1 /*
2 * Copyright (c) 2001, 2016, 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/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.inline.hpp"
36 #include "utilities/bitMap.inline.hpp"
37 #include "utilities/globalDefinitions.hpp"
38 #include "utilities/growableArray.hpp"
39
40 class PerRegionTable: public CHeapObj<mtGC> {
41 friend class OtherRegionsTable;
42 friend class HeapRegionRemSetIterator;
43
44 HeapRegion* _hr;
45 BitMap _bm;
46 jint _occupied;
47
48 // next pointer for free/allocated 'all' list
49 PerRegionTable* _next;
50
51 // prev pointer for the allocated 'all' list
52 PerRegionTable* _prev;
53
54 // next pointer in collision list
55 PerRegionTable * _collision_list_next;
56
57 // Global free list of PRTs
58 static PerRegionTable* _free_list;
59
60 protected:
61 // We need access in order to union things into the base table.
62 BitMap* bm() { return &_bm; }
63
64 void recount_occupied() {
65 _occupied = (jint) bm()->count_one_bits();
66 }
67
68 PerRegionTable(HeapRegion* hr) :
69 _hr(hr),
70 _occupied(0),
71 _bm(HeapRegion::CardsPerRegion, false /* in-resource-area */),
72 _collision_list_next(NULL), _next(NULL), _prev(NULL)
73 {}
74
75 void add_card_work(CardIdx_t from_card, bool par) {
76 if (!_bm.at(from_card)) {
77 if (par) {
78 if (_bm.par_at_put(from_card, 1)) {
79 Atomic::inc(&_occupied);
80 }
81 } else {
82 _bm.at_put(from_card, 1);
83 _occupied++;
84 }
85 }
86 }
87
88 void add_reference_work(OopOrNarrowOopStar from, bool par) {
89 // Must make this robust in case "from" is not in "_hr", because of
90 // concurrency.
91
92 HeapRegion* loc_hr = hr();
93 // If the test below fails, then this table was reused concurrently
94 // with this operation. This is OK, since the old table was coarsened,
95 // and adding a bit to the new table is never incorrect.
96 // If the table used to belong to a continues humongous region and is
97 // now reused for the corresponding start humongous region, we need to
98 // make sure that we detect this. Thus, we call is_in_reserved_raw()
99 // instead of just is_in_reserved() here.
100 if (loc_hr->is_in_reserved(from)) {
101 size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom());
102 CardIdx_t from_card = (CardIdx_t)
103 hw_offset >> (CardTableModRefBS::card_shift - LogHeapWordSize);
104
105 assert(0 <= from_card && (size_t)from_card < HeapRegion::CardsPerRegion,
106 "Must be in range.");
107 add_card_work(from_card, par);
108 }
109 }
110
111 public:
112
113 HeapRegion* hr() const { return _hr; }
114
115 jint occupied() const {
116 // Overkill, but if we ever need it...
117 // guarantee(_occupied == _bm.count_one_bits(), "Check");
118 return _occupied;
119 }
120
121 void init(HeapRegion* hr, bool clear_links_to_all_list) {
122 if (clear_links_to_all_list) {
123 set_next(NULL);
124 set_prev(NULL);
125 }
126 _collision_list_next = NULL;
127 _occupied = 0;
128 _bm.clear();
129 // Make sure that the bitmap clearing above has been finished before publishing
130 // this PRT to concurrent threads.
131 OrderAccess::release_store_ptr(&_hr, hr);
132 }
133
134 void add_reference(OopOrNarrowOopStar from) {
135 add_reference_work(from, /*parallel*/ true);
136 }
137
138 void seq_add_reference(OopOrNarrowOopStar from) {
139 add_reference_work(from, /*parallel*/ false);
140 }
141
142 void scrub(CardTableModRefBS* ctbs, BitMap* card_bm) {
143 HeapWord* hr_bot = hr()->bottom();
144 size_t hr_first_card_index = ctbs->index_for(hr_bot);
145 bm()->set_intersection_at_offset(*card_bm, hr_first_card_index);
146 recount_occupied();
147 }
148
149 void add_card(CardIdx_t from_card_index) {
150 add_card_work(from_card_index, /*parallel*/ true);
151 }
152
153 void seq_add_card(CardIdx_t from_card_index) {
154 add_card_work(from_card_index, /*parallel*/ false);
155 }
156
157 // (Destructively) union the bitmap of the current table into the given
158 // bitmap (which is assumed to be of the same size.)
159 void union_bitmap_into(BitMap* bm) {
160 bm->set_union(_bm);
161 }
162
163 // Mem size in bytes.
164 size_t mem_size() const {
165 return sizeof(PerRegionTable) + _bm.size_in_words() * HeapWordSize;
166 }
167
168 // Requires "from" to be in "hr()".
169 bool contains_reference(OopOrNarrowOopStar from) const {
170 assert(hr()->is_in_reserved(from), "Precondition.");
171 size_t card_ind = pointer_delta(from, hr()->bottom(),
172 CardTableModRefBS::card_size);
173 return _bm.at(card_ind);
174 }
175
176 // Bulk-free the PRTs from prt to last, assumes that they are
177 // linked together using their _next field.
178 static void bulk_free(PerRegionTable* prt, PerRegionTable* last) {
179 while (true) {
180 PerRegionTable* fl = _free_list;
181 last->set_next(fl);
182 PerRegionTable* res = (PerRegionTable*) Atomic::cmpxchg_ptr(prt, &_free_list, fl);
183 if (res == fl) {
184 return;
185 }
186 }
187 ShouldNotReachHere();
188 }
189
190 static void free(PerRegionTable* prt) {
191 bulk_free(prt, prt);
192 }
193
194 // Returns an initialized PerRegionTable instance.
195 static PerRegionTable* alloc(HeapRegion* hr) {
196 PerRegionTable* fl = _free_list;
197 while (fl != NULL) {
198 PerRegionTable* nxt = fl->next();
199 PerRegionTable* res =
200 (PerRegionTable*)
201 Atomic::cmpxchg_ptr(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* 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(),
262 false /* in-resource-area */),
263 _fine_grain_regions(NULL),
264 _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
265 _n_fine_entries(0), _n_coarse_entries(0),
266 _fine_eviction_start(0),
267 _sparse_table(hr)
268 {
269 typedef PerRegionTable* PerRegionTablePtr;
270
271 if (_max_fine_entries == 0) {
272 assert(_mod_max_fine_entries_mask == 0, "Both or none.");
273 size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
274 _max_fine_entries = (size_t)1 << max_entries_log;
275 _mod_max_fine_entries_mask = _max_fine_entries - 1;
276
277 assert(_fine_eviction_sample_size == 0
278 && _fine_eviction_stride == 0, "All init at same time.");
279 _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
280 _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
281 }
282
283 _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
284 mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
285
286 if (_fine_grain_regions == NULL) {
287 vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
288 "Failed to allocate _fine_grain_entries.");
289 }
290
291 for (size_t i = 0; i < _max_fine_entries; i++) {
292 _fine_grain_regions[i] = NULL;
293 }
294 }
295
296 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
297 // We always append to the beginning of the list for convenience;
298 // the order of entries in this list does not matter.
299 if (_first_all_fine_prts != NULL) {
300 assert(_first_all_fine_prts->prev() == NULL, "invariant");
301 _first_all_fine_prts->set_prev(prt);
302 prt->set_next(_first_all_fine_prts);
303 } else {
304 // this is the first element we insert. Adjust the "last" pointer
305 _last_all_fine_prts = prt;
306 assert(prt->next() == NULL, "just checking");
307 }
308 // the new element is always the first element without a predecessor
309 prt->set_prev(NULL);
310 _first_all_fine_prts = prt;
311
312 assert(prt->prev() == NULL, "just checking");
313 assert(_first_all_fine_prts == prt, "just checking");
314 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
315 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
316 "just checking");
317 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
318 "just checking");
319 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
320 "just checking");
321 }
322
323 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
324 if (prt->prev() != NULL) {
325 assert(_first_all_fine_prts != prt, "just checking");
326 prt->prev()->set_next(prt->next());
327 // removing the last element in the list?
328 if (_last_all_fine_prts == prt) {
329 _last_all_fine_prts = prt->prev();
330 }
331 } else {
332 assert(_first_all_fine_prts == prt, "just checking");
333 _first_all_fine_prts = prt->next();
334 // list is empty now?
335 if (_first_all_fine_prts == NULL) {
336 _last_all_fine_prts = NULL;
337 }
338 }
339
340 if (prt->next() != NULL) {
341 prt->next()->set_prev(prt->prev());
342 }
343
344 prt->set_next(NULL);
345 prt->set_prev(NULL);
346
347 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
348 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
349 "just checking");
350 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
351 "just checking");
352 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
353 "just checking");
354 }
355
356 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
357 uint cur_hrm_ind = _hr->hrm_index();
358
359 int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
360
361 if (G1FromCardCache::contains_or_replace(tid, cur_hrm_ind, from_card)) {
362 assert(contains_reference(from), "We just found " PTR_FORMAT " in the FromCardCache", p2i(from));
363 return;
364 }
365
366 // Note that this may be a continued H region.
367 HeapRegion* from_hr = _g1h->heap_region_containing(from);
368 RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
369
370 // If the region is already coarsened, return.
371 if (_coarse_map.at(from_hrm_ind)) {
372 assert(contains_reference(from), "We just found " PTR_FORMAT " in the Coarse table", p2i(from));
373 return;
374 }
375
376 // Otherwise find a per-region table to add it to.
377 size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
378 PerRegionTable* prt = find_region_table(ind, from_hr);
379 if (prt == NULL) {
380 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
381 // Confirm that it's really not there...
382 prt = find_region_table(ind, from_hr);
383 if (prt == NULL) {
384
385 uintptr_t from_hr_bot_card_index =
386 uintptr_t(from_hr->bottom())
387 >> CardTableModRefBS::card_shift;
388 CardIdx_t card_index = from_card - from_hr_bot_card_index;
389 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
390 "Must be in range.");
391 if (G1HRRSUseSparseTable &&
392 _sparse_table.add_card(from_hrm_ind, card_index)) {
393 assert(contains_reference_locked(from), "We just added " PTR_FORMAT " to the Sparse table", p2i(from));
394 return;
395 }
396
397 if (_n_fine_entries == _max_fine_entries) {
398 prt = delete_region_table();
399 // There is no need to clear the links to the 'all' list here:
400 // prt will be reused immediately, i.e. remain in the 'all' list.
401 prt->init(from_hr, false /* clear_links_to_all_list */);
402 } else {
403 prt = PerRegionTable::alloc(from_hr);
404 link_to_all(prt);
405 }
406
407 PerRegionTable* first_prt = _fine_grain_regions[ind];
408 prt->set_collision_list_next(first_prt);
409 // The assignment into _fine_grain_regions allows the prt to
410 // start being used concurrently. In addition to
411 // collision_list_next which must be visible (else concurrent
412 // parsing of the list, if any, may fail to see other entries),
413 // the content of the prt must be visible (else for instance
414 // some mark bits may not yet seem cleared or a 'later' update
415 // performed by a concurrent thread could be undone when the
416 // zeroing becomes visible). This requires store ordering.
417 OrderAccess::release_store_ptr((volatile PerRegionTable*)&_fine_grain_regions[ind], prt);
418 _n_fine_entries++;
419
420 if (G1HRRSUseSparseTable) {
421 // Transfer from sparse to fine-grain.
422 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
423 assert(sprt_entry != NULL, "There should have been an entry");
424 for (int i = 0; i < SparsePRTEntry::cards_num(); i++) {
425 CardIdx_t c = sprt_entry->card(i);
426 if (c != SparsePRTEntry::NullEntry) {
427 prt->add_card(c);
428 }
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(CardTableModRefBS* ctbs,
517 BitMap* region_bm, BitMap* card_bm) {
518 // First eliminated garbage regions from the coarse map.
519 log_develop_trace(gc, remset, scrub)("Scrubbing region %u:", _hr->hrm_index());
520
521 assert(_coarse_map.size() == region_bm->size(), "Precondition");
522 log_develop_trace(gc, remset, scrub)(" Coarse map: before = " SIZE_FORMAT "...", _n_coarse_entries);
523 _coarse_map.set_intersection(*region_bm);
524 _n_coarse_entries = _coarse_map.count_one_bits();
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 (!region_bm->at((size_t) 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(ctbs, card_bm);
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 _coarse_map.clear();
651 _n_fine_entries = 0;
652 _n_coarse_entries = 0;
653
654 clear_fcc();
655 }
656
657 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
658 // Cast away const in this case.
659 MutexLockerEx x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
660 return contains_reference_locked(from);
661 }
662
663 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
664 HeapRegion* hr = _g1h->heap_region_containing(from);
665 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
666 // Is this region in the coarse map?
667 if (_coarse_map.at(hr_ind)) return true;
668
669 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
670 hr);
671 if (prt != NULL) {
672 return prt->contains_reference(from);
673
674 } else {
675 uintptr_t from_card =
676 (uintptr_t(from) >> CardTableModRefBS::card_shift);
677 uintptr_t hr_bot_card_index =
678 uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
679 assert(from_card >= hr_bot_card_index, "Inv");
680 CardIdx_t card_index = from_card - hr_bot_card_index;
681 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
682 "Must be in range.");
683 return _sparse_table.contains_card(hr_ind, card_index);
684 }
685 }
686
687 void
688 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
689 _sparse_table.do_cleanup_work(hrrs_cleanup_task);
690 }
691
692 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetTable* bot,
693 HeapRegion* hr)
694 : _bot(bot),
695 _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Monitor::_safepoint_check_never),
696 _code_roots(), _other_regions(hr, &_m), _iter_state(Unclaimed), _iter_claimed(0) {
697 reset_for_par_iteration();
698 }
699
700 void HeapRegionRemSet::setup_remset_size() {
701 // Setup sparse and fine-grain tables sizes.
702 // table_size = base * (log(region_size / 1M) + 1)
703 const int LOG_M = 20;
704 int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
705 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
706 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
707 }
708 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
709 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
710 }
711 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
712 }
713
714 bool HeapRegionRemSet::claim_iter() {
715 if (_iter_state != Unclaimed) return false;
716 jint res = Atomic::cmpxchg(Claimed, (jint*)(&_iter_state), Unclaimed);
717 return (res == Unclaimed);
718 }
719
720 void HeapRegionRemSet::set_iter_complete() {
721 _iter_state = Complete;
722 }
723
724 bool HeapRegionRemSet::iter_is_complete() {
725 return _iter_state == Complete;
726 }
727
728 #ifndef PRODUCT
729 void HeapRegionRemSet::print() {
730 HeapRegionRemSetIterator iter(this);
731 size_t card_index;
732 while (iter.has_next(card_index)) {
733 HeapWord* card_start = _bot->address_for_index(card_index);
734 tty->print_cr(" Card " PTR_FORMAT, p2i(card_start));
735 }
736 if (iter.n_yielded() != occupied()) {
737 tty->print_cr("Yielded disagrees with occupied:");
738 tty->print_cr(" " SIZE_FORMAT_W(6) " yielded (" SIZE_FORMAT_W(6)
739 " coarse, " SIZE_FORMAT_W(6) " fine).",
740 iter.n_yielded(),
741 iter.n_yielded_coarse(), iter.n_yielded_fine());
742 tty->print_cr(" " SIZE_FORMAT_W(6) " occ (" SIZE_FORMAT_W(6)
743 " coarse, " SIZE_FORMAT_W(6) " fine).",
744 occupied(), occ_coarse(), occ_fine());
745 }
746 guarantee(iter.n_yielded() == occupied(),
747 "We should have yielded all the represented cards.");
748 }
749 #endif
750
751 void HeapRegionRemSet::cleanup() {
752 SparsePRT::cleanup_all();
753 }
754
755 void HeapRegionRemSet::clear() {
756 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
757 clear_locked();
758 }
759
760 void HeapRegionRemSet::clear_locked() {
761 _code_roots.clear();
762 _other_regions.clear();
763 assert(occupied_locked() == 0, "Should be clear.");
764 reset_for_par_iteration();
765 }
766
767 void HeapRegionRemSet::reset_for_par_iteration() {
768 _iter_state = Unclaimed;
769 _iter_claimed = 0;
770 // It's good to check this to make sure that the two methods are in sync.
771 assert(verify_ready_for_par_iteration(), "post-condition");
772 }
773
774 void HeapRegionRemSet::scrub(CardTableModRefBS* ctbs,
775 BitMap* region_bm, BitMap* card_bm) {
776 _other_regions.scrub(ctbs, region_bm, card_bm);
777 }
778
779 // Code roots support
780 //
781 // The code root set is protected by two separate locking schemes
782 // When at safepoint the per-hrrs lock must be held during modifications
783 // except when doing a full gc.
784 // When not at safepoint the CodeCache_lock must be held during modifications.
785 // When concurrent readers access the contains() function
786 // (during the evacuation phase) no removals are allowed.
787
788 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
789 assert(nm != NULL, "sanity");
790 // Optimistic unlocked contains-check
791 if (!_code_roots.contains(nm)) {
792 MutexLockerEx ml(&_m, Mutex::_no_safepoint_check_flag);
793 add_strong_code_root_locked(nm);
794 }
795 }
796
797 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
798 assert(nm != NULL, "sanity");
799 _code_roots.add(nm);
800 }
801
802 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
803 assert(nm != NULL, "sanity");
804 assert_locked_or_safepoint(CodeCache_lock);
805
806 MutexLockerEx ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
807 _code_roots.remove(nm);
808
809 // Check that there were no duplicates
810 guarantee(!_code_roots.contains(nm), "duplicate entry found");
811 }
812
813 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
814 _code_roots.nmethods_do(blk);
815 }
816
817 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
818 _code_roots.clean(hr);
819 }
820
821 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
822 return _code_roots.mem_size();
823 }
824
825 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
826 _hrrs(hrrs),
827 _g1h(G1CollectedHeap::heap()),
828 _coarse_map(&hrrs->_other_regions._coarse_map),
829 _bot(hrrs->_bot),
830 _is(Sparse),
831 // Set these values so that we increment to the first region.
832 _coarse_cur_region_index(-1),
833 _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
834 _cur_card_in_prt(HeapRegion::CardsPerRegion),
835 _fine_cur_prt(NULL),
836 _n_yielded_coarse(0),
837 _n_yielded_fine(0),
838 _n_yielded_sparse(0),
839 _sparse_iter(&hrrs->_other_regions._sparse_table) {}
840
841 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
842 if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
843 // Go to the next card.
844 _coarse_cur_region_cur_card++;
845 // Was the last the last card in the current region?
846 if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
847 // Yes: find the next region. This may leave _coarse_cur_region_index
848 // Set to the last index, in which case there are no more coarse
849 // regions.
850 _coarse_cur_region_index =
851 (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
852 if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
853 _coarse_cur_region_cur_card = 0;
854 HeapWord* r_bot =
855 _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
856 _cur_region_card_offset = _bot->index_for(r_bot);
857 } else {
858 return false;
859 }
860 }
861 // If we didn't return false above, then we can yield a card.
862 card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
863 return true;
864 }
865
866 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
867 if (fine_has_next()) {
868 _cur_card_in_prt =
869 _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
870 }
871 if (_cur_card_in_prt == HeapRegion::CardsPerRegion) {
872 // _fine_cur_prt may still be NULL in case if there are not PRTs at all for
873 // the remembered set.
874 if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) {
875 return false;
876 }
877 PerRegionTable* next_prt = _fine_cur_prt->next();
878 switch_to_prt(next_prt);
879 _cur_card_in_prt = _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
880 }
881
882 card_index = _cur_region_card_offset + _cur_card_in_prt;
883 guarantee(_cur_card_in_prt < HeapRegion::CardsPerRegion,
884 "Card index " SIZE_FORMAT " must be within the region", _cur_card_in_prt);
885 return true;
886 }
887
888 bool HeapRegionRemSetIterator::fine_has_next() {
889 return _cur_card_in_prt != HeapRegion::CardsPerRegion;
890 }
891
892 void HeapRegionRemSetIterator::switch_to_prt(PerRegionTable* prt) {
893 assert(prt != NULL, "Cannot switch to NULL prt");
894 _fine_cur_prt = prt;
895
896 HeapWord* r_bot = _fine_cur_prt->hr()->bottom();
897 _cur_region_card_offset = _bot->index_for(r_bot);
898
899 // The bitmap scan for the PRT always scans from _cur_region_cur_card + 1.
900 // To avoid special-casing this start case, and not miss the first bitmap
901 // entry, initialize _cur_region_cur_card with -1 instead of 0.
902 _cur_card_in_prt = (size_t)-1;
903 }
904
905 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
906 switch (_is) {
907 case Sparse: {
908 if (_sparse_iter.has_next(card_index)) {
909 _n_yielded_sparse++;
910 return true;
911 }
912 // Otherwise, deliberate fall-through
913 _is = Fine;
914 PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts;
915 if (initial_fine_prt != NULL) {
916 switch_to_prt(_hrrs->_other_regions._first_all_fine_prts);
917 }
918 }
919 case Fine:
920 if (fine_has_next(card_index)) {
921 _n_yielded_fine++;
922 return true;
923 }
924 // Otherwise, deliberate fall-through
925 _is = Coarse;
926 case Coarse:
927 if (coarse_has_next(card_index)) {
928 _n_yielded_coarse++;
929 return true;
930 }
931 // Otherwise...
932 break;
933 }
934 assert(ParallelGCThreads > 1 ||
935 n_yielded() == _hrrs->occupied(),
936 "Should have yielded all the cards in the rem set "
937 "(in the non-par case).");
938 return false;
939 }
940
941 void HeapRegionRemSet::reset_for_cleanup_tasks() {
942 SparsePRT::reset_for_cleanup_tasks();
943 }
944
945 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
946 _other_regions.do_cleanup_work(hrrs_cleanup_task);
947 }
948
949 void
950 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
951 SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
952 }
953
954 #ifndef PRODUCT
955 void HeapRegionRemSet::test() {
956 os::sleep(Thread::current(), (jlong)5000, false);
957 G1CollectedHeap* g1h = G1CollectedHeap::heap();
958
959 // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
960 // hash bucket.
961 HeapRegion* hr0 = g1h->region_at(0);
962 HeapRegion* hr1 = g1h->region_at(1);
963 HeapRegion* hr2 = g1h->region_at(5);
964 HeapRegion* hr3 = g1h->region_at(6);
965 HeapRegion* hr4 = g1h->region_at(7);
966 HeapRegion* hr5 = g1h->region_at(8);
967
968 HeapWord* hr1_start = hr1->bottom();
969 HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
970 HeapWord* hr1_last = hr1->end() - 1;
971
972 HeapWord* hr2_start = hr2->bottom();
973 HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
974 HeapWord* hr2_last = hr2->end() - 1;
975
976 HeapWord* hr3_start = hr3->bottom();
977 HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
978 HeapWord* hr3_last = hr3->end() - 1;
979
980 HeapRegionRemSet* hrrs = hr0->rem_set();
981
982 // Make three references from region 0x101...
983 hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
984 hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
985 hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
986
987 hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
988 hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
989 hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
990
991 hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
992 hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
993 hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
994
995 // Now cause a coarsening.
996 hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
997 hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
998
999 // Now, does iteration yield these three?
1000 HeapRegionRemSetIterator iter(hrrs);
1001 size_t sum = 0;
1002 size_t card_index;
1003 while (iter.has_next(card_index)) {
1004 HeapWord* card_start =
1005 G1CollectedHeap::heap()->bot()->address_for_index(card_index);
1006 tty->print_cr(" Card " PTR_FORMAT ".", p2i(card_start));
1007 sum++;
1008 }
1009 guarantee(sum == 11 - 3 + 2048, "Failure");
1010 guarantee(sum == hrrs->occupied(), "Failure");
1011 }
1012 #endif