1 /*
2 * Copyright (c) 2001, 2015, 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 log_develop(gc, remset)(" PRT::Add_reference_work(" PTR_FORMAT "->" PTR_FORMAT ").",
93 p2i(from),
94 UseCompressedOops
95 ? p2i(oopDesc::load_decode_heap_oop((narrowOop*)from))
96 : p2i(oopDesc::load_decode_heap_oop((oop*)from)));
97
98 HeapRegion* loc_hr = hr();
99 // If the test below fails, then this table was reused concurrently
100 // with this operation. This is OK, since the old table was coarsened,
101 // and adding a bit to the new table is never incorrect.
102 // If the table used to belong to a continues humongous region and is
103 // now reused for the corresponding start humongous region, we need to
104 // make sure that we detect this. Thus, we call is_in_reserved_raw()
105 // instead of just is_in_reserved() here.
106 if (loc_hr->is_in_reserved(from)) {
107 size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom());
108 CardIdx_t from_card = (CardIdx_t)
109 hw_offset >> (CardTableModRefBS::card_shift - LogHeapWordSize);
110
111 assert(0 <= from_card && (size_t)from_card < HeapRegion::CardsPerRegion,
112 "Must be in range.");
113 add_card_work(from_card, par);
114 }
115 }
116
117 public:
118
119 HeapRegion* hr() const { return _hr; }
120
121 jint occupied() const {
122 // Overkill, but if we ever need it...
123 // guarantee(_occupied == _bm.count_one_bits(), "Check");
124 return _occupied;
125 }
126
127 void init(HeapRegion* hr, bool clear_links_to_all_list) {
128 if (clear_links_to_all_list) {
129 set_next(NULL);
130 set_prev(NULL);
131 }
132 _hr = hr;
133 _collision_list_next = NULL;
134 _occupied = 0;
135 _bm.clear();
136 }
137
138 void add_reference(OopOrNarrowOopStar from) {
139 add_reference_work(from, /*parallel*/ true);
140 }
141
142 void seq_add_reference(OopOrNarrowOopStar from) {
143 add_reference_work(from, /*parallel*/ false);
144 }
145
146 void scrub(CardTableModRefBS* ctbs, BitMap* card_bm) {
147 HeapWord* hr_bot = hr()->bottom();
148 size_t hr_first_card_index = ctbs->index_for(hr_bot);
149 bm()->set_intersection_at_offset(*card_bm, hr_first_card_index);
150 recount_occupied();
151 }
152
153 void add_card(CardIdx_t from_card_index) {
154 add_card_work(from_card_index, /*parallel*/ true);
155 }
156
157 void seq_add_card(CardIdx_t from_card_index) {
158 add_card_work(from_card_index, /*parallel*/ false);
159 }
160
161 // (Destructively) union the bitmap of the current table into the given
162 // bitmap (which is assumed to be of the same size.)
163 void union_bitmap_into(BitMap* bm) {
164 bm->set_union(_bm);
165 }
166
167 // Mem size in bytes.
168 size_t mem_size() const {
169 return sizeof(PerRegionTable) + _bm.size_in_words() * HeapWordSize;
170 }
171
172 // Requires "from" to be in "hr()".
173 bool contains_reference(OopOrNarrowOopStar from) const {
174 assert(hr()->is_in_reserved(from), "Precondition.");
175 size_t card_ind = pointer_delta(from, hr()->bottom(),
176 CardTableModRefBS::card_size);
177 return _bm.at(card_ind);
178 }
179
180 // Bulk-free the PRTs from prt to last, assumes that they are
181 // linked together using their _next field.
182 static void bulk_free(PerRegionTable* prt, PerRegionTable* last) {
183 while (true) {
184 PerRegionTable* fl = _free_list;
185 last->set_next(fl);
186 PerRegionTable* res = (PerRegionTable*) Atomic::cmpxchg_ptr(prt, &_free_list, fl);
187 if (res == fl) {
188 return;
189 }
190 }
191 ShouldNotReachHere();
192 }
193
194 static void free(PerRegionTable* prt) {
195 bulk_free(prt, prt);
196 }
197
198 // Returns an initialized PerRegionTable instance.
199 static PerRegionTable* alloc(HeapRegion* hr) {
200 PerRegionTable* fl = _free_list;
201 while (fl != NULL) {
202 PerRegionTable* nxt = fl->next();
203 PerRegionTable* res =
204 (PerRegionTable*)
205 Atomic::cmpxchg_ptr(nxt, &_free_list, fl);
206 if (res == fl) {
207 fl->init(hr, true);
208 return fl;
209 } else {
210 fl = _free_list;
211 }
212 }
213 assert(fl == NULL, "Loop condition.");
214 return new PerRegionTable(hr);
215 }
216
217 PerRegionTable* next() const { return _next; }
218 void set_next(PerRegionTable* next) { _next = next; }
219 PerRegionTable* prev() const { return _prev; }
220 void set_prev(PerRegionTable* prev) { _prev = prev; }
221
222 // Accessor and Modification routines for the pointer for the
223 // singly linked collision list that links the PRTs within the
224 // OtherRegionsTable::_fine_grain_regions hash table.
225 //
226 // It might be useful to also make the collision list doubly linked
227 // to avoid iteration over the collisions list during scrubbing/deletion.
228 // OTOH there might not be many collisions.
229
230 PerRegionTable* collision_list_next() const {
231 return _collision_list_next;
232 }
233
234 void set_collision_list_next(PerRegionTable* next) {
235 _collision_list_next = next;
236 }
237
238 PerRegionTable** collision_list_next_addr() {
239 return &_collision_list_next;
240 }
241
242 static size_t fl_mem_size() {
243 PerRegionTable* cur = _free_list;
244 size_t res = 0;
245 while (cur != NULL) {
246 res += cur->mem_size();
247 cur = cur->next();
248 }
249 return res;
250 }
251
252 static void test_fl_mem_size();
253 };
254
255 PerRegionTable* PerRegionTable::_free_list = NULL;
256
257 size_t OtherRegionsTable::_max_fine_entries = 0;
258 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
259 size_t OtherRegionsTable::_fine_eviction_stride = 0;
260 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
261
262 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr, Mutex* m) :
263 _g1h(G1CollectedHeap::heap()),
264 _hr(hr), _m(m),
265 _coarse_map(G1CollectedHeap::heap()->max_regions(),
266 false /* in-resource-area */),
267 _fine_grain_regions(NULL),
268 _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
269 _n_fine_entries(0), _n_coarse_entries(0),
270 _fine_eviction_start(0),
271 _sparse_table(hr)
272 {
273 typedef PerRegionTable* PerRegionTablePtr;
274
275 if (_max_fine_entries == 0) {
276 assert(_mod_max_fine_entries_mask == 0, "Both or none.");
277 size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
278 _max_fine_entries = (size_t)1 << max_entries_log;
279 _mod_max_fine_entries_mask = _max_fine_entries - 1;
280
281 assert(_fine_eviction_sample_size == 0
282 && _fine_eviction_stride == 0, "All init at same time.");
283 _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
284 _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
285 }
286
287 _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
288 mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
289
290 if (_fine_grain_regions == NULL) {
291 vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
292 "Failed to allocate _fine_grain_entries.");
293 }
294
295 for (size_t i = 0; i < _max_fine_entries; i++) {
296 _fine_grain_regions[i] = NULL;
297 }
298 }
299
300 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
301 // We always append to the beginning of the list for convenience;
302 // the order of entries in this list does not matter.
303 if (_first_all_fine_prts != NULL) {
304 assert(_first_all_fine_prts->prev() == NULL, "invariant");
305 _first_all_fine_prts->set_prev(prt);
306 prt->set_next(_first_all_fine_prts);
307 } else {
308 // this is the first element we insert. Adjust the "last" pointer
309 _last_all_fine_prts = prt;
310 assert(prt->next() == NULL, "just checking");
311 }
312 // the new element is always the first element without a predecessor
313 prt->set_prev(NULL);
314 _first_all_fine_prts = prt;
315
316 assert(prt->prev() == NULL, "just checking");
317 assert(_first_all_fine_prts == prt, "just checking");
318 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
319 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
320 "just checking");
321 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
322 "just checking");
323 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
324 "just checking");
325 }
326
327 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
328 if (prt->prev() != NULL) {
329 assert(_first_all_fine_prts != prt, "just checking");
330 prt->prev()->set_next(prt->next());
331 // removing the last element in the list?
332 if (_last_all_fine_prts == prt) {
333 _last_all_fine_prts = prt->prev();
334 }
335 } else {
336 assert(_first_all_fine_prts == prt, "just checking");
337 _first_all_fine_prts = prt->next();
338 // list is empty now?
339 if (_first_all_fine_prts == NULL) {
340 _last_all_fine_prts = NULL;
341 }
342 }
343
344 if (prt->next() != NULL) {
345 prt->next()->set_prev(prt->prev());
346 }
347
348 prt->set_next(NULL);
349 prt->set_prev(NULL);
350
351 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
352 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
353 "just checking");
354 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
355 "just checking");
356 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
357 "just checking");
358 }
359
360 int** FromCardCache::_cache = NULL;
361 uint FromCardCache::_max_regions = 0;
362 size_t FromCardCache::_static_mem_size = 0;
363
364 void FromCardCache::initialize(uint n_par_rs, uint max_num_regions) {
365 guarantee(_cache == NULL, "Should not call this multiple times");
366
367 _max_regions = max_num_regions;
368 _cache = Padded2DArray<int, mtGC>::create_unfreeable(n_par_rs,
369 _max_regions,
370 &_static_mem_size);
371
372 invalidate(0, _max_regions);
373 }
374
375 void FromCardCache::invalidate(uint start_idx, size_t new_num_regions) {
376 guarantee((size_t)start_idx + new_num_regions <= max_uintx,
377 "Trying to invalidate beyond maximum region, from %u size " SIZE_FORMAT,
378 start_idx, new_num_regions);
379 for (uint i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
380 uint end_idx = (start_idx + (uint)new_num_regions);
381 assert(end_idx <= _max_regions, "Must be within max.");
382 for (uint j = start_idx; j < end_idx; j++) {
383 set(i, j, InvalidCard);
384 }
385 }
386 }
387
388 #ifndef PRODUCT
389 void FromCardCache::print(outputStream* out) {
390 for (uint i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
391 for (uint j = 0; j < _max_regions; j++) {
392 out->print_cr("_from_card_cache[%u][%u] = %d.",
393 i, j, at(i, j));
394 }
395 }
396 }
397 #endif
398
399 void FromCardCache::clear(uint region_idx) {
400 uint num_par_remsets = HeapRegionRemSet::num_par_rem_sets();
401 for (uint i = 0; i < num_par_remsets; i++) {
402 set(i, region_idx, InvalidCard);
403 }
404 }
405
406 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
407 uint cur_hrm_ind = _hr->hrm_index();
408
409 log_develop(gc, remset)("ORT::add_reference_work(" PTR_FORMAT "->" PTR_FORMAT ").",
410 p2i(from),
411 UseCompressedOops
412 ? p2i(oopDesc::load_decode_heap_oop((narrowOop*)from))
413 : p2i(oopDesc::load_decode_heap_oop((oop*)from)));
414
415 int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
416
417 log_develop(gc, remset)("Table for [" PTR_FORMAT "...): card %d (cache = %d)",
418 p2i(_hr->bottom()), from_card,
419 FromCardCache::at(tid, cur_hrm_ind));
420
421 if (FromCardCache::contains_or_replace(tid, cur_hrm_ind, from_card)) {
422 log_develop(gc, remset)(" from-card cache hit.");
423 assert(contains_reference(from), "We just added it!");
424 return;
425 }
426
427 // Note that this may be a continued H region.
428 HeapRegion* from_hr = _g1h->heap_region_containing(from);
429 RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
430
431 // If the region is already coarsened, return.
432 if (_coarse_map.at(from_hrm_ind)) {
433 log_develop(gc, remset)(" coarse map hit.");
434 assert(contains_reference(from), "We just added it!");
435 return;
436 }
437
438 // Otherwise find a per-region table to add it to.
439 size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
440 PerRegionTable* prt = find_region_table(ind, from_hr);
441 if (prt == NULL) {
442 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
443 // Confirm that it's really not there...
444 prt = find_region_table(ind, from_hr);
445 if (prt == NULL) {
446
447 uintptr_t from_hr_bot_card_index =
448 uintptr_t(from_hr->bottom())
449 >> CardTableModRefBS::card_shift;
450 CardIdx_t card_index = from_card - from_hr_bot_card_index;
451 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
452 "Must be in range.");
453 if (G1HRRSUseSparseTable &&
454 _sparse_table.add_card(from_hrm_ind, card_index)) {
455 log_develop(gc, remset)(" added card to sparse table.");
456 assert(contains_reference_locked(from), "We just added it!");
457 return;
458 } else {
459 log_develop(gc, remset)(" [tid %u] sparse table entry overflow(f: %d, t: %u)",
460 tid, from_hrm_ind, cur_hrm_ind);
461 }
462
463 if (_n_fine_entries == _max_fine_entries) {
464 prt = delete_region_table();
465 // There is no need to clear the links to the 'all' list here:
466 // prt will be reused immediately, i.e. remain in the 'all' list.
467 prt->init(from_hr, false /* clear_links_to_all_list */);
468 } else {
469 prt = PerRegionTable::alloc(from_hr);
470 link_to_all(prt);
471 }
472
473 PerRegionTable* first_prt = _fine_grain_regions[ind];
474 prt->set_collision_list_next(first_prt);
475 // The assignment into _fine_grain_regions allows the prt to
476 // start being used concurrently. In addition to
477 // collision_list_next which must be visible (else concurrent
478 // parsing of the list, if any, may fail to see other entries),
479 // the content of the prt must be visible (else for instance
480 // some mark bits may not yet seem cleared or a 'later' update
481 // performed by a concurrent thread could be undone when the
482 // zeroing becomes visible). This requires store ordering.
483 OrderAccess::release_store_ptr((volatile PerRegionTable*)&_fine_grain_regions[ind], prt);
484 _n_fine_entries++;
485
486 if (G1HRRSUseSparseTable) {
487 // Transfer from sparse to fine-grain.
488 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
489 assert(sprt_entry != NULL, "There should have been an entry");
490 for (int i = 0; i < SparsePRTEntry::cards_num(); i++) {
491 CardIdx_t c = sprt_entry->card(i);
492 if (c != SparsePRTEntry::NullEntry) {
493 prt->add_card(c);
494 }
495 }
496 // Now we can delete the sparse entry.
497 bool res = _sparse_table.delete_entry(from_hrm_ind);
498 assert(res, "It should have been there.");
499 }
500 }
501 assert(prt != NULL && prt->hr() == from_hr, "consequence");
502 }
503 // Note that we can't assert "prt->hr() == from_hr", because of the
504 // possibility of concurrent reuse. But see head comment of
505 // OtherRegionsTable for why this is OK.
506 assert(prt != NULL, "Inv");
507
508 prt->add_reference(from);
509 assert(contains_reference(from), "We just added it!");
510 }
511
512 PerRegionTable*
513 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
514 assert(ind < _max_fine_entries, "Preconditions.");
515 PerRegionTable* prt = _fine_grain_regions[ind];
516 while (prt != NULL && prt->hr() != hr) {
517 prt = prt->collision_list_next();
518 }
519 // Loop postcondition is the method postcondition.
520 return prt;
521 }
522
523 jint OtherRegionsTable::_n_coarsenings = 0;
524
525 PerRegionTable* OtherRegionsTable::delete_region_table() {
526 assert(_m->owned_by_self(), "Precondition");
527 assert(_n_fine_entries == _max_fine_entries, "Precondition");
528 PerRegionTable* max = NULL;
529 jint max_occ = 0;
530 PerRegionTable** max_prev = NULL;
531 size_t max_ind;
532
533 size_t i = _fine_eviction_start;
534 for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
535 size_t ii = i;
536 // Make sure we get a non-NULL sample.
537 while (_fine_grain_regions[ii] == NULL) {
538 ii++;
539 if (ii == _max_fine_entries) ii = 0;
540 guarantee(ii != i, "We must find one.");
541 }
542 PerRegionTable** prev = &_fine_grain_regions[ii];
543 PerRegionTable* cur = *prev;
544 while (cur != NULL) {
545 jint cur_occ = cur->occupied();
546 if (max == NULL || cur_occ > max_occ) {
547 max = cur;
548 max_prev = prev;
549 max_ind = i;
550 max_occ = cur_occ;
551 }
552 prev = cur->collision_list_next_addr();
553 cur = cur->collision_list_next();
554 }
555 i = i + _fine_eviction_stride;
556 if (i >= _n_fine_entries) i = i - _n_fine_entries;
557 }
558
559 _fine_eviction_start++;
560
561 if (_fine_eviction_start >= _n_fine_entries) {
562 _fine_eviction_start -= _n_fine_entries;
563 }
564
565 guarantee(max != NULL, "Since _n_fine_entries > 0");
566 guarantee(max_prev != NULL, "Since max != NULL.");
567
568 // Set the corresponding coarse bit.
569 size_t max_hrm_index = (size_t) max->hr()->hrm_index();
570 if (!_coarse_map.at(max_hrm_index)) {
571 _coarse_map.at_put(max_hrm_index, true);
572 _n_coarse_entries++;
573 log_develop(gc, remset)("Coarsened entry in region [" PTR_FORMAT "...] for region [" PTR_FORMAT "...] (" SIZE_FORMAT " coarse entries)",
574 p2i(_hr->bottom()), p2i(max->hr()->bottom()), _n_coarse_entries);
575 }
576
577 // Unsplice.
578 *max_prev = max->collision_list_next();
579 Atomic::inc(&_n_coarsenings);
580 _n_fine_entries--;
581 return max;
582 }
583
584 void OtherRegionsTable::scrub(CardTableModRefBS* ctbs,
585 BitMap* region_bm, BitMap* card_bm) {
586 // First eliminated garbage regions from the coarse map.
587 log_develop(gc, remset, scrub)("Scrubbing region %u:", _hr->hrm_index());
588
589 assert(_coarse_map.size() == region_bm->size(), "Precondition");
590 log_develop(gc, remset, scrub)(" Coarse map: before = " SIZE_FORMAT "...", _n_coarse_entries);
591 _coarse_map.set_intersection(*region_bm);
592 _n_coarse_entries = _coarse_map.count_one_bits();
593 log_develop(gc, remset, scrub)(" after = " SIZE_FORMAT ".", _n_coarse_entries);
594
595 // Now do the fine-grained maps.
596 for (size_t i = 0; i < _max_fine_entries; i++) {
597 PerRegionTable* cur = _fine_grain_regions[i];
598 PerRegionTable** prev = &_fine_grain_regions[i];
599 while (cur != NULL) {
600 PerRegionTable* nxt = cur->collision_list_next();
601 // If the entire region is dead, eliminate.
602 log_develop(gc, remset, scrub)(" For other region %u:", cur->hr()->hrm_index());
603 if (!region_bm->at((size_t) cur->hr()->hrm_index())) {
604 *prev = nxt;
605 cur->set_collision_list_next(NULL);
606 _n_fine_entries--;
607 log_develop(gc, remset, scrub)(" deleted via region map.");
608 unlink_from_all(cur);
609 PerRegionTable::free(cur);
610 } else {
611 // Do fine-grain elimination.
612 log_develop(gc, remset, scrub)(" occ: before = %4d.", cur->occupied());
613 cur->scrub(ctbs, card_bm);
614 log_develop(gc, remset, scrub)(" after = %4d.", cur->occupied());
615 // Did that empty the table completely?
616 if (cur->occupied() == 0) {
617 *prev = nxt;
618 cur->set_collision_list_next(NULL);
619 _n_fine_entries--;
620 unlink_from_all(cur);
621 PerRegionTable::free(cur);
622 } else {
623 prev = cur->collision_list_next_addr();
624 }
625 }
626 cur = nxt;
627 }
628 }
629 // Since we may have deleted a from_card_cache entry from the RS, clear
630 // the FCC.
631 clear_fcc();
632 }
633
634 bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {
635 if (limit <= (size_t)G1RSetSparseRegionEntries) {
636 return occ_coarse() == 0 && _first_all_fine_prts == NULL && occ_sparse() <= limit;
637 } else {
638 // Current uses of this method may only use values less than G1RSetSparseRegionEntries
639 // for the limit. The solution, comparing against occupied() would be too slow
640 // at this time.
641 Unimplemented();
642 return false;
643 }
644 }
645
646 bool OtherRegionsTable::is_empty() const {
647 return occ_sparse() == 0 && occ_coarse() == 0 && _first_all_fine_prts == NULL;
648 }
649
650 size_t OtherRegionsTable::occupied() const {
651 size_t sum = occ_fine();
652 sum += occ_sparse();
653 sum += occ_coarse();
654 return sum;
655 }
656
657 size_t OtherRegionsTable::occ_fine() const {
658 size_t sum = 0;
659
660 size_t num = 0;
661 PerRegionTable * cur = _first_all_fine_prts;
662 while (cur != NULL) {
663 sum += cur->occupied();
664 cur = cur->next();
665 num++;
666 }
667 guarantee(num == _n_fine_entries, "just checking");
668 return sum;
669 }
670
671 size_t OtherRegionsTable::occ_coarse() const {
672 return (_n_coarse_entries * HeapRegion::CardsPerRegion);
673 }
674
675 size_t OtherRegionsTable::occ_sparse() const {
676 return _sparse_table.occupied();
677 }
678
679 size_t OtherRegionsTable::mem_size() const {
680 size_t sum = 0;
681 // all PRTs are of the same size so it is sufficient to query only one of them.
682 if (_first_all_fine_prts != NULL) {
683 assert(_last_all_fine_prts != NULL &&
684 _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
685 sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
686 }
687 sum += (sizeof(PerRegionTable*) * _max_fine_entries);
688 sum += (_coarse_map.size_in_words() * HeapWordSize);
689 sum += (_sparse_table.mem_size());
690 sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
691 return sum;
692 }
693
694 size_t OtherRegionsTable::static_mem_size() {
695 return FromCardCache::static_mem_size();
696 }
697
698 size_t OtherRegionsTable::fl_mem_size() {
699 return PerRegionTable::fl_mem_size();
700 }
701
702 void OtherRegionsTable::clear_fcc() {
703 FromCardCache::clear(_hr->hrm_index());
704 }
705
706 void OtherRegionsTable::clear() {
707 // if there are no entries, skip this step
708 if (_first_all_fine_prts != NULL) {
709 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
710 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
711 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
712 } else {
713 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
714 }
715
716 _first_all_fine_prts = _last_all_fine_prts = NULL;
717 _sparse_table.clear();
718 _coarse_map.clear();
719 _n_fine_entries = 0;
720 _n_coarse_entries = 0;
721
722 clear_fcc();
723 }
724
725 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
726 // Cast away const in this case.
727 MutexLockerEx x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
728 return contains_reference_locked(from);
729 }
730
731 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
732 HeapRegion* hr = _g1h->heap_region_containing(from);
733 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
734 // Is this region in the coarse map?
735 if (_coarse_map.at(hr_ind)) return true;
736
737 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
738 hr);
739 if (prt != NULL) {
740 return prt->contains_reference(from);
741
742 } else {
743 uintptr_t from_card =
744 (uintptr_t(from) >> CardTableModRefBS::card_shift);
745 uintptr_t hr_bot_card_index =
746 uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
747 assert(from_card >= hr_bot_card_index, "Inv");
748 CardIdx_t card_index = from_card - hr_bot_card_index;
749 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
750 "Must be in range.");
751 return _sparse_table.contains_card(hr_ind, card_index);
752 }
753 }
754
755 void
756 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
757 _sparse_table.do_cleanup_work(hrrs_cleanup_task);
758 }
759
760 // Determines how many threads can add records to an rset in parallel.
761 // This can be done by either mutator threads together with the
762 // concurrent refinement threads or GC threads.
763 uint HeapRegionRemSet::num_par_rem_sets() {
764 return MAX2(DirtyCardQueueSet::num_par_ids() + ConcurrentG1Refine::thread_num(), ParallelGCThreads);
765 }
766
767 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetSharedArray* bosa,
768 HeapRegion* hr)
769 : _bosa(bosa),
770 _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Monitor::_safepoint_check_never),
771 _code_roots(), _other_regions(hr, &_m), _iter_state(Unclaimed), _iter_claimed(0) {
772 reset_for_par_iteration();
773 }
774
775 void HeapRegionRemSet::setup_remset_size() {
776 // Setup sparse and fine-grain tables sizes.
777 // table_size = base * (log(region_size / 1M) + 1)
778 const int LOG_M = 20;
779 int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
780 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
781 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
782 }
783 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
784 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
785 }
786 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
787 }
788
789 bool HeapRegionRemSet::claim_iter() {
790 if (_iter_state != Unclaimed) return false;
791 jint res = Atomic::cmpxchg(Claimed, (jint*)(&_iter_state), Unclaimed);
792 return (res == Unclaimed);
793 }
794
795 void HeapRegionRemSet::set_iter_complete() {
796 _iter_state = Complete;
797 }
798
799 bool HeapRegionRemSet::iter_is_complete() {
800 return _iter_state == Complete;
801 }
802
803 #ifndef PRODUCT
804 void HeapRegionRemSet::print() {
805 HeapRegionRemSetIterator iter(this);
806 size_t card_index;
807 while (iter.has_next(card_index)) {
808 HeapWord* card_start =
809 G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
810 tty->print_cr(" Card " PTR_FORMAT, p2i(card_start));
811 }
812 if (iter.n_yielded() != occupied()) {
813 tty->print_cr("Yielded disagrees with occupied:");
814 tty->print_cr(" " SIZE_FORMAT_W(6) " yielded (" SIZE_FORMAT_W(6)
815 " coarse, " SIZE_FORMAT_W(6) " fine).",
816 iter.n_yielded(),
817 iter.n_yielded_coarse(), iter.n_yielded_fine());
818 tty->print_cr(" " SIZE_FORMAT_W(6) " occ (" SIZE_FORMAT_W(6)
819 " coarse, " SIZE_FORMAT_W(6) " fine).",
820 occupied(), occ_coarse(), occ_fine());
821 }
822 guarantee(iter.n_yielded() == occupied(),
823 "We should have yielded all the represented cards.");
824 }
825 #endif
826
827 void HeapRegionRemSet::cleanup() {
828 SparsePRT::cleanup_all();
829 }
830
831 void HeapRegionRemSet::clear() {
832 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
833 clear_locked();
834 }
835
836 void HeapRegionRemSet::clear_locked() {
837 _code_roots.clear();
838 _other_regions.clear();
839 assert(occupied_locked() == 0, "Should be clear.");
840 reset_for_par_iteration();
841 }
842
843 void HeapRegionRemSet::reset_for_par_iteration() {
844 _iter_state = Unclaimed;
845 _iter_claimed = 0;
846 // It's good to check this to make sure that the two methods are in sync.
847 assert(verify_ready_for_par_iteration(), "post-condition");
848 }
849
850 void HeapRegionRemSet::scrub(CardTableModRefBS* ctbs,
851 BitMap* region_bm, BitMap* card_bm) {
852 _other_regions.scrub(ctbs, region_bm, card_bm);
853 }
854
855 // Code roots support
856 //
857 // The code root set is protected by two separate locking schemes
858 // When at safepoint the per-hrrs lock must be held during modifications
859 // except when doing a full gc.
860 // When not at safepoint the CodeCache_lock must be held during modifications.
861 // When concurrent readers access the contains() function
862 // (during the evacuation phase) no removals are allowed.
863
864 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
865 assert(nm != NULL, "sanity");
866 // Optimistic unlocked contains-check
867 if (!_code_roots.contains(nm)) {
868 MutexLockerEx ml(&_m, Mutex::_no_safepoint_check_flag);
869 add_strong_code_root_locked(nm);
870 }
871 }
872
873 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
874 assert(nm != NULL, "sanity");
875 _code_roots.add(nm);
876 }
877
878 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
879 assert(nm != NULL, "sanity");
880 assert_locked_or_safepoint(CodeCache_lock);
881
882 MutexLockerEx ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
883 _code_roots.remove(nm);
884
885 // Check that there were no duplicates
886 guarantee(!_code_roots.contains(nm), "duplicate entry found");
887 }
888
889 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
890 _code_roots.nmethods_do(blk);
891 }
892
893 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
894 _code_roots.clean(hr);
895 }
896
897 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
898 return _code_roots.mem_size();
899 }
900
901 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
902 _hrrs(hrrs),
903 _g1h(G1CollectedHeap::heap()),
904 _coarse_map(&hrrs->_other_regions._coarse_map),
905 _bosa(hrrs->_bosa),
906 _is(Sparse),
907 // Set these values so that we increment to the first region.
908 _coarse_cur_region_index(-1),
909 _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
910 _cur_card_in_prt(HeapRegion::CardsPerRegion),
911 _fine_cur_prt(NULL),
912 _n_yielded_coarse(0),
913 _n_yielded_fine(0),
914 _n_yielded_sparse(0),
915 _sparse_iter(&hrrs->_other_regions._sparse_table) {}
916
917 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
918 if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
919 // Go to the next card.
920 _coarse_cur_region_cur_card++;
921 // Was the last the last card in the current region?
922 if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
923 // Yes: find the next region. This may leave _coarse_cur_region_index
924 // Set to the last index, in which case there are no more coarse
925 // regions.
926 _coarse_cur_region_index =
927 (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
928 if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
929 _coarse_cur_region_cur_card = 0;
930 HeapWord* r_bot =
931 _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
932 _cur_region_card_offset = _bosa->index_for(r_bot);
933 } else {
934 return false;
935 }
936 }
937 // If we didn't return false above, then we can yield a card.
938 card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
939 return true;
940 }
941
942 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
943 if (fine_has_next()) {
944 _cur_card_in_prt =
945 _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
946 }
947 if (_cur_card_in_prt == HeapRegion::CardsPerRegion) {
948 // _fine_cur_prt may still be NULL in case if there are not PRTs at all for
949 // the remembered set.
950 if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) {
951 return false;
952 }
953 PerRegionTable* next_prt = _fine_cur_prt->next();
954 switch_to_prt(next_prt);
955 _cur_card_in_prt = _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
956 }
957
958 card_index = _cur_region_card_offset + _cur_card_in_prt;
959 guarantee(_cur_card_in_prt < HeapRegion::CardsPerRegion,
960 "Card index " SIZE_FORMAT " must be within the region", _cur_card_in_prt);
961 return true;
962 }
963
964 bool HeapRegionRemSetIterator::fine_has_next() {
965 return _cur_card_in_prt != HeapRegion::CardsPerRegion;
966 }
967
968 void HeapRegionRemSetIterator::switch_to_prt(PerRegionTable* prt) {
969 assert(prt != NULL, "Cannot switch to NULL prt");
970 _fine_cur_prt = prt;
971
972 HeapWord* r_bot = _fine_cur_prt->hr()->bottom();
973 _cur_region_card_offset = _bosa->index_for(r_bot);
974
975 // The bitmap scan for the PRT always scans from _cur_region_cur_card + 1.
976 // To avoid special-casing this start case, and not miss the first bitmap
977 // entry, initialize _cur_region_cur_card with -1 instead of 0.
978 _cur_card_in_prt = (size_t)-1;
979 }
980
981 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
982 switch (_is) {
983 case Sparse: {
984 if (_sparse_iter.has_next(card_index)) {
985 _n_yielded_sparse++;
986 return true;
987 }
988 // Otherwise, deliberate fall-through
989 _is = Fine;
990 PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts;
991 if (initial_fine_prt != NULL) {
992 switch_to_prt(_hrrs->_other_regions._first_all_fine_prts);
993 }
994 }
995 case Fine:
996 if (fine_has_next(card_index)) {
997 _n_yielded_fine++;
998 return true;
999 }
1000 // Otherwise, deliberate fall-through
1001 _is = Coarse;
1002 case Coarse:
1003 if (coarse_has_next(card_index)) {
1004 _n_yielded_coarse++;
1005 return true;
1006 }
1007 // Otherwise...
1008 break;
1009 }
1010 assert(ParallelGCThreads > 1 ||
1011 n_yielded() == _hrrs->occupied(),
1012 "Should have yielded all the cards in the rem set "
1013 "(in the non-par case).");
1014 return false;
1015 }
1016
1017 void HeapRegionRemSet::reset_for_cleanup_tasks() {
1018 SparsePRT::reset_for_cleanup_tasks();
1019 }
1020
1021 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
1022 _other_regions.do_cleanup_work(hrrs_cleanup_task);
1023 }
1024
1025 void
1026 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
1027 SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
1028 }
1029
1030 #ifndef PRODUCT
1031 void PerRegionTable::test_fl_mem_size() {
1032 PerRegionTable* dummy = alloc(NULL);
1033
1034 size_t min_prt_size = sizeof(void*) + dummy->bm()->size_in_words() * HeapWordSize;
1035 assert(dummy->mem_size() > min_prt_size,
1036 "PerRegionTable memory usage is suspiciously small, only has " SIZE_FORMAT " bytes. "
1037 "Should be at least " SIZE_FORMAT " bytes.", dummy->mem_size(), min_prt_size);
1038 free(dummy);
1039 guarantee(dummy->mem_size() == fl_mem_size(), "fl_mem_size() does not return the correct element size");
1040 // try to reset the state
1041 _free_list = NULL;
1042 delete dummy;
1043 }
1044
1045 void HeapRegionRemSet::test_prt() {
1046 PerRegionTable::test_fl_mem_size();
1047 }
1048
1049 void HeapRegionRemSet::test() {
1050 os::sleep(Thread::current(), (jlong)5000, false);
1051 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1052
1053 // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
1054 // hash bucket.
1055 HeapRegion* hr0 = g1h->region_at(0);
1056 HeapRegion* hr1 = g1h->region_at(1);
1057 HeapRegion* hr2 = g1h->region_at(5);
1058 HeapRegion* hr3 = g1h->region_at(6);
1059 HeapRegion* hr4 = g1h->region_at(7);
1060 HeapRegion* hr5 = g1h->region_at(8);
1061
1062 HeapWord* hr1_start = hr1->bottom();
1063 HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
1064 HeapWord* hr1_last = hr1->end() - 1;
1065
1066 HeapWord* hr2_start = hr2->bottom();
1067 HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
1068 HeapWord* hr2_last = hr2->end() - 1;
1069
1070 HeapWord* hr3_start = hr3->bottom();
1071 HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
1072 HeapWord* hr3_last = hr3->end() - 1;
1073
1074 HeapRegionRemSet* hrrs = hr0->rem_set();
1075
1076 // Make three references from region 0x101...
1077 hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
1078 hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
1079 hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
1080
1081 hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
1082 hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
1083 hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
1084
1085 hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
1086 hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
1087 hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
1088
1089 // Now cause a coarsening.
1090 hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
1091 hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
1092
1093 // Now, does iteration yield these three?
1094 HeapRegionRemSetIterator iter(hrrs);
1095 size_t sum = 0;
1096 size_t card_index;
1097 while (iter.has_next(card_index)) {
1098 HeapWord* card_start =
1099 G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
1100 tty->print_cr(" Card " PTR_FORMAT ".", p2i(card_start));
1101 sum++;
1102 }
1103 guarantee(sum == 11 - 3 + 2048, "Failure");
1104 guarantee(sum == hrrs->occupied(), "Failure");
1105 }
1106 #endif