1/*
2 * Copyright (c) 2001, 2019, 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.
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23 */
24
25#include "precompiled.hpp"
26#include "gc/g1/g1BlockOffsetTable.inline.hpp"
27#include "gc/g1/g1CollectedHeap.inline.hpp"
28#include "gc/g1/g1ConcurrentRefine.hpp"
29#include "gc/g1/heapRegionManager.inline.hpp"
30#include "gc/g1/heapRegionRemSet.hpp"
31#include "gc/shared/space.inline.hpp"
32#include "memory/allocation.hpp"
33#include "memory/padded.inline.hpp"
34#include "oops/oop.inline.hpp"
35#include "runtime/atomic.hpp"
36#include "utilities/bitMap.inline.hpp"
37#include "utilities/debug.hpp"
38#include "utilities/formatBuffer.hpp"
39#include "utilities/globalDefinitions.hpp"
40#include "utilities/growableArray.hpp"
41
42const char* HeapRegionRemSet::_state_strings[] = {"Untracked", "Updating", "Complete"};
43const char* HeapRegionRemSet::_short_state_strings[] = {"UNTRA", "UPDAT", "CMPLT"};
44
45class PerRegionTable: public CHeapObj<mtGC> {
46 friend class OtherRegionsTable;
47 friend class HeapRegionRemSetIterator;
48
49 HeapRegion* _hr;
50 CHeapBitMap _bm;
51 jint _occupied;
52
53 // next pointer for free/allocated 'all' list
54 PerRegionTable* _next;
55
56 // prev pointer for the allocated 'all' list
57 PerRegionTable* _prev;
58
59 // next pointer in collision list
60 PerRegionTable * _collision_list_next;
61
62 // Global free list of PRTs
63 static PerRegionTable* volatile _free_list;
64
65protected:
66 // We need access in order to union things into the base table.
67 BitMap* bm() { return &_bm; }
68
69 PerRegionTable(HeapRegion* hr) :
70 _hr(hr),
71 _bm(HeapRegion::CardsPerRegion, mtGC),
72 _occupied(0),
73 _next(NULL), _prev(NULL),
74 _collision_list_next(NULL)
75 {}
76
77 void add_card_work(CardIdx_t from_card, bool par) {
78 if (!_bm.at(from_card)) {
79 if (par) {
80 if (_bm.par_at_put(from_card, 1)) {
81 Atomic::inc(&_occupied);
82 }
83 } else {
84 _bm.at_put(from_card, 1);
85 _occupied++;
86 }
87 }
88 }
89
90 void add_reference_work(OopOrNarrowOopStar from, bool par) {
91 // Must make this robust in case "from" is not in "_hr", because of
92 // concurrency.
93
94 HeapRegion* loc_hr = hr();
95 // If the test below fails, then this table was reused concurrently
96 // with this operation. This is OK, since the old table was coarsened,
97 // and adding a bit to the new table is never incorrect.
98 if (loc_hr->is_in_reserved(from)) {
99 CardIdx_t from_card = OtherRegionsTable::card_within_region(from, loc_hr);
100 add_card_work(from_card, par);
101 }
102 }
103
104public:
105
106 HeapRegion* hr() const { return OrderAccess::load_acquire(&_hr); }
107
108 jint occupied() const {
109 // Overkill, but if we ever need it...
110 // guarantee(_occupied == _bm.count_one_bits(), "Check");
111 return _occupied;
112 }
113
114 void init(HeapRegion* hr, bool clear_links_to_all_list) {
115 if (clear_links_to_all_list) {
116 set_next(NULL);
117 set_prev(NULL);
118 }
119 _collision_list_next = NULL;
120 _occupied = 0;
121 _bm.clear();
122 // Make sure that the bitmap clearing above has been finished before publishing
123 // this PRT to concurrent threads.
124 OrderAccess::release_store(&_hr, hr);
125 }
126
127 void add_reference(OopOrNarrowOopStar from) {
128 add_reference_work(from, /*parallel*/ true);
129 }
130
131 void seq_add_reference(OopOrNarrowOopStar from) {
132 add_reference_work(from, /*parallel*/ false);
133 }
134
135 void add_card(CardIdx_t from_card_index) {
136 add_card_work(from_card_index, /*parallel*/ true);
137 }
138
139 void seq_add_card(CardIdx_t from_card_index) {
140 add_card_work(from_card_index, /*parallel*/ false);
141 }
142
143 // (Destructively) union the bitmap of the current table into the given
144 // bitmap (which is assumed to be of the same size.)
145 void union_bitmap_into(BitMap* bm) {
146 bm->set_union(_bm);
147 }
148
149 // Mem size in bytes.
150 size_t mem_size() const {
151 return sizeof(PerRegionTable) + _bm.size_in_words() * HeapWordSize;
152 }
153
154 // Requires "from" to be in "hr()".
155 bool contains_reference(OopOrNarrowOopStar from) const {
156 assert(hr()->is_in_reserved(from), "Precondition.");
157 size_t card_ind = pointer_delta(from, hr()->bottom(),
158 G1CardTable::card_size);
159 return _bm.at(card_ind);
160 }
161
162 // Bulk-free the PRTs from prt to last, assumes that they are
163 // linked together using their _next field.
164 static void bulk_free(PerRegionTable* prt, PerRegionTable* last) {
165 while (true) {
166 PerRegionTable* fl = _free_list;
167 last->set_next(fl);
168 PerRegionTable* res = Atomic::cmpxchg(prt, &_free_list, fl);
169 if (res == fl) {
170 return;
171 }
172 }
173 ShouldNotReachHere();
174 }
175
176 static void free(PerRegionTable* prt) {
177 bulk_free(prt, prt);
178 }
179
180 // Returns an initialized PerRegionTable instance.
181 static PerRegionTable* alloc(HeapRegion* hr) {
182 PerRegionTable* fl = _free_list;
183 while (fl != NULL) {
184 PerRegionTable* nxt = fl->next();
185 PerRegionTable* res = Atomic::cmpxchg(nxt, &_free_list, fl);
186 if (res == fl) {
187 fl->init(hr, true);
188 return fl;
189 } else {
190 fl = _free_list;
191 }
192 }
193 assert(fl == NULL, "Loop condition.");
194 return new PerRegionTable(hr);
195 }
196
197 PerRegionTable* next() const { return _next; }
198 void set_next(PerRegionTable* next) { _next = next; }
199 PerRegionTable* prev() const { return _prev; }
200 void set_prev(PerRegionTable* prev) { _prev = prev; }
201
202 // Accessor and Modification routines for the pointer for the
203 // singly linked collision list that links the PRTs within the
204 // OtherRegionsTable::_fine_grain_regions hash table.
205 //
206 // It might be useful to also make the collision list doubly linked
207 // to avoid iteration over the collisions list during scrubbing/deletion.
208 // OTOH there might not be many collisions.
209
210 PerRegionTable* collision_list_next() const {
211 return _collision_list_next;
212 }
213
214 void set_collision_list_next(PerRegionTable* next) {
215 _collision_list_next = next;
216 }
217
218 PerRegionTable** collision_list_next_addr() {
219 return &_collision_list_next;
220 }
221
222 static size_t fl_mem_size() {
223 PerRegionTable* cur = _free_list;
224 size_t res = 0;
225 while (cur != NULL) {
226 res += cur->mem_size();
227 cur = cur->next();
228 }
229 return res;
230 }
231
232 static void test_fl_mem_size();
233};
234
235PerRegionTable* volatile PerRegionTable::_free_list = NULL;
236
237size_t OtherRegionsTable::_max_fine_entries = 0;
238size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
239size_t OtherRegionsTable::_fine_eviction_stride = 0;
240size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
241
242OtherRegionsTable::OtherRegionsTable(Mutex* m) :
243 _g1h(G1CollectedHeap::heap()),
244 _m(m),
245 _coarse_map(G1CollectedHeap::heap()->max_regions(), mtGC),
246 _n_coarse_entries(0),
247 _fine_grain_regions(NULL),
248 _n_fine_entries(0),
249 _first_all_fine_prts(NULL),
250 _last_all_fine_prts(NULL),
251 _fine_eviction_start(0),
252 _sparse_table()
253{
254 typedef PerRegionTable* PerRegionTablePtr;
255
256 if (_max_fine_entries == 0) {
257 assert(_mod_max_fine_entries_mask == 0, "Both or none.");
258 size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
259 _max_fine_entries = (size_t)1 << max_entries_log;
260 _mod_max_fine_entries_mask = _max_fine_entries - 1;
261
262 assert(_fine_eviction_sample_size == 0
263 && _fine_eviction_stride == 0, "All init at same time.");
264 _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
265 _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
266 }
267
268 _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
269 mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
270
271 if (_fine_grain_regions == NULL) {
272 vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
273 "Failed to allocate _fine_grain_entries.");
274 }
275
276 for (size_t i = 0; i < _max_fine_entries; i++) {
277 _fine_grain_regions[i] = NULL;
278 }
279}
280
281void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
282 // We always append to the beginning of the list for convenience;
283 // the order of entries in this list does not matter.
284 if (_first_all_fine_prts != NULL) {
285 assert(_first_all_fine_prts->prev() == NULL, "invariant");
286 _first_all_fine_prts->set_prev(prt);
287 prt->set_next(_first_all_fine_prts);
288 } else {
289 // this is the first element we insert. Adjust the "last" pointer
290 _last_all_fine_prts = prt;
291 assert(prt->next() == NULL, "just checking");
292 }
293 // the new element is always the first element without a predecessor
294 prt->set_prev(NULL);
295 _first_all_fine_prts = prt;
296
297 assert(prt->prev() == NULL, "just checking");
298 assert(_first_all_fine_prts == prt, "just checking");
299 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
300 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
301 "just checking");
302 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
303 "just checking");
304 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
305 "just checking");
306}
307
308void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
309 if (prt->prev() != NULL) {
310 assert(_first_all_fine_prts != prt, "just checking");
311 prt->prev()->set_next(prt->next());
312 // removing the last element in the list?
313 if (_last_all_fine_prts == prt) {
314 _last_all_fine_prts = prt->prev();
315 }
316 } else {
317 assert(_first_all_fine_prts == prt, "just checking");
318 _first_all_fine_prts = prt->next();
319 // list is empty now?
320 if (_first_all_fine_prts == NULL) {
321 _last_all_fine_prts = NULL;
322 }
323 }
324
325 if (prt->next() != NULL) {
326 prt->next()->set_prev(prt->prev());
327 }
328
329 prt->set_next(NULL);
330 prt->set_prev(NULL);
331
332 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
333 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
334 "just checking");
335 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
336 "just checking");
337 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
338 "just checking");
339}
340
341CardIdx_t OtherRegionsTable::card_within_region(OopOrNarrowOopStar within_region, HeapRegion* hr) {
342 assert(hr->is_in_reserved(within_region),
343 "HeapWord " PTR_FORMAT " is outside of region %u [" PTR_FORMAT ", " PTR_FORMAT ")",
344 p2i(within_region), hr->hrm_index(), p2i(hr->bottom()), p2i(hr->end()));
345 CardIdx_t result = (CardIdx_t)(pointer_delta((HeapWord*)within_region, hr->bottom()) >> (CardTable::card_shift - LogHeapWordSize));
346 return result;
347}
348
349void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
350 // Note that this may be a continued H region.
351 HeapRegion* from_hr = _g1h->heap_region_containing(from);
352 RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
353
354 // If the region is already coarsened, return.
355 if (_coarse_map.at(from_hrm_ind)) {
356 assert(contains_reference(from), "We just found " PTR_FORMAT " in the Coarse table", p2i(from));
357 return;
358 }
359
360 // Otherwise find a per-region table to add it to.
361 size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
362 PerRegionTable* prt = find_region_table(ind, from_hr);
363 if (prt == NULL) {
364 MutexLocker x(_m, Mutex::_no_safepoint_check_flag);
365 // Confirm that it's really not there...
366 prt = find_region_table(ind, from_hr);
367 if (prt == NULL) {
368
369 CardIdx_t card_index = card_within_region(from, from_hr);
370
371 if (_sparse_table.add_card(from_hrm_ind, card_index)) {
372 assert(contains_reference_locked(from), "We just added " PTR_FORMAT " to the Sparse table", p2i(from));
373 return;
374 }
375
376 if (_n_fine_entries == _max_fine_entries) {
377 prt = delete_region_table();
378 // There is no need to clear the links to the 'all' list here:
379 // prt will be reused immediately, i.e. remain in the 'all' list.
380 prt->init(from_hr, false /* clear_links_to_all_list */);
381 } else {
382 prt = PerRegionTable::alloc(from_hr);
383 link_to_all(prt);
384 }
385
386 PerRegionTable* first_prt = _fine_grain_regions[ind];
387 prt->set_collision_list_next(first_prt);
388 // The assignment into _fine_grain_regions allows the prt to
389 // start being used concurrently. In addition to
390 // collision_list_next which must be visible (else concurrent
391 // parsing of the list, if any, may fail to see other entries),
392 // the content of the prt must be visible (else for instance
393 // some mark bits may not yet seem cleared or a 'later' update
394 // performed by a concurrent thread could be undone when the
395 // zeroing becomes visible). This requires store ordering.
396 OrderAccess::release_store(&_fine_grain_regions[ind], prt);
397 _n_fine_entries++;
398
399 // Transfer from sparse to fine-grain.
400 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
401 assert(sprt_entry != NULL, "There should have been an entry");
402 for (int i = 0; i < sprt_entry->num_valid_cards(); i++) {
403 CardIdx_t c = sprt_entry->card(i);
404 prt->add_card(c);
405 }
406 // Now we can delete the sparse entry.
407 bool res = _sparse_table.delete_entry(from_hrm_ind);
408 assert(res, "It should have been there.");
409 }
410 assert(prt != NULL && prt->hr() == from_hr, "consequence");
411 }
412 // Note that we can't assert "prt->hr() == from_hr", because of the
413 // possibility of concurrent reuse. But see head comment of
414 // OtherRegionsTable for why this is OK.
415 assert(prt != NULL, "Inv");
416
417 prt->add_reference(from);
418 assert(contains_reference(from), "We just added " PTR_FORMAT " to the PRT (%d)", p2i(from), prt->contains_reference(from));
419}
420
421PerRegionTable*
422OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
423 assert(ind < _max_fine_entries, "Preconditions.");
424 PerRegionTable* prt = _fine_grain_regions[ind];
425 while (prt != NULL && prt->hr() != hr) {
426 prt = prt->collision_list_next();
427 }
428 // Loop postcondition is the method postcondition.
429 return prt;
430}
431
432jint OtherRegionsTable::_n_coarsenings = 0;
433
434PerRegionTable* OtherRegionsTable::delete_region_table() {
435 assert(_m->owned_by_self(), "Precondition");
436 assert(_n_fine_entries == _max_fine_entries, "Precondition");
437 PerRegionTable* max = NULL;
438 jint max_occ = 0;
439 PerRegionTable** max_prev = NULL;
440 size_t max_ind;
441
442 size_t i = _fine_eviction_start;
443 for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
444 size_t ii = i;
445 // Make sure we get a non-NULL sample.
446 while (_fine_grain_regions[ii] == NULL) {
447 ii++;
448 if (ii == _max_fine_entries) ii = 0;
449 guarantee(ii != i, "We must find one.");
450 }
451 PerRegionTable** prev = &_fine_grain_regions[ii];
452 PerRegionTable* cur = *prev;
453 while (cur != NULL) {
454 jint cur_occ = cur->occupied();
455 if (max == NULL || cur_occ > max_occ) {
456 max = cur;
457 max_prev = prev;
458 max_ind = i;
459 max_occ = cur_occ;
460 }
461 prev = cur->collision_list_next_addr();
462 cur = cur->collision_list_next();
463 }
464 i = i + _fine_eviction_stride;
465 if (i >= _n_fine_entries) i = i - _n_fine_entries;
466 }
467
468 _fine_eviction_start++;
469
470 if (_fine_eviction_start >= _n_fine_entries) {
471 _fine_eviction_start -= _n_fine_entries;
472 }
473
474 guarantee(max != NULL, "Since _n_fine_entries > 0");
475 guarantee(max_prev != NULL, "Since max != NULL.");
476
477 // Set the corresponding coarse bit.
478 size_t max_hrm_index = (size_t) max->hr()->hrm_index();
479 if (!_coarse_map.at(max_hrm_index)) {
480 _coarse_map.at_put(max_hrm_index, true);
481 _n_coarse_entries++;
482 }
483
484 // Unsplice.
485 *max_prev = max->collision_list_next();
486 Atomic::inc(&_n_coarsenings);
487 _n_fine_entries--;
488 return max;
489}
490
491bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {
492 if (limit <= (size_t)G1RSetSparseRegionEntries) {
493 return occ_coarse() == 0 && _first_all_fine_prts == NULL && occ_sparse() <= limit;
494 } else {
495 // Current uses of this method may only use values less than G1RSetSparseRegionEntries
496 // for the limit. The solution, comparing against occupied() would be too slow
497 // at this time.
498 Unimplemented();
499 return false;
500 }
501}
502
503bool OtherRegionsTable::is_empty() const {
504 return occ_sparse() == 0 && occ_coarse() == 0 && _first_all_fine_prts == NULL;
505}
506
507size_t OtherRegionsTable::occupied() const {
508 size_t sum = occ_fine();
509 sum += occ_sparse();
510 sum += occ_coarse();
511 return sum;
512}
513
514size_t OtherRegionsTable::occ_fine() const {
515 size_t sum = 0;
516
517 size_t num = 0;
518 PerRegionTable * cur = _first_all_fine_prts;
519 while (cur != NULL) {
520 sum += cur->occupied();
521 cur = cur->next();
522 num++;
523 }
524 guarantee(num == _n_fine_entries, "just checking");
525 return sum;
526}
527
528size_t OtherRegionsTable::occ_coarse() const {
529 return (_n_coarse_entries * HeapRegion::CardsPerRegion);
530}
531
532size_t OtherRegionsTable::occ_sparse() const {
533 return _sparse_table.occupied();
534}
535
536size_t OtherRegionsTable::mem_size() const {
537 size_t sum = 0;
538 // all PRTs are of the same size so it is sufficient to query only one of them.
539 if (_first_all_fine_prts != NULL) {
540 assert(_last_all_fine_prts != NULL &&
541 _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
542 sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
543 }
544 sum += (sizeof(PerRegionTable*) * _max_fine_entries);
545 sum += (_coarse_map.size_in_words() * HeapWordSize);
546 sum += (_sparse_table.mem_size());
547 sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
548 return sum;
549}
550
551size_t OtherRegionsTable::static_mem_size() {
552 return G1FromCardCache::static_mem_size();
553}
554
555size_t OtherRegionsTable::fl_mem_size() {
556 return PerRegionTable::fl_mem_size();
557}
558
559void OtherRegionsTable::clear() {
560 // if there are no entries, skip this step
561 if (_first_all_fine_prts != NULL) {
562 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
563 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
564 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
565 } else {
566 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
567 }
568
569 _first_all_fine_prts = _last_all_fine_prts = NULL;
570 _sparse_table.clear();
571 if (_n_coarse_entries > 0) {
572 _coarse_map.clear();
573 }
574 _n_fine_entries = 0;
575 _n_coarse_entries = 0;
576}
577
578bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
579 // Cast away const in this case.
580 MutexLocker x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
581 return contains_reference_locked(from);
582}
583
584bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
585 HeapRegion* hr = _g1h->heap_region_containing(from);
586 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
587 // Is this region in the coarse map?
588 if (_coarse_map.at(hr_ind)) return true;
589
590 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
591 hr);
592 if (prt != NULL) {
593 return prt->contains_reference(from);
594
595 } else {
596 CardIdx_t card_index = card_within_region(from, hr);
597 return _sparse_table.contains_card(hr_ind, card_index);
598 }
599}
600
601HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetTable* bot,
602 HeapRegion* hr)
603 : _bot(bot),
604 _code_roots(),
605 _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Monitor::_safepoint_check_never),
606 _other_regions(&_m),
607 _hr(hr),
608 _state(Untracked)
609{
610}
611
612void HeapRegionRemSet::clear_fcc() {
613 G1FromCardCache::clear(_hr->hrm_index());
614}
615
616void HeapRegionRemSet::setup_remset_size() {
617 const int LOG_M = 20;
618 guarantee(HeapRegion::LogOfHRGrainBytes >= LOG_M, "Code assumes the region size >= 1M, but is " SIZE_FORMAT "B", HeapRegion::GrainBytes);
619
620 int region_size_log_mb = HeapRegion::LogOfHRGrainBytes - LOG_M;
621 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
622 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * ((size_t)1 << (region_size_log_mb + 1));
623 }
624 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
625 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
626 }
627 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
628}
629
630void HeapRegionRemSet::clear(bool only_cardset) {
631 MutexLocker x(&_m, Mutex::_no_safepoint_check_flag);
632 clear_locked(only_cardset);
633}
634
635void HeapRegionRemSet::clear_locked(bool only_cardset) {
636 if (!only_cardset) {
637 _code_roots.clear();
638 }
639 clear_fcc();
640 _other_regions.clear();
641 set_state_empty();
642 assert(occupied_locked() == 0, "Should be clear.");
643}
644
645// Code roots support
646//
647// The code root set is protected by two separate locking schemes
648// When at safepoint the per-hrrs lock must be held during modifications
649// except when doing a full gc.
650// When not at safepoint the CodeCache_lock must be held during modifications.
651// When concurrent readers access the contains() function
652// (during the evacuation phase) no removals are allowed.
653
654void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
655 assert(nm != NULL, "sanity");
656 assert((!CodeCache_lock->owned_by_self() || SafepointSynchronize::is_at_safepoint()),
657 "should call add_strong_code_root_locked instead. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s",
658 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()));
659 // Optimistic unlocked contains-check
660 if (!_code_roots.contains(nm)) {
661 MutexLocker ml(&_m, Mutex::_no_safepoint_check_flag);
662 add_strong_code_root_locked(nm);
663 }
664}
665
666void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
667 assert(nm != NULL, "sanity");
668 assert((CodeCache_lock->owned_by_self() ||
669 (SafepointSynchronize::is_at_safepoint() &&
670 (_m.owned_by_self() || Thread::current()->is_VM_thread()))),
671 "not safely locked. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s, _m.owned_by_self(): %s, Thread::current()->is_VM_thread(): %s",
672 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),
673 BOOL_TO_STR(_m.owned_by_self()), BOOL_TO_STR(Thread::current()->is_VM_thread()));
674 _code_roots.add(nm);
675}
676
677void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
678 assert(nm != NULL, "sanity");
679 assert_locked_or_safepoint(CodeCache_lock);
680
681 MutexLocker ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
682 _code_roots.remove(nm);
683
684 // Check that there were no duplicates
685 guarantee(!_code_roots.contains(nm), "duplicate entry found");
686}
687
688void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
689 _code_roots.nmethods_do(blk);
690}
691
692void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
693 _code_roots.clean(hr);
694}
695
696size_t HeapRegionRemSet::strong_code_roots_mem_size() {
697 return _code_roots.mem_size();
698}
699
700HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
701 _hrrs(hrrs),
702 _coarse_map(&hrrs->_other_regions._coarse_map),
703 _bot(hrrs->_bot),
704 _g1h(G1CollectedHeap::heap()),
705 _n_yielded_fine(0),
706 _n_yielded_coarse(0),
707 _n_yielded_sparse(0),
708 _is(Sparse),
709 _cur_region_card_offset(0),
710 // Set these values so that we increment to the first region.
711 _coarse_cur_region_index(-1),
712 _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
713 _fine_cur_prt(NULL),
714 _cur_card_in_prt(HeapRegion::CardsPerRegion),
715 _sparse_iter(&hrrs->_other_regions._sparse_table) {}
716
717bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
718 if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
719 // Go to the next card.
720 _coarse_cur_region_cur_card++;
721 // Was the last the last card in the current region?
722 if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
723 // Yes: find the next region. This may leave _coarse_cur_region_index
724 // Set to the last index, in which case there are no more coarse
725 // regions.
726 _coarse_cur_region_index =
727 (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
728 if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
729 _coarse_cur_region_cur_card = 0;
730 HeapWord* r_bot =
731 _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
732 _cur_region_card_offset = _bot->index_for_raw(r_bot);
733 } else {
734 return false;
735 }
736 }
737 // If we didn't return false above, then we can yield a card.
738 card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
739 return true;
740}
741
742bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
743 if (fine_has_next()) {
744 _cur_card_in_prt =
745 _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
746 }
747 if (_cur_card_in_prt == HeapRegion::CardsPerRegion) {
748 // _fine_cur_prt may still be NULL in case if there are not PRTs at all for
749 // the remembered set.
750 if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) {
751 return false;
752 }
753 PerRegionTable* next_prt = _fine_cur_prt->next();
754 switch_to_prt(next_prt);
755 _cur_card_in_prt = _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
756 }
757
758 card_index = _cur_region_card_offset + _cur_card_in_prt;
759 guarantee(_cur_card_in_prt < HeapRegion::CardsPerRegion,
760 "Card index " SIZE_FORMAT " must be within the region", _cur_card_in_prt);
761 return true;
762}
763
764bool HeapRegionRemSetIterator::fine_has_next() {
765 return _cur_card_in_prt != HeapRegion::CardsPerRegion;
766}
767
768void HeapRegionRemSetIterator::switch_to_prt(PerRegionTable* prt) {
769 assert(prt != NULL, "Cannot switch to NULL prt");
770 _fine_cur_prt = prt;
771
772 HeapWord* r_bot = _fine_cur_prt->hr()->bottom();
773 _cur_region_card_offset = _bot->index_for_raw(r_bot);
774
775 // The bitmap scan for the PRT always scans from _cur_region_cur_card + 1.
776 // To avoid special-casing this start case, and not miss the first bitmap
777 // entry, initialize _cur_region_cur_card with -1 instead of 0.
778 _cur_card_in_prt = (size_t)-1;
779}
780
781bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
782 switch (_is) {
783 case Sparse: {
784 if (_sparse_iter.has_next(card_index)) {
785 _n_yielded_sparse++;
786 return true;
787 }
788 // Otherwise, deliberate fall-through
789 _is = Fine;
790 PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts;
791 if (initial_fine_prt != NULL) {
792 switch_to_prt(_hrrs->_other_regions._first_all_fine_prts);
793 }
794 }
795 case Fine:
796 if (fine_has_next(card_index)) {
797 _n_yielded_fine++;
798 return true;
799 }
800 // Otherwise, deliberate fall-through
801 _is = Coarse;
802 case Coarse:
803 if (coarse_has_next(card_index)) {
804 _n_yielded_coarse++;
805 return true;
806 }
807 // Otherwise...
808 break;
809 }
810 return false;
811}
812
813#ifndef PRODUCT
814void HeapRegionRemSet::test() {
815 os::sleep(Thread::current(), (jlong)5000, false);
816 G1CollectedHeap* g1h = G1CollectedHeap::heap();
817
818 // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
819 // hash bucket.
820 HeapRegion* hr0 = g1h->region_at(0);
821 HeapRegion* hr1 = g1h->region_at(1);
822 HeapRegion* hr2 = g1h->region_at(5);
823 HeapRegion* hr3 = g1h->region_at(6);
824 HeapRegion* hr4 = g1h->region_at(7);
825 HeapRegion* hr5 = g1h->region_at(8);
826
827 HeapWord* hr1_start = hr1->bottom();
828 HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
829 HeapWord* hr1_last = hr1->end() - 1;
830
831 HeapWord* hr2_start = hr2->bottom();
832 HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
833 HeapWord* hr2_last = hr2->end() - 1;
834
835 HeapWord* hr3_start = hr3->bottom();
836 HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
837 HeapWord* hr3_last = hr3->end() - 1;
838
839 HeapRegionRemSet* hrrs = hr0->rem_set();
840
841 // Make three references from region 0x101...
842 hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
843 hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
844 hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
845
846 hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
847 hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
848 hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
849
850 hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
851 hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
852 hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
853
854 // Now cause a coarsening.
855 hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
856 hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
857
858 // Now, does iteration yield these three?
859 HeapRegionRemSetIterator iter(hrrs);
860 size_t sum = 0;
861 size_t card_index;
862 while (iter.has_next(card_index)) {
863 HeapWord* card_start = g1h->bot()->address_for_index(card_index);
864 tty->print_cr(" Card " PTR_FORMAT ".", p2i(card_start));
865 sum++;
866 }
867 guarantee(sum == 11 - 3 + 2048, "Failure");
868 guarantee(sum == hrrs->occupied(), "Failure");
869}
870#endif
871