1 /*
2 * Copyright (c) 2001, 2018, 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/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
42 const char* HeapRegionRemSet::_state_strings[] = {"Untracked", "Updating", "Complete"};
43 const char* HeapRegionRemSet::_short_state_strings[] = {"UNTRA", "UPDAT", "CMPLT"};
44
45 class 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
65 protected:
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 _occupied(0),
72 _bm(HeapRegion::CardsPerRegion, mtGC),
73 _collision_list_next(NULL), _next(NULL), _prev(NULL)
74 {}
75
76 void add_card_work(CardIdx_t from_card, bool par) {
77 if (!_bm.at(from_card)) {
78 if (par) {
79 if (_bm.par_at_put(from_card, 1)) {
80 Atomic::inc(&_occupied);
81 }
82 } else {
83 _bm.at_put(from_card, 1);
84 _occupied++;
85 }
86 }
87 }
88
89 void add_reference_work(OopOrNarrowOopStar from, bool par) {
90 // Must make this robust in case "from" is not in "_hr", because of
91 // concurrency.
92
93 HeapRegion* loc_hr = hr();
94 // If the test below fails, then this table was reused concurrently
95 // with this operation. This is OK, since the old table was coarsened,
96 // and adding a bit to the new table is never incorrect.
97 if (loc_hr->is_in_reserved(from)) {
98 CardIdx_t from_card = OtherRegionsTable::card_within_region(from, loc_hr);
99 add_card_work(from_card, par);
100 }
101 }
102
103 public:
104
105 HeapRegion* hr() const { return OrderAccess::load_acquire(&_hr); }
106
107 jint occupied() const {
108 // Overkill, but if we ever need it...
109 // guarantee(_occupied == _bm.count_one_bits(), "Check");
110 return _occupied;
111 }
112
113 void init(HeapRegion* hr, bool clear_links_to_all_list) {
114 if (clear_links_to_all_list) {
115 set_next(NULL);
116 set_prev(NULL);
117 }
118 _collision_list_next = NULL;
119 _occupied = 0;
120 _bm.clear();
121 // Make sure that the bitmap clearing above has been finished before publishing
122 // this PRT to concurrent threads.
123 OrderAccess::release_store(&_hr, hr);
124 }
125
126 void add_reference(OopOrNarrowOopStar from) {
127 add_reference_work(from, /*parallel*/ true);
128 }
129
130 void seq_add_reference(OopOrNarrowOopStar from) {
131 add_reference_work(from, /*parallel*/ false);
132 }
133
134 void add_card(CardIdx_t from_card_index) {
135 add_card_work(from_card_index, /*parallel*/ true);
136 }
137
138 void seq_add_card(CardIdx_t from_card_index) {
139 add_card_work(from_card_index, /*parallel*/ false);
140 }
141
142 // (Destructively) union the bitmap of the current table into the given
143 // bitmap (which is assumed to be of the same size.)
144 void union_bitmap_into(BitMap* bm) {
145 bm->set_union(_bm);
146 }
147
148 // Mem size in bytes.
149 size_t mem_size() const {
150 return sizeof(PerRegionTable) + _bm.size_in_words() * HeapWordSize;
151 }
152
153 // Requires "from" to be in "hr()".
154 bool contains_reference(OopOrNarrowOopStar from) const {
155 assert(hr()->is_in_reserved(from), "Precondition.");
156 size_t card_ind = pointer_delta(from, hr()->bottom(),
157 G1CardTable::card_size);
158 return _bm.at(card_ind);
159 }
160
161 // Bulk-free the PRTs from prt to last, assumes that they are
162 // linked together using their _next field.
163 static void bulk_free(PerRegionTable* prt, PerRegionTable* last) {
164 while (true) {
165 PerRegionTable* fl = _free_list;
166 last->set_next(fl);
167 PerRegionTable* res = Atomic::cmpxchg(prt, &_free_list, fl);
168 if (res == fl) {
169 return;
170 }
171 }
172 ShouldNotReachHere();
173 }
174
175 static void free(PerRegionTable* prt) {
176 bulk_free(prt, prt);
177 }
178
179 // Returns an initialized PerRegionTable instance.
180 static PerRegionTable* alloc(HeapRegion* hr) {
181 PerRegionTable* fl = _free_list;
182 while (fl != NULL) {
183 PerRegionTable* nxt = fl->next();
184 PerRegionTable* res = Atomic::cmpxchg(nxt, &_free_list, fl);
185 if (res == fl) {
186 fl->init(hr, true);
187 return fl;
188 } else {
189 fl = _free_list;
190 }
191 }
192 assert(fl == NULL, "Loop condition.");
193 return new PerRegionTable(hr);
194 }
195
196 PerRegionTable* next() const { return _next; }
197 void set_next(PerRegionTable* next) { _next = next; }
198 PerRegionTable* prev() const { return _prev; }
199 void set_prev(PerRegionTable* prev) { _prev = prev; }
200
201 // Accessor and Modification routines for the pointer for the
202 // singly linked collision list that links the PRTs within the
203 // OtherRegionsTable::_fine_grain_regions hash table.
204 //
205 // It might be useful to also make the collision list doubly linked
206 // to avoid iteration over the collisions list during scrubbing/deletion.
207 // OTOH there might not be many collisions.
208
209 PerRegionTable* collision_list_next() const {
210 return _collision_list_next;
211 }
212
213 void set_collision_list_next(PerRegionTable* next) {
214 _collision_list_next = next;
215 }
216
217 PerRegionTable** collision_list_next_addr() {
218 return &_collision_list_next;
219 }
220
221 static size_t fl_mem_size() {
222 PerRegionTable* cur = _free_list;
223 size_t res = 0;
224 while (cur != NULL) {
225 res += cur->mem_size();
226 cur = cur->next();
227 }
228 return res;
229 }
230
231 static void test_fl_mem_size();
232 };
233
234 PerRegionTable* volatile PerRegionTable::_free_list = NULL;
235
236 size_t OtherRegionsTable::_max_fine_entries = 0;
237 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
238 size_t OtherRegionsTable::_fine_eviction_stride = 0;
239 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
240
241 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr, Mutex* m) :
242 _g1h(G1CollectedHeap::heap()),
243 _hr(hr), _m(m),
244 _coarse_map(G1CollectedHeap::heap()->max_regions(), mtGC),
245 _fine_grain_regions(NULL),
246 _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
247 _n_fine_entries(0), _n_coarse_entries(0),
248 _fine_eviction_start(0),
249 _sparse_table(hr)
250 {
251 typedef PerRegionTable* PerRegionTablePtr;
252
253 if (_max_fine_entries == 0) {
254 assert(_mod_max_fine_entries_mask == 0, "Both or none.");
255 size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
256 _max_fine_entries = (size_t)1 << max_entries_log;
257 _mod_max_fine_entries_mask = _max_fine_entries - 1;
258
259 assert(_fine_eviction_sample_size == 0
260 && _fine_eviction_stride == 0, "All init at same time.");
261 _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
262 _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
263 }
264
265 _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
266 mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
267
268 if (_fine_grain_regions == NULL) {
269 vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
270 "Failed to allocate _fine_grain_entries.");
271 }
272
273 for (size_t i = 0; i < _max_fine_entries; i++) {
274 _fine_grain_regions[i] = NULL;
275 }
276 }
277
278 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
279 // We always append to the beginning of the list for convenience;
280 // the order of entries in this list does not matter.
281 if (_first_all_fine_prts != NULL) {
282 assert(_first_all_fine_prts->prev() == NULL, "invariant");
283 _first_all_fine_prts->set_prev(prt);
284 prt->set_next(_first_all_fine_prts);
285 } else {
286 // this is the first element we insert. Adjust the "last" pointer
287 _last_all_fine_prts = prt;
288 assert(prt->next() == NULL, "just checking");
289 }
290 // the new element is always the first element without a predecessor
291 prt->set_prev(NULL);
292 _first_all_fine_prts = prt;
293
294 assert(prt->prev() == NULL, "just checking");
295 assert(_first_all_fine_prts == prt, "just checking");
296 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
297 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
298 "just checking");
299 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
300 "just checking");
301 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
302 "just checking");
303 }
304
305 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
306 if (prt->prev() != NULL) {
307 assert(_first_all_fine_prts != prt, "just checking");
308 prt->prev()->set_next(prt->next());
309 // removing the last element in the list?
310 if (_last_all_fine_prts == prt) {
311 _last_all_fine_prts = prt->prev();
312 }
313 } else {
314 assert(_first_all_fine_prts == prt, "just checking");
315 _first_all_fine_prts = prt->next();
316 // list is empty now?
317 if (_first_all_fine_prts == NULL) {
318 _last_all_fine_prts = NULL;
319 }
320 }
321
322 if (prt->next() != NULL) {
323 prt->next()->set_prev(prt->prev());
324 }
325
326 prt->set_next(NULL);
327 prt->set_prev(NULL);
328
329 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
330 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
331 "just checking");
332 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
333 "just checking");
334 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
335 "just checking");
336 }
337
338 CardIdx_t OtherRegionsTable::card_within_region(OopOrNarrowOopStar within_region, HeapRegion* hr) {
339 assert(hr->is_in_reserved(within_region),
340 "HeapWord " PTR_FORMAT " is outside of region %u [" PTR_FORMAT ", " PTR_FORMAT ")",
341 p2i(within_region), hr->hrm_index(), p2i(hr->bottom()), p2i(hr->end()));
342 CardIdx_t result = (CardIdx_t)(pointer_delta((HeapWord*)within_region, hr->bottom()) >> (CardTable::card_shift - LogHeapWordSize));
343 return result;
344 }
345
346 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
347 uint cur_hrm_ind = _hr->hrm_index();
348
349 uintptr_t from_card = uintptr_t(from) >> CardTable::card_shift;
350
351 if (G1FromCardCache::contains_or_replace(tid, cur_hrm_ind, from_card)) {
352 assert(contains_reference(from), "We just found " PTR_FORMAT " in the FromCardCache", p2i(from));
353 return;
354 }
355
356 // Note that this may be a continued H region.
357 HeapRegion* from_hr = _g1h->heap_region_containing(from);
358 RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
359
360 // If the region is already coarsened, return.
361 if (_coarse_map.at(from_hrm_ind)) {
362 assert(contains_reference(from), "We just found " PTR_FORMAT " in the Coarse table", p2i(from));
363 return;
364 }
365
366 // Otherwise find a per-region table to add it to.
367 size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
368 PerRegionTable* prt = find_region_table(ind, from_hr);
369 if (prt == NULL) {
370 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
371 // Confirm that it's really not there...
372 prt = find_region_table(ind, from_hr);
373 if (prt == NULL) {
374
375 CardIdx_t card_index = card_within_region(from, from_hr);
376
377 if (G1HRRSUseSparseTable &&
378 _sparse_table.add_card(from_hrm_ind, card_index)) {
379 assert(contains_reference_locked(from), "We just added " PTR_FORMAT " to the Sparse table", p2i(from));
380 return;
381 }
382
383 if (_n_fine_entries == _max_fine_entries) {
384 prt = delete_region_table();
385 // There is no need to clear the links to the 'all' list here:
386 // prt will be reused immediately, i.e. remain in the 'all' list.
387 prt->init(from_hr, false /* clear_links_to_all_list */);
388 } else {
389 prt = PerRegionTable::alloc(from_hr);
390 link_to_all(prt);
391 }
392
393 PerRegionTable* first_prt = _fine_grain_regions[ind];
394 prt->set_collision_list_next(first_prt);
395 // The assignment into _fine_grain_regions allows the prt to
396 // start being used concurrently. In addition to
397 // collision_list_next which must be visible (else concurrent
398 // parsing of the list, if any, may fail to see other entries),
399 // the content of the prt must be visible (else for instance
400 // some mark bits may not yet seem cleared or a 'later' update
401 // performed by a concurrent thread could be undone when the
402 // zeroing becomes visible). This requires store ordering.
403 OrderAccess::release_store(&_fine_grain_regions[ind], prt);
404 _n_fine_entries++;
405
406 if (G1HRRSUseSparseTable) {
407 // Transfer from sparse to fine-grain.
408 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
409 assert(sprt_entry != NULL, "There should have been an entry");
410 for (int i = 0; i < sprt_entry->num_valid_cards(); i++) {
411 CardIdx_t c = sprt_entry->card(i);
412 prt->add_card(c);
413 }
414 // Now we can delete the sparse entry.
415 bool res = _sparse_table.delete_entry(from_hrm_ind);
416 assert(res, "It should have been there.");
417 }
418 }
419 assert(prt != NULL && prt->hr() == from_hr, "consequence");
420 }
421 // Note that we can't assert "prt->hr() == from_hr", because of the
422 // possibility of concurrent reuse. But see head comment of
423 // OtherRegionsTable for why this is OK.
424 assert(prt != NULL, "Inv");
425
426 prt->add_reference(from);
427 assert(contains_reference(from), "We just added " PTR_FORMAT " to the PRT (%d)", p2i(from), prt->contains_reference(from));
428 }
429
430 PerRegionTable*
431 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
432 assert(ind < _max_fine_entries, "Preconditions.");
433 PerRegionTable* prt = _fine_grain_regions[ind];
434 while (prt != NULL && prt->hr() != hr) {
435 prt = prt->collision_list_next();
436 }
437 // Loop postcondition is the method postcondition.
438 return prt;
439 }
440
441 jint OtherRegionsTable::_n_coarsenings = 0;
442
443 PerRegionTable* OtherRegionsTable::delete_region_table() {
444 assert(_m->owned_by_self(), "Precondition");
445 assert(_n_fine_entries == _max_fine_entries, "Precondition");
446 PerRegionTable* max = NULL;
447 jint max_occ = 0;
448 PerRegionTable** max_prev = NULL;
449 size_t max_ind;
450
451 size_t i = _fine_eviction_start;
452 for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
453 size_t ii = i;
454 // Make sure we get a non-NULL sample.
455 while (_fine_grain_regions[ii] == NULL) {
456 ii++;
457 if (ii == _max_fine_entries) ii = 0;
458 guarantee(ii != i, "We must find one.");
459 }
460 PerRegionTable** prev = &_fine_grain_regions[ii];
461 PerRegionTable* cur = *prev;
462 while (cur != NULL) {
463 jint cur_occ = cur->occupied();
464 if (max == NULL || cur_occ > max_occ) {
465 max = cur;
466 max_prev = prev;
467 max_ind = i;
468 max_occ = cur_occ;
469 }
470 prev = cur->collision_list_next_addr();
471 cur = cur->collision_list_next();
472 }
473 i = i + _fine_eviction_stride;
474 if (i >= _n_fine_entries) i = i - _n_fine_entries;
475 }
476
477 _fine_eviction_start++;
478
479 if (_fine_eviction_start >= _n_fine_entries) {
480 _fine_eviction_start -= _n_fine_entries;
481 }
482
483 guarantee(max != NULL, "Since _n_fine_entries > 0");
484 guarantee(max_prev != NULL, "Since max != NULL.");
485
486 // Set the corresponding coarse bit.
487 size_t max_hrm_index = (size_t) max->hr()->hrm_index();
488 if (!_coarse_map.at(max_hrm_index)) {
489 _coarse_map.at_put(max_hrm_index, true);
490 _n_coarse_entries++;
491 }
492
493 // Unsplice.
494 *max_prev = max->collision_list_next();
495 Atomic::inc(&_n_coarsenings);
496 _n_fine_entries--;
497 return max;
498 }
499
500 bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {
501 if (limit <= (size_t)G1RSetSparseRegionEntries) {
502 return occ_coarse() == 0 && _first_all_fine_prts == NULL && occ_sparse() <= limit;
503 } else {
504 // Current uses of this method may only use values less than G1RSetSparseRegionEntries
505 // for the limit. The solution, comparing against occupied() would be too slow
506 // at this time.
507 Unimplemented();
508 return false;
509 }
510 }
511
512 bool OtherRegionsTable::is_empty() const {
513 return occ_sparse() == 0 && occ_coarse() == 0 && _first_all_fine_prts == NULL;
514 }
515
516 size_t OtherRegionsTable::occupied() const {
517 size_t sum = occ_fine();
518 sum += occ_sparse();
519 sum += occ_coarse();
520 return sum;
521 }
522
523 size_t OtherRegionsTable::occ_fine() const {
524 size_t sum = 0;
525
526 size_t num = 0;
527 PerRegionTable * cur = _first_all_fine_prts;
528 while (cur != NULL) {
529 sum += cur->occupied();
530 cur = cur->next();
531 num++;
532 }
533 guarantee(num == _n_fine_entries, "just checking");
534 return sum;
535 }
536
537 size_t OtherRegionsTable::occ_coarse() const {
538 return (_n_coarse_entries * HeapRegion::CardsPerRegion);
539 }
540
541 size_t OtherRegionsTable::occ_sparse() const {
542 return _sparse_table.occupied();
543 }
544
545 size_t OtherRegionsTable::mem_size() const {
546 size_t sum = 0;
547 // all PRTs are of the same size so it is sufficient to query only one of them.
548 if (_first_all_fine_prts != NULL) {
549 assert(_last_all_fine_prts != NULL &&
550 _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
551 sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
552 }
553 sum += (sizeof(PerRegionTable*) * _max_fine_entries);
554 sum += (_coarse_map.size_in_words() * HeapWordSize);
555 sum += (_sparse_table.mem_size());
556 sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
557 return sum;
558 }
559
560 size_t OtherRegionsTable::static_mem_size() {
561 return G1FromCardCache::static_mem_size();
562 }
563
564 size_t OtherRegionsTable::fl_mem_size() {
565 return PerRegionTable::fl_mem_size();
566 }
567
568 void OtherRegionsTable::clear_fcc() {
569 G1FromCardCache::clear(_hr->hrm_index());
570 }
571
572 void OtherRegionsTable::clear() {
573 // if there are no entries, skip this step
574 if (_first_all_fine_prts != NULL) {
575 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
576 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
577 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
578 } else {
579 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
580 }
581
582 _first_all_fine_prts = _last_all_fine_prts = NULL;
583 _sparse_table.clear();
584 if (_n_coarse_entries > 0) {
585 _coarse_map.clear();
586 }
587 _n_fine_entries = 0;
588 _n_coarse_entries = 0;
589
590 clear_fcc();
591 }
592
593 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
594 // Cast away const in this case.
595 MutexLockerEx x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
596 return contains_reference_locked(from);
597 }
598
599 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
600 HeapRegion* hr = _g1h->heap_region_containing(from);
601 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
602 // Is this region in the coarse map?
603 if (_coarse_map.at(hr_ind)) return true;
604
605 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
606 hr);
607 if (prt != NULL) {
608 return prt->contains_reference(from);
609
610 } else {
611 CardIdx_t card_index = card_within_region(from, hr);
612 return _sparse_table.contains_card(hr_ind, card_index);
613 }
614 }
615
616 void
617 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
618 _sparse_table.do_cleanup_work(hrrs_cleanup_task);
619 }
620
621 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetTable* bot,
622 HeapRegion* hr)
623 : _bot(bot),
624 _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Monitor::_safepoint_check_never),
625 _code_roots(),
626 _state(Untracked),
627 _other_regions(hr, &_m) {
628 }
629
630 void HeapRegionRemSet::setup_remset_size() {
631 // Setup sparse and fine-grain tables sizes.
632 // table_size = base * (log(region_size / 1M) + 1)
633 const int LOG_M = 20;
634 int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
635 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
636 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
637 }
638 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
639 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
640 }
641 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
642 }
643
644 void HeapRegionRemSet::cleanup() {
645 SparsePRT::cleanup_all();
646 }
647
648 void HeapRegionRemSet::clear(bool only_cardset) {
649 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
650 clear_locked(only_cardset);
651 }
652
653 void HeapRegionRemSet::clear_locked(bool only_cardset) {
654 if (!only_cardset) {
655 _code_roots.clear();
656 }
657 _other_regions.clear();
658 set_state_empty();
659 assert(occupied_locked() == 0, "Should be clear.");
660 }
661
662 // Code roots support
663 //
664 // The code root set is protected by two separate locking schemes
665 // When at safepoint the per-hrrs lock must be held during modifications
666 // except when doing a full gc.
667 // When not at safepoint the CodeCache_lock must be held during modifications.
668 // When concurrent readers access the contains() function
669 // (during the evacuation phase) no removals are allowed.
670
671 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
672 assert(nm != NULL, "sanity");
673 assert((!CodeCache_lock->owned_by_self() || SafepointSynchronize::is_at_safepoint()),
674 "should call add_strong_code_root_locked instead. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s",
675 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()));
676 // Optimistic unlocked contains-check
677 if (!_code_roots.contains(nm)) {
678 MutexLockerEx ml(&_m, Mutex::_no_safepoint_check_flag);
679 add_strong_code_root_locked(nm);
680 }
681 }
682
683 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
684 assert(nm != NULL, "sanity");
685 assert((CodeCache_lock->owned_by_self() ||
686 (SafepointSynchronize::is_at_safepoint() &&
687 (_m.owned_by_self() || Thread::current()->is_VM_thread()))),
688 "not safely locked. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s, _m.owned_by_self(): %s, Thread::current()->is_VM_thread(): %s",
689 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),
690 BOOL_TO_STR(_m.owned_by_self()), BOOL_TO_STR(Thread::current()->is_VM_thread()));
691 _code_roots.add(nm);
692 }
693
694 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
695 assert(nm != NULL, "sanity");
696 assert_locked_or_safepoint(CodeCache_lock);
697
698 MutexLockerEx ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
699 _code_roots.remove(nm);
700
701 // Check that there were no duplicates
702 guarantee(!_code_roots.contains(nm), "duplicate entry found");
703 }
704
705 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
706 _code_roots.nmethods_do(blk);
707 }
708
709 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
710 _code_roots.clean(hr);
711 }
712
713 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
714 return _code_roots.mem_size();
715 }
716
717 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
718 _hrrs(hrrs),
719 _g1h(G1CollectedHeap::heap()),
720 _coarse_map(&hrrs->_other_regions._coarse_map),
721 _bot(hrrs->_bot),
722 _is(Sparse),
723 // Set these values so that we increment to the first region.
724 _coarse_cur_region_index(-1),
725 _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
726 _cur_card_in_prt(HeapRegion::CardsPerRegion),
727 _fine_cur_prt(NULL),
728 _n_yielded_coarse(0),
729 _n_yielded_fine(0),
730 _n_yielded_sparse(0),
731 _sparse_iter(&hrrs->_other_regions._sparse_table) {}
732
733 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
734 if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
735 // Go to the next card.
736 _coarse_cur_region_cur_card++;
737 // Was the last the last card in the current region?
738 if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
739 // Yes: find the next region. This may leave _coarse_cur_region_index
740 // Set to the last index, in which case there are no more coarse
741 // regions.
742 _coarse_cur_region_index =
743 (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
744 if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
745 _coarse_cur_region_cur_card = 0;
746 HeapWord* r_bot =
747 _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
748 _cur_region_card_offset = _bot->index_for(r_bot);
749 } else {
750 return false;
751 }
752 }
753 // If we didn't return false above, then we can yield a card.
754 card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
755 return true;
756 }
757
758 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
759 if (fine_has_next()) {
760 _cur_card_in_prt =
761 _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
762 }
763 if (_cur_card_in_prt == HeapRegion::CardsPerRegion) {
764 // _fine_cur_prt may still be NULL in case if there are not PRTs at all for
765 // the remembered set.
766 if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) {
767 return false;
768 }
769 PerRegionTable* next_prt = _fine_cur_prt->next();
770 switch_to_prt(next_prt);
771 _cur_card_in_prt = _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
772 }
773
774 card_index = _cur_region_card_offset + _cur_card_in_prt;
775 guarantee(_cur_card_in_prt < HeapRegion::CardsPerRegion,
776 "Card index " SIZE_FORMAT " must be within the region", _cur_card_in_prt);
777 return true;
778 }
779
780 bool HeapRegionRemSetIterator::fine_has_next() {
781 return _cur_card_in_prt != HeapRegion::CardsPerRegion;
782 }
783
784 void HeapRegionRemSetIterator::switch_to_prt(PerRegionTable* prt) {
785 assert(prt != NULL, "Cannot switch to NULL prt");
786 _fine_cur_prt = prt;
787
788 HeapWord* r_bot = _fine_cur_prt->hr()->bottom();
789 _cur_region_card_offset = _bot->index_for(r_bot);
790
791 // The bitmap scan for the PRT always scans from _cur_region_cur_card + 1.
792 // To avoid special-casing this start case, and not miss the first bitmap
793 // entry, initialize _cur_region_cur_card with -1 instead of 0.
794 _cur_card_in_prt = (size_t)-1;
795 }
796
797 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
798 switch (_is) {
799 case Sparse: {
800 if (_sparse_iter.has_next(card_index)) {
801 _n_yielded_sparse++;
802 return true;
803 }
804 // Otherwise, deliberate fall-through
805 _is = Fine;
806 PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts;
807 if (initial_fine_prt != NULL) {
808 switch_to_prt(_hrrs->_other_regions._first_all_fine_prts);
809 }
810 }
811 case Fine:
812 if (fine_has_next(card_index)) {
813 _n_yielded_fine++;
814 return true;
815 }
816 // Otherwise, deliberate fall-through
817 _is = Coarse;
818 case Coarse:
819 if (coarse_has_next(card_index)) {
820 _n_yielded_coarse++;
821 return true;
822 }
823 // Otherwise...
824 break;
825 }
826 return false;
827 }
828
829 void HeapRegionRemSet::reset_for_cleanup_tasks() {
830 SparsePRT::reset_for_cleanup_tasks();
831 }
832
833 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
834 _other_regions.do_cleanup_work(hrrs_cleanup_task);
835 }
836
837 void HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
838 SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
839 }
840
841 #ifndef PRODUCT
842 void HeapRegionRemSet::test() {
843 os::sleep(Thread::current(), (jlong)5000, false);
844 G1CollectedHeap* g1h = G1CollectedHeap::heap();
845
846 // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
847 // hash bucket.
848 HeapRegion* hr0 = g1h->region_at(0);
849 HeapRegion* hr1 = g1h->region_at(1);
850 HeapRegion* hr2 = g1h->region_at(5);
851 HeapRegion* hr3 = g1h->region_at(6);
852 HeapRegion* hr4 = g1h->region_at(7);
853 HeapRegion* hr5 = g1h->region_at(8);
854
855 HeapWord* hr1_start = hr1->bottom();
856 HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
857 HeapWord* hr1_last = hr1->end() - 1;
858
859 HeapWord* hr2_start = hr2->bottom();
860 HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
861 HeapWord* hr2_last = hr2->end() - 1;
862
863 HeapWord* hr3_start = hr3->bottom();
864 HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
865 HeapWord* hr3_last = hr3->end() - 1;
866
867 HeapRegionRemSet* hrrs = hr0->rem_set();
868
869 // Make three references from region 0x101...
870 hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
871 hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
872 hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
873
874 hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
875 hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
876 hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
877
878 hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
879 hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
880 hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
881
882 // Now cause a coarsening.
883 hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
884 hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
885
886 // Now, does iteration yield these three?
887 HeapRegionRemSetIterator iter(hrrs);
888 size_t sum = 0;
889 size_t card_index;
890 while (iter.has_next(card_index)) {
891 HeapWord* card_start =
892 G1CollectedHeap::heap()->bot()->address_for_index(card_index);
893 tty->print_cr(" Card " PTR_FORMAT ".", p2i(card_start));
894 sum++;
895 }
896 guarantee(sum == 11 - 3 + 2048, "Failure");
897 guarantee(sum == hrrs->occupied(), "Failure");
898 }
899 #endif