted_elapsed_time_ms; }
781 size_t predicted_bytes_to_copy() const { return _predicted_bytes_to_copy; }
783 void set_recorded_rs_length(size_t rs_length) {
784 _recorded_rs_length = rs_length;
785 }
787 void set_predicted_elapsed_time_ms(double ms) {
788 _predicted_elapsed_time_ms = ms;
789 }
791 void set_predicted_bytes_to_copy(size_t bytes) {
792 _predicted_bytes_to_copy = bytes;
793 }
795 #define HeapRegion_OOP_SINCE_SAVE_MARKS_DECL(OopClosureType, nv_suffix) \
796 virtual void oop_since_save_marks_iterate##nv_suffix(OopClosureType* cl);
797 SPECIALIZED_SINCE_SAVE_MARKS_CLOSURES(HeapRegion_OOP_SINCE_SAVE_MARKS_DECL)
799 virtual CompactibleSpace* next_compaction_space() const;
801 virtual void reset_after_compaction();
803 // Routines for managing a list of code roots (attached to the
804 // this region's RSet) that point into this heap region.
805 void add_strong_code_root(nmethod* nm);
806 void remove_strong_code_root(nmethod* nm);
808 // During a collection, migrate the successfully evacuated
809 // strong code roots that referenced into this region to the
810 // new regions that they now point into. Unsuccessfully
811 // evacuated code roots are not migrated.
812 void migrate_strong_code_roots();
814 // Applies blk->do_code_blob() to each of the entries in
815 // the strong code roots list for this region
816 void strong_code_roots_do(CodeBlobClosure* blk) const;
818 // Verify that the entries on the strong code root list for this
819 // region are live and include at least one pointer into this region.
820 void verify_strong_code_roots(VerifyOption vo, bool* failures) const;
822 void print() const;
823 void print_on(outputStream* st) const;
825 // vo == UsePrevMarking -> use "prev" marking information,
826 // vo == UseNextMarking -> use "next" marking information
827 // vo == UseMarkWord -> use the mark word in the object header
828 //
829 // NOTE: Only the "prev" marking information is guaranteed to be
830 // consistent most of the time, so most calls to this should use
831 // vo == UsePrevMarking.
832 // Currently, there is only one case where this is called with
833 // vo == UseNextMarking, which is to verify the "next" marking
834 // information at the end of remark.
835 // Currently there is only one place where this is called with
836 // vo == UseMarkWord, which is to verify the marking during a
837 // full GC.
838 void verify(VerifyOption vo, bool *failures) const;
840 // Override; it uses the "prev" marking information
841 virtual void verify() const;
842 };
844 // HeapRegionClosure is used for iterating over regions.
845 // Terminates the iteration when the "doHeapRegion" method returns "true".
846 class HeapRegionClosure : public StackObj {
847 friend class HeapRegionSeq;
848 friend class G1CollectedHeap;
850 bool _complete;
851 void incomplete() { _complete = false; }
853 public:
854 HeapRegionClosure(): _complete(true) {}
856 // Typically called on each region until it returns true.
857 virtual bool doHeapRegion(HeapRegion* r) = 0;
859 // True after iteration if the closure was applied to all heap regions
860 // and returned "false" in all cases.
861 bool complete() { return _complete; }
862 };
864 #endif // INCLUDE_ALL_GCS
866 #endif // SHARE_VM_GC_IMPLEMENTATION_G1_HEAPREGION_HPP