1 /*
2 * Copyright (c) 2001, 2017, 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/concurrentG1Refine.hpp"
27 #include "gc/g1/g1BlockOffsetTable.inline.hpp"
28 #include "gc/g1/g1CollectedHeap.inline.hpp"
29 #include "gc/g1/g1CardLiveData.inline.hpp"
30 #include "gc/g1/heapRegionManager.inline.hpp"
31 #include "gc/g1/heapRegionRemSet.hpp"
32 #include "gc/shared/space.inline.hpp"
33 #include "memory/allocation.hpp"
34 #include "memory/padded.inline.hpp"
35 #include "oops/oop.inline.hpp"
36 #include "runtime/atomic.hpp"
37 #include "utilities/bitMap.inline.hpp"
38 #include "utilities/debug.hpp"
39 #include "utilities/formatBuffer.hpp"
40 #include "utilities/globalDefinitions.hpp"
41 #include "utilities/growableArray.hpp"
42
43 class PerRegionTable: public CHeapObj<mtGC> {
44 friend class OtherRegionsTable;
45 friend class HeapRegionRemSetIterator;
46
47 HeapRegion* _hr;
48 CHeapBitMap _bm;
49 jint _occupied;
50
51 // next pointer for free/allocated 'all' list
52 PerRegionTable* _next;
53
54 // prev pointer for the allocated 'all' list
55 PerRegionTable* _prev;
56
57 // next pointer in collision list
58 PerRegionTable * _collision_list_next;
59
60 // Global free list of PRTs
61 static PerRegionTable* volatile _free_list;
62
63 protected:
64 // We need access in order to union things into the base table.
65 BitMap* bm() { return &_bm; }
66
67 void recount_occupied() {
68 _occupied = (jint) bm()->count_one_bits();
69 }
70
71 PerRegionTable(HeapRegion* hr) :
72 _hr(hr),
73 _occupied(0),
74 _bm(HeapRegion::CardsPerRegion, mtGC),
75 _collision_list_next(NULL), _next(NULL), _prev(NULL)
76 {}
77
78 void add_card_work(CardIdx_t from_card, bool par) {
79 if (!_bm.at(from_card)) {
80 if (par) {
81 if (_bm.par_at_put(from_card, 1)) {
82 Atomic::inc(&_occupied);
83 }
84 } else {
85 _bm.at_put(from_card, 1);
86 _occupied++;
87 }
88 }
89 }
90
91 void add_reference_work(OopOrNarrowOopStar from, bool par) {
92 // Must make this robust in case "from" is not in "_hr", because of
93 // concurrency.
94
95 HeapRegion* loc_hr = hr();
96 // If the test below fails, then this table was reused concurrently
97 // with this operation. This is OK, since the old table was coarsened,
98 // and adding a bit to the new table is never incorrect.
99 // If the table used to belong to a continues humongous region and is
100 // now reused for the corresponding start humongous region, we need to
101 // make sure that we detect this. Thus, we call is_in_reserved_raw()
102 // instead of just is_in_reserved() here.
103 if (loc_hr->is_in_reserved(from)) {
104 size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom());
105 CardIdx_t from_card = (CardIdx_t)
106 hw_offset >> (CardTableModRefBS::card_shift - LogHeapWordSize);
107
108 assert((size_t)from_card < HeapRegion::CardsPerRegion,
109 "Must be in range.");
110 add_card_work(from_card, par);
111 }
112 }
113
114 public:
115
116 HeapRegion* hr() const {
117 return (HeapRegion*) OrderAccess::load_ptr_acquire(&_hr);
118 }
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 _collision_list_next = NULL;
132 _occupied = 0;
133 _bm.clear();
134 // Make sure that the bitmap clearing above has been finished before publishing
135 // this PRT to concurrent threads.
136 OrderAccess::release_store_ptr(&_hr, hr);
137 }
138
139 void add_reference(OopOrNarrowOopStar from) {
140 add_reference_work(from, /*parallel*/ true);
141 }
142
143 void seq_add_reference(OopOrNarrowOopStar from) {
144 add_reference_work(from, /*parallel*/ false);
145 }
146
147 void scrub(G1CardLiveData* live_data) {
148 live_data->remove_nonlive_cards(hr()->hrm_index(), &_bm);
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(PerRegionTable) + _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* volatile 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, Mutex* m) :
262 _g1h(G1CollectedHeap::heap()),
263 _hr(hr), _m(m),
264 _coarse_map(G1CollectedHeap::heap()->max_regions(), mtGC),
265 _fine_grain_regions(NULL),
266 _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
267 _n_fine_entries(0), _n_coarse_entries(0),
268 _fine_eviction_start(0),
269 _sparse_table(hr)
270 {
271 typedef PerRegionTable* PerRegionTablePtr;
272
273 if (_max_fine_entries == 0) {
274 assert(_mod_max_fine_entries_mask == 0, "Both or none.");
275 size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
276 _max_fine_entries = (size_t)1 << max_entries_log;
277 _mod_max_fine_entries_mask = _max_fine_entries - 1;
278
279 assert(_fine_eviction_sample_size == 0
280 && _fine_eviction_stride == 0, "All init at same time.");
281 _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
282 _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
283 }
284
285 _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
286 mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
287
288 if (_fine_grain_regions == NULL) {
289 vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
290 "Failed to allocate _fine_grain_entries.");
291 }
292
293 for (size_t i = 0; i < _max_fine_entries; i++) {
294 _fine_grain_regions[i] = NULL;
295 }
296 }
297
298 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
299 // We always append to the beginning of the list for convenience;
300 // the order of entries in this list does not matter.
301 if (_first_all_fine_prts != NULL) {
302 assert(_first_all_fine_prts->prev() == NULL, "invariant");
303 _first_all_fine_prts->set_prev(prt);
304 prt->set_next(_first_all_fine_prts);
305 } else {
306 // this is the first element we insert. Adjust the "last" pointer
307 _last_all_fine_prts = prt;
308 assert(prt->next() == NULL, "just checking");
309 }
310 // the new element is always the first element without a predecessor
311 prt->set_prev(NULL);
312 _first_all_fine_prts = prt;
313
314 assert(prt->prev() == NULL, "just checking");
315 assert(_first_all_fine_prts == prt, "just checking");
316 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
317 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
318 "just checking");
319 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
320 "just checking");
321 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
322 "just checking");
323 }
324
325 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
326 if (prt->prev() != NULL) {
327 assert(_first_all_fine_prts != prt, "just checking");
328 prt->prev()->set_next(prt->next());
329 // removing the last element in the list?
330 if (_last_all_fine_prts == prt) {
331 _last_all_fine_prts = prt->prev();
332 }
333 } else {
334 assert(_first_all_fine_prts == prt, "just checking");
335 _first_all_fine_prts = prt->next();
336 // list is empty now?
337 if (_first_all_fine_prts == NULL) {
338 _last_all_fine_prts = NULL;
339 }
340 }
341
342 if (prt->next() != NULL) {
343 prt->next()->set_prev(prt->prev());
344 }
345
346 prt->set_next(NULL);
347 prt->set_prev(NULL);
348
349 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
350 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
351 "just checking");
352 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
353 "just checking");
354 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
355 "just checking");
356 }
357
358 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
359 uint cur_hrm_ind = _hr->hrm_index();
360
361 int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
362
363 if (G1FromCardCache::contains_or_replace(tid, cur_hrm_ind, from_card)) {
364 assert(contains_reference(from), "We just found " PTR_FORMAT " in the FromCardCache", p2i(from));
365 return;
366 }
367
368 // Note that this may be a continued H region.
369 HeapRegion* from_hr = _g1h->heap_region_containing(from);
370 RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
371
372 // If the region is already coarsened, return.
373 if (_coarse_map.at(from_hrm_ind)) {
374 assert(contains_reference(from), "We just found " PTR_FORMAT " in the Coarse table", p2i(from));
375 return;
376 }
377
378 // Otherwise find a per-region table to add it to.
379 size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
380 PerRegionTable* prt = find_region_table(ind, from_hr);
381 if (prt == NULL) {
382 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
383 // Confirm that it's really not there...
384 prt = find_region_table(ind, from_hr);
385 if (prt == NULL) {
386
387 uintptr_t from_hr_bot_card_index =
388 uintptr_t(from_hr->bottom())
389 >> CardTableModRefBS::card_shift;
390 CardIdx_t card_index = from_card - from_hr_bot_card_index;
391 assert((size_t)card_index < HeapRegion::CardsPerRegion,
392 "Must be in range.");
393 if (G1HRRSUseSparseTable &&
394 _sparse_table.add_card(from_hrm_ind, card_index)) {
395 assert(contains_reference_locked(from), "We just added " PTR_FORMAT " to the Sparse table", p2i(from));
396 return;
397 }
398
399 if (_n_fine_entries == _max_fine_entries) {
400 prt = delete_region_table();
401 // There is no need to clear the links to the 'all' list here:
402 // prt will be reused immediately, i.e. remain in the 'all' list.
403 prt->init(from_hr, false /* clear_links_to_all_list */);
404 } else {
405 prt = PerRegionTable::alloc(from_hr);
406 link_to_all(prt);
407 }
408
409 PerRegionTable* first_prt = _fine_grain_regions[ind];
410 prt->set_collision_list_next(first_prt);
411 // The assignment into _fine_grain_regions allows the prt to
412 // start being used concurrently. In addition to
413 // collision_list_next which must be visible (else concurrent
414 // parsing of the list, if any, may fail to see other entries),
415 // the content of the prt must be visible (else for instance
416 // some mark bits may not yet seem cleared or a 'later' update
417 // performed by a concurrent thread could be undone when the
418 // zeroing becomes visible). This requires store ordering.
419 OrderAccess::release_store_ptr((volatile PerRegionTable*)&_fine_grain_regions[ind], prt);
420 _n_fine_entries++;
421
422 if (G1HRRSUseSparseTable) {
423 // Transfer from sparse to fine-grain.
424 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
425 assert(sprt_entry != NULL, "There should have been an entry");
426 for (int i = 0; i < sprt_entry->num_valid_cards(); i++) {
427 CardIdx_t c = sprt_entry->card(i);
428 prt->add_card(c);
429 }
430 // Now we can delete the sparse entry.
431 bool res = _sparse_table.delete_entry(from_hrm_ind);
432 assert(res, "It should have been there.");
433 }
434 }
435 assert(prt != NULL && prt->hr() == from_hr, "consequence");
436 }
437 // Note that we can't assert "prt->hr() == from_hr", because of the
438 // possibility of concurrent reuse. But see head comment of
439 // OtherRegionsTable for why this is OK.
440 assert(prt != NULL, "Inv");
441
442 prt->add_reference(from);
443 assert(contains_reference(from), "We just added " PTR_FORMAT " to the PRT", p2i(from));
444 }
445
446 PerRegionTable*
447 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
448 assert(ind < _max_fine_entries, "Preconditions.");
449 PerRegionTable* prt = _fine_grain_regions[ind];
450 while (prt != NULL && prt->hr() != hr) {
451 prt = prt->collision_list_next();
452 }
453 // Loop postcondition is the method postcondition.
454 return prt;
455 }
456
457 jint OtherRegionsTable::_n_coarsenings = 0;
458
459 PerRegionTable* OtherRegionsTable::delete_region_table() {
460 assert(_m->owned_by_self(), "Precondition");
461 assert(_n_fine_entries == _max_fine_entries, "Precondition");
462 PerRegionTable* max = NULL;
463 jint max_occ = 0;
464 PerRegionTable** max_prev = NULL;
465 size_t max_ind;
466
467 size_t i = _fine_eviction_start;
468 for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
469 size_t ii = i;
470 // Make sure we get a non-NULL sample.
471 while (_fine_grain_regions[ii] == NULL) {
472 ii++;
473 if (ii == _max_fine_entries) ii = 0;
474 guarantee(ii != i, "We must find one.");
475 }
476 PerRegionTable** prev = &_fine_grain_regions[ii];
477 PerRegionTable* cur = *prev;
478 while (cur != NULL) {
479 jint cur_occ = cur->occupied();
480 if (max == NULL || cur_occ > max_occ) {
481 max = cur;
482 max_prev = prev;
483 max_ind = i;
484 max_occ = cur_occ;
485 }
486 prev = cur->collision_list_next_addr();
487 cur = cur->collision_list_next();
488 }
489 i = i + _fine_eviction_stride;
490 if (i >= _n_fine_entries) i = i - _n_fine_entries;
491 }
492
493 _fine_eviction_start++;
494
495 if (_fine_eviction_start >= _n_fine_entries) {
496 _fine_eviction_start -= _n_fine_entries;
497 }
498
499 guarantee(max != NULL, "Since _n_fine_entries > 0");
500 guarantee(max_prev != NULL, "Since max != NULL.");
501
502 // Set the corresponding coarse bit.
503 size_t max_hrm_index = (size_t) max->hr()->hrm_index();
504 if (!_coarse_map.at(max_hrm_index)) {
505 _coarse_map.at_put(max_hrm_index, true);
506 _n_coarse_entries++;
507 }
508
509 // Unsplice.
510 *max_prev = max->collision_list_next();
511 Atomic::inc(&_n_coarsenings);
512 _n_fine_entries--;
513 return max;
514 }
515
516 void OtherRegionsTable::scrub(G1CardLiveData* live_data) {
517 // First eliminated garbage regions from the coarse map.
518 log_develop_trace(gc, remset, scrub)("Scrubbing region %u:", _hr->hrm_index());
519
520 log_develop_trace(gc, remset, scrub)(" Coarse map: before = " SIZE_FORMAT "...", _n_coarse_entries);
521 if (_n_coarse_entries > 0) {
522 live_data->remove_nonlive_regions(&_coarse_map);
523 _n_coarse_entries = _coarse_map.count_one_bits();
524 }
525 log_develop_trace(gc, remset, scrub)(" after = " SIZE_FORMAT ".", _n_coarse_entries);
526
527 // Now do the fine-grained maps.
528 for (size_t i = 0; i < _max_fine_entries; i++) {
529 PerRegionTable* cur = _fine_grain_regions[i];
530 PerRegionTable** prev = &_fine_grain_regions[i];
531 while (cur != NULL) {
532 PerRegionTable* nxt = cur->collision_list_next();
533 // If the entire region is dead, eliminate.
534 log_develop_trace(gc, remset, scrub)(" For other region %u:", cur->hr()->hrm_index());
535 if (!live_data->is_region_live(cur->hr()->hrm_index())) {
536 *prev = nxt;
537 cur->set_collision_list_next(NULL);
538 _n_fine_entries--;
539 log_develop_trace(gc, remset, scrub)(" deleted via region map.");
540 unlink_from_all(cur);
541 PerRegionTable::free(cur);
542 } else {
543 // Do fine-grain elimination.
544 log_develop_trace(gc, remset, scrub)(" occ: before = %4d.", cur->occupied());
545 cur->scrub(live_data);
546 log_develop_trace(gc, remset, scrub)(" after = %4d.", cur->occupied());
547 // Did that empty the table completely?
548 if (cur->occupied() == 0) {
549 *prev = nxt;
550 cur->set_collision_list_next(NULL);
551 _n_fine_entries--;
552 unlink_from_all(cur);
553 PerRegionTable::free(cur);
554 } else {
555 prev = cur->collision_list_next_addr();
556 }
557 }
558 cur = nxt;
559 }
560 }
561 // Since we may have deleted a from_card_cache entry from the RS, clear
562 // the FCC.
563 clear_fcc();
564 }
565
566 bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {
567 if (limit <= (size_t)G1RSetSparseRegionEntries) {
568 return occ_coarse() == 0 && _first_all_fine_prts == NULL && occ_sparse() <= limit;
569 } else {
570 // Current uses of this method may only use values less than G1RSetSparseRegionEntries
571 // for the limit. The solution, comparing against occupied() would be too slow
572 // at this time.
573 Unimplemented();
574 return false;
575 }
576 }
577
578 bool OtherRegionsTable::is_empty() const {
579 return occ_sparse() == 0 && occ_coarse() == 0 && _first_all_fine_prts == NULL;
580 }
581
582 size_t OtherRegionsTable::occupied() const {
583 size_t sum = occ_fine();
584 sum += occ_sparse();
585 sum += occ_coarse();
586 return sum;
587 }
588
589 size_t OtherRegionsTable::occ_fine() const {
590 size_t sum = 0;
591
592 size_t num = 0;
593 PerRegionTable * cur = _first_all_fine_prts;
594 while (cur != NULL) {
595 sum += cur->occupied();
596 cur = cur->next();
597 num++;
598 }
599 guarantee(num == _n_fine_entries, "just checking");
600 return sum;
601 }
602
603 size_t OtherRegionsTable::occ_coarse() const {
604 return (_n_coarse_entries * HeapRegion::CardsPerRegion);
605 }
606
607 size_t OtherRegionsTable::occ_sparse() const {
608 return _sparse_table.occupied();
609 }
610
611 size_t OtherRegionsTable::mem_size() const {
612 size_t sum = 0;
613 // all PRTs are of the same size so it is sufficient to query only one of them.
614 if (_first_all_fine_prts != NULL) {
615 assert(_last_all_fine_prts != NULL &&
616 _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
617 sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
618 }
619 sum += (sizeof(PerRegionTable*) * _max_fine_entries);
620 sum += (_coarse_map.size_in_words() * HeapWordSize);
621 sum += (_sparse_table.mem_size());
622 sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
623 return sum;
624 }
625
626 size_t OtherRegionsTable::static_mem_size() {
627 return G1FromCardCache::static_mem_size();
628 }
629
630 size_t OtherRegionsTable::fl_mem_size() {
631 return PerRegionTable::fl_mem_size();
632 }
633
634 void OtherRegionsTable::clear_fcc() {
635 G1FromCardCache::clear(_hr->hrm_index());
636 }
637
638 void OtherRegionsTable::clear() {
639 // if there are no entries, skip this step
640 if (_first_all_fine_prts != NULL) {
641 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
642 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
643 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
644 } else {
645 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
646 }
647
648 _first_all_fine_prts = _last_all_fine_prts = NULL;
649 _sparse_table.clear();
650 if (_n_coarse_entries > 0) {
651 _coarse_map.clear();
652 }
653 _n_fine_entries = 0;
654 _n_coarse_entries = 0;
655
656 clear_fcc();
657 }
658
659 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
660 // Cast away const in this case.
661 MutexLockerEx x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
662 return contains_reference_locked(from);
663 }
664
665 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
666 HeapRegion* hr = _g1h->heap_region_containing(from);
667 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
668 // Is this region in the coarse map?
669 if (_coarse_map.at(hr_ind)) return true;
670
671 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
672 hr);
673 if (prt != NULL) {
674 return prt->contains_reference(from);
675
676 } else {
677 uintptr_t from_card =
678 (uintptr_t(from) >> CardTableModRefBS::card_shift);
679 uintptr_t hr_bot_card_index =
680 uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
681 assert(from_card >= hr_bot_card_index, "Inv");
682 CardIdx_t card_index = from_card - hr_bot_card_index;
683 assert((size_t)card_index < HeapRegion::CardsPerRegion,
684 "Must be in range.");
685 return _sparse_table.contains_card(hr_ind, card_index);
686 }
687 }
688
689 void
690 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
691 _sparse_table.do_cleanup_work(hrrs_cleanup_task);
692 }
693
694 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetTable* bot,
695 HeapRegion* hr)
696 : _bot(bot),
697 _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Monitor::_safepoint_check_never),
698 _code_roots(),
699 _other_regions(hr, &_m) {
700 }
701
702 void HeapRegionRemSet::setup_remset_size() {
703 // Setup sparse and fine-grain tables sizes.
704 // table_size = base * (log(region_size / 1M) + 1)
705 const int LOG_M = 20;
706 int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
707 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
708 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
709 }
710 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
711 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
712 }
713 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
714 }
715
716 void HeapRegionRemSet::cleanup() {
717 SparsePRT::cleanup_all();
718 }
719
720 void HeapRegionRemSet::clear() {
721 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
722 clear_locked();
723 }
724
725 void HeapRegionRemSet::clear_locked() {
726 _code_roots.clear();
727 _other_regions.clear();
728 assert(occupied_locked() == 0, "Should be clear.");
729 }
730
731 void HeapRegionRemSet::scrub(G1CardLiveData* live_data) {
732 _other_regions.scrub(live_data);
733 }
734
735 // Code roots support
736 //
737 // The code root set is protected by two separate locking schemes
738 // When at safepoint the per-hrrs lock must be held during modifications
739 // except when doing a full gc.
740 // When not at safepoint the CodeCache_lock must be held during modifications.
741 // When concurrent readers access the contains() function
742 // (during the evacuation phase) no removals are allowed.
743
744 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
745 assert(nm != NULL, "sanity");
746 assert((!CodeCache_lock->owned_by_self() || SafepointSynchronize::is_at_safepoint()),
747 "should call add_strong_code_root_locked instead. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s",
748 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()));
749 // Optimistic unlocked contains-check
750 if (!_code_roots.contains(nm)) {
751 MutexLockerEx ml(&_m, Mutex::_no_safepoint_check_flag);
752 add_strong_code_root_locked(nm);
753 }
754 }
755
756 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
757 assert(nm != NULL, "sanity");
758 assert((CodeCache_lock->owned_by_self() ||
759 (SafepointSynchronize::is_at_safepoint() &&
760 (_m.owned_by_self() || Thread::current()->is_VM_thread()))),
761 "not safely locked. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s, _m.owned_by_self(): %s, Thread::current()->is_VM_thread(): %s",
762 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),
763 BOOL_TO_STR(_m.owned_by_self()), BOOL_TO_STR(Thread::current()->is_VM_thread()));
764 _code_roots.add(nm);
765 }
766
767 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
768 assert(nm != NULL, "sanity");
769 assert_locked_or_safepoint(CodeCache_lock);
770
771 MutexLockerEx ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
772 _code_roots.remove(nm);
773
774 // Check that there were no duplicates
775 guarantee(!_code_roots.contains(nm), "duplicate entry found");
776 }
777
778 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
779 _code_roots.nmethods_do(blk);
780 }
781
782 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
783 _code_roots.clean(hr);
784 }
785
786 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
787 return _code_roots.mem_size();
788 }
789
790 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
791 _hrrs(hrrs),
792 _g1h(G1CollectedHeap::heap()),
793 _coarse_map(&hrrs->_other_regions._coarse_map),
794 _bot(hrrs->_bot),
795 _is(Sparse),
796 // Set these values so that we increment to the first region.
797 _coarse_cur_region_index(-1),
798 _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
799 _cur_card_in_prt(HeapRegion::CardsPerRegion),
800 _fine_cur_prt(NULL),
801 _n_yielded_coarse(0),
802 _n_yielded_fine(0),
803 _n_yielded_sparse(0),
804 _sparse_iter(&hrrs->_other_regions._sparse_table) {}
805
806 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
807 if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
808 // Go to the next card.
809 _coarse_cur_region_cur_card++;
810 // Was the last the last card in the current region?
811 if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
812 // Yes: find the next region. This may leave _coarse_cur_region_index
813 // Set to the last index, in which case there are no more coarse
814 // regions.
815 _coarse_cur_region_index =
816 (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
817 if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
818 _coarse_cur_region_cur_card = 0;
819 HeapWord* r_bot =
820 _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
821 _cur_region_card_offset = _bot->index_for(r_bot);
822 } else {
823 return false;
824 }
825 }
826 // If we didn't return false above, then we can yield a card.
827 card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
828 return true;
829 }
830
831 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
832 if (fine_has_next()) {
833 _cur_card_in_prt =
834 _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
835 }
836 if (_cur_card_in_prt == HeapRegion::CardsPerRegion) {
837 // _fine_cur_prt may still be NULL in case if there are not PRTs at all for
838 // the remembered set.
839 if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) {
840 return false;
841 }
842 PerRegionTable* next_prt = _fine_cur_prt->next();
843 switch_to_prt(next_prt);
844 _cur_card_in_prt = _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
845 }
846
847 card_index = _cur_region_card_offset + _cur_card_in_prt;
848 guarantee(_cur_card_in_prt < HeapRegion::CardsPerRegion,
849 "Card index " SIZE_FORMAT " must be within the region", _cur_card_in_prt);
850 return true;
851 }
852
853 bool HeapRegionRemSetIterator::fine_has_next() {
854 return _cur_card_in_prt != HeapRegion::CardsPerRegion;
855 }
856
857 void HeapRegionRemSetIterator::switch_to_prt(PerRegionTable* prt) {
858 assert(prt != NULL, "Cannot switch to NULL prt");
859 _fine_cur_prt = prt;
860
861 HeapWord* r_bot = _fine_cur_prt->hr()->bottom();
862 _cur_region_card_offset = _bot->index_for(r_bot);
863
864 // The bitmap scan for the PRT always scans from _cur_region_cur_card + 1.
865 // To avoid special-casing this start case, and not miss the first bitmap
866 // entry, initialize _cur_region_cur_card with -1 instead of 0.
867 _cur_card_in_prt = (size_t)-1;
868 }
869
870 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
871 switch (_is) {
872 case Sparse: {
873 if (_sparse_iter.has_next(card_index)) {
874 _n_yielded_sparse++;
875 return true;
876 }
877 // Otherwise, deliberate fall-through
878 _is = Fine;
879 PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts;
880 if (initial_fine_prt != NULL) {
881 switch_to_prt(_hrrs->_other_regions._first_all_fine_prts);
882 }
883 }
884 case Fine:
885 if (fine_has_next(card_index)) {
886 _n_yielded_fine++;
887 return true;
888 }
889 // Otherwise, deliberate fall-through
890 _is = Coarse;
891 case Coarse:
892 if (coarse_has_next(card_index)) {
893 _n_yielded_coarse++;
894 return true;
895 }
896 // Otherwise...
897 break;
898 }
899 return false;
900 }
901
902 void HeapRegionRemSet::reset_for_cleanup_tasks() {
903 SparsePRT::reset_for_cleanup_tasks();
904 }
905
906 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
907 _other_regions.do_cleanup_work(hrrs_cleanup_task);
908 }
909
910 void
911 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
912 SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
913 }
914
915 #ifndef PRODUCT
916 void HeapRegionRemSet::test() {
917 os::sleep(Thread::current(), (jlong)5000, false);
918 G1CollectedHeap* g1h = G1CollectedHeap::heap();
919
920 // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
921 // hash bucket.
922 HeapRegion* hr0 = g1h->region_at(0);
923 HeapRegion* hr1 = g1h->region_at(1);
924 HeapRegion* hr2 = g1h->region_at(5);
925 HeapRegion* hr3 = g1h->region_at(6);
926 HeapRegion* hr4 = g1h->region_at(7);
927 HeapRegion* hr5 = g1h->region_at(8);
928
929 HeapWord* hr1_start = hr1->bottom();
930 HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
931 HeapWord* hr1_last = hr1->end() - 1;
932
933 HeapWord* hr2_start = hr2->bottom();
934 HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
935 HeapWord* hr2_last = hr2->end() - 1;
936
937 HeapWord* hr3_start = hr3->bottom();
938 HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
939 HeapWord* hr3_last = hr3->end() - 1;
940
941 HeapRegionRemSet* hrrs = hr0->rem_set();
942
943 // Make three references from region 0x101...
944 hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
945 hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
946 hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
947
948 hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
949 hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
950 hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
951
952 hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
953 hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
954 hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
955
956 // Now cause a coarsening.
957 hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
958 hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
959
960 // Now, does iteration yield these three?
961 HeapRegionRemSetIterator iter(hrrs);
962 size_t sum = 0;
963 size_t card_index;
964 while (iter.has_next(card_index)) {
965 HeapWord* card_start =
966 G1CollectedHeap::heap()->bot()->address_for_index(card_index);
967 tty->print_cr(" Card " PTR_FORMAT ".", p2i(card_start));
968 sum++;
969 }
970 guarantee(sum == 11 - 3 + 2048, "Failure");
971 guarantee(sum == hrrs->occupied(), "Failure");
972 }
973 #endif