1 /*
2 * Copyright (c) 2001, 2012, 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 */
24
25 #include "precompiled.hpp"
26 #include "gc_implementation/g1/concurrentG1Refine.hpp"
27 #include "gc_implementation/g1/g1BlockOffsetTable.inline.hpp"
28 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
29 #include "gc_implementation/g1/heapRegionRemSet.hpp"
30 #include "gc_implementation/g1/heapRegionSeq.inline.hpp"
31 #include "memory/allocation.hpp"
32 #include "memory/space.inline.hpp"
33 #include "oops/oop.inline.hpp"
34 #include "utilities/bitMap.inline.hpp"
35 #include "utilities/globalDefinitions.hpp"
36
37 class PerRegionTable: public CHeapObj<mtGC> {
38 friend class OtherRegionsTable;
39 friend class HeapRegionRemSetIterator;
40
41 HeapRegion* _hr;
42 BitMap _bm;
43 jint _occupied;
44
45 // next pointer for free/allocated 'all' list
46 PerRegionTable* _next;
47
48 // prev pointer for the allocated 'all' list
49 PerRegionTable* _prev;
50
51 // next pointer in collision list
52 PerRegionTable * _collision_list_next;
53
54 // Global free list of PRTs
55 static PerRegionTable* _free_list;
56
57 protected:
58 // We need access in order to union things into the base table.
59 BitMap* bm() { return &_bm; }
60
61 void recount_occupied() {
62 _occupied = (jint) bm()->count_one_bits();
63 }
64
65 PerRegionTable(HeapRegion* hr) :
66 _hr(hr),
67 _occupied(0),
68 _bm(HeapRegion::CardsPerRegion, false /* in-resource-area */),
69 _collision_list_next(NULL), _next(NULL), _prev(NULL)
70 {}
71
72 void add_card_work(CardIdx_t from_card, bool par) {
73 if (!_bm.at(from_card)) {
74 if (par) {
75 if (_bm.par_at_put(from_card, 1)) {
76 Atomic::inc(&_occupied);
77 }
78 } else {
79 _bm.at_put(from_card, 1);
80 _occupied++;
81 }
82 }
83 }
84
85 void add_reference_work(OopOrNarrowOopStar from, bool par) {
86 // Must make this robust in case "from" is not in "_hr", because of
87 // concurrency.
88
89 if (G1TraceHeapRegionRememberedSet) {
90 gclog_or_tty->print_cr(" PRT::Add_reference_work(" PTR_FORMAT "->" PTR_FORMAT").",
91 from,
92 UseCompressedOops
93 ? oopDesc::load_decode_heap_oop((narrowOop*)from)
94 : oopDesc::load_decode_heap_oop((oop*)from));
95 }
96
97 HeapRegion* loc_hr = hr();
98 // If the test below fails, then this table was reused concurrently
99 // with this operation. This is OK, since the old table was coarsened,
100 // and adding a bit to the new table is never incorrect.
101 // If the table used to belong to a continues humongous region and is
102 // now reused for the corresponding start humongous region, we need to
103 // make sure that we detect this. Thus, we call is_in_reserved_raw()
104 // instead of just is_in_reserved() here.
105 if (loc_hr->is_in_reserved_raw(from)) {
106 size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom());
107 CardIdx_t from_card = (CardIdx_t)
108 hw_offset >> (CardTableModRefBS::card_shift - LogHeapWordSize);
109
110 assert(0 <= from_card && (size_t)from_card < HeapRegion::CardsPerRegion,
111 "Must be in range.");
112 add_card_work(from_card, par);
113 }
114 }
115
116 public:
117
118 HeapRegion* hr() const { return _hr; }
119
120 jint occupied() const {
121 // Overkill, but if we ever need it...
122 // guarantee(_occupied == _bm.count_one_bits(), "Check");
123 return _occupied;
124 }
125
126 void init(HeapRegion* hr, bool clear_links_to_all_list) {
127 if (clear_links_to_all_list) {
128 set_next(NULL);
129 set_prev(NULL);
130 }
131 _hr = hr;
132 _collision_list_next = NULL;
133 _occupied = 0;
134 _bm.clear();
135 }
136
137 void add_reference(OopOrNarrowOopStar from) {
138 add_reference_work(from, /*parallel*/ true);
139 }
140
141 void seq_add_reference(OopOrNarrowOopStar from) {
142 add_reference_work(from, /*parallel*/ false);
143 }
144
145 void scrub(CardTableModRefBS* ctbs, BitMap* card_bm) {
146 HeapWord* hr_bot = hr()->bottom();
147 size_t hr_first_card_index = ctbs->index_for(hr_bot);
148 bm()->set_intersection_at_offset(*card_bm, hr_first_card_index);
149 recount_occupied();
150 }
151
152 void add_card(CardIdx_t from_card_index) {
153 add_card_work(from_card_index, /*parallel*/ true);
154 }
155
156 void seq_add_card(CardIdx_t from_card_index) {
157 add_card_work(from_card_index, /*parallel*/ false);
158 }
159
160 // (Destructively) union the bitmap of the current table into the given
161 // bitmap (which is assumed to be of the same size.)
162 void union_bitmap_into(BitMap* bm) {
163 bm->set_union(_bm);
164 }
165
166 // Mem size in bytes.
167 size_t mem_size() const {
168 return sizeof(this) + _bm.size_in_words() * HeapWordSize;
169 }
170
171 // Requires "from" to be in "hr()".
172 bool contains_reference(OopOrNarrowOopStar from) const {
173 assert(hr()->is_in_reserved(from), "Precondition.");
174 size_t card_ind = pointer_delta(from, hr()->bottom(),
175 CardTableModRefBS::card_size);
176 return _bm.at(card_ind);
177 }
178
179 // Bulk-free the PRTs from prt to last, assumes that they are
180 // linked together using their _next field.
181 static void bulk_free(PerRegionTable* prt, PerRegionTable* last) {
182 while (true) {
183 PerRegionTable* fl = _free_list;
184 last->set_next(fl);
185 PerRegionTable* res = (PerRegionTable*) Atomic::cmpxchg_ptr(prt, &_free_list, fl);
186 if (res == fl) {
187 return;
188 }
189 }
190 ShouldNotReachHere();
191 }
192
193 static void free(PerRegionTable* prt) {
194 bulk_free(prt, prt);
195 }
196
197 // Returns an initialized PerRegionTable instance.
198 static PerRegionTable* alloc(HeapRegion* hr) {
199 PerRegionTable* fl = _free_list;
200 while (fl != NULL) {
201 PerRegionTable* nxt = fl->next();
202 PerRegionTable* res =
203 (PerRegionTable*)
204 Atomic::cmpxchg_ptr(nxt, &_free_list, fl);
205 if (res == fl) {
206 fl->init(hr, true);
207 return fl;
208 } else {
209 fl = _free_list;
210 }
211 }
212 assert(fl == NULL, "Loop condition.");
213 return new PerRegionTable(hr);
214 }
215
216 PerRegionTable* next() const { return _next; }
217 void set_next(PerRegionTable* next) { _next = next; }
218 PerRegionTable* prev() const { return _prev; }
219 void set_prev(PerRegionTable* prev) { _prev = prev; }
220
221 // Accessor and Modification routines for the pointer for the
222 // singly linked collision list that links the PRTs within the
223 // OtherRegionsTable::_fine_grain_regions hash table.
224 //
225 // It might be useful to also make the collision list doubly linked
226 // to avoid iteration over the collisions list during scrubbing/deletion.
227 // OTOH there might not be many collisions.
228
229 PerRegionTable* collision_list_next() const {
230 return _collision_list_next;
231 }
232
233 void set_collision_list_next(PerRegionTable* next) {
234 _collision_list_next = next;
235 }
236
237 PerRegionTable** collision_list_next_addr() {
238 return &_collision_list_next;
239 }
240
241 static size_t fl_mem_size() {
242 PerRegionTable* cur = _free_list;
243 size_t res = 0;
244 while (cur != NULL) {
245 res += cur->mem_size();
246 cur = cur->next();
247 }
248 return res;
249 }
250
251 #ifndef PRODUCT
252 static void test() {
253 PerRegionTable* dummy = alloc(NULL);
254 free(dummy);
255 guarantee(dummy->mem_size() == fl_mem_size(), "fl_mem_size() does not return the correct element size");
256 }
257 #endif
258 };
259
260 PerRegionTable* PerRegionTable::_free_list = NULL;
261
262 size_t OtherRegionsTable::_max_fine_entries = 0;
263 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
264 size_t OtherRegionsTable::_fine_eviction_stride = 0;
265 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
266
267 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr) :
268 _g1h(G1CollectedHeap::heap()),
269 _m(Mutex::leaf, "An OtherRegionsTable lock", true),
270 _hr(hr),
271 _coarse_map(G1CollectedHeap::heap()->max_regions(),
272 false /* in-resource-area */),
273 _fine_grain_regions(NULL),
274 _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
275 _n_fine_entries(0), _n_coarse_entries(0),
276 _fine_eviction_start(0),
277 _sparse_table(hr)
278 {
279 typedef PerRegionTable* PerRegionTablePtr;
280
281 if (_max_fine_entries == 0) {
282 assert(_mod_max_fine_entries_mask == 0, "Both or none.");
283 size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
284 _max_fine_entries = (size_t)1 << max_entries_log;
285 _mod_max_fine_entries_mask = _max_fine_entries - 1;
286
287 assert(_fine_eviction_sample_size == 0
288 && _fine_eviction_stride == 0, "All init at same time.");
289 _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
290 _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
291 }
292
293 _fine_grain_regions = new PerRegionTablePtr[_max_fine_entries];
294
295 if (_fine_grain_regions == NULL) {
296 vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
297 "Failed to allocate _fine_grain_entries.");
298 }
299
300 for (size_t i = 0; i < _max_fine_entries; i++) {
301 _fine_grain_regions[i] = NULL;
302 }
303 }
304
305 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
306 // We always append to the beginning of the list for convenience;
307 // the order of entries in this list does not matter.
308 if (_first_all_fine_prts != NULL) {
309 assert(_first_all_fine_prts->prev() == NULL, "invariant");
310 _first_all_fine_prts->set_prev(prt);
311 prt->set_next(_first_all_fine_prts);
312 } else {
313 // this is the first element we insert. Adjust the "last" pointer
314 _last_all_fine_prts = prt;
315 assert(prt->next() == NULL, "just checking");
316 }
317 // the new element is always the first element without a predecessor
318 prt->set_prev(NULL);
319 _first_all_fine_prts = prt;
320
321 assert(prt->prev() == NULL, "just checking");
322 assert(_first_all_fine_prts == prt, "just checking");
323 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
324 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
325 "just checking");
326 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
327 "just checking");
328 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
329 "just checking");
330 }
331
332 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
333 if (prt->prev() != NULL) {
334 assert(_first_all_fine_prts != prt, "just checking");
335 prt->prev()->set_next(prt->next());
336 // removing the last element in the list?
337 if (_last_all_fine_prts == prt) {
338 _last_all_fine_prts = prt->prev();
339 }
340 } else {
341 assert(_first_all_fine_prts == prt, "just checking");
342 _first_all_fine_prts = prt->next();
343 // list is empty now?
344 if (_first_all_fine_prts == NULL) {
345 _last_all_fine_prts = NULL;
346 }
347 }
348
349 if (prt->next() != NULL) {
350 prt->next()->set_prev(prt->prev());
351 }
352
353 prt->set_next(NULL);
354 prt->set_prev(NULL);
355
356 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
357 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
358 "just checking");
359 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
360 "just checking");
361 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
362 "just checking");
363 }
364
365 int** OtherRegionsTable::_from_card_cache = NULL;
366 size_t OtherRegionsTable::_from_card_cache_max_regions = 0;
367 size_t OtherRegionsTable::_from_card_cache_mem_size = 0;
368
369 void OtherRegionsTable::init_from_card_cache(size_t max_regions) {
370 _from_card_cache_max_regions = max_regions;
371
372 int n_par_rs = HeapRegionRemSet::num_par_rem_sets();
373 _from_card_cache = NEW_C_HEAP_ARRAY(int*, n_par_rs, mtGC);
374 for (int i = 0; i < n_par_rs; i++) {
375 _from_card_cache[i] = NEW_C_HEAP_ARRAY(int, max_regions, mtGC);
376 for (size_t j = 0; j < max_regions; j++) {
377 _from_card_cache[i][j] = -1; // An invalid value.
378 }
379 }
380 _from_card_cache_mem_size = n_par_rs * max_regions * sizeof(int);
381 }
382
383 void OtherRegionsTable::shrink_from_card_cache(size_t new_n_regs) {
384 for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
385 assert(new_n_regs <= _from_card_cache_max_regions, "Must be within max.");
386 for (size_t j = new_n_regs; j < _from_card_cache_max_regions; j++) {
387 _from_card_cache[i][j] = -1; // An invalid value.
388 }
389 }
390 }
391
392 #ifndef PRODUCT
393 void OtherRegionsTable::print_from_card_cache() {
394 for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
395 for (size_t j = 0; j < _from_card_cache_max_regions; j++) {
396 gclog_or_tty->print_cr("_from_card_cache[%d][%d] = %d.",
397 i, j, _from_card_cache[i][j]);
398 }
399 }
400 }
401 #endif
402
403 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, int tid) {
404 size_t cur_hrs_ind = (size_t) hr()->hrs_index();
405
406 if (G1TraceHeapRegionRememberedSet) {
407 gclog_or_tty->print_cr("ORT::add_reference_work(" PTR_FORMAT "->" PTR_FORMAT ").",
408 from,
409 UseCompressedOops
410 ? oopDesc::load_decode_heap_oop((narrowOop*)from)
411 : oopDesc::load_decode_heap_oop((oop*)from));
412 }
413
414 int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
415
416 if (G1TraceHeapRegionRememberedSet) {
417 gclog_or_tty->print_cr("Table for [" PTR_FORMAT "...): card %d (cache = %d)",
418 hr()->bottom(), from_card,
419 _from_card_cache[tid][cur_hrs_ind]);
420 }
421
422 if (from_card == _from_card_cache[tid][cur_hrs_ind]) {
423 if (G1TraceHeapRegionRememberedSet) {
424 gclog_or_tty->print_cr(" from-card cache hit.");
425 }
426 assert(contains_reference(from), "We just added it!");
427 return;
428 } else {
429 _from_card_cache[tid][cur_hrs_ind] = from_card;
430 }
431
432 // Note that this may be a continued H region.
433 HeapRegion* from_hr = _g1h->heap_region_containing_raw(from);
434 RegionIdx_t from_hrs_ind = (RegionIdx_t) from_hr->hrs_index();
435
436 // If the region is already coarsened, return.
437 if (_coarse_map.at(from_hrs_ind)) {
438 if (G1TraceHeapRegionRememberedSet) {
439 gclog_or_tty->print_cr(" coarse map hit.");
440 }
441 assert(contains_reference(from), "We just added it!");
442 return;
443 }
444
445 // Otherwise find a per-region table to add it to.
446 size_t ind = from_hrs_ind & _mod_max_fine_entries_mask;
447 PerRegionTable* prt = find_region_table(ind, from_hr);
448 if (prt == NULL) {
449 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
450 // Confirm that it's really not there...
451 prt = find_region_table(ind, from_hr);
452 if (prt == NULL) {
453
454 uintptr_t from_hr_bot_card_index =
455 uintptr_t(from_hr->bottom())
456 >> CardTableModRefBS::card_shift;
457 CardIdx_t card_index = from_card - from_hr_bot_card_index;
458 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
459 "Must be in range.");
460 if (G1HRRSUseSparseTable &&
461 _sparse_table.add_card(from_hrs_ind, card_index)) {
462 if (G1RecordHRRSOops) {
463 HeapRegionRemSet::record(hr(), from);
464 if (G1TraceHeapRegionRememberedSet) {
465 gclog_or_tty->print(" Added card " PTR_FORMAT " to region "
466 "[" PTR_FORMAT "...) for ref " PTR_FORMAT ".\n",
467 align_size_down(uintptr_t(from),
468 CardTableModRefBS::card_size),
469 hr()->bottom(), from);
470 }
471 }
472 if (G1TraceHeapRegionRememberedSet) {
473 gclog_or_tty->print_cr(" added card to sparse table.");
474 }
475 assert(contains_reference_locked(from), "We just added it!");
476 return;
477 } else {
478 if (G1TraceHeapRegionRememberedSet) {
479 gclog_or_tty->print_cr(" [tid %d] sparse table entry "
480 "overflow(f: %d, t: %d)",
481 tid, from_hrs_ind, cur_hrs_ind);
482 }
483 }
484
485 if (_n_fine_entries == _max_fine_entries) {
486 prt = delete_region_table();
487 // There is no need to clear the links to the 'all' list here:
488 // prt will be reused immediately, i.e. remain in the 'all' list.
489 prt->init(from_hr, false /* clear_links_to_all_list */);
490 } else {
491 prt = PerRegionTable::alloc(from_hr);
492 link_to_all(prt);
493 }
494
495 PerRegionTable* first_prt = _fine_grain_regions[ind];
496 prt->set_collision_list_next(first_prt);
497 _fine_grain_regions[ind] = prt;
498 _n_fine_entries++;
499
500 if (G1HRRSUseSparseTable) {
501 // Transfer from sparse to fine-grain.
502 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrs_ind);
503 assert(sprt_entry != NULL, "There should have been an entry");
504 for (int i = 0; i < SparsePRTEntry::cards_num(); i++) {
505 CardIdx_t c = sprt_entry->card(i);
506 if (c != SparsePRTEntry::NullEntry) {
507 prt->add_card(c);
508 }
509 }
510 // Now we can delete the sparse entry.
511 bool res = _sparse_table.delete_entry(from_hrs_ind);
512 assert(res, "It should have been there.");
513 }
514 }
515 assert(prt != NULL && prt->hr() == from_hr, "consequence");
516 }
517 // Note that we can't assert "prt->hr() == from_hr", because of the
518 // possibility of concurrent reuse. But see head comment of
519 // OtherRegionsTable for why this is OK.
520 assert(prt != NULL, "Inv");
521
522 prt->add_reference(from);
523
524 if (G1RecordHRRSOops) {
525 HeapRegionRemSet::record(hr(), from);
526 if (G1TraceHeapRegionRememberedSet) {
527 gclog_or_tty->print("Added card " PTR_FORMAT " to region "
528 "[" PTR_FORMAT "...) for ref " PTR_FORMAT ".\n",
529 align_size_down(uintptr_t(from),
530 CardTableModRefBS::card_size),
531 hr()->bottom(), from);
532 }
533 }
534 assert(contains_reference(from), "We just added it!");
535 }
536
537 PerRegionTable*
538 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
539 assert(0 <= ind && ind < _max_fine_entries, "Preconditions.");
540 PerRegionTable* prt = _fine_grain_regions[ind];
541 while (prt != NULL && prt->hr() != hr) {
542 prt = prt->collision_list_next();
543 }
544 // Loop postcondition is the method postcondition.
545 return prt;
546 }
547
548 jint OtherRegionsTable::_n_coarsenings = 0;
549
550 PerRegionTable* OtherRegionsTable::delete_region_table() {
551 assert(_m.owned_by_self(), "Precondition");
552 assert(_n_fine_entries == _max_fine_entries, "Precondition");
553 PerRegionTable* max = NULL;
554 jint max_occ = 0;
555 PerRegionTable** max_prev;
556 size_t max_ind;
557
558 size_t i = _fine_eviction_start;
559 for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
560 size_t ii = i;
561 // Make sure we get a non-NULL sample.
562 while (_fine_grain_regions[ii] == NULL) {
563 ii++;
564 if (ii == _max_fine_entries) ii = 0;
565 guarantee(ii != i, "We must find one.");
566 }
567 PerRegionTable** prev = &_fine_grain_regions[ii];
568 PerRegionTable* cur = *prev;
569 while (cur != NULL) {
570 jint cur_occ = cur->occupied();
571 if (max == NULL || cur_occ > max_occ) {
572 max = cur;
573 max_prev = prev;
574 max_ind = i;
575 max_occ = cur_occ;
576 }
577 prev = cur->collision_list_next_addr();
578 cur = cur->collision_list_next();
579 }
580 i = i + _fine_eviction_stride;
581 if (i >= _n_fine_entries) i = i - _n_fine_entries;
582 }
583
584 _fine_eviction_start++;
585
586 if (_fine_eviction_start >= _n_fine_entries) {
587 _fine_eviction_start -= _n_fine_entries;
588 }
589
590 guarantee(max != NULL, "Since _n_fine_entries > 0");
591
592 // Set the corresponding coarse bit.
593 size_t max_hrs_index = (size_t) max->hr()->hrs_index();
594 if (!_coarse_map.at(max_hrs_index)) {
595 _coarse_map.at_put(max_hrs_index, true);
596 _n_coarse_entries++;
597 if (G1TraceHeapRegionRememberedSet) {
598 gclog_or_tty->print("Coarsened entry in region [" PTR_FORMAT "...] "
599 "for region [" PTR_FORMAT "...] (%d coarse entries).\n",
600 hr()->bottom(),
601 max->hr()->bottom(),
602 _n_coarse_entries);
603 }
604 }
605
606 // Unsplice.
607 *max_prev = max->collision_list_next();
608 Atomic::inc(&_n_coarsenings);
609 _n_fine_entries--;
610 return max;
611 }
612
613
614 // At present, this must be called stop-world single-threaded.
615 void OtherRegionsTable::scrub(CardTableModRefBS* ctbs,
616 BitMap* region_bm, BitMap* card_bm) {
617 // First eliminated garbage regions from the coarse map.
618 if (G1RSScrubVerbose) {
619 gclog_or_tty->print_cr("Scrubbing region %u:", hr()->hrs_index());
620 }
621
622 assert(_coarse_map.size() == region_bm->size(), "Precondition");
623 if (G1RSScrubVerbose) {
624 gclog_or_tty->print(" Coarse map: before = "SIZE_FORMAT"...",
625 _n_coarse_entries);
626 }
627 _coarse_map.set_intersection(*region_bm);
628 _n_coarse_entries = _coarse_map.count_one_bits();
629 if (G1RSScrubVerbose) {
630 gclog_or_tty->print_cr(" after = "SIZE_FORMAT".", _n_coarse_entries);
631 }
632
633 // Now do the fine-grained maps.
634 for (size_t i = 0; i < _max_fine_entries; i++) {
635 PerRegionTable* cur = _fine_grain_regions[i];
636 PerRegionTable** prev = &_fine_grain_regions[i];
637 while (cur != NULL) {
638 PerRegionTable* nxt = cur->collision_list_next();
639 // If the entire region is dead, eliminate.
640 if (G1RSScrubVerbose) {
641 gclog_or_tty->print_cr(" For other region %u:",
642 cur->hr()->hrs_index());
643 }
644 if (!region_bm->at((size_t) cur->hr()->hrs_index())) {
645 *prev = nxt;
646 cur->set_collision_list_next(NULL);
647 _n_fine_entries--;
648 if (G1RSScrubVerbose) {
649 gclog_or_tty->print_cr(" deleted via region map.");
650 }
651 unlink_from_all(cur);
652 PerRegionTable::free(cur);
653 } else {
654 // Do fine-grain elimination.
655 if (G1RSScrubVerbose) {
656 gclog_or_tty->print(" occ: before = %4d.", cur->occupied());
657 }
658 cur->scrub(ctbs, card_bm);
659 if (G1RSScrubVerbose) {
660 gclog_or_tty->print_cr(" after = %4d.", cur->occupied());
661 }
662 // Did that empty the table completely?
663 if (cur->occupied() == 0) {
664 *prev = nxt;
665 cur->set_collision_list_next(NULL);
666 _n_fine_entries--;
667 unlink_from_all(cur);
668 PerRegionTable::free(cur);
669 } else {
670 prev = cur->collision_list_next_addr();
671 }
672 }
673 cur = nxt;
674 }
675 }
676 // Since we may have deleted a from_card_cache entry from the RS, clear
677 // the FCC.
678 clear_fcc();
679 }
680
681
682 size_t OtherRegionsTable::occupied() const {
683 // Cast away const in this case.
684 MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
685 size_t sum = occ_fine();
686 sum += occ_sparse();
687 sum += occ_coarse();
688 return sum;
689 }
690
691 size_t OtherRegionsTable::occ_fine() const {
692 size_t sum = 0;
693
694 size_t num = 0;
695 PerRegionTable * cur = _first_all_fine_prts;
696 while (cur != NULL) {
697 sum += cur->occupied();
698 cur = cur->next();
699 num++;
700 }
701 guarantee(num == _n_fine_entries, "just checking");
702 return sum;
703 }
704
705 size_t OtherRegionsTable::occ_coarse() const {
706 return (_n_coarse_entries * HeapRegion::CardsPerRegion);
707 }
708
709 size_t OtherRegionsTable::occ_sparse() const {
710 return _sparse_table.occupied();
711 }
712
713 size_t OtherRegionsTable::mem_size() const {
714 // Cast away const in this case.
715 MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
716 size_t sum = 0;
717 PerRegionTable * cur = _first_all_fine_prts;
718 while (cur != NULL) {
719 sum += cur->mem_size();
720 cur = cur->next();
721 }
722 sum += (sizeof(PerRegionTable*) * _max_fine_entries);
723 sum += (_coarse_map.size_in_words() * HeapWordSize);
724 sum += (_sparse_table.mem_size());
725 sum += sizeof(*this) - sizeof(_sparse_table); // Avoid double counting above.
726 return sum;
727 }
728
729 size_t OtherRegionsTable::static_mem_size() {
730 return _from_card_cache_mem_size;
731 }
732
733 size_t OtherRegionsTable::fl_mem_size() {
734 return PerRegionTable::fl_mem_size();
735 }
736
737 void OtherRegionsTable::clear_fcc() {
738 size_t hrs_idx = hr()->hrs_index();
739 for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
740 _from_card_cache[i][hrs_idx] = -1;
741 }
742 }
743
744 void OtherRegionsTable::clear() {
745 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
746 // if there are no entries, skip this step
747 if (_first_all_fine_prts != NULL) {
748 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
749 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
750 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
751 } else {
752 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
753 }
754
755 _first_all_fine_prts = _last_all_fine_prts = NULL;
756 _sparse_table.clear();
757 _coarse_map.clear();
758 _n_fine_entries = 0;
759 _n_coarse_entries = 0;
760
761 clear_fcc();
762 }
763
764 void OtherRegionsTable::clear_incoming_entry(HeapRegion* from_hr) {
765 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
766 size_t hrs_ind = (size_t) from_hr->hrs_index();
767 size_t ind = hrs_ind & _mod_max_fine_entries_mask;
768 if (del_single_region_table(ind, from_hr)) {
769 assert(!_coarse_map.at(hrs_ind), "Inv");
770 } else {
771 _coarse_map.par_at_put(hrs_ind, 0);
772 }
773 // Check to see if any of the fcc entries come from here.
774 size_t hr_ind = (size_t) hr()->hrs_index();
775 for (int tid = 0; tid < HeapRegionRemSet::num_par_rem_sets(); tid++) {
776 int fcc_ent = _from_card_cache[tid][hr_ind];
777 if (fcc_ent != -1) {
778 HeapWord* card_addr = (HeapWord*)
779 (uintptr_t(fcc_ent) << CardTableModRefBS::card_shift);
780 if (hr()->is_in_reserved(card_addr)) {
781 // Clear the from card cache.
782 _from_card_cache[tid][hr_ind] = -1;
783 }
784 }
785 }
786 }
787
788 bool OtherRegionsTable::del_single_region_table(size_t ind,
789 HeapRegion* hr) {
790 assert(0 <= ind && ind < _max_fine_entries, "Preconditions.");
791 PerRegionTable** prev_addr = &_fine_grain_regions[ind];
792 PerRegionTable* prt = *prev_addr;
793 while (prt != NULL && prt->hr() != hr) {
794 prev_addr = prt->collision_list_next_addr();
795 prt = prt->collision_list_next();
796 }
797 if (prt != NULL) {
798 assert(prt->hr() == hr, "Loop postcondition.");
799 *prev_addr = prt->collision_list_next();
800 unlink_from_all(prt);
801 PerRegionTable::free(prt);
802 _n_fine_entries--;
803 return true;
804 } else {
805 return false;
806 }
807 }
808
809 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
810 // Cast away const in this case.
811 MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
812 return contains_reference_locked(from);
813 }
814
815 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
816 HeapRegion* hr = _g1h->heap_region_containing_raw(from);
817 if (hr == NULL) return false;
818 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrs_index();
819 // Is this region in the coarse map?
820 if (_coarse_map.at(hr_ind)) return true;
821
822 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
823 hr);
824 if (prt != NULL) {
825 return prt->contains_reference(from);
826
827 } else {
828 uintptr_t from_card =
829 (uintptr_t(from) >> CardTableModRefBS::card_shift);
830 uintptr_t hr_bot_card_index =
831 uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
832 assert(from_card >= hr_bot_card_index, "Inv");
833 CardIdx_t card_index = from_card - hr_bot_card_index;
834 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
835 "Must be in range.");
836 return _sparse_table.contains_card(hr_ind, card_index);
837 }
838
839
840 }
841
842 void
843 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
844 _sparse_table.do_cleanup_work(hrrs_cleanup_task);
845 }
846
847 // Determines how many threads can add records to an rset in parallel.
848 // This can be done by either mutator threads together with the
849 // concurrent refinement threads or GC threads.
850 int HeapRegionRemSet::num_par_rem_sets() {
851 return (int)MAX2(DirtyCardQueueSet::num_par_ids() + ConcurrentG1Refine::thread_num(), ParallelGCThreads);
852 }
853
854 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetSharedArray* bosa,
855 HeapRegion* hr)
856 : _bosa(bosa), _other_regions(hr) {
857 reset_for_par_iteration();
858 }
859
860 void HeapRegionRemSet::setup_remset_size() {
861 // Setup sparse and fine-grain tables sizes.
862 // table_size = base * (log(region_size / 1M) + 1)
863 const int LOG_M = 20;
864 int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
865 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
866 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
867 }
868 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
869 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
870 }
871 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
872 }
873
874 bool HeapRegionRemSet::claim_iter() {
875 if (_iter_state != Unclaimed) return false;
876 jint res = Atomic::cmpxchg(Claimed, (jint*)(&_iter_state), Unclaimed);
877 return (res == Unclaimed);
878 }
879
880 void HeapRegionRemSet::set_iter_complete() {
881 _iter_state = Complete;
882 }
883
884 bool HeapRegionRemSet::iter_is_complete() {
885 return _iter_state == Complete;
886 }
887
888 #ifndef PRODUCT
889 void HeapRegionRemSet::print() const {
890 HeapRegionRemSetIterator iter(this);
891 size_t card_index;
892 while (iter.has_next(card_index)) {
893 HeapWord* card_start =
894 G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
895 gclog_or_tty->print_cr(" Card " PTR_FORMAT, card_start);
896 }
897 if (iter.n_yielded() != occupied()) {
898 gclog_or_tty->print_cr("Yielded disagrees with occupied:");
899 gclog_or_tty->print_cr(" %6d yielded (%6d coarse, %6d fine).",
900 iter.n_yielded(),
901 iter.n_yielded_coarse(), iter.n_yielded_fine());
902 gclog_or_tty->print_cr(" %6d occ (%6d coarse, %6d fine).",
903 occupied(), occ_coarse(), occ_fine());
904 }
905 guarantee(iter.n_yielded() == occupied(),
906 "We should have yielded all the represented cards.");
907 }
908 #endif
909
910 void HeapRegionRemSet::cleanup() {
911 SparsePRT::cleanup_all();
912 }
913
914 void HeapRegionRemSet::clear() {
915 _other_regions.clear();
916 assert(occupied() == 0, "Should be clear.");
917 reset_for_par_iteration();
918 }
919
920 void HeapRegionRemSet::reset_for_par_iteration() {
921 _iter_state = Unclaimed;
922 _iter_claimed = 0;
923 // It's good to check this to make sure that the two methods are in sync.
924 assert(verify_ready_for_par_iteration(), "post-condition");
925 }
926
927 void HeapRegionRemSet::scrub(CardTableModRefBS* ctbs,
928 BitMap* region_bm, BitMap* card_bm) {
929 _other_regions.scrub(ctbs, region_bm, card_bm);
930 }
931
932 //-------------------- Iteration --------------------
933
934 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(const HeapRegionRemSet* hrrs) :
935 _hrrs(hrrs),
936 _g1h(G1CollectedHeap::heap()),
937 _coarse_map(&hrrs->_other_regions._coarse_map),
938 _fine_grain_regions(hrrs->_other_regions._fine_grain_regions),
939 _bosa(hrrs->bosa()),
940 _is(Sparse),
941 // Set these values so that we increment to the first region.
942 _coarse_cur_region_index(-1),
943 _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
944 _cur_region_cur_card(0),
945 _fine_array_index(-1),
946 _fine_cur_prt(NULL),
947 _n_yielded_coarse(0),
948 _n_yielded_fine(0),
949 _n_yielded_sparse(0),
950 _sparse_iter(&hrrs->_other_regions._sparse_table) {}
951
952 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
953 if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
954 // Go to the next card.
955 _coarse_cur_region_cur_card++;
956 // Was the last the last card in the current region?
957 if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
958 // Yes: find the next region. This may leave _coarse_cur_region_index
959 // Set to the last index, in which case there are no more coarse
960 // regions.
961 _coarse_cur_region_index =
962 (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
963 if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
964 _coarse_cur_region_cur_card = 0;
965 HeapWord* r_bot =
966 _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
967 _cur_region_card_offset = _bosa->index_for(r_bot);
968 } else {
969 return false;
970 }
971 }
972 // If we didn't return false above, then we can yield a card.
973 card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
974 return true;
975 }
976
977 void HeapRegionRemSetIterator::fine_find_next_non_null_prt() {
978 // Otherwise, find the next bucket list in the array.
979 _fine_array_index++;
980 while (_fine_array_index < (int) OtherRegionsTable::_max_fine_entries) {
981 _fine_cur_prt = _fine_grain_regions[_fine_array_index];
982 if (_fine_cur_prt != NULL) return;
983 else _fine_array_index++;
984 }
985 assert(_fine_cur_prt == NULL, "Loop post");
986 }
987
988 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
989 if (fine_has_next()) {
990 _cur_region_cur_card =
991 _fine_cur_prt->_bm.get_next_one_offset(_cur_region_cur_card + 1);
992 }
993 while (!fine_has_next()) {
994 if (_cur_region_cur_card == (size_t) HeapRegion::CardsPerRegion) {
995 _cur_region_cur_card = 0;
996 _fine_cur_prt = _fine_cur_prt->collision_list_next();
997 }
998 if (_fine_cur_prt == NULL) {
999 fine_find_next_non_null_prt();
1000 if (_fine_cur_prt == NULL) return false;
1001 }
1002 assert(_fine_cur_prt != NULL && _cur_region_cur_card == 0,
1003 "inv.");
1004 HeapWord* r_bot =
1005 _fine_cur_prt->hr()->bottom();
1006 _cur_region_card_offset = _bosa->index_for(r_bot);
1007 _cur_region_cur_card = _fine_cur_prt->_bm.get_next_one_offset(0);
1008 }
1009 assert(fine_has_next(), "Or else we exited the loop via the return.");
1010 card_index = _cur_region_card_offset + _cur_region_cur_card;
1011 return true;
1012 }
1013
1014 bool HeapRegionRemSetIterator::fine_has_next() {
1015 return
1016 _fine_cur_prt != NULL &&
1017 _cur_region_cur_card < HeapRegion::CardsPerRegion;
1018 }
1019
1020 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
1021 switch (_is) {
1022 case Sparse:
1023 if (_sparse_iter.has_next(card_index)) {
1024 _n_yielded_sparse++;
1025 return true;
1026 }
1027 // Otherwise, deliberate fall-through
1028 _is = Fine;
1029 case Fine:
1030 if (fine_has_next(card_index)) {
1031 _n_yielded_fine++;
1032 return true;
1033 }
1034 // Otherwise, deliberate fall-through
1035 _is = Coarse;
1036 case Coarse:
1037 if (coarse_has_next(card_index)) {
1038 _n_yielded_coarse++;
1039 return true;
1040 }
1041 // Otherwise...
1042 break;
1043 }
1044 assert(ParallelGCThreads > 1 ||
1045 n_yielded() == _hrrs->occupied(),
1046 "Should have yielded all the cards in the rem set "
1047 "(in the non-par case).");
1048 return false;
1049 }
1050
1051
1052
1053 OopOrNarrowOopStar* HeapRegionRemSet::_recorded_oops = NULL;
1054 HeapWord** HeapRegionRemSet::_recorded_cards = NULL;
1055 HeapRegion** HeapRegionRemSet::_recorded_regions = NULL;
1056 int HeapRegionRemSet::_n_recorded = 0;
1057
1058 HeapRegionRemSet::Event* HeapRegionRemSet::_recorded_events = NULL;
1059 int* HeapRegionRemSet::_recorded_event_index = NULL;
1060 int HeapRegionRemSet::_n_recorded_events = 0;
1061
1062 void HeapRegionRemSet::record(HeapRegion* hr, OopOrNarrowOopStar f) {
1063 if (_recorded_oops == NULL) {
1064 assert(_n_recorded == 0
1065 && _recorded_cards == NULL
1066 && _recorded_regions == NULL,
1067 "Inv");
1068 _recorded_oops = NEW_C_HEAP_ARRAY(OopOrNarrowOopStar, MaxRecorded, mtGC);
1069 _recorded_cards = NEW_C_HEAP_ARRAY(HeapWord*, MaxRecorded, mtGC);
1070 _recorded_regions = NEW_C_HEAP_ARRAY(HeapRegion*, MaxRecorded, mtGC);
1071 }
1072 if (_n_recorded == MaxRecorded) {
1073 gclog_or_tty->print_cr("Filled up 'recorded' (%d).", MaxRecorded);
1074 } else {
1075 _recorded_cards[_n_recorded] =
1076 (HeapWord*)align_size_down(uintptr_t(f),
1077 CardTableModRefBS::card_size);
1078 _recorded_oops[_n_recorded] = f;
1079 _recorded_regions[_n_recorded] = hr;
1080 _n_recorded++;
1081 }
1082 }
1083
1084 void HeapRegionRemSet::record_event(Event evnt) {
1085 if (!G1RecordHRRSEvents) return;
1086
1087 if (_recorded_events == NULL) {
1088 assert(_n_recorded_events == 0
1089 && _recorded_event_index == NULL,
1090 "Inv");
1091 _recorded_events = NEW_C_HEAP_ARRAY(Event, MaxRecordedEvents, mtGC);
1092 _recorded_event_index = NEW_C_HEAP_ARRAY(int, MaxRecordedEvents, mtGC);
1093 }
1094 if (_n_recorded_events == MaxRecordedEvents) {
1095 gclog_or_tty->print_cr("Filled up 'recorded_events' (%d).", MaxRecordedEvents);
1096 } else {
1097 _recorded_events[_n_recorded_events] = evnt;
1098 _recorded_event_index[_n_recorded_events] = _n_recorded;
1099 _n_recorded_events++;
1100 }
1101 }
1102
1103 void HeapRegionRemSet::print_event(outputStream* str, Event evnt) {
1104 switch (evnt) {
1105 case Event_EvacStart:
1106 str->print("Evac Start");
1107 break;
1108 case Event_EvacEnd:
1109 str->print("Evac End");
1110 break;
1111 case Event_RSUpdateEnd:
1112 str->print("RS Update End");
1113 break;
1114 }
1115 }
1116
1117 void HeapRegionRemSet::print_recorded() {
1118 int cur_evnt = 0;
1119 Event cur_evnt_kind;
1120 int cur_evnt_ind = 0;
1121 if (_n_recorded_events > 0) {
1122 cur_evnt_kind = _recorded_events[cur_evnt];
1123 cur_evnt_ind = _recorded_event_index[cur_evnt];
1124 }
1125
1126 for (int i = 0; i < _n_recorded; i++) {
1127 while (cur_evnt < _n_recorded_events && i == cur_evnt_ind) {
1128 gclog_or_tty->print("Event: ");
1129 print_event(gclog_or_tty, cur_evnt_kind);
1130 gclog_or_tty->print_cr("");
1131 cur_evnt++;
1132 if (cur_evnt < MaxRecordedEvents) {
1133 cur_evnt_kind = _recorded_events[cur_evnt];
1134 cur_evnt_ind = _recorded_event_index[cur_evnt];
1135 }
1136 }
1137 gclog_or_tty->print("Added card " PTR_FORMAT " to region [" PTR_FORMAT "...]"
1138 " for ref " PTR_FORMAT ".\n",
1139 _recorded_cards[i], _recorded_regions[i]->bottom(),
1140 _recorded_oops[i]);
1141 }
1142 }
1143
1144 void HeapRegionRemSet::reset_for_cleanup_tasks() {
1145 SparsePRT::reset_for_cleanup_tasks();
1146 }
1147
1148 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
1149 _other_regions.do_cleanup_work(hrrs_cleanup_task);
1150 }
1151
1152 void
1153 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
1154 SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
1155 }
1156
1157 #ifndef PRODUCT
1158 void HeapRegionRemSet::test_prt() {
1159 PerRegionTable::test();
1160 }
1161
1162 void HeapRegionRemSet::test() {
1163 os::sleep(Thread::current(), (jlong)5000, false);
1164 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1165
1166 // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
1167 // hash bucket.
1168 HeapRegion* hr0 = g1h->region_at(0);
1169 HeapRegion* hr1 = g1h->region_at(1);
1170 HeapRegion* hr2 = g1h->region_at(5);
1171 HeapRegion* hr3 = g1h->region_at(6);
1172 HeapRegion* hr4 = g1h->region_at(7);
1173 HeapRegion* hr5 = g1h->region_at(8);
1174
1175 HeapWord* hr1_start = hr1->bottom();
1176 HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
1177 HeapWord* hr1_last = hr1->end() - 1;
1178
1179 HeapWord* hr2_start = hr2->bottom();
1180 HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
1181 HeapWord* hr2_last = hr2->end() - 1;
1182
1183 HeapWord* hr3_start = hr3->bottom();
1184 HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
1185 HeapWord* hr3_last = hr3->end() - 1;
1186
1187 HeapRegionRemSet* hrrs = hr0->rem_set();
1188
1189 // Make three references from region 0x101...
1190 hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
1191 hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
1192 hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
1193
1194 hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
1195 hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
1196 hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
1197
1198 hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
1199 hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
1200 hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
1201
1202 // Now cause a coarsening.
1203 hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
1204 hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
1205
1206 // Now, does iteration yield these three?
1207 HeapRegionRemSetIterator iter(hrrs);
1208 size_t sum = 0;
1209 size_t card_index;
1210 while (iter.has_next(card_index)) {
1211 HeapWord* card_start =
1212 G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
1213 gclog_or_tty->print_cr(" Card " PTR_FORMAT ".", card_start);
1214 sum++;
1215 }
1216 guarantee(sum == 11 - 3 + 2048, "Failure");
1217 guarantee(sum == hrrs->occupied(), "Failure");
1218 }
1219 #endif