1 /*
2 * Copyright (c) 2001, 2019, 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/g1BlockOffsetTable.inline.hpp"
27 #include "gc/g1/g1CollectedHeap.inline.hpp"
28 #include "gc/g1/g1ConcurrentRefine.hpp"
29 #include "gc/g1/heapRegionManager.inline.hpp"
30 #include "gc/g1/heapRegionRemSet.inline.hpp"
31 #include "gc/g1/sparsePRT.inline.hpp"
32 #include "memory/allocation.hpp"
33 #include "memory/padded.inline.hpp"
34 #include "oops/oop.inline.hpp"
35 #include "runtime/atomic.hpp"
36 #include "utilities/bitMap.inline.hpp"
37 #include "utilities/debug.hpp"
38 #include "utilities/formatBuffer.hpp"
39 #include "utilities/globalDefinitions.hpp"
40 #include "utilities/growableArray.hpp"
41
42 const char* HeapRegionRemSet::_state_strings[] = {"Untracked", "Updating", "Complete"};
43 const char* HeapRegionRemSet::_short_state_strings[] = {"UNTRA", "UPDAT", "CMPLT"};
44
45 PerRegionTable* PerRegionTable::alloc(HeapRegion* hr) {
46 PerRegionTable* fl = _free_list;
47 while (fl != NULL) {
48 PerRegionTable* nxt = fl->next();
49 PerRegionTable* res = Atomic::cmpxchg(&_free_list, fl, nxt);
50 if (res == fl) {
51 fl->init(hr, true);
52 return fl;
53 } else {
54 fl = _free_list;
55 }
56 }
57 assert(fl == NULL, "Loop condition.");
58 return new PerRegionTable(hr);
59 }
60
61 PerRegionTable* volatile PerRegionTable::_free_list = NULL;
62
63 size_t OtherRegionsTable::_max_fine_entries = 0;
64 size_t OtherRegionsTable::_mod_max_fine_entries_mask = 0;
65 size_t OtherRegionsTable::_fine_eviction_stride = 0;
66 size_t OtherRegionsTable::_fine_eviction_sample_size = 0;
67
68 OtherRegionsTable::OtherRegionsTable(Mutex* m) :
69 _g1h(G1CollectedHeap::heap()),
70 _m(m),
71 _num_occupied(0),
72 _coarse_map(G1CollectedHeap::heap()->max_regions(), mtGC),
73 _n_coarse_entries(0),
74 _fine_grain_regions(NULL),
75 _n_fine_entries(0),
76 _first_all_fine_prts(NULL),
77 _last_all_fine_prts(NULL),
78 _fine_eviction_start(0),
79 _sparse_table()
80 {
81 typedef PerRegionTable* PerRegionTablePtr;
82
83 if (_max_fine_entries == 0) {
84 assert(_mod_max_fine_entries_mask == 0, "Both or none.");
85 size_t max_entries_log = (size_t)log2_long((jlong)G1RSetRegionEntries);
86 _max_fine_entries = (size_t)1 << max_entries_log;
87 _mod_max_fine_entries_mask = _max_fine_entries - 1;
88
89 assert(_fine_eviction_sample_size == 0
90 && _fine_eviction_stride == 0, "All init at same time.");
91 _fine_eviction_sample_size = MAX2((size_t)4, max_entries_log);
92 _fine_eviction_stride = _max_fine_entries / _fine_eviction_sample_size;
93 }
94
95 _fine_grain_regions = NEW_C_HEAP_ARRAY(PerRegionTablePtr, _max_fine_entries, mtGC);
96 for (size_t i = 0; i < _max_fine_entries; i++) {
97 _fine_grain_regions[i] = NULL;
98 }
99 }
100
101 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
102 // We always append to the beginning of the list for convenience;
103 // the order of entries in this list does not matter.
104 if (_first_all_fine_prts != NULL) {
105 assert(_first_all_fine_prts->prev() == NULL, "invariant");
106 _first_all_fine_prts->set_prev(prt);
107 prt->set_next(_first_all_fine_prts);
108 } else {
109 // this is the first element we insert. Adjust the "last" pointer
110 _last_all_fine_prts = prt;
111 assert(prt->next() == NULL, "just checking");
112 }
113 // the new element is always the first element without a predecessor
114 prt->set_prev(NULL);
115 _first_all_fine_prts = prt;
116
117 assert(prt->prev() == NULL, "just checking");
118 assert(_first_all_fine_prts == prt, "just checking");
119 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
120 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
121 "just checking");
122 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
123 "just checking");
124 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
125 "just checking");
126 }
127
128 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
129 if (prt->prev() != NULL) {
130 assert(_first_all_fine_prts != prt, "just checking");
131 prt->prev()->set_next(prt->next());
132 // removing the last element in the list?
133 if (_last_all_fine_prts == prt) {
134 _last_all_fine_prts = prt->prev();
135 }
136 } else {
137 assert(_first_all_fine_prts == prt, "just checking");
138 _first_all_fine_prts = prt->next();
139 // list is empty now?
140 if (_first_all_fine_prts == NULL) {
141 _last_all_fine_prts = NULL;
142 }
143 }
144
145 if (prt->next() != NULL) {
146 prt->next()->set_prev(prt->prev());
147 }
148
149 prt->set_next(NULL);
150 prt->set_prev(NULL);
151
152 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
153 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
154 "just checking");
155 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
156 "just checking");
157 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
158 "just checking");
159 }
160
161 CardIdx_t OtherRegionsTable::card_within_region(OopOrNarrowOopStar within_region, HeapRegion* hr) {
162 assert(hr->is_in_reserved(within_region),
163 "HeapWord " PTR_FORMAT " is outside of region %u [" PTR_FORMAT ", " PTR_FORMAT ")",
164 p2i(within_region), hr->hrm_index(), p2i(hr->bottom()), p2i(hr->end()));
165 CardIdx_t result = (CardIdx_t)(pointer_delta((HeapWord*)within_region, hr->bottom()) >> (CardTable::card_shift - LogHeapWordSize));
166 return result;
167 }
168
169 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
170 // Note that this may be a continued H region.
171 HeapRegion* from_hr = _g1h->heap_region_containing(from);
172 RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
173
174 // If the region is already coarsened, return.
175 if (_coarse_map.at(from_hrm_ind)) {
176 assert(contains_reference(from), "We just found " PTR_FORMAT " in the Coarse table", p2i(from));
177 return;
178 }
179
180 size_t num_added_by_coarsening = 0;
181 // Otherwise find a per-region table to add it to.
182 size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
183 PerRegionTable* prt = find_region_table(ind, from_hr);
184 if (prt == NULL) {
185 MutexLocker x(_m, Mutex::_no_safepoint_check_flag);
186 // Confirm that it's really not there...
187 prt = find_region_table(ind, from_hr);
188 if (prt == NULL) {
189
190 CardIdx_t card_index = card_within_region(from, from_hr);
191
192 SparsePRT::AddCardResult result = _sparse_table.add_card(from_hrm_ind, card_index);
193 if (result != SparsePRT::overflow) {
194 if (result == SparsePRT::added) {
195 Atomic::inc(&_num_occupied, memory_order_relaxed);
196 }
197 assert(contains_reference_locked(from), "We just added " PTR_FORMAT " to the Sparse table", p2i(from));
198 return;
199 }
200
201 if (_n_fine_entries == _max_fine_entries) {
202 prt = delete_region_table(num_added_by_coarsening);
203 // There is no need to clear the links to the 'all' list here:
204 // prt will be reused immediately, i.e. remain in the 'all' list.
205 prt->init(from_hr, false /* clear_links_to_all_list */);
206 } else {
207 prt = PerRegionTable::alloc(from_hr);
208 link_to_all(prt);
209 }
210
211 PerRegionTable* first_prt = _fine_grain_regions[ind];
212 prt->set_collision_list_next(first_prt);
213 // The assignment into _fine_grain_regions allows the prt to
214 // start being used concurrently. In addition to
215 // collision_list_next which must be visible (else concurrent
216 // parsing of the list, if any, may fail to see other entries),
217 // the content of the prt must be visible (else for instance
218 // some mark bits may not yet seem cleared or a 'later' update
219 // performed by a concurrent thread could be undone when the
220 // zeroing becomes visible). This requires store ordering.
221 Atomic::release_store(&_fine_grain_regions[ind], prt);
222 _n_fine_entries++;
223
224 // Transfer from sparse to fine-grain. The cards from the sparse table
225 // were already added to the total in _num_occupied.
226 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
227 assert(sprt_entry != NULL, "There should have been an entry");
228 for (int i = 0; i < sprt_entry->num_valid_cards(); i++) {
229 CardIdx_t c = sprt_entry->card(i);
230 prt->add_card(c);
231 }
232 // Now we can delete the sparse entry.
233 bool res = _sparse_table.delete_entry(from_hrm_ind);
234 assert(res, "It should have been there.");
235 }
236 assert(prt != NULL && prt->hr() == from_hr, "consequence");
237 }
238 // Note that we can't assert "prt->hr() == from_hr", because of the
239 // possibility of concurrent reuse. But see head comment of
240 // OtherRegionsTable for why this is OK.
241 assert(prt != NULL, "Inv");
242
243 bool added = prt->add_reference(from);
244 if (prt->add_reference(from)) {
245 num_added_by_coarsening++;
246 }
247 Atomic::add(&_num_occupied, num_added_by_coarsening, memory_order_relaxed);
248 assert(contains_reference(from), "We just added " PTR_FORMAT " to the PRT (%d)", p2i(from), prt->contains_reference(from));
249 }
250
251 PerRegionTable*
252 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
253 assert(ind < _max_fine_entries, "Preconditions.");
254 PerRegionTable* prt = _fine_grain_regions[ind];
255 while (prt != NULL && prt->hr() != hr) {
256 prt = prt->collision_list_next();
257 }
258 // Loop postcondition is the method postcondition.
259 return prt;
260 }
261
262 jint OtherRegionsTable::_n_coarsenings = 0;
263
264 PerRegionTable* OtherRegionsTable::delete_region_table(size_t& added_by_deleted) {
265 assert(_m->owned_by_self(), "Precondition");
266 assert(_n_fine_entries == _max_fine_entries, "Precondition");
267 PerRegionTable* max = NULL;
268 jint max_occ = 0;
269 PerRegionTable** max_prev = NULL;
270 size_t max_ind;
271
272 size_t i = _fine_eviction_start;
273 for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
274 size_t ii = i;
275 // Make sure we get a non-NULL sample.
276 while (_fine_grain_regions[ii] == NULL) {
277 ii++;
278 if (ii == _max_fine_entries) ii = 0;
279 guarantee(ii != i, "We must find one.");
280 }
281 PerRegionTable** prev = &_fine_grain_regions[ii];
282 PerRegionTable* cur = *prev;
283 while (cur != NULL) {
284 jint cur_occ = cur->occupied();
285 if (max == NULL || cur_occ > max_occ) {
286 max = cur;
287 max_prev = prev;
288 max_ind = i;
289 max_occ = cur_occ;
290 }
291 prev = cur->collision_list_next_addr();
292 cur = cur->collision_list_next();
293 }
294 i = i + _fine_eviction_stride;
295 if (i >= _n_fine_entries) i = i - _n_fine_entries;
296 }
297
298 _fine_eviction_start++;
299
300 if (_fine_eviction_start >= _n_fine_entries) {
301 _fine_eviction_start -= _n_fine_entries;
302 }
303
304 guarantee(max != NULL, "Since _n_fine_entries > 0");
305 guarantee(max_prev != NULL, "Since max != NULL.");
306
307 // Set the corresponding coarse bit.
308 size_t max_hrm_index = (size_t) max->hr()->hrm_index();
309 if (!_coarse_map.at(max_hrm_index)) {
310 _coarse_map.at_put(max_hrm_index, true);
311 _n_coarse_entries++;
312 }
313
314 added_by_deleted = HeapRegion::CardsPerRegion - max_occ;
315 // Unsplice.
316 *max_prev = max->collision_list_next();
317 Atomic::inc(&_n_coarsenings);
318 _n_fine_entries--;
319 return max;
320 }
321
322 bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {
323 return occupied() <= limit;
324 }
325
326 bool OtherRegionsTable::is_empty() const {
327 return occupied() == 0;
328 }
329
330 size_t OtherRegionsTable::occupied() const {
331 return _num_occupied;
332 }
333
334 size_t OtherRegionsTable::mem_size() const {
335 size_t sum = 0;
336 // all PRTs are of the same size so it is sufficient to query only one of them.
337 if (_first_all_fine_prts != NULL) {
338 assert(_last_all_fine_prts != NULL &&
339 _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
340 sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
341 }
342 sum += (sizeof(PerRegionTable*) * _max_fine_entries);
343 sum += (_coarse_map.size_in_words() * HeapWordSize);
344 sum += (_sparse_table.mem_size());
345 sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
346 return sum;
347 }
348
349 size_t OtherRegionsTable::static_mem_size() {
350 return G1FromCardCache::static_mem_size();
351 }
352
353 size_t OtherRegionsTable::fl_mem_size() {
354 return PerRegionTable::fl_mem_size();
355 }
356
357 void OtherRegionsTable::clear() {
358 // if there are no entries, skip this step
359 if (_first_all_fine_prts != NULL) {
360 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
361 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
362 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
363 } else {
364 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
365 }
366
367 _first_all_fine_prts = _last_all_fine_prts = NULL;
368 _sparse_table.clear();
369 if (_n_coarse_entries > 0) {
370 _coarse_map.clear();
371 }
372 _n_fine_entries = 0;
373 _n_coarse_entries = 0;
374
375 _num_occupied = 0;
376 }
377
378 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
379 // Cast away const in this case.
380 MutexLocker x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
381 return contains_reference_locked(from);
382 }
383
384 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
385 HeapRegion* hr = _g1h->heap_region_containing(from);
386 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
387 // Is this region in the coarse map?
388 if (_coarse_map.at(hr_ind)) return true;
389
390 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
391 hr);
392 if (prt != NULL) {
393 return prt->contains_reference(from);
394
395 } else {
396 CardIdx_t card_index = card_within_region(from, hr);
397 return _sparse_table.contains_card(hr_ind, card_index);
398 }
399 }
400
401 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetTable* bot,
402 HeapRegion* hr)
403 : _bot(bot),
404 _code_roots(),
405 _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Mutex::_safepoint_check_never),
406 _other_regions(&_m),
407 _hr(hr),
408 _state(Untracked)
409 {
410 }
411
412 void HeapRegionRemSet::clear_fcc() {
413 G1FromCardCache::clear(_hr->hrm_index());
414 }
415
416 void HeapRegionRemSet::setup_remset_size() {
417 const int LOG_M = 20;
418 guarantee(HeapRegion::LogOfHRGrainBytes >= LOG_M, "Code assumes the region size >= 1M, but is " SIZE_FORMAT "B", HeapRegion::GrainBytes);
419
420 int region_size_log_mb = HeapRegion::LogOfHRGrainBytes - LOG_M;
421 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
422 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * ((size_t)1 << (region_size_log_mb + 1));
423 }
424 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
425 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
426 }
427 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
428 }
429
430 void HeapRegionRemSet::clear(bool only_cardset) {
431 MutexLocker x(&_m, Mutex::_no_safepoint_check_flag);
432 clear_locked(only_cardset);
433 }
434
435 void HeapRegionRemSet::clear_locked(bool only_cardset) {
436 if (!only_cardset) {
437 _code_roots.clear();
438 }
439 clear_fcc();
440 _other_regions.clear();
441 set_state_empty();
442 assert(occupied() == 0, "Should be clear.");
443 }
444
445 // Code roots support
446 //
447 // The code root set is protected by two separate locking schemes
448 // When at safepoint the per-hrrs lock must be held during modifications
449 // except when doing a full gc.
450 // When not at safepoint the CodeCache_lock must be held during modifications.
451 // When concurrent readers access the contains() function
452 // (during the evacuation phase) no removals are allowed.
453
454 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
455 assert(nm != NULL, "sanity");
456 assert((!CodeCache_lock->owned_by_self() || SafepointSynchronize::is_at_safepoint()),
457 "should call add_strong_code_root_locked instead. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s",
458 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()));
459 // Optimistic unlocked contains-check
460 if (!_code_roots.contains(nm)) {
461 MutexLocker ml(&_m, Mutex::_no_safepoint_check_flag);
462 add_strong_code_root_locked(nm);
463 }
464 }
465
466 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
467 assert(nm != NULL, "sanity");
468 assert((CodeCache_lock->owned_by_self() ||
469 (SafepointSynchronize::is_at_safepoint() &&
470 (_m.owned_by_self() || Thread::current()->is_VM_thread()))),
471 "not safely locked. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s, _m.owned_by_self(): %s, Thread::current()->is_VM_thread(): %s",
472 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),
473 BOOL_TO_STR(_m.owned_by_self()), BOOL_TO_STR(Thread::current()->is_VM_thread()));
474 _code_roots.add(nm);
475 }
476
477 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
478 assert(nm != NULL, "sanity");
479 assert_locked_or_safepoint(CodeCache_lock);
480
481 MutexLocker ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
482 _code_roots.remove(nm);
483
484 // Check that there were no duplicates
485 guarantee(!_code_roots.contains(nm), "duplicate entry found");
486 }
487
488 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
489 _code_roots.nmethods_do(blk);
490 }
491
492 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
493 _code_roots.clean(hr);
494 }
495
496 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
497 return _code_roots.mem_size();
498 }