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 if (G1TraceHeapRegionRememberedSet) {
93 gclog_or_tty->print_cr(" PRT::Add_reference_work(" PTR_FORMAT "->" PTR_FORMAT ").",
94 p2i(from),
95 UseCompressedOops
96 ? p2i(oopDesc::load_decode_heap_oop((narrowOop*)from))
97 : p2i(oopDesc::load_decode_heap_oop((oop*)from)));
98 }
99
100 HeapRegion* loc_hr = hr();
101 // If the test below fails, then this table was reused concurrently
102 // with this operation. This is OK, since the old table was coarsened,
103 // and adding a bit to the new table is never incorrect.
104 // If the table used to belong to a continues humongous region and is
105 // now reused for the corresponding start humongous region, we need to
106 // make sure that we detect this. Thus, we call is_in_reserved_raw()
107 // instead of just is_in_reserved() here.
108 if (loc_hr->is_in_reserved(from)) {
109 size_t hw_offset = pointer_delta((HeapWord*)from, loc_hr->bottom());
110 CardIdx_t from_card = (CardIdx_t)
111 hw_offset >> (CardTableModRefBS::card_shift - LogHeapWordSize);
112
113 assert(0 <= from_card && (size_t)from_card < HeapRegion::CardsPerRegion,
114 "Must be in range.");
115 add_card_work(from_card, par);
116 }
117 }
118
119 public:
120
121 HeapRegion* hr() const { return _hr; }
122
123 jint occupied() const {
124 // Overkill, but if we ever need it...
125 // guarantee(_occupied == _bm.count_one_bits(), "Check");
126 return _occupied;
127 }
128
129 void init(HeapRegion* hr, bool clear_links_to_all_list) {
130 if (clear_links_to_all_list) {
131 set_next(NULL);
132 set_prev(NULL);
133 }
134 _hr = hr;
135 _collision_list_next = NULL;
136 _occupied = 0;
137 _bm.clear();
138 }
139
140 void add_reference(OopOrNarrowOopStar from) {
141 add_reference_work(from, /*parallel*/ true);
142 }
143
144 void seq_add_reference(OopOrNarrowOopStar from) {
145 add_reference_work(from, /*parallel*/ false);
146 }
147
148 void scrub(CardTableModRefBS* ctbs, BitMap* card_bm) {
149 HeapWord* hr_bot = hr()->bottom();
150 size_t hr_first_card_index = ctbs->index_for(hr_bot);
151 bm()->set_intersection_at_offset(*card_bm, hr_first_card_index);
152 recount_occupied();
153 }
154
155 void add_card(CardIdx_t from_card_index) {
156 add_card_work(from_card_index, /*parallel*/ true);
157 }
158
159 void seq_add_card(CardIdx_t from_card_index) {
160 add_card_work(from_card_index, /*parallel*/ false);
161 }
162
163 // (Destructively) union the bitmap of the current table into the given
164 // bitmap (which is assumed to be of the same size.)
165 void union_bitmap_into(BitMap* bm) {
166 bm->set_union(_bm);
167 }
168
169 // Mem size in bytes.
170 size_t mem_size() const {
171 return sizeof(PerRegionTable) + _bm.size_in_words() * HeapWordSize;
172 }
173
174 // Requires "from" to be in "hr()".
175 bool contains_reference(OopOrNarrowOopStar from) const {
176 assert(hr()->is_in_reserved(from), "Precondition.");
177 size_t card_ind = pointer_delta(from, hr()->bottom(),
178 CardTableModRefBS::card_size);
179 return _bm.at(card_ind);
180 }
181
182 // Bulk-free the PRTs from prt to last, assumes that they are
183 // linked together using their _next field.
184 static void bulk_free(PerRegionTable* prt, PerRegionTable* last) {
185 while (true) {
186 PerRegionTable* fl = _free_list;
187 last->set_next(fl);
188 PerRegionTable* res = (PerRegionTable*) Atomic::cmpxchg_ptr(prt, &_free_list, fl);
189 if (res == fl) {
190 return;
191 }
192 }
193 ShouldNotReachHere();
194 }
195
196 static void free(PerRegionTable* prt) {
197 bulk_free(prt, prt);
198 }
199
200 // Returns an initialized PerRegionTable instance.
201 static PerRegionTable* alloc(HeapRegion* hr) {
202 PerRegionTable* fl = _free_list;
203 while (fl != NULL) {
204 PerRegionTable* nxt = fl->next();
205 PerRegionTable* res =
206 (PerRegionTable*)
207 Atomic::cmpxchg_ptr(nxt, &_free_list, fl);
208 if (res == fl) {
209 fl->init(hr, true);
210 return fl;
211 } else {
212 fl = _free_list;
213 }
214 }
215 assert(fl == NULL, "Loop condition.");
216 return new PerRegionTable(hr);
217 }
218
219 PerRegionTable* next() const { return _next; }
220 void set_next(PerRegionTable* next) { _next = next; }
221 PerRegionTable* prev() const { return _prev; }
222 void set_prev(PerRegionTable* prev) { _prev = prev; }
223
224 // Accessor and Modification routines for the pointer for the
225 // singly linked collision list that links the PRTs within the
226 // OtherRegionsTable::_fine_grain_regions hash table.
227 //
228 // It might be useful to also make the collision list doubly linked
229 // to avoid iteration over the collisions list during scrubbing/deletion.
230 // OTOH there might not be many collisions.
231
232 PerRegionTable* collision_list_next() const {
233 return _collision_list_next;
234 }
235
236 void set_collision_list_next(PerRegionTable* next) {
237 _collision_list_next = next;
238 }
239
240 PerRegionTable** collision_list_next_addr() {
241 return &_collision_list_next;
242 }
243
244 static size_t fl_mem_size() {
245 PerRegionTable* cur = _free_list;
246 size_t res = 0;
247 while (cur != NULL) {
248 res += cur->mem_size();
249 cur = cur->next();
250 }
251 return res;
252 }
253
254 static void test_fl_mem_size();
255 };
256
257 PerRegionTable* PerRegionTable::_free_list = NULL;
258
259 size_t OtherRegionsTable::_max_fine_entries = 0;
260 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
261 size_t OtherRegionsTable::_fine_eviction_stride = 0;
262 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
263
264 OtherRegionsTable::OtherRegionsTable(HeapRegion* hr, Mutex* m) :
265 _g1h(G1CollectedHeap::heap()),
266 _hr(hr), _m(m),
267 _coarse_map(G1CollectedHeap::heap()->max_regions(),
268 false /* in-resource-area */),
269 _fine_grain_regions(NULL),
270 _first_all_fine_prts(NULL), _last_all_fine_prts(NULL),
271 _n_fine_entries(0), _n_coarse_entries(0),
272 _fine_eviction_start(0),
273 _sparse_table(hr)
274 {
275 typedef PerRegionTable* PerRegionTablePtr;
276
277 if (_max_fine_entries == 0) {
278 assert(_mod_max_fine_entries_mask == 0, "Both or none.");
279 size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
280 _max_fine_entries = (size_t)1 << max_entries_log;
281 _mod_max_fine_entries_mask = _max_fine_entries - 1;
282
283 assert(_fine_eviction_sample_size == 0
284 && _fine_eviction_stride == 0, "All init at same time.");
285 _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
286 _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
287 }
288
289 _fine_grain_regions = NEW_C_HEAP_ARRAY3(PerRegionTablePtr, _max_fine_entries,
290 mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
291
292 if (_fine_grain_regions == NULL) {
293 vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
294 "Failed to allocate _fine_grain_entries.");
295 }
296
297 for (size_t i = 0; i < _max_fine_entries; i++) {
298 _fine_grain_regions[i] = NULL;
299 }
300 }
301
302 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
303 // We always append to the beginning of the list for convenience;
304 // the order of entries in this list does not matter.
305 if (_first_all_fine_prts != NULL) {
306 assert(_first_all_fine_prts->prev() == NULL, "invariant");
307 _first_all_fine_prts->set_prev(prt);
308 prt->set_next(_first_all_fine_prts);
309 } else {
310 // this is the first element we insert. Adjust the "last" pointer
311 _last_all_fine_prts = prt;
312 assert(prt->next() == NULL, "just checking");
313 }
314 // the new element is always the first element without a predecessor
315 prt->set_prev(NULL);
316 _first_all_fine_prts = prt;
317
318 assert(prt->prev() == NULL, "just checking");
319 assert(_first_all_fine_prts == prt, "just checking");
320 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
321 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
322 "just checking");
323 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
324 "just checking");
325 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
326 "just checking");
327 }
328
329 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
330 if (prt->prev() != NULL) {
331 assert(_first_all_fine_prts != prt, "just checking");
332 prt->prev()->set_next(prt->next());
333 // removing the last element in the list?
334 if (_last_all_fine_prts == prt) {
335 _last_all_fine_prts = prt->prev();
336 }
337 } else {
338 assert(_first_all_fine_prts == prt, "just checking");
339 _first_all_fine_prts = prt->next();
340 // list is empty now?
341 if (_first_all_fine_prts == NULL) {
342 _last_all_fine_prts = NULL;
343 }
344 }
345
346 if (prt->next() != NULL) {
347 prt->next()->set_prev(prt->prev());
348 }
349
350 prt->set_next(NULL);
351 prt->set_prev(NULL);
352
353 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
354 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
355 "just checking");
356 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
357 "just checking");
358 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
359 "just checking");
360 }
361
362 int** FromCardCache::_cache = NULL;
363 uint FromCardCache::_max_regions = 0;
364 size_t FromCardCache::_static_mem_size = 0;
365
366 void FromCardCache::initialize(uint n_par_rs, uint max_num_regions) {
367 guarantee(_cache == NULL, "Should not call this multiple times");
368
369 _max_regions = max_num_regions;
370 _cache = Padded2DArray<int, mtGC>::create_unfreeable(n_par_rs,
371 _max_regions,
372 &_static_mem_size);
373
374 invalidate(0, _max_regions);
375 }
376
377 void FromCardCache::invalidate(uint start_idx, size_t new_num_regions) {
378 guarantee((size_t)start_idx + new_num_regions <= max_uintx,
379 "Trying to invalidate beyond maximum region, from %u size " SIZE_FORMAT,
380 start_idx, new_num_regions);
381 for (uint i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
382 uint end_idx = (start_idx + (uint)new_num_regions);
383 assert(end_idx <= _max_regions, "Must be within max.");
384 for (uint j = start_idx; j < end_idx; j++) {
385 set(i, j, InvalidCard);
386 }
387 }
388 }
389
390 #ifndef PRODUCT
391 void FromCardCache::print(outputStream* out) {
392 for (uint i = 0; i < HeapRegionRemSet::num_par_rem_sets(); i++) {
393 for (uint j = 0; j < _max_regions; j++) {
394 out->print_cr("_from_card_cache[%u][%u] = %d.",
395 i, j, at(i, j));
396 }
397 }
398 }
399 #endif
400
401 void FromCardCache::clear(uint region_idx) {
402 uint num_par_remsets = HeapRegionRemSet::num_par_rem_sets();
403 for (uint i = 0; i < num_par_remsets; i++) {
404 set(i, region_idx, InvalidCard);
405 }
406 }
407
408 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
409 uint cur_hrm_ind = _hr->hrm_index();
410
411 if (G1TraceHeapRegionRememberedSet) {
412 gclog_or_tty->print_cr("ORT::add_reference_work(" PTR_FORMAT "->" PTR_FORMAT ").",
413 p2i(from),
414 UseCompressedOops
415 ? p2i(oopDesc::load_decode_heap_oop((narrowOop*)from))
416 : p2i(oopDesc::load_decode_heap_oop((oop*)from)));
417 }
418
419 int from_card = (int)(uintptr_t(from) >> CardTableModRefBS::card_shift);
420
421 if (G1TraceHeapRegionRememberedSet) {
422 gclog_or_tty->print_cr("Table for [" PTR_FORMAT "...): card %d (cache = %d)",
423 p2i(_hr->bottom()), from_card,
424 FromCardCache::at(tid, cur_hrm_ind));
425 }
426
427 if (FromCardCache::contains_or_replace(tid, cur_hrm_ind, from_card)) {
428 if (G1TraceHeapRegionRememberedSet) {
429 gclog_or_tty->print_cr(" from-card cache hit.");
430 }
431 assert(contains_reference(from), "We just added it!");
432 return;
433 }
434
435 // Note that this may be a continued H region.
436 HeapRegion* from_hr = _g1h->heap_region_containing(from);
437 RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
438
439 // If the region is already coarsened, return.
440 if (_coarse_map.at(from_hrm_ind)) {
441 if (G1TraceHeapRegionRememberedSet) {
442 gclog_or_tty->print_cr(" coarse map hit.");
443 }
444 assert(contains_reference(from), "We just added it!");
445 return;
446 }
447
448 // Otherwise find a per-region table to add it to.
449 size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
450 PerRegionTable* prt = find_region_table(ind, from_hr);
451 if (prt == NULL) {
452 MutexLockerEx x(_m, Mutex::_no_safepoint_check_flag);
453 // Confirm that it's really not there...
454 prt = find_region_table(ind, from_hr);
455 if (prt == NULL) {
456
457 uintptr_t from_hr_bot_card_index =
458 uintptr_t(from_hr->bottom())
459 >> CardTableModRefBS::card_shift;
460 CardIdx_t card_index = from_card - from_hr_bot_card_index;
461 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
462 "Must be in range.");
463 if (G1HRRSUseSparseTable &&
464 _sparse_table.add_card(from_hrm_ind, card_index)) {
465 if (G1TraceHeapRegionRememberedSet) {
466 gclog_or_tty->print_cr(" added card to sparse table.");
467 }
468 assert(contains_reference_locked(from), "We just added it!");
469 return;
470 } else {
471 if (G1TraceHeapRegionRememberedSet) {
472 gclog_or_tty->print_cr(" [tid %u] sparse table entry "
473 "overflow(f: %d, t: %u)",
474 tid, from_hrm_ind, cur_hrm_ind);
475 }
476 }
477
478 if (_n_fine_entries == _max_fine_entries) {
479 prt = delete_region_table();
480 // There is no need to clear the links to the 'all' list here:
481 // prt will be reused immediately, i.e. remain in the 'all' list.
482 prt->init(from_hr, false /* clear_links_to_all_list */);
483 } else {
484 prt = PerRegionTable::alloc(from_hr);
485 link_to_all(prt);
486 }
487
488 PerRegionTable* first_prt = _fine_grain_regions[ind];
489 prt->set_collision_list_next(first_prt);
490 // The assignment into _fine_grain_regions allows the prt to
491 // start being used concurrently. In addition to
492 // collision_list_next which must be visible (else concurrent
493 // parsing of the list, if any, may fail to see other entries),
494 // the content of the prt must be visible (else for instance
495 // some mark bits may not yet seem cleared or a 'later' update
496 // performed by a concurrent thread could be undone when the
497 // zeroing becomes visible). This requires store ordering.
498 OrderAccess::release_store_ptr((volatile PerRegionTable*)&_fine_grain_regions[ind], prt);
499 _n_fine_entries++;
500
501 if (G1HRRSUseSparseTable) {
502 // Transfer from sparse to fine-grain.
503 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
504 assert(sprt_entry != NULL, "There should have been an entry");
505 for (int i = 0; i < SparsePRTEntry::cards_num(); i++) {
506 CardIdx_t c = sprt_entry->card(i);
507 if (c != SparsePRTEntry::NullEntry) {
508 prt->add_card(c);
509 }
510 }
511 // Now we can delete the sparse entry.
512 bool res = _sparse_table.delete_entry(from_hrm_ind);
513 assert(res, "It should have been there.");
514 }
515 }
516 assert(prt != NULL && prt->hr() == from_hr, "consequence");
517 }
518 // Note that we can't assert "prt->hr() == from_hr", because of the
519 // possibility of concurrent reuse. But see head comment of
520 // OtherRegionsTable for why this is OK.
521 assert(prt != NULL, "Inv");
522
523 prt->add_reference(from);
524 assert(contains_reference(from), "We just added it!");
525 }
526
527 PerRegionTable*
528 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
529 assert(ind < _max_fine_entries, "Preconditions.");
530 PerRegionTable* prt = _fine_grain_regions[ind];
531 while (prt != NULL && prt->hr() != hr) {
532 prt = prt->collision_list_next();
533 }
534 // Loop postcondition is the method postcondition.
535 return prt;
536 }
537
538 jint OtherRegionsTable::_n_coarsenings = 0;
539
540 PerRegionTable* OtherRegionsTable::delete_region_table() {
541 assert(_m->owned_by_self(), "Precondition");
542 assert(_n_fine_entries == _max_fine_entries, "Precondition");
543 PerRegionTable* max = NULL;
544 jint max_occ = 0;
545 PerRegionTable** max_prev = NULL;
546 size_t max_ind;
547
548 size_t i = _fine_eviction_start;
549 for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
550 size_t ii = i;
551 // Make sure we get a non-NULL sample.
552 while (_fine_grain_regions[ii] == NULL) {
553 ii++;
554 if (ii == _max_fine_entries) ii = 0;
555 guarantee(ii != i, "We must find one.");
556 }
557 PerRegionTable** prev = &_fine_grain_regions[ii];
558 PerRegionTable* cur = *prev;
559 while (cur != NULL) {
560 jint cur_occ = cur->occupied();
561 if (max == NULL || cur_occ > max_occ) {
562 max = cur;
563 max_prev = prev;
564 max_ind = i;
565 max_occ = cur_occ;
566 }
567 prev = cur->collision_list_next_addr();
568 cur = cur->collision_list_next();
569 }
570 i = i + _fine_eviction_stride;
571 if (i >= _n_fine_entries) i = i - _n_fine_entries;
572 }
573
574 _fine_eviction_start++;
575
576 if (_fine_eviction_start >= _n_fine_entries) {
577 _fine_eviction_start -= _n_fine_entries;
578 }
579
580 guarantee(max != NULL, "Since _n_fine_entries > 0");
581 guarantee(max_prev != NULL, "Since max != NULL.");
582
583 // Set the corresponding coarse bit.
584 size_t max_hrm_index = (size_t) max->hr()->hrm_index();
585 if (!_coarse_map.at(max_hrm_index)) {
586 _coarse_map.at_put(max_hrm_index, true);
587 _n_coarse_entries++;
588 if (G1TraceHeapRegionRememberedSet) {
589 gclog_or_tty->print("Coarsened entry in region [" PTR_FORMAT "...] "
590 "for region [" PTR_FORMAT "...] (" SIZE_FORMAT " coarse entries).\n",
591 p2i(_hr->bottom()),
592 p2i(max->hr()->bottom()),
593 _n_coarse_entries);
594 }
595 }
596
597 // Unsplice.
598 *max_prev = max->collision_list_next();
599 Atomic::inc(&_n_coarsenings);
600 _n_fine_entries--;
601 return max;
602 }
603
604 void OtherRegionsTable::scrub(CardTableModRefBS* ctbs,
605 BitMap* region_bm, BitMap* card_bm) {
606 // First eliminated garbage regions from the coarse map.
607 if (G1RSScrubVerbose) {
608 gclog_or_tty->print_cr("Scrubbing region %u:", _hr->hrm_index());
609 }
610
611 assert(_coarse_map.size() == region_bm->size(), "Precondition");
612 if (G1RSScrubVerbose) {
613 gclog_or_tty->print(" Coarse map: before = " SIZE_FORMAT "...",
614 _n_coarse_entries);
615 }
616 _coarse_map.set_intersection(*region_bm);
617 _n_coarse_entries = _coarse_map.count_one_bits();
618 if (G1RSScrubVerbose) {
619 gclog_or_tty->print_cr(" after = " SIZE_FORMAT ".", _n_coarse_entries);
620 }
621
622 // Now do the fine-grained maps.
623 for (size_t i = 0; i < _max_fine_entries; i++) {
624 PerRegionTable* cur = _fine_grain_regions[i];
625 PerRegionTable** prev = &_fine_grain_regions[i];
626 while (cur != NULL) {
627 PerRegionTable* nxt = cur->collision_list_next();
628 // If the entire region is dead, eliminate.
629 if (G1RSScrubVerbose) {
630 gclog_or_tty->print_cr(" For other region %u:",
631 cur->hr()->hrm_index());
632 }
633 if (!region_bm->at((size_t) cur->hr()->hrm_index())) {
634 *prev = nxt;
635 cur->set_collision_list_next(NULL);
636 _n_fine_entries--;
637 if (G1RSScrubVerbose) {
638 gclog_or_tty->print_cr(" deleted via region map.");
639 }
640 unlink_from_all(cur);
641 PerRegionTable::free(cur);
642 } else {
643 // Do fine-grain elimination.
644 if (G1RSScrubVerbose) {
645 gclog_or_tty->print(" occ: before = %4d.", cur->occupied());
646 }
647 cur->scrub(ctbs, card_bm);
648 if (G1RSScrubVerbose) {
649 gclog_or_tty->print_cr(" after = %4d.", cur->occupied());
650 }
651 // Did that empty the table completely?
652 if (cur->occupied() == 0) {
653 *prev = nxt;
654 cur->set_collision_list_next(NULL);
655 _n_fine_entries--;
656 unlink_from_all(cur);
657 PerRegionTable::free(cur);
658 } else {
659 prev = cur->collision_list_next_addr();
660 }
661 }
662 cur = nxt;
663 }
664 }
665 // Since we may have deleted a from_card_cache entry from the RS, clear
666 // the FCC.
667 clear_fcc();
668 }
669
670 bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {
671 if (limit <= (size_t)G1RSetSparseRegionEntries) {
672 return occ_coarse() == 0 && _first_all_fine_prts == NULL && occ_sparse() <= limit;
673 } else {
674 // Current uses of this method may only use values less than G1RSetSparseRegionEntries
675 // for the limit. The solution, comparing against occupied() would be too slow
676 // at this time.
677 Unimplemented();
678 return false;
679 }
680 }
681
682 bool OtherRegionsTable::is_empty() const {
683 return occ_sparse() == 0 && occ_coarse() == 0 && _first_all_fine_prts == NULL;
684 }
685
686 size_t OtherRegionsTable::occupied() const {
687 size_t sum = occ_fine();
688 sum += occ_sparse();
689 sum += occ_coarse();
690 return sum;
691 }
692
693 size_t OtherRegionsTable::occ_fine() const {
694 size_t sum = 0;
695
696 size_t num = 0;
697 PerRegionTable * cur = _first_all_fine_prts;
698 while (cur != NULL) {
699 sum += cur->occupied();
700 cur = cur->next();
701 num++;
702 }
703 guarantee(num == _n_fine_entries, "just checking");
704 return sum;
705 }
706
707 size_t OtherRegionsTable::occ_coarse() const {
708 return (_n_coarse_entries * HeapRegion::CardsPerRegion);
709 }
710
711 size_t OtherRegionsTable::occ_sparse() const {
712 return _sparse_table.occupied();
713 }
714
715 size_t OtherRegionsTable::mem_size() const {
716 size_t sum = 0;
717 // all PRTs are of the same size so it is sufficient to query only one of them.
718 if (_first_all_fine_prts != NULL) {
719 assert(_last_all_fine_prts != NULL &&
720 _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
721 sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
722 }
723 sum += (sizeof(PerRegionTable*) * _max_fine_entries);
724 sum += (_coarse_map.size_in_words() * HeapWordSize);
725 sum += (_sparse_table.mem_size());
726 sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
727 return sum;
728 }
729
730 size_t OtherRegionsTable::static_mem_size() {
731 return FromCardCache::static_mem_size();
732 }
733
734 size_t OtherRegionsTable::fl_mem_size() {
735 return PerRegionTable::fl_mem_size();
736 }
737
738 void OtherRegionsTable::clear_fcc() {
739 FromCardCache::clear(_hr->hrm_index());
740 }
741
742 void OtherRegionsTable::clear() {
743 // if there are no entries, skip this step
744 if (_first_all_fine_prts != NULL) {
745 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
746 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
747 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
748 } else {
749 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
750 }
751
752 _first_all_fine_prts = _last_all_fine_prts = NULL;
753 _sparse_table.clear();
754 _coarse_map.clear();
755 _n_fine_entries = 0;
756 _n_coarse_entries = 0;
757
758 clear_fcc();
759 }
760
761 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
762 // Cast away const in this case.
763 MutexLockerEx x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
764 return contains_reference_locked(from);
765 }
766
767 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
768 HeapRegion* hr = _g1h->heap_region_containing(from);
769 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
770 // Is this region in the coarse map?
771 if (_coarse_map.at(hr_ind)) return true;
772
773 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
774 hr);
775 if (prt != NULL) {
776 return prt->contains_reference(from);
777
778 } else {
779 uintptr_t from_card =
780 (uintptr_t(from) >> CardTableModRefBS::card_shift);
781 uintptr_t hr_bot_card_index =
782 uintptr_t(hr->bottom()) >> CardTableModRefBS::card_shift;
783 assert(from_card >= hr_bot_card_index, "Inv");
784 CardIdx_t card_index = from_card - hr_bot_card_index;
785 assert(0 <= card_index && (size_t)card_index < HeapRegion::CardsPerRegion,
786 "Must be in range.");
787 return _sparse_table.contains_card(hr_ind, card_index);
788 }
789 }
790
791 void
792 OtherRegionsTable::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
793 _sparse_table.do_cleanup_work(hrrs_cleanup_task);
794 }
795
796 // Determines how many threads can add records to an rset in parallel.
797 // This can be done by either mutator threads together with the
798 // concurrent refinement threads or GC threads.
799 uint HeapRegionRemSet::num_par_rem_sets() {
800 return MAX2(DirtyCardQueueSet::num_par_ids() + ConcurrentG1Refine::thread_num(), ParallelGCThreads);
801 }
802
803 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetSharedArray* bosa,
804 HeapRegion* hr)
805 : _bosa(bosa),
806 _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Monitor::_safepoint_check_never),
807 _code_roots(), _other_regions(hr, &_m), _iter_state(Unclaimed), _iter_claimed(0) {
808 reset_for_par_iteration();
809 }
810
811 void HeapRegionRemSet::setup_remset_size() {
812 // Setup sparse and fine-grain tables sizes.
813 // table_size = base * (log(region_size / 1M) + 1)
814 const int LOG_M = 20;
815 int region_size_log_mb = MAX2(HeapRegion::LogOfHRGrainBytes - LOG_M, 0);
816 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
817 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * (region_size_log_mb + 1);
818 }
819 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
820 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
821 }
822 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
823 }
824
825 bool HeapRegionRemSet::claim_iter() {
826 if (_iter_state != Unclaimed) return false;
827 jint res = Atomic::cmpxchg(Claimed, (jint*)(&_iter_state), Unclaimed);
828 return (res == Unclaimed);
829 }
830
831 void HeapRegionRemSet::set_iter_complete() {
832 _iter_state = Complete;
833 }
834
835 bool HeapRegionRemSet::iter_is_complete() {
836 return _iter_state == Complete;
837 }
838
839 #ifndef PRODUCT
840 void HeapRegionRemSet::print() {
841 HeapRegionRemSetIterator iter(this);
842 size_t card_index;
843 while (iter.has_next(card_index)) {
844 HeapWord* card_start =
845 G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
846 gclog_or_tty->print_cr(" Card " PTR_FORMAT, p2i(card_start));
847 }
848 if (iter.n_yielded() != occupied()) {
849 gclog_or_tty->print_cr("Yielded disagrees with occupied:");
850 gclog_or_tty->print_cr(" " SIZE_FORMAT_W(6) " yielded (" SIZE_FORMAT_W(6)
851 " coarse, " SIZE_FORMAT_W(6) " fine).",
852 iter.n_yielded(),
853 iter.n_yielded_coarse(), iter.n_yielded_fine());
854 gclog_or_tty->print_cr(" " SIZE_FORMAT_W(6) " occ (" SIZE_FORMAT_W(6)
855 " coarse, " SIZE_FORMAT_W(6) " fine).",
856 occupied(), occ_coarse(), occ_fine());
857 }
858 guarantee(iter.n_yielded() == occupied(),
859 "We should have yielded all the represented cards.");
860 }
861 #endif
862
863 void HeapRegionRemSet::cleanup() {
864 SparsePRT::cleanup_all();
865 }
866
867 void HeapRegionRemSet::clear() {
868 MutexLockerEx x(&_m, Mutex::_no_safepoint_check_flag);
869 clear_locked();
870 }
871
872 void HeapRegionRemSet::clear_locked() {
873 _code_roots.clear();
874 _other_regions.clear();
875 assert(occupied_locked() == 0, "Should be clear.");
876 reset_for_par_iteration();
877 }
878
879 void HeapRegionRemSet::reset_for_par_iteration() {
880 _iter_state = Unclaimed;
881 _iter_claimed = 0;
882 // It's good to check this to make sure that the two methods are in sync.
883 assert(verify_ready_for_par_iteration(), "post-condition");
884 }
885
886 void HeapRegionRemSet::scrub(CardTableModRefBS* ctbs,
887 BitMap* region_bm, BitMap* card_bm) {
888 _other_regions.scrub(ctbs, region_bm, card_bm);
889 }
890
891 // Code roots support
892 //
893 // The code root set is protected by two separate locking schemes
894 // When at safepoint the per-hrrs lock must be held during modifications
895 // except when doing a full gc.
896 // When not at safepoint the CodeCache_lock must be held during modifications.
897 // When concurrent readers access the contains() function
898 // (during the evacuation phase) no removals are allowed.
899
900 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
901 assert(nm != NULL, "sanity");
902 // Optimistic unlocked contains-check
903 if (!_code_roots.contains(nm)) {
904 MutexLockerEx ml(&_m, Mutex::_no_safepoint_check_flag);
905 add_strong_code_root_locked(nm);
906 }
907 }
908
909 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
910 assert(nm != NULL, "sanity");
911 _code_roots.add(nm);
912 }
913
914 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
915 assert(nm != NULL, "sanity");
916 assert_locked_or_safepoint(CodeCache_lock);
917
918 MutexLockerEx ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
919 _code_roots.remove(nm);
920
921 // Check that there were no duplicates
922 guarantee(!_code_roots.contains(nm), "duplicate entry found");
923 }
924
925 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
926 _code_roots.nmethods_do(blk);
927 }
928
929 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
930 _code_roots.clean(hr);
931 }
932
933 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
934 return _code_roots.mem_size();
935 }
936
937 HeapRegionRemSetIterator:: HeapRegionRemSetIterator(HeapRegionRemSet* hrrs) :
938 _hrrs(hrrs),
939 _g1h(G1CollectedHeap::heap()),
940 _coarse_map(&hrrs->_other_regions._coarse_map),
941 _bosa(hrrs->_bosa),
942 _is(Sparse),
943 // Set these values so that we increment to the first region.
944 _coarse_cur_region_index(-1),
945 _coarse_cur_region_cur_card(HeapRegion::CardsPerRegion-1),
946 _cur_card_in_prt(HeapRegion::CardsPerRegion),
947 _fine_cur_prt(NULL),
948 _n_yielded_coarse(0),
949 _n_yielded_fine(0),
950 _n_yielded_sparse(0),
951 _sparse_iter(&hrrs->_other_regions._sparse_table) {}
952
953 bool HeapRegionRemSetIterator::coarse_has_next(size_t& card_index) {
954 if (_hrrs->_other_regions._n_coarse_entries == 0) return false;
955 // Go to the next card.
956 _coarse_cur_region_cur_card++;
957 // Was the last the last card in the current region?
958 if (_coarse_cur_region_cur_card == HeapRegion::CardsPerRegion) {
959 // Yes: find the next region. This may leave _coarse_cur_region_index
960 // Set to the last index, in which case there are no more coarse
961 // regions.
962 _coarse_cur_region_index =
963 (int) _coarse_map->get_next_one_offset(_coarse_cur_region_index + 1);
964 if ((size_t)_coarse_cur_region_index < _coarse_map->size()) {
965 _coarse_cur_region_cur_card = 0;
966 HeapWord* r_bot =
967 _g1h->region_at((uint) _coarse_cur_region_index)->bottom();
968 _cur_region_card_offset = _bosa->index_for(r_bot);
969 } else {
970 return false;
971 }
972 }
973 // If we didn't return false above, then we can yield a card.
974 card_index = _cur_region_card_offset + _coarse_cur_region_cur_card;
975 return true;
976 }
977
978 bool HeapRegionRemSetIterator::fine_has_next(size_t& card_index) {
979 if (fine_has_next()) {
980 _cur_card_in_prt =
981 _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
982 }
983 if (_cur_card_in_prt == HeapRegion::CardsPerRegion) {
984 // _fine_cur_prt may still be NULL in case if there are not PRTs at all for
985 // the remembered set.
986 if (_fine_cur_prt == NULL || _fine_cur_prt->next() == NULL) {
987 return false;
988 }
989 PerRegionTable* next_prt = _fine_cur_prt->next();
990 switch_to_prt(next_prt);
991 _cur_card_in_prt = _fine_cur_prt->_bm.get_next_one_offset(_cur_card_in_prt + 1);
992 }
993
994 card_index = _cur_region_card_offset + _cur_card_in_prt;
995 guarantee(_cur_card_in_prt < HeapRegion::CardsPerRegion,
996 "Card index " SIZE_FORMAT " must be within the region", _cur_card_in_prt);
997 return true;
998 }
999
1000 bool HeapRegionRemSetIterator::fine_has_next() {
1001 return _cur_card_in_prt != HeapRegion::CardsPerRegion;
1002 }
1003
1004 void HeapRegionRemSetIterator::switch_to_prt(PerRegionTable* prt) {
1005 assert(prt != NULL, "Cannot switch to NULL prt");
1006 _fine_cur_prt = prt;
1007
1008 HeapWord* r_bot = _fine_cur_prt->hr()->bottom();
1009 _cur_region_card_offset = _bosa->index_for(r_bot);
1010
1011 // The bitmap scan for the PRT always scans from _cur_region_cur_card + 1.
1012 // To avoid special-casing this start case, and not miss the first bitmap
1013 // entry, initialize _cur_region_cur_card with -1 instead of 0.
1014 _cur_card_in_prt = (size_t)-1;
1015 }
1016
1017 bool HeapRegionRemSetIterator::has_next(size_t& card_index) {
1018 switch (_is) {
1019 case Sparse: {
1020 if (_sparse_iter.has_next(card_index)) {
1021 _n_yielded_sparse++;
1022 return true;
1023 }
1024 // Otherwise, deliberate fall-through
1025 _is = Fine;
1026 PerRegionTable* initial_fine_prt = _hrrs->_other_regions._first_all_fine_prts;
1027 if (initial_fine_prt != NULL) {
1028 switch_to_prt(_hrrs->_other_regions._first_all_fine_prts);
1029 }
1030 }
1031 case Fine:
1032 if (fine_has_next(card_index)) {
1033 _n_yielded_fine++;
1034 return true;
1035 }
1036 // Otherwise, deliberate fall-through
1037 _is = Coarse;
1038 case Coarse:
1039 if (coarse_has_next(card_index)) {
1040 _n_yielded_coarse++;
1041 return true;
1042 }
1043 // Otherwise...
1044 break;
1045 }
1046 assert(ParallelGCThreads > 1 ||
1047 n_yielded() == _hrrs->occupied(),
1048 "Should have yielded all the cards in the rem set "
1049 "(in the non-par case).");
1050 return false;
1051 }
1052
1053 void HeapRegionRemSet::reset_for_cleanup_tasks() {
1054 SparsePRT::reset_for_cleanup_tasks();
1055 }
1056
1057 void HeapRegionRemSet::do_cleanup_work(HRRSCleanupTask* hrrs_cleanup_task) {
1058 _other_regions.do_cleanup_work(hrrs_cleanup_task);
1059 }
1060
1061 void
1062 HeapRegionRemSet::finish_cleanup_task(HRRSCleanupTask* hrrs_cleanup_task) {
1063 SparsePRT::finish_cleanup_task(hrrs_cleanup_task);
1064 }
1065
1066 #ifndef PRODUCT
1067 void PerRegionTable::test_fl_mem_size() {
1068 PerRegionTable* dummy = alloc(NULL);
1069
1070 size_t min_prt_size = sizeof(void*) + dummy->bm()->size_in_words() * HeapWordSize;
1071 assert(dummy->mem_size() > min_prt_size,
1072 "PerRegionTable memory usage is suspiciously small, only has " SIZE_FORMAT " bytes. "
1073 "Should be at least " SIZE_FORMAT " bytes.", dummy->mem_size(), min_prt_size);
1074 free(dummy);
1075 guarantee(dummy->mem_size() == fl_mem_size(), "fl_mem_size() does not return the correct element size");
1076 // try to reset the state
1077 _free_list = NULL;
1078 delete dummy;
1079 }
1080
1081 void HeapRegionRemSet::test_prt() {
1082 PerRegionTable::test_fl_mem_size();
1083 }
1084
1085 void HeapRegionRemSet::test() {
1086 os::sleep(Thread::current(), (jlong)5000, false);
1087 G1CollectedHeap* g1h = G1CollectedHeap::heap();
1088
1089 // Run with "-XX:G1LogRSetRegionEntries=2", so that 1 and 5 end up in same
1090 // hash bucket.
1091 HeapRegion* hr0 = g1h->region_at(0);
1092 HeapRegion* hr1 = g1h->region_at(1);
1093 HeapRegion* hr2 = g1h->region_at(5);
1094 HeapRegion* hr3 = g1h->region_at(6);
1095 HeapRegion* hr4 = g1h->region_at(7);
1096 HeapRegion* hr5 = g1h->region_at(8);
1097
1098 HeapWord* hr1_start = hr1->bottom();
1099 HeapWord* hr1_mid = hr1_start + HeapRegion::GrainWords/2;
1100 HeapWord* hr1_last = hr1->end() - 1;
1101
1102 HeapWord* hr2_start = hr2->bottom();
1103 HeapWord* hr2_mid = hr2_start + HeapRegion::GrainWords/2;
1104 HeapWord* hr2_last = hr2->end() - 1;
1105
1106 HeapWord* hr3_start = hr3->bottom();
1107 HeapWord* hr3_mid = hr3_start + HeapRegion::GrainWords/2;
1108 HeapWord* hr3_last = hr3->end() - 1;
1109
1110 HeapRegionRemSet* hrrs = hr0->rem_set();
1111
1112 // Make three references from region 0x101...
1113 hrrs->add_reference((OopOrNarrowOopStar)hr1_start);
1114 hrrs->add_reference((OopOrNarrowOopStar)hr1_mid);
1115 hrrs->add_reference((OopOrNarrowOopStar)hr1_last);
1116
1117 hrrs->add_reference((OopOrNarrowOopStar)hr2_start);
1118 hrrs->add_reference((OopOrNarrowOopStar)hr2_mid);
1119 hrrs->add_reference((OopOrNarrowOopStar)hr2_last);
1120
1121 hrrs->add_reference((OopOrNarrowOopStar)hr3_start);
1122 hrrs->add_reference((OopOrNarrowOopStar)hr3_mid);
1123 hrrs->add_reference((OopOrNarrowOopStar)hr3_last);
1124
1125 // Now cause a coarsening.
1126 hrrs->add_reference((OopOrNarrowOopStar)hr4->bottom());
1127 hrrs->add_reference((OopOrNarrowOopStar)hr5->bottom());
1128
1129 // Now, does iteration yield these three?
1130 HeapRegionRemSetIterator iter(hrrs);
1131 size_t sum = 0;
1132 size_t card_index;
1133 while (iter.has_next(card_index)) {
1134 HeapWord* card_start =
1135 G1CollectedHeap::heap()->bot_shared()->address_for_index(card_index);
1136 gclog_or_tty->print_cr(" Card " PTR_FORMAT ".", p2i(card_start));
1137 sum++;
1138 }
1139 guarantee(sum == 11 - 3 + 2048, "Failure");
1140 guarantee(sum == hrrs->occupied(), "Failure");
1141 }
1142 #endif