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 */
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 static void test_fl_mem_size();
252 };
253
254 PerRegionTable* PerRegionTable::_free_list = NULL;
255
256 size_t OtherRegionsTable::_max_fine_entries = 0;
257 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
258 size_t OtherRegionsTable::_fine_eviction_stride = 0;
259 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
260
261 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr) :
262 _g1h(G1CollectedHeap::heap()),
263 _m(Mutex::leaf, "An OtherRegionsTable lock", true),
264 _hr(hr),
265 _coarse_map(G1CollectedHeap::heap()->max_regions(),
266 false /* in-resource-area */),
267 _fine_grain_regions(NULL),
268 _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
269 _n_fine_entries(0), _n_coarse_entries(0),
270 _fine_eviction_start(0),
271 _sparse_table(hr)
272 {
273 typedef PerRegionTable* PerRegionTablePtr;
274
275 if (_max_fine_entries == 0) {
276 assert(_mod_max_fine_entries_mask == 0, "Both or none.");
277 size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
278 _max_fine_entries = (size_t)1 << max_entries_log;
279 _mod_max_fine_entries_mask = _max_fine_entries - 1;
280
281 assert(_fine_eviction_sample_size == 0
282 && _fine_eviction_stride == 0, "All init at same time.");
283 _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
284 _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
285 }
286
287 _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
288 mtGC, 0, AllocFailStrategy::RETURN_NULL);
289
290 if (_fine_grain_regions == NULL) {
291 vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
292 "Failed to allocate _fine_grain_entries.");
293 }
294
295 for (size_t i = 0; i < _max_fine_entries; i++) {
296 _fine_grain_regions[i] = NULL;
297 }
298 }
299
300 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
301 // We always append to the beginning of the list for convenience;
302 // the order of entries in this list does not matter.
303 if (_first_all_fine_prts != NULL) {
304 assert(_first_all_fine_prts->prev() == NULL, "invariant");
305 _first_all_fine_prts->set_prev(prt);
306 prt->set_next(_first_all_fine_prts);
307 } else {
308 // this is the first element we insert. Adjust the "last" pointer
309 _last_all_fine_prts = prt;
310 assert(prt->next() == NULL, "just checking");
311 }
312 // the new element is always the first element without a predecessor
313 prt->set_prev(NULL);
314 _first_all_fine_prts = prt;
315
316 assert(prt->prev() == NULL, "just checking");
317 assert(_first_all_fine_prts == prt, "just checking");
318 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
319 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
320 "just checking");
321 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
322 "just checking");
323 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
324 "just checking");
325 }
326
327 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
328 if (prt->prev() != NULL) {
329 assert(_first_all_fine_prts != prt, "just checking");
330 prt->prev()->set_next(prt->next());
331 // removing the last element in the list?
332 if (_last_all_fine_prts == prt) {
333 _last_all_fine_prts = prt->prev();
334 }
335 } else {
336 assert(_first_all_fine_prts == prt, "just checking");
337 _first_all_fine_prts = prt->next();
338 // list is empty now?
339 if (_first_all_fine_prts == NULL) {
340 _last_all_fine_prts = NULL;
341 }
342 }
343
344 if (prt->next() != NULL) {
345 prt->next()->set_prev(prt->prev());
346 }
347
348 prt->set_next(NULL);
349 prt->set_prev(NULL);
350
351 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
352 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
353 "just checking");
354 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
355 "just checking");
356 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
357 "just checking");
358 }
359
360 int** OtherRegionsTable::_from_card_cache = NULL;
361 size_t OtherRegionsTable::_from_card_cache_max_regions = 0;
362 size_t OtherRegionsTable::_from_card_cache_mem_size = 0;
363
364 void OtherRegionsTable::init_from_card_cache(size_t max_regions) {
365 _from_card_cache_max_regions = max_regions;
366
367 int n_par_rs = HeapRegionRemSet::num_par_rem_sets();
368 _from_card_cache = NEW_C_HEAP_ARRAY(int*, n_par_rs, mtGC);
369 for (int i = 0; i < n_par_rs; i++) {
370 _from_card_cache[i] = NEW_C_HEAP_ARRAY(int, max_regions, mtGC);
371 for (size_t j = 0; j < max_regions; j++) {
372 _from_card_cache[i][j] = -1; // An invalid value.
373 }
374 }
375 _from_card_cache_mem_size = n_par_rs * max_regions * sizeof(int);
376 }
377
378 void OtherRegionsTable::shrink_from_card_cache(size_t new_n_regs) {
379 for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
380 assert(new_n_regs <= _from_card_cache_max_regions, "Must be within max.");
381 for (size_t j = new_n_regs; j < _from_card_cache_max_regions; j++) {
382 _from_card_cache[i][j] = -1; // An invalid value.
383 }
384 }
385 }
386
387 #ifndef PRODUCT
388 void OtherRegionsTable::print_from_card_cache() {
389 for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
390 for (size_t j = 0; j < _from_card_cache_max_regions; j++) {
391 gclog_or_tty->print_cr("_from_card_cache[%d][%d] = %d.",
392 i, j, _from_card_cache[i][j]);
393 }
394 }
395 }
396 #endif
397
398 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, int tid) {
399 size_t cur_hrs_ind = (size_t) hr()->hrs_index();
400
401 if (G1TraceHeapRegionRememberedSet) {
402 gclog_or_tty->print_cr("ORT::add_reference_work(" PTR_FORMAT "->" PTR_FORMAT ").",
403 from,
404 UseCompressedOops
405 ? oopDesc::load_decode_heap_oop((narrowOop*)from)
406 : oopDesc::load_decode_heap_oop((oop*)from));
407 }
408
409 int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
410
411 if (G1TraceHeapRegionRememberedSet) {
412 gclog_or_tty->print_cr("Table for [" PTR_FORMAT "...): card %d (cache = %d)",
413 hr()->bottom(), from_card,
414 _from_card_cache[tid][cur_hrs_ind]);
415 }
416
417 if (from_card == _from_card_cache[tid][cur_hrs_ind]) {
418 if (G1TraceHeapRegionRememberedSet) {
419 gclog_or_tty->print_cr(" from-card cache hit.");
420 }
421 assert(contains_reference(from), "We just added it!");
422 return;
423 } else {
424 _from_card_cache[tid][cur_hrs_ind] = from_card;
425 }
426
427 // Note that this may be a continued H region.
428 HeapRegion* from_hr = _g1h->heap_region_containing_raw(from);
429 RegionIdx_t from_hrs_ind = (RegionIdx_t) from_hr->hrs_index();
430
431 // If the region is already coarsened, return.
432 if (_coarse_map.at(from_hrs_ind)) {
433 if (G1TraceHeapRegionRememberedSet) {
434 gclog_or_tty->print_cr(" coarse map hit.");
435 }
436 assert(contains_reference(from), "We just added it!");
437 return;
438 }
439
440 // Otherwise find a per-region table to add it to.
441 size_t ind = from_hrs_ind & _mod_max_fine_entries_mask;
442 PerRegionTable* prt = find_region_table(ind, from_hr);
443 if (prt == NULL) {
444 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
445 // Confirm that it's really not there...
446 prt = find_region_table(ind, from_hr);
447 if (prt == NULL) {
448
449 uintptr_t from_hr_bot_card_index =
450 uintptr_t(from_hr->bottom())
451 >> CardTableModRefBS::card_shift;
452 CardIdx_t card_index = from_card - from_hr_bot_card_index;
453 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
454 "Must be in range.");
455 if (G1HRRSUseSparseTable &&
456 _sparse_table.add_card(from_hrs_ind, card_index)) {
457 if (G1RecordHRRSOops) {
458 HeapRegionRemSet::record(hr(), from);
459 if (G1TraceHeapRegionRememberedSet) {
460 gclog_or_tty->print(" Added card " PTR_FORMAT " to region "
461 "[" PTR_FORMAT "...) for ref " PTR_FORMAT ".\n",
462 align_size_down(uintptr_t(from),
463 CardTableModRefBS::card_size),
464 hr()->bottom(), from);
465 }
466 }
467 if (G1TraceHeapRegionRememberedSet) {
468 gclog_or_tty->print_cr(" added card to sparse table.");
469 }
470 assert(contains_reference_locked(from), "We just added it!");
471 return;
472 } else {
473 if (G1TraceHeapRegionRememberedSet) {
474 gclog_or_tty->print_cr(" [tid %d] sparse table entry "
475 "overflow(f: %d, t: %d)",
476 tid, from_hrs_ind, cur_hrs_ind);
477 }
478 }
479
480 if (_n_fine_entries == _max_fine_entries) {
481 prt = delete_region_table();
482 // There is no need to clear the links to the 'all' list here:
483 // prt will be reused immediately, i.e. remain in the 'all' list.
484 prt->init(from_hr, false /* clear_links_to_all_list */);
485 } else {
486 prt = PerRegionTable::alloc(from_hr);
487 link_to_all(prt);
488 }
489
490 PerRegionTable* first_prt = _fine_grain_regions[ind];
491 prt->set_collision_list_next(first_prt);
492 _fine_grain_regions[ind] = prt;
493 _n_fine_entries++;
494
495 if (G1HRRSUseSparseTable) {
496 // Transfer from sparse to fine-grain.
497 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrs_ind);
498 assert(sprt_entry != NULL, "There should have been an entry");
499 for (int i = 0; i < SparsePRTEntry::cards_num(); i++) {
500 CardIdx_t c = sprt_entry->card(i);
501 if (c != SparsePRTEntry::NullEntry) {
502 prt->add_card(c);
503 }
504 }
505 // Now we can delete the sparse entry.
506 bool res = _sparse_table.delete_entry(from_hrs_ind);
507 assert(res, "It should have been there.");
508 }
509 }
510 assert(prt != NULL && prt->hr() == from_hr, "consequence");
511 }
512 // Note that we can't assert "prt->hr() == from_hr", because of the
513 // possibility of concurrent reuse. But see head comment of
514 // OtherRegionsTable for why this is OK.
515 assert(prt != NULL, "Inv");
516
517 prt->add_reference(from);
518
519 if (G1RecordHRRSOops) {
520 HeapRegionRemSet::record(hr(), from);
521 if (G1TraceHeapRegionRememberedSet) {
522 gclog_or_tty->print("Added card " PTR_FORMAT " to region "
523 "[" PTR_FORMAT "...) for ref " PTR_FORMAT ".\n",
524 align_size_down(uintptr_t(from),
525 CardTableModRefBS::card_size),
526 hr()->bottom(), from);
527 }
528 }
529 assert(contains_reference(from), "We just added it!");
530 }
531
532 PerRegionTable*
533 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
534 assert(0 <= ind && ind < _max_fine_entries, "Preconditions.");
535 PerRegionTable* prt = _fine_grain_regions[ind];
536 while (prt != NULL && prt->hr() != hr) {
537 prt = prt->collision_list_next();
538 }
539 // Loop postcondition is the method postcondition.
540 return prt;
541 }
542
543 jint OtherRegionsTable::_n_coarsenings = 0;
544
545 PerRegionTable* OtherRegionsTable::delete_region_table() {
546 assert(_m.owned_by_self(), "Precondition");
547 assert(_n_fine_entries == _max_fine_entries, "Precondition");
548 PerRegionTable* max = NULL;
549 jint max_occ = 0;
550 PerRegionTable** max_prev;
551 size_t max_ind;
552
553 size_t i = _fine_eviction_start;
554 for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
555 size_t ii = i;
556 // Make sure we get a non-NULL sample.
557 while (_fine_grain_regions[ii] == NULL) {
558 ii++;
559 if (ii == _max_fine_entries) ii = 0;
560 guarantee(ii != i, "We must find one.");
561 }
562 PerRegionTable** prev = &_fine_grain_regions[ii];
563 PerRegionTable* cur = *prev;
564 while (cur != NULL) {
565 jint cur_occ = cur->occupied();
566 if (max == NULL || cur_occ > max_occ) {
567 max = cur;
568 max_prev = prev;
569 max_ind = i;
570 max_occ = cur_occ;
571 }
572 prev = cur->collision_list_next_addr();
573 cur = cur->collision_list_next();
574 }
575 i = i + _fine_eviction_stride;
576 if (i >= _n_fine_entries) i = i - _n_fine_entries;
577 }
578
579 _fine_eviction_start++;
580
581 if (_fine_eviction_start >= _n_fine_entries) {
582 _fine_eviction_start -= _n_fine_entries;
583 }
584
585 guarantee(max != NULL, "Since _n_fine_entries > 0");
586
587 // Set the corresponding coarse bit.
588 size_t max_hrs_index = (size_t) max->hr()->hrs_index();
589 if (!_coarse_map.at(max_hrs_index)) {
590 _coarse_map.at_put(max_hrs_index, true);
591 _n_coarse_entries++;
592 if (G1TraceHeapRegionRememberedSet) {
593 gclog_or_tty->print("Coarsened entry in region [" PTR_FORMAT "...] "
594 "for region [" PTR_FORMAT "...] (%d coarse entries).\n",
595 hr()->bottom(),
596 max->hr()->bottom(),
597 _n_coarse_entries);
598 }
599 }
600
601 // Unsplice.
602 *max_prev = max->collision_list_next();
603 Atomic::inc(&_n_coarsenings);
604 _n_fine_entries--;
605 return max;
606 }
607
608
609 // At present, this must be called stop-world single-threaded.
610 void OtherRegionsTable::scrub(CardTableModRefBS* ctbs,
611 BitMap* region_bm, BitMap* card_bm) {
612 // First eliminated garbage regions from the coarse map.
613 if (G1RSScrubVerbose) {
614 gclog_or_tty->print_cr("Scrubbing region %u:", hr()->hrs_index());
615 }
616
617 assert(_coarse_map.size() == region_bm->size(), "Precondition");
618 if (G1RSScrubVerbose) {
619 gclog_or_tty->print(" Coarse map: before = "SIZE_FORMAT"...",
620 _n_coarse_entries);
621 }
622 _coarse_map.set_intersection(*region_bm);
623 _n_coarse_entries = _coarse_map.count_one_bits();
624 if (G1RSScrubVerbose) {
625 gclog_or_tty->print_cr(" after = "SIZE_FORMAT".", _n_coarse_entries);
626 }
627
628 // Now do the fine-grained maps.
629 for (size_t i = 0; i < _max_fine_entries; i++) {
630 PerRegionTable* cur = _fine_grain_regions[i];
631 PerRegionTable** prev = &_fine_grain_regions[i];
632 while (cur != NULL) {
633 PerRegionTable* nxt = cur->collision_list_next();
634 // If the entire region is dead, eliminate.
635 if (G1RSScrubVerbose) {
636 gclog_or_tty->print_cr(" For other region %u:",
637 cur->hr()->hrs_index());
638 }
639 if (!region_bm->at((size_t) cur->hr()->hrs_index())) {
640 *prev = nxt;
641 cur->set_collision_list_next(NULL);
642 _n_fine_entries--;
643 if (G1RSScrubVerbose) {
644 gclog_or_tty->print_cr(" deleted via region map.");
645 }
646 unlink_from_all(cur);
647 PerRegionTable::free(cur);
648 } else {
649 // Do fine-grain elimination.
650 if (G1RSScrubVerbose) {
651 gclog_or_tty->print(" occ: before = %4d.", cur->occupied());
652 }
653 cur->scrub(ctbs, card_bm);
654 if (G1RSScrubVerbose) {
655 gclog_or_tty->print_cr(" after = %4d.", cur->occupied());
656 }
657 // Did that empty the table completely?
658 if (cur->occupied() == 0) {
659 *prev = nxt;
660 cur->set_collision_list_next(NULL);
661 _n_fine_entries--;
662 unlink_from_all(cur);
663 PerRegionTable::free(cur);
664 } else {
665 prev = cur->collision_list_next_addr();
666 }
667 }
668 cur = nxt;
669 }
670 }
671 // Since we may have deleted a from_card_cache entry from the RS, clear
672 // the FCC.
673 clear_fcc();
674 }
675
676
677 size_t OtherRegionsTable::occupied() const {
678 // Cast away const in this case.
679 MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
680 size_t sum = occ_fine();
681 sum += occ_sparse();
682 sum += occ_coarse();
683 return sum;
684 }
685
686 size_t OtherRegionsTable::occ_fine() const {
687 size_t sum = 0;
688
689 size_t num = 0;
690 PerRegionTable * cur = _first_all_fine_prts;
691 while (cur != NULL) {
692 sum += cur->occupied();
693 cur = cur->next();
694 num++;
695 }
696 guarantee(num == _n_fine_entries, "just checking");
697 return sum;
698 }
699
700 size_t OtherRegionsTable::occ_coarse() const {
701 return (_n_coarse_entries * HeapRegion::CardsPerRegion);
702 }
703
704 size_t OtherRegionsTable::occ_sparse() const {
705 return _sparse_table.occupied();
706 }
707
708 size_t OtherRegionsTable::mem_size() const {
709 // Cast away const in this case.
710 MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
711 size_t sum = 0;
712 // all PRTs are of the same size so it is sufficient to query only one of them.
713 if (_first_all_fine_prts != NULL) {
714 assert(_last_all_fine_prts != NULL &&
715 _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
716 sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
717 }
718 sum += (sizeof(PerRegionTable*) * _max_fine_entries);
719 sum += (_coarse_map.size_in_words() * HeapWordSize);
720 sum += (_sparse_table.mem_size());
721 sum += sizeof(*this) - sizeof(_sparse_table); // Avoid double counting above.
722 return sum;
723 }
724
725 size_t OtherRegionsTable::static_mem_size() {
726 return _from_card_cache_mem_size;
727 }
728
729 size_t OtherRegionsTable::fl_mem_size() {
730 return PerRegionTable::fl_mem_size();
731 }
732
733 void OtherRegionsTable::clear_fcc() {
734 size_t hrs_idx = hr()->hrs_index();
735 for (int i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
736 _from_card_cache[i][hrs_idx] = -1;
737 }
738 }
739
740 void OtherRegionsTable::clear() {
741 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
742 // if there are no entries, skip this step
743 if (_first_all_fine_prts != NULL) {
744 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
745 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
746 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
747 } else {
748 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
749 }
750
751 _first_all_fine_prts = _last_all_fine_prts = NULL;
752 _sparse_table.clear();
753 _coarse_map.clear();
754 _n_fine_entries = 0;
755 _n_coarse_entries = 0;
756
757 clear_fcc();
758 }
759
760 void OtherRegionsTable::clear_incoming_entry(HeapRegion* from_hr) {
761 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
762 size_t hrs_ind = (size_t) from_hr->hrs_index();
763 size_t ind = hrs_ind & _mod_max_fine_entries_mask;
764 if (del_single_region_table(ind, from_hr)) {
765 assert(!_coarse_map.at(hrs_ind), "Inv");
766 } else {
767 _coarse_map.par_at_put(hrs_ind, 0);
768 }
769 // Check to see if any of the fcc entries come from here.
770 size_t hr_ind = (size_t) hr()->hrs_index();
771 for (int tid = 0; tid < HeapRegionRemSet::num_par_rem_sets(); tid++) {
772 int fcc_ent = _from_card_cache[tid][hr_ind];
773 if (fcc_ent != -1) {
774 HeapWord* card_addr = (HeapWord*)
775 (uintptr_t(fcc_ent) << CardTableModRefBS::card_shift);
776 if (hr()->is_in_reserved(card_addr)) {
777 // Clear the from card cache.
778 _from_card_cache[tid][hr_ind] = -1;
779 }
780 }
781 }
782 }
783
784 bool OtherRegionsTable::del_single_region_table(size_t ind,
785 HeapRegion* hr) {
786 assert(0 <= ind && ind < _max_fine_entries, "Preconditions.");
787 PerRegionTable** prev_addr = &_fine_grain_regions[ind];
788 PerRegionTable* prt = *prev_addr;
789 while (prt != NULL && prt->hr() != hr) {
790 prev_addr = prt->collision_list_next_addr();
791 prt = prt->collision_list_next();
792 }
793 if (prt != NULL) {
794 assert(prt->hr() == hr, "Loop postcondition.");
795 *prev_addr = prt->collision_list_next();
796 unlink_from_all(prt);
797 PerRegionTable::free(prt);
798 _n_fine_entries--;
799 return true;
800 } else {
801 return false;
802 }
803 }
804
805 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
806 // Cast away const in this case.
807 MutexLockerEx x((Mutex*)&_m, Mutex::_no_safepoint_check_flag);
808 return contains_reference_locked(from);
809 }
810
811 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
812 HeapRegion* hr = _g1h->heap_region_containing_raw(from);
813 if (hr == NULL) return false;
814 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrs_index();
815 // Is this region in the coarse map?
816 if (_coarse_map.at(hr_ind)) return true;
817
818 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
819 hr);
820 if (prt != NULL) {
821 return prt->contains_reference(from);
822
823 } else {
824 uintptr_t from_card =
825 (uintptr_t(from) >> CardTableModRefBS::card_shift);
826 uintptr_t hr_bot_card_index =
827 uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
828 assert(from_card >= hr_bot_card_index, "Inv");
829 CardIdx_t card_index = from_card - hr_bot_card_index;
830 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
831 "Must be in range.");
832 return _sparse_table.contains_card(hr_ind, card_index);
833 }
834
835
836 }
837
838 void
839 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
840 _sparse_table.do_cleanup_work(hrrs_cleanup_task);
841 }
842
843 // Determines how many threads can add records to an rset in parallel.
844 // This can be done by either mutator threads together with the
845 // concurrent refinement threads or GC threads.
846 int HeapRegionRemSet::num_par_rem_sets() {
847 return (int)MAX2(DirtyCardQueueSet::num_par_ids() + ConcurrentG1Refine::thread_num(), ParallelGCThreads);
848 }
849
850 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetSharedArray* bosa,
851 HeapRegion* hr)
852 : _bosa(bosa), _other_regions(hr) {
853 reset_for_par_iteration();
854 }
855
856 void HeapRegionRemSet::setup_remset_size() {
857 // Setup sparse and fine-grain tables sizes.
858 // table_size = base * (log(region_size / 1M) + 1)
859 const int LOG_M = 20;
860 int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
861 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
862 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
863 }
864 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
865 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
866 }
867 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
868 }
869
870 bool HeapRegionRemSet::claim_iter() {
871 if (_iter_state != Unclaimed) return false;
872 jint res = Atomic::cmpxchg(Claimed, (jint*)(&_iter_state), Unclaimed);
873 return (res == Unclaimed);
874 }
875
876 void HeapRegionRemSet::set_iter_complete() {
877 _iter_state = Complete;
878 }
879
880 bool HeapRegionRemSet::iter_is_complete() {
881 return _iter_state == Complete;
882 }
883
884 #ifndef PRODUCT
885 void HeapRegionRemSet::print() const {
886 HeapRegionRemSetIterator iter(this);
887 size_t card_index;
888 while (iter.has_next(card_index)) {
889 HeapWord* card_start =
890 G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
891 gclog_or_tty->print_cr(" Card " PTR_FORMAT, card_start);
892 }
893 if (iter.n_yielded() != occupied()) {
894 gclog_or_tty->print_cr("Yielded disagrees with occupied:");
895 gclog_or_tty->print_cr(" %6d yielded (%6d coarse, %6d fine).",
896 iter.n_yielded(),
897 iter.n_yielded_coarse(), iter.n_yielded_fine());
898 gclog_or_tty->print_cr(" %6d occ (%6d coarse, %6d fine).",
899 occupied(), occ_coarse(), occ_fine());
900 }
901 guarantee(iter.n_yielded() == occupied(),
902 "We should have yielded all the represented cards.");
903 }
904 #endif
905
906 void HeapRegionRemSet::cleanup() {
907 SparsePRT::cleanup_all();
908 }
909
910 void HeapRegionRemSet::clear() {
911 _other_regions.clear();
912 assert(occupied() == 0, "Should be clear.");
913 reset_for_par_iteration();
914 }
915
916 void HeapRegionRemSet::reset_for_par_iteration() {
917 _iter_state = Unclaimed;
918 _iter_claimed = 0;
919 // It's good to check this to make sure that the two methods are in sync.
920 assert(verify_ready_for_par_iteration(), "post-condition");
921 }
922
923 void HeapRegionRemSet::scrub(CardTableModRefBS* ctbs,
924 BitMap* region_bm, BitMap* card_bm) {
925 _other_regions.scrub(ctbs, region_bm, card_bm);
926 }
927
928 //-------------------- Iteration --------------------
929
930 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(const HeapRegionRemSet* hrrs) :
931 _hrrs(hrrs),
932 _g1h(G1CollectedHeap::heap()),
933 _coarse_map(&hrrs->_other_regions._coarse_map),
934 _fine_grain_regions(hrrs->_other_regions._fine_grain_regions),
935 _bosa(hrrs->bosa()),
936 _is(Sparse),
937 // Set these values so that we increment to the first region.
938 _coarse_cur_region_index(-1),
939 _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
940 _cur_region_cur_card(0),
941 _fine_array_index(-1),
942 _fine_cur_prt(NULL),
943 _n_yielded_coarse(0),
944 _n_yielded_fine(0),
945 _n_yielded_sparse(0),
946 _sparse_iter(&hrrs->_other_regions._sparse_table) {}
947
948 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
949 if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
950 // Go to the next card.
951 _coarse_cur_region_cur_card++;
952 // Was the last the last card in the current region?
953 if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
954 // Yes: find the next region. This may leave _coarse_cur_region_index
955 // Set to the last index, in which case there are no more coarse
956 // regions.
957 _coarse_cur_region_index =
958 (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
959 if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
960 _coarse_cur_region_cur_card = 0;
961 HeapWord* r_bot =
962 _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
963 _cur_region_card_offset = _bosa->index_for(r_bot);
964 } else {
965 return false;
966 }
967 }
968 // If we didn't return false above, then we can yield a card.
969 card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
970 return true;
971 }
972
973 void HeapRegionRemSetIterator::fine_find_next_non_null_prt() {
974 // Otherwise, find the next bucket list in the array.
975 _fine_array_index++;
976 while (_fine_array_index < (int) OtherRegionsTable::_max_fine_entries) {
977 _fine_cur_prt = _fine_grain_regions[_fine_array_index];
978 if (_fine_cur_prt != NULL) return;
979 else _fine_array_index++;
980 }
981 assert(_fine_cur_prt == NULL, "Loop post");
982 }
983
984 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
985 if (fine_has_next()) {
986 _cur_region_cur_card =
987 _fine_cur_prt->_bm.get_next_one_offset(_cur_region_cur_card + 1);
988 }
989 while (!fine_has_next()) {
990 if (_cur_region_cur_card == (size_t) HeapRegion::CardsPerRegion) {
991 _cur_region_cur_card = 0;
992 _fine_cur_prt = _fine_cur_prt->collision_list_next();
993 }
994 if (_fine_cur_prt == NULL) {
995 fine_find_next_non_null_prt();
996 if (_fine_cur_prt == NULL) return false;
997 }
998 assert(_fine_cur_prt != NULL && _cur_region_cur_card == 0,
999 "inv.");
1000 HeapWord* r_bot =
1001 _fine_cur_prt->hr()->bottom();
1002 _cur_region_card_offset = _bosa->index_for(r_bot);
1003 _cur_region_cur_card = _fine_cur_prt->_bm.get_next_one_offset(0);
1004 }
1005 assert(fine_has_next(), "Or else we exited the loop via the return.");
1006 card_index = _cur_region_card_offset + _cur_region_cur_card;
1007 return true;
1008 }
1009
1010 bool HeapRegionRemSetIterator::fine_has_next() {
1011 return
1012 _fine_cur_prt != NULL &&
1013 _cur_region_cur_card < HeapRegion::CardsPerRegion;
1014 }
1015
1016 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
1017 switch (_is) {
1018 case Sparse:
1019 if (_sparse_iter.has_next(card_index)) {
1020 _n_yielded_sparse++;
1021 return true;
1022 }
1023 // Otherwise, deliberate fall-through
1024 _is = Fine;
1025 case Fine:
1026 if (fine_has_next(card_index)) {
1027 _n_yielded_fine++;
1028 return true;
1029 }
1030 // Otherwise, deliberate fall-through
1031 _is = Coarse;
1032 case Coarse:
1033 if (coarse_has_next(card_index)) {
1034 _n_yielded_coarse++;
1035 return true;
1036 }
1037 // Otherwise...
1038 break;
1039 }
1040 assert(ParallelGCThreads > 1 ||
1041 n_yielded() == _hrrs->occupied(),
1042 "Should have yielded all the cards in the rem set "
1043 "(in the non-par case).");
1044 return false;
1045 }
1046
1047
1048
1049 OopOrNarrowOopStar* HeapRegionRemSet::_recorded_oops = NULL;
1050 HeapWord** HeapRegionRemSet::_recorded_cards = NULL;
1051 HeapRegion** HeapRegionRemSet::_recorded_regions = NULL;
1052 int HeapRegionRemSet::_n_recorded = 0;
1053
1054 HeapRegionRemSet::Event* HeapRegionRemSet::_recorded_events = NULL;
1055 int* HeapRegionRemSet::_recorded_event_index = NULL;
1056 int HeapRegionRemSet::_n_recorded_events = 0;
1057
1058 void HeapRegionRemSet::record(HeapRegion* hr, OopOrNarrowOopStar f) {
1059 if (_recorded_oops == NULL) {
1060 assert(_n_recorded == 0
1061 && _recorded_cards == NULL
1062 && _recorded_regions == NULL,
1063 "Inv");
1064 _recorded_oops = NEW_C_HEAP_ARRAY(OopOrNarrowOopStar, MaxRecorded, mtGC);
1065 _recorded_cards = NEW_C_HEAP_ARRAY(HeapWord*, MaxRecorded, mtGC);
1066 _recorded_regions = NEW_C_HEAP_ARRAY(HeapRegion*, MaxRecorded, mtGC);
1067 }
1068 if (_n_recorded == MaxRecorded) {
1069 gclog_or_tty->print_cr("Filled up 'recorded' (%d).", MaxRecorded);
1070 } else {
1071 _recorded_cards[_n_recorded] =
1072 (HeapWord*)align_size_down(uintptr_t(f),
1073 CardTableModRefBS::card_size);
1074 _recorded_oops[_n_recorded] = f;
1075 _recorded_regions[_n_recorded] = hr;
1076 _n_recorded++;
1077 }
1078 }
1079
1080 void HeapRegionRemSet::record_event(Event evnt) {
1081 if (!G1RecordHRRSEvents) return;
1082
1083 if (_recorded_events == NULL) {
1084 assert(_n_recorded_events == 0
1085 && _recorded_event_index == NULL,
1086 "Inv");
1087 _recorded_events = NEW_C_HEAP_ARRAY(Event, MaxRecordedEvents, mtGC);
1088 _recorded_event_index = NEW_C_HEAP_ARRAY(int, MaxRecordedEvents, mtGC);
1089 }
1090 if (_n_recorded_events == MaxRecordedEvents) {
1091 gclog_or_tty->print_cr("Filled up 'recorded_events' (%d).", MaxRecordedEvents);
1092 } else {
1093 _recorded_events[_n_recorded_events] = evnt;
1094 _recorded_event_index[_n_recorded_events] = _n_recorded;
1095 _n_recorded_events++;
1096 }
1097 }
1098
1099 void HeapRegionRemSet::print_event(outputStream* str, Event evnt) {
1100 switch (evnt) {
1101 case Event_EvacStart:
1102 str->print("Evac Start");
1103 break;
1104 case Event_EvacEnd:
1105 str->print("Evac End");
1106 break;
1107 case Event_RSUpdateEnd:
1108 str->print("RS Update End");
1109 break;
1110 }
1111 }
1112
1113 void HeapRegionRemSet::print_recorded() {
1114 int cur_evnt = 0;
1115 Event cur_evnt_kind;
1116 int cur_evnt_ind = 0;
1117 if (_n_recorded_events > 0) {
1118 cur_evnt_kind = _recorded_events[cur_evnt];
1119 cur_evnt_ind = _recorded_event_index[cur_evnt];
1120 }
1121
1122 for (int i = 0; i < _n_recorded; i++) {
1123 while (cur_evnt < _n_recorded_events && i == cur_evnt_ind) {
1124 gclog_or_tty->print("Event: ");
1125 print_event(gclog_or_tty, cur_evnt_kind);
1126 gclog_or_tty->print_cr("");
1127 cur_evnt++;
1128 if (cur_evnt < MaxRecordedEvents) {
1129 cur_evnt_kind = _recorded_events[cur_evnt];
1130 cur_evnt_ind = _recorded_event_index[cur_evnt];
1131 }
1132 }
1133 gclog_or_tty->print("Added card " PTR_FORMAT " to region [" PTR_FORMAT "...]"
1134 " for ref " PTR_FORMAT ".\n",
1135 _recorded_cards[i], _recorded_regions[i]->bottom(),
1136 _recorded_oops[i]);
1137 }
1138 }
1139
1140 void HeapRegionRemSet::reset_for_cleanup_tasks() {
1141 SparsePRT::reset_for_cleanup_tasks();
1142 }
1143
1144 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
1145 _other_regions.do_cleanup_work(hrrs_cleanup_task);
1146 }
1147
1148 void
1149 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
1150 SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
1151 }
1152
1153 #ifndef PRODUCT
1154 void PerRegionTable::test_fl_mem_size() {
1155 PerRegionTable* dummy = alloc(NULL);
1156 free(dummy);
1157 guarantee(dummy->mem_size() == fl_mem_size(), "fl_mem_size() does not return the correct element size");
1158 // try to reset the state
1159 _free_list = NULL;
1160 delete dummy;
1161 }
1162
1163 void HeapRegionRemSet::test_prt() {
1164 PerRegionTable::test_fl_mem_size();
1165 }
1166
1167 void HeapRegionRemSet::test() {
1168 os::sleep(Thread::current(), (jlong)5000, false);
1169 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1170
1171 // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
1172 // hash bucket.
1173 HeapRegion* hr0 = g1h->region_at(0);
1174 HeapRegion* hr1 = g1h->region_at(1);
1175 HeapRegion* hr2 = g1h->region_at(5);
1176 HeapRegion* hr3 = g1h->region_at(6);
1177 HeapRegion* hr4 = g1h->region_at(7);
1178 HeapRegion* hr5 = g1h->region_at(8);
1179
1180 HeapWord* hr1_start = hr1->bottom();
1181 HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
1182 HeapWord* hr1_last = hr1->end() - 1;
1183
1184 HeapWord* hr2_start = hr2->bottom();
1185 HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
1186 HeapWord* hr2_last = hr2->end() - 1;
1187
1188 HeapWord* hr3_start = hr3->bottom();
1189 HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
1190 HeapWord* hr3_last = hr3->end() - 1;
1191
1192 HeapRegionRemSet* hrrs = hr0->rem_set();
1193
1194 // Make three references from region 0x101...
1195 hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
1196 hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
1197 hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
1198
1199 hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
1200 hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
1201 hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
1202
1203 hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
1204 hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
1205 hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
1206
1207 // Now cause a coarsening.
1208 hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
1209 hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
1210
1211 // Now, does iteration yield these three?
1212 HeapRegionRemSetIterator iter(hrrs);
1213 size_t sum = 0;
1214 size_t card_index;
1215 while (iter.has_next(card_index)) {
1216 HeapWord* card_start =
1217 G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
1218 gclog_or_tty->print_cr(" Card " PTR_FORMAT ".", card_start);
1219 sum++;
1220 }
1221 guarantee(sum == 11 - 3 + 2048, "Failure");
1222 guarantee(sum == hrrs->occupied(), "Failure");
1223 }
1224 #endif