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 { return OrderAccess::load_acquire(&_hr); }
117
118 jint occupied() const {
119 // Overkill, but if we ever need it...
120 // guarantee(_occupied == _bm.count_one_bits(), "Check");
121 return _occupied;
122 }
123
124 void init(HeapRegion* hr, bool clear_links_to_all_list) {
125 if (clear_links_to_all_list) {
126 set_next(NULL);
127 set_prev(NULL);
128 }
129 _collision_list_next = NULL;
130 _occupied = 0;
131 _bm.clear();
132 // Make sure that the bitmap clearing above has been finished before publishing
133 // this PRT to concurrent threads.
134 OrderAccess::release_store(&_hr, hr);
135 }
136
137 void add_reference(OopOrNarrowOopStar from) {
138 add_reference_work(from, /*parallel*/ true);
139 }
140
141 void seq_add_reference(OopOrNarrowOopStar from) {
142 add_reference_work(from, /*parallel*/ false);
143 }
144
145 void scrub(G1CardLiveData* live_data) {
146 live_data->remove_nonlive_cards(hr()->hrm_index(), &_bm);
147 recount_occupied();
148 }
149
150 void add_card(CardIdx_t from_card_index) {
151 add_card_work(from_card_index, /*parallel*/ true);
152 }
153
154 void seq_add_card(CardIdx_t from_card_index) {
155 add_card_work(from_card_index, /*parallel*/ false);
156 }
157
158 // (Destructively) union the bitmap of the current table into the given
159 // bitmap (which is assumed to be of the same size.)
160 void union_bitmap_into(BitMap* bm) {
161 bm->set_union(_bm);
162 }
163
164 // Mem size in bytes.
165 size_t mem_size() const {
166 return sizeof(PerRegionTable) + _bm.size_in_words() * HeapWordSize;
167 }
168
169 // Requires "from" to be in "hr()".
170 bool contains_reference(OopOrNarrowOopStar from) const {
171 assert(hr()->is_in_reserved(from), "Precondition.");
172 size_t card_ind = pointer_delta(from, hr()->bottom(),
173 CardTableModRefBS::card_size);
174 return _bm.at(card_ind);
175 }
176
177 // Bulk-free the PRTs from prt to last, assumes that they are
178 // linked together using their _next field.
179 static void bulk_free(PerRegionTable* prt, PerRegionTable* last) {
180 while (true) {
181 PerRegionTable* fl = _free_list;
182 last->set_next(fl);
183 PerRegionTable* res = Atomic::cmpxchg(prt, &_free_list, fl);
184 if (res == fl) {
185 return;
186 }
187 }
188 ShouldNotReachHere();
189 }
190
191 static void free(PerRegionTable* prt) {
192 bulk_free(prt, prt);
193 }
194
195 // Returns an initialized PerRegionTable instance.
196 static PerRegionTable* alloc(HeapRegion* hr) {
197 PerRegionTable* fl = _free_list;
198 while (fl != NULL) {
199 PerRegionTable* nxt = fl->next();
200 PerRegionTable* res =
201 Atomic::cmpxchg(nxt, &_free_list, fl);
202 if (res == fl) {
203 fl->init(hr, true);
204 return fl;
205 } else {
206 fl = _free_list;
207 }
208 }
209 assert(fl == NULL, "Loop condition.");
210 return new PerRegionTable(hr);
211 }
212
213 PerRegionTable* next() const { return _next; }
214 void set_next(PerRegionTable* next) { _next = next; }
215 PerRegionTable* prev() const { return _prev; }
216 void set_prev(PerRegionTable* prev) { _prev = prev; }
217
218 // Accessor and Modification routines for the pointer for the
219 // singly linked collision list that links the PRTs within the
220 // OtherRegionsTable::_fine_grain_regions hash table.
221 //
222 // It might be useful to also make the collision list doubly linked
223 // to avoid iteration over the collisions list during scrubbing/deletion.
224 // OTOH there might not be many collisions.
225
226 PerRegionTable* collision_list_next() const {
227 return _collision_list_next;
228 }
229
230 void set_collision_list_next(PerRegionTable* next) {
231 _collision_list_next = next;
232 }
233
234 PerRegionTable** collision_list_next_addr() {
235 return &_collision_list_next;
236 }
237
238 static size_t fl_mem_size() {
239 PerRegionTable* cur = _free_list;
240 size_t res = 0;
241 while (cur != NULL) {
242 res += cur->mem_size();
243 cur = cur->next();
244 }
245 return res;
246 }
247
248 static void test_fl_mem_size();
249 };
250
251 PerRegionTable* volatile PerRegionTable::_free_list = NULL;
252
253 size_t OtherRegionsTable::_max_fine_entries = 0;
254 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
255 size_t OtherRegionsTable::_fine_eviction_stride = 0;
256 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
257
258 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr, Mutex* m) :
259 _g1h(G1CollectedHeap::heap()),
260 _hr(hr), _m(m),
261 _coarse_map(G1CollectedHeap::heap()->max_regions(), mtGC),
262 _fine_grain_regions(NULL),
263 _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
264 _n_fine_entries(0), _n_coarse_entries(0),
265 _fine_eviction_start(0),
266 _sparse_table(hr)
267 {
268 typedef PerRegionTable* PerRegionTablePtr;
269
270 if (_max_fine_entries == 0) {
271 assert(_mod_max_fine_entries_mask == 0, "Both or none.");
272 size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
273 _max_fine_entries = (size_t)1 << max_entries_log;
274 _mod_max_fine_entries_mask = _max_fine_entries - 1;
275
276 assert(_fine_eviction_sample_size == 0
277 && _fine_eviction_stride == 0, "All init at same time.");
278 _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
279 _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
280 }
281
282 _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
283 mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
284
285 if (_fine_grain_regions == NULL) {
286 vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
287 "Failed to allocate _fine_grain_entries.");
288 }
289
290 for (size_t i = 0; i < _max_fine_entries; i++) {
291 _fine_grain_regions[i] = NULL;
292 }
293 }
294
295 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
296 // We always append to the beginning of the list for convenience;
297 // the order of entries in this list does not matter.
298 if (_first_all_fine_prts != NULL) {
299 assert(_first_all_fine_prts->prev() == NULL, "invariant");
300 _first_all_fine_prts->set_prev(prt);
301 prt->set_next(_first_all_fine_prts);
302 } else {
303 // this is the first element we insert. Adjust the "last" pointer
304 _last_all_fine_prts = prt;
305 assert(prt->next() == NULL, "just checking");
306 }
307 // the new element is always the first element without a predecessor
308 prt->set_prev(NULL);
309 _first_all_fine_prts = prt;
310
311 assert(prt->prev() == NULL, "just checking");
312 assert(_first_all_fine_prts == prt, "just checking");
313 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
314 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
315 "just checking");
316 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
317 "just checking");
318 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
319 "just checking");
320 }
321
322 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
323 if (prt->prev() != NULL) {
324 assert(_first_all_fine_prts != prt, "just checking");
325 prt->prev()->set_next(prt->next());
326 // removing the last element in the list?
327 if (_last_all_fine_prts == prt) {
328 _last_all_fine_prts = prt->prev();
329 }
330 } else {
331 assert(_first_all_fine_prts == prt, "just checking");
332 _first_all_fine_prts = prt->next();
333 // list is empty now?
334 if (_first_all_fine_prts == NULL) {
335 _last_all_fine_prts = NULL;
336 }
337 }
338
339 if (prt->next() != NULL) {
340 prt->next()->set_prev(prt->prev());
341 }
342
343 prt->set_next(NULL);
344 prt->set_prev(NULL);
345
346 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
347 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
348 "just checking");
349 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
350 "just checking");
351 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
352 "just checking");
353 }
354
355 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
356 uint cur_hrm_ind = _hr->hrm_index();
357
358 int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
359
360 if (G1FromCardCache::contains_or_replace(tid, cur_hrm_ind, from_card)) {
361 assert(contains_reference(from), "We just found " PTR_FORMAT " in the FromCardCache", p2i(from));
362 return;
363 }
364
365 // Note that this may be a continued H region.
366 HeapRegion* from_hr = _g1h->heap_region_containing(from);
367 RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
368
369 // If the region is already coarsened, return.
370 if (_coarse_map.at(from_hrm_ind)) {
371 assert(contains_reference(from), "We just found " PTR_FORMAT " in the Coarse table", p2i(from));
372 return;
373 }
374
375 // Otherwise find a per-region table to add it to.
376 size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
377 PerRegionTable* prt = find_region_table(ind, from_hr);
378 if (prt == NULL) {
379 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
380 // Confirm that it's really not there...
381 prt = find_region_table(ind, from_hr);
382 if (prt == NULL) {
383
384 uintptr_t from_hr_bot_card_index =
385 uintptr_t(from_hr->bottom())
386 >> CardTableModRefBS::card_shift;
387 CardIdx_t card_index = from_card - from_hr_bot_card_index;
388 assert((size_t)card_index < HeapRegion::CardsPerRegion,
389 "Must be in range.");
390 if (G1HRRSUseSparseTable &&
391 _sparse_table.add_card(from_hrm_ind, card_index)) {
392 assert(contains_reference_locked(from), "We just added " PTR_FORMAT " to the Sparse table", p2i(from));
393 return;
394 }
395
396 if (_n_fine_entries == _max_fine_entries) {
397 prt = delete_region_table();
398 // There is no need to clear the links to the 'all' list here:
399 // prt will be reused immediately, i.e. remain in the 'all' list.
400 prt->init(from_hr, false /* clear_links_to_all_list */);
401 } else {
402 prt = PerRegionTable::alloc(from_hr);
403 link_to_all(prt);
404 }
405
406 PerRegionTable* first_prt = _fine_grain_regions[ind];
407 prt->set_collision_list_next(first_prt);
408 // The assignment into _fine_grain_regions allows the prt to
409 // start being used concurrently. In addition to
410 // collision_list_next which must be visible (else concurrent
411 // parsing of the list, if any, may fail to see other entries),
412 // the content of the prt must be visible (else for instance
413 // some mark bits may not yet seem cleared or a 'later' update
414 // performed by a concurrent thread could be undone when the
415 // zeroing becomes visible). This requires store ordering.
416 OrderAccess::release_store(&_fine_grain_regions[ind], prt);
417 _n_fine_entries++;
418
419 if (G1HRRSUseSparseTable) {
420 // Transfer from sparse to fine-grain.
421 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
422 assert(sprt_entry != NULL, "There should have been an entry");
423 for (int i = 0; i < sprt_entry->num_valid_cards(); i++) {
424 CardIdx_t c = sprt_entry->card(i);
425 prt->add_card(c);
426 }
427 // Now we can delete the sparse entry.
428 bool res = _sparse_table.delete_entry(from_hrm_ind);
429 assert(res, "It should have been there.");
430 }
431 }
432 assert(prt != NULL && prt->hr() == from_hr, "consequence");
433 }
434 // Note that we can't assert "prt->hr() == from_hr", because of the
435 // possibility of concurrent reuse. But see head comment of
436 // OtherRegionsTable for why this is OK.
437 assert(prt != NULL, "Inv");
438
439 prt->add_reference(from);
440 assert(contains_reference(from), "We just added " PTR_FORMAT " to the PRT", p2i(from));
441 }
442
443 PerRegionTable*
444 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
445 assert(ind < _max_fine_entries, "Preconditions.");
446 PerRegionTable* prt = _fine_grain_regions[ind];
447 while (prt != NULL && prt->hr() != hr) {
448 prt = prt->collision_list_next();
449 }
450 // Loop postcondition is the method postcondition.
451 return prt;
452 }
453
454 jint OtherRegionsTable::_n_coarsenings = 0;
455
456 PerRegionTable* OtherRegionsTable::delete_region_table() {
457 assert(_m->owned_by_self(), "Precondition");
458 assert(_n_fine_entries == _max_fine_entries, "Precondition");
459 PerRegionTable* max = NULL;
460 jint max_occ = 0;
461 PerRegionTable** max_prev = NULL;
462 size_t max_ind;
463
464 size_t i = _fine_eviction_start;
465 for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
466 size_t ii = i;
467 // Make sure we get a non-NULL sample.
468 while (_fine_grain_regions[ii] == NULL) {
469 ii++;
470 if (ii == _max_fine_entries) ii = 0;
471 guarantee(ii != i, "We must find one.");
472 }
473 PerRegionTable** prev = &_fine_grain_regions[ii];
474 PerRegionTable* cur = *prev;
475 while (cur != NULL) {
476 jint cur_occ = cur->occupied();
477 if (max == NULL || cur_occ > max_occ) {
478 max = cur;
479 max_prev = prev;
480 max_ind = i;
481 max_occ = cur_occ;
482 }
483 prev = cur->collision_list_next_addr();
484 cur = cur->collision_list_next();
485 }
486 i = i + _fine_eviction_stride;
487 if (i >= _n_fine_entries) i = i - _n_fine_entries;
488 }
489
490 _fine_eviction_start++;
491
492 if (_fine_eviction_start >= _n_fine_entries) {
493 _fine_eviction_start -= _n_fine_entries;
494 }
495
496 guarantee(max != NULL, "Since _n_fine_entries > 0");
497 guarantee(max_prev != NULL, "Since max != NULL.");
498
499 // Set the corresponding coarse bit.
500 size_t max_hrm_index = (size_t) max->hr()->hrm_index();
501 if (!_coarse_map.at(max_hrm_index)) {
502 _coarse_map.at_put(max_hrm_index, true);
503 _n_coarse_entries++;
504 }
505
506 // Unsplice.
507 *max_prev = max->collision_list_next();
508 Atomic::inc(&_n_coarsenings);
509 _n_fine_entries--;
510 return max;
511 }
512
513 void OtherRegionsTable::scrub(G1CardLiveData* live_data) {
514 // First eliminated garbage regions from the coarse map.
515 log_develop_trace(gc, remset, scrub)("Scrubbing region %u:", _hr->hrm_index());
516
517 log_develop_trace(gc, remset, scrub)(" Coarse map: before = " SIZE_FORMAT "...", _n_coarse_entries);
518 if (_n_coarse_entries > 0) {
519 live_data->remove_nonlive_regions(&_coarse_map);
520 _n_coarse_entries = _coarse_map.count_one_bits();
521 }
522 log_develop_trace(gc, remset, scrub)(" after = " SIZE_FORMAT ".", _n_coarse_entries);
523
524 // Now do the fine-grained maps.
525 for (size_t i = 0; i < _max_fine_entries; i++) {
526 PerRegionTable* cur = _fine_grain_regions[i];
527 PerRegionTable** prev = &_fine_grain_regions[i];
528 while (cur != NULL) {
529 PerRegionTable* nxt = cur->collision_list_next();
530 // If the entire region is dead, eliminate.
531 log_develop_trace(gc, remset, scrub)(" For other region %u:", cur->hr()->hrm_index());
532 if (!live_data->is_region_live(cur->hr()->hrm_index())) {
533 *prev = nxt;
534 cur->set_collision_list_next(NULL);
535 _n_fine_entries--;
536 log_develop_trace(gc, remset, scrub)(" deleted via region map.");
537 unlink_from_all(cur);
538 PerRegionTable::free(cur);
539 } else {
540 // Do fine-grain elimination.
541 log_develop_trace(gc, remset, scrub)(" occ: before = %4d.", cur->occupied());
542 cur->scrub(live_data);
543 log_develop_trace(gc, remset, scrub)(" after = %4d.", cur->occupied());
544 // Did that empty the table completely?
545 if (cur->occupied() == 0) {
546 *prev = nxt;
547 cur->set_collision_list_next(NULL);
548 _n_fine_entries--;
549 unlink_from_all(cur);
550 PerRegionTable::free(cur);
551 } else {
552 prev = cur->collision_list_next_addr();
553 }
554 }
555 cur = nxt;
556 }
557 }
558 // Since we may have deleted a from_card_cache entry from the RS, clear
559 // the FCC.
560 clear_fcc();
561 }
562
563 bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {
564 if (limit <= (size_t)G1RSetSparseRegionEntries) {
565 return occ_coarse() == 0 && _first_all_fine_prts == NULL && occ_sparse() <= limit;
566 } else {
567 // Current uses of this method may only use values less than G1RSetSparseRegionEntries
568 // for the limit. The solution, comparing against occupied() would be too slow
569 // at this time.
570 Unimplemented();
571 return false;
572 }
573 }
574
575 bool OtherRegionsTable::is_empty() const {
576 return occ_sparse() == 0 && occ_coarse() == 0 && _first_all_fine_prts == NULL;
577 }
578
579 size_t OtherRegionsTable::occupied() const {
580 size_t sum = occ_fine();
581 sum += occ_sparse();
582 sum += occ_coarse();
583 return sum;
584 }
585
586 size_t OtherRegionsTable::occ_fine() const {
587 size_t sum = 0;
588
589 size_t num = 0;
590 PerRegionTable * cur = _first_all_fine_prts;
591 while (cur != NULL) {
592 sum += cur->occupied();
593 cur = cur->next();
594 num++;
595 }
596 guarantee(num == _n_fine_entries, "just checking");
597 return sum;
598 }
599
600 size_t OtherRegionsTable::occ_coarse() const {
601 return (_n_coarse_entries * HeapRegion::CardsPerRegion);
602 }
603
604 size_t OtherRegionsTable::occ_sparse() const {
605 return _sparse_table.occupied();
606 }
607
608 size_t OtherRegionsTable::mem_size() const {
609 size_t sum = 0;
610 // all PRTs are of the same size so it is sufficient to query only one of them.
611 if (_first_all_fine_prts != NULL) {
612 assert(_last_all_fine_prts != NULL &&
613 _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
614 sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
615 }
616 sum += (sizeof(PerRegionTable*) * _max_fine_entries);
617 sum += (_coarse_map.size_in_words() * HeapWordSize);
618 sum += (_sparse_table.mem_size());
619 sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
620 return sum;
621 }
622
623 size_t OtherRegionsTable::static_mem_size() {
624 return G1FromCardCache::static_mem_size();
625 }
626
627 size_t OtherRegionsTable::fl_mem_size() {
628 return PerRegionTable::fl_mem_size();
629 }
630
631 void OtherRegionsTable::clear_fcc() {
632 G1FromCardCache::clear(_hr->hrm_index());
633 }
634
635 void OtherRegionsTable::clear() {
636 // if there are no entries, skip this step
637 if (_first_all_fine_prts != NULL) {
638 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
639 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
640 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
641 } else {
642 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
643 }
644
645 _first_all_fine_prts = _last_all_fine_prts = NULL;
646 _sparse_table.clear();
647 if (_n_coarse_entries > 0) {
648 _coarse_map.clear();
649 }
650 _n_fine_entries = 0;
651 _n_coarse_entries = 0;
652
653 clear_fcc();
654 }
655
656 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
657 // Cast away const in this case.
658 MutexLockerEx x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
659 return contains_reference_locked(from);
660 }
661
662 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
663 HeapRegion* hr = _g1h->heap_region_containing(from);
664 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
665 // Is this region in the coarse map?
666 if (_coarse_map.at(hr_ind)) return true;
667
668 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
669 hr);
670 if (prt != NULL) {
671 return prt->contains_reference(from);
672
673 } else {
674 uintptr_t from_card =
675 (uintptr_t(from) >> CardTableModRefBS::card_shift);
676 uintptr_t hr_bot_card_index =
677 uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
678 assert(from_card >= hr_bot_card_index, "Inv");
679 CardIdx_t card_index = from_card - hr_bot_card_index;
680 assert((size_t)card_index < HeapRegion::CardsPerRegion,
681 "Must be in range.");
682 return _sparse_table.contains_card(hr_ind, card_index);
683 }
684 }
685
686 void
687 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
688 _sparse_table.do_cleanup_work(hrrs_cleanup_task);
689 }
690
691 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetTable* bot,
692 HeapRegion* hr)
693 : _bot(bot),
694 _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Monitor::_safepoint_check_never),
695 _code_roots(),
696 _other_regions(hr, &_m) {
697 }
698
699 void HeapRegionRemSet::setup_remset_size() {
700 // Setup sparse and fine-grain tables sizes.
701 // table_size = base * (log(region_size / 1M) + 1)
702 const int LOG_M = 20;
703 int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
704 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
705 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
706 }
707 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
708 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
709 }
710 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
711 }
712
713 void HeapRegionRemSet::cleanup() {
714 SparsePRT::cleanup_all();
715 }
716
717 void HeapRegionRemSet::clear() {
718 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
719 clear_locked();
720 }
721
722 void HeapRegionRemSet::clear_locked() {
723 _code_roots.clear();
724 _other_regions.clear();
725 assert(occupied_locked() == 0, "Should be clear.");
726 }
727
728 void HeapRegionRemSet::scrub(G1CardLiveData* live_data) {
729 _other_regions.scrub(live_data);
730 }
731
732 // Code roots support
733 //
734 // The code root set is protected by two separate locking schemes
735 // When at safepoint the per-hrrs lock must be held during modifications
736 // except when doing a full gc.
737 // When not at safepoint the CodeCache_lock must be held during modifications.
738 // When concurrent readers access the contains() function
739 // (during the evacuation phase) no removals are allowed.
740
741 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
742 assert(nm != NULL, "sanity");
743 assert((!CodeCache_lock->owned_by_self() || SafepointSynchronize::is_at_safepoint()),
744 "should call add_strong_code_root_locked instead. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s",
745 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()));
746 // Optimistic unlocked contains-check
747 if (!_code_roots.contains(nm)) {
748 MutexLockerEx ml(&_m, Mutex::_no_safepoint_check_flag);
749 add_strong_code_root_locked(nm);
750 }
751 }
752
753 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
754 assert(nm != NULL, "sanity");
755 assert((CodeCache_lock->owned_by_self() ||
756 (SafepointSynchronize::is_at_safepoint() &&
757 (_m.owned_by_self() || Thread::current()->is_VM_thread()))),
758 "not safely locked. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s, _m.owned_by_self(): %s, Thread::current()->is_VM_thread(): %s",
759 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),
760 BOOL_TO_STR(_m.owned_by_self()), BOOL_TO_STR(Thread::current()->is_VM_thread()));
761 _code_roots.add(nm);
762 }
763
764 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
765 assert(nm != NULL, "sanity");
766 assert_locked_or_safepoint(CodeCache_lock);
767
768 MutexLockerEx ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
769 _code_roots.remove(nm);
770
771 // Check that there were no duplicates
772 guarantee(!_code_roots.contains(nm), "duplicate entry found");
773 }
774
775 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
776 _code_roots.nmethods_do(blk);
777 }
778
779 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
780 _code_roots.clean(hr);
781 }
782
783 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
784 return _code_roots.mem_size();
785 }
786
787 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
788 _hrrs(hrrs),
789 _g1h(G1CollectedHeap::heap()),
790 _coarse_map(&hrrs->_other_regions._coarse_map),
791 _bot(hrrs->_bot),
792 _is(Sparse),
793 // Set these values so that we increment to the first region.
794 _coarse_cur_region_index(-1),
795 _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
796 _cur_card_in_prt(HeapRegion::CardsPerRegion),
797 _fine_cur_prt(NULL),
798 _n_yielded_coarse(0),
799 _n_yielded_fine(0),
800 _n_yielded_sparse(0),
801 _sparse_iter(&hrrs->_other_regions._sparse_table) {}
802
803 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
804 if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
805 // Go to the next card.
806 _coarse_cur_region_cur_card++;
807 // Was the last the last card in the current region?
808 if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
809 // Yes: find the next region. This may leave _coarse_cur_region_index
810 // Set to the last index, in which case there are no more coarse
811 // regions.
812 _coarse_cur_region_index =
813 (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
814 if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
815 _coarse_cur_region_cur_card = 0;
816 HeapWord* r_bot =
817 _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
818 _cur_region_card_offset = _bot->index_for(r_bot);
819 } else {
820 return false;
821 }
822 }
823 // If we didn't return false above, then we can yield a card.
824 card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
825 return true;
826 }
827
828 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
829 if (fine_has_next()) {
830 _cur_card_in_prt =
831 _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
832 }
833 if (_cur_card_in_prt == HeapRegion::CardsPerRegion) {
834 // _fine_cur_prt may still be NULL in case if there are not PRTs at all for
835 // the remembered set.
836 if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) {
837 return false;
838 }
839 PerRegionTable* next_prt = _fine_cur_prt->next();
840 switch_to_prt(next_prt);
841 _cur_card_in_prt = _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
842 }
843
844 card_index = _cur_region_card_offset + _cur_card_in_prt;
845 guarantee(_cur_card_in_prt < HeapRegion::CardsPerRegion,
846 "Card index " SIZE_FORMAT " must be within the region", _cur_card_in_prt);
847 return true;
848 }
849
850 bool HeapRegionRemSetIterator::fine_has_next() {
851 return _cur_card_in_prt != HeapRegion::CardsPerRegion;
852 }
853
854 void HeapRegionRemSetIterator::switch_to_prt(PerRegionTable* prt) {
855 assert(prt != NULL, "Cannot switch to NULL prt");
856 _fine_cur_prt = prt;
857
858 HeapWord* r_bot = _fine_cur_prt->hr()->bottom();
859 _cur_region_card_offset = _bot->index_for(r_bot);
860
861 // The bitmap scan for the PRT always scans from _cur_region_cur_card + 1.
862 // To avoid special-casing this start case, and not miss the first bitmap
863 // entry, initialize _cur_region_cur_card with -1 instead of 0.
864 _cur_card_in_prt = (size_t)-1;
865 }
866
867 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
868 switch (_is) {
869 case Sparse: {
870 if (_sparse_iter.has_next(card_index)) {
871 _n_yielded_sparse++;
872 return true;
873 }
874 // Otherwise, deliberate fall-through
875 _is = Fine;
876 PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts;
877 if (initial_fine_prt != NULL) {
878 switch_to_prt(_hrrs->_other_regions._first_all_fine_prts);
879 }
880 }
881 case Fine:
882 if (fine_has_next(card_index)) {
883 _n_yielded_fine++;
884 return true;
885 }
886 // Otherwise, deliberate fall-through
887 _is = Coarse;
888 case Coarse:
889 if (coarse_has_next(card_index)) {
890 _n_yielded_coarse++;
891 return true;
892 }
893 // Otherwise...
894 break;
895 }
896 return false;
897 }
898
899 void HeapRegionRemSet::reset_for_cleanup_tasks() {
900 SparsePRT::reset_for_cleanup_tasks();
901 }
902
903 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
904 _other_regions.do_cleanup_work(hrrs_cleanup_task);
905 }
906
907 void
908 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
909 SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
910 }
911
912 #ifndef PRODUCT
913 void HeapRegionRemSet::test() {
914 os::sleep(Thread::current(), (jlong)5000, false);
915 G1CollectedHeap* g1h = G1CollectedHeap::heap();
916
917 // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
918 // hash bucket.
919 HeapRegion* hr0 = g1h->region_at(0);
920 HeapRegion* hr1 = g1h->region_at(1);
921 HeapRegion* hr2 = g1h->region_at(5);
922 HeapRegion* hr3 = g1h->region_at(6);
923 HeapRegion* hr4 = g1h->region_at(7);
924 HeapRegion* hr5 = g1h->region_at(8);
925
926 HeapWord* hr1_start = hr1->bottom();
927 HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
928 HeapWord* hr1_last = hr1->end() - 1;
929
930 HeapWord* hr2_start = hr2->bottom();
931 HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
932 HeapWord* hr2_last = hr2->end() - 1;
933
934 HeapWord* hr3_start = hr3->bottom();
935 HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
936 HeapWord* hr3_last = hr3->end() - 1;
937
938 HeapRegionRemSet* hrrs = hr0->rem_set();
939
940 // Make three references from region 0x101...
941 hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
942 hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
943 hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
944
945 hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
946 hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
947 hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
948
949 hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
950 hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
951 hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
952
953 // Now cause a coarsening.
954 hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
955 hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
956
957 // Now, does iteration yield these three?
958 HeapRegionRemSetIterator iter(hrrs);
959 size_t sum = 0;
960 size_t card_index;
961 while (iter.has_next(card_index)) {
962 HeapWord* card_start =
963 G1CollectedHeap::heap()->bot()->address_for_index(card_index);
964 tty->print_cr(" Card " PTR_FORMAT ".", p2i(card_start));
965 sum++;
966 }
967 guarantee(sum == 11 - 3 + 2048, "Failure");
968 guarantee(sum == hrrs->occupied(), "Failure");
969 }
970 #endif