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/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.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(nxt, &_free_list, fl);
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_ARRAY3(PerRegionTablePtr, _max_fine_entries,
96 mtGC, CURRENT_PC, AllocFailStrategy::RETURN_NULL);
97
98 if (_fine_grain_regions == NULL) {
99 vm_exit_out_of_memory(sizeof(void*)*_max_fine_entries, OOM_MALLOC_ERROR,
100 "Failed to allocate _fine_grain_entries.");
101 }
102
103 for (size_t i = 0; i < _max_fine_entries; i++) {
104 _fine_grain_regions[i] = NULL;
105 }
106 }
107
108 void OtherRegionsTable::link_to_all(PerRegionTable* prt) {
109 // We always append to the beginning of the list for convenience;
110 // the order of entries in this list does not matter.
111 if (_first_all_fine_prts != NULL) {
112 assert(_first_all_fine_prts->prev() == NULL, "invariant");
113 _first_all_fine_prts->set_prev(prt);
114 prt->set_next(_first_all_fine_prts);
115 } else {
116 // this is the first element we insert. Adjust the "last" pointer
117 _last_all_fine_prts = prt;
118 assert(prt->next() == NULL, "just checking");
119 }
120 // the new element is always the first element without a predecessor
121 prt->set_prev(NULL);
122 _first_all_fine_prts = prt;
123
124 assert(prt->prev() == NULL, "just checking");
125 assert(_first_all_fine_prts == prt, "just checking");
126 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
127 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
128 "just checking");
129 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
130 "just checking");
131 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
132 "just checking");
133 }
134
135 void OtherRegionsTable::unlink_from_all(PerRegionTable* prt) {
136 if (prt->prev() != NULL) {
137 assert(_first_all_fine_prts != prt, "just checking");
138 prt->prev()->set_next(prt->next());
139 // removing the last element in the list?
140 if (_last_all_fine_prts == prt) {
141 _last_all_fine_prts = prt->prev();
142 }
143 } else {
144 assert(_first_all_fine_prts == prt, "just checking");
145 _first_all_fine_prts = prt->next();
146 // list is empty now?
147 if (_first_all_fine_prts == NULL) {
148 _last_all_fine_prts = NULL;
149 }
150 }
151
152 if (prt->next() != NULL) {
153 prt->next()->set_prev(prt->prev());
154 }
155
156 prt->set_next(NULL);
157 prt->set_prev(NULL);
158
159 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
160 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
161 "just checking");
162 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
163 "just checking");
164 assert(_first_all_fine_prts == NULL || _first_all_fine_prts->prev() == NULL,
165 "just checking");
166 }
167
168 CardIdx_t OtherRegionsTable::card_within_region(OopOrNarrowOopStar within_region, HeapRegion* hr) {
169 assert(hr->is_in_reserved(within_region),
170 "HeapWord " PTR_FORMAT " is outside of region %u [" PTR_FORMAT ", " PTR_FORMAT ")",
171 p2i(within_region), hr->hrm_index(), p2i(hr->bottom()), p2i(hr->end()));
172 CardIdx_t result = (CardIdx_t)(pointer_delta((HeapWord*)within_region, hr->bottom()) >> (CardTable::card_shift - LogHeapWordSize));
173 return result;
174 }
175
176 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
177 // Note that this may be a continued H region.
178 HeapRegion* from_hr = _g1h->heap_region_containing(from);
179 RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
180
181 // If the region is already coarsened, return.
182 if (_coarse_map.at(from_hrm_ind)) {
183 assert(contains_reference(from), "We just found " PTR_FORMAT " in the Coarse table", p2i(from));
184 return;
185 }
186
187 size_t num_added_by_coarsening = 0;
188 // Otherwise find a per-region table to add it to.
189 size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
190 PerRegionTable* prt = find_region_table(ind, from_hr);
191 if (prt == NULL) {
192 MutexLocker x(_m, Mutex::_no_safepoint_check_flag);
193 // Confirm that it's really not there...
194 prt = find_region_table(ind, from_hr);
195 if (prt == NULL) {
196
197 CardIdx_t card_index = card_within_region(from, from_hr);
198
199 if (_sparse_table.add_card(from_hrm_ind, card_index)) {
200 Atomic::inc(&_num_occupied, memory_order_relaxed);
201 assert(contains_reference_locked(from), "We just added " PTR_FORMAT " to the Sparse table", p2i(from));
202 return;
203 }
204
205 if (_n_fine_entries == _max_fine_entries) {
206 prt = delete_region_table(num_added_by_coarsening);
207 // There is no need to clear the links to the 'all' list here:
208 // prt will be reused immediately, i.e. remain in the 'all' list.
209 prt->init(from_hr, false /* clear_links_to_all_list */);
210 } else {
211 prt = PerRegionTable::alloc(from_hr);
212 link_to_all(prt);
213 }
214
215 PerRegionTable* first_prt = _fine_grain_regions[ind];
216 prt->set_collision_list_next(first_prt);
217 // The assignment into _fine_grain_regions allows the prt to
218 // start being used concurrently. In addition to
219 // collision_list_next which must be visible (else concurrent
220 // parsing of the list, if any, may fail to see other entries),
221 // the content of the prt must be visible (else for instance
222 // some mark bits may not yet seem cleared or a 'later' update
223 // performed by a concurrent thread could be undone when the
224 // zeroing becomes visible). This requires store ordering.
225 OrderAccess::release_store(&_fine_grain_regions[ind], prt);
226 _n_fine_entries++;
227
228 // Transfer from sparse to fine-grain. The cards from the sparse table
229 // were already added to the total in _num_occupied.
230 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
231 assert(sprt_entry != NULL, "There should have been an entry");
232 for (int i = 0; i < sprt_entry->num_valid_cards(); i++) {
233 CardIdx_t c = sprt_entry->card(i);
234 prt->add_card(c);
235 }
236 // Now we can delete the sparse entry.
237 bool res = _sparse_table.delete_entry(from_hrm_ind);
238 assert(res, "It should have been there.");
239 }
240 assert(prt != NULL && prt->hr() == from_hr, "consequence");
241 }
242 // Note that we can't assert "prt->hr() == from_hr", because of the
243 // possibility of concurrent reuse. But see head comment of
244 // OtherRegionsTable for why this is OK.
245 assert(prt != NULL, "Inv");
246
247 bool added = prt->add_reference(from);
248 Atomic::add(num_added_by_coarsening + (added ? 1 : 0), &_num_occupied, memory_order_relaxed);
249 assert(contains_reference(from), "We just added " PTR_FORMAT " to the PRT (%d)", p2i(from), prt->contains_reference(from));
250 }
251
252 PerRegionTable*
253 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
254 assert(ind < _max_fine_entries, "Preconditions.");
255 PerRegionTable* prt = _fine_grain_regions[ind];
256 while (prt != NULL && prt->hr() != hr) {
257 prt = prt->collision_list_next();
258 }
259 // Loop postcondition is the method postcondition.
260 return prt;
261 }
262
263 jint OtherRegionsTable::_n_coarsenings = 0;
264
265 PerRegionTable* OtherRegionsTable::delete_region_table(size_t& added_by_deleted) {
266 assert(_m->owned_by_self(), "Precondition");
267 assert(_n_fine_entries == _max_fine_entries, "Precondition");
268 PerRegionTable* max = NULL;
269 jint max_occ = 0;
270 PerRegionTable** max_prev = NULL;
271 size_t max_ind;
272
273 size_t i = _fine_eviction_start;
274 for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
275 size_t ii = i;
276 // Make sure we get a non-NULL sample.
277 while (_fine_grain_regions[ii] == NULL) {
278 ii++;
279 if (ii == _max_fine_entries) ii = 0;
280 guarantee(ii != i, "We must find one.");
281 }
282 PerRegionTable** prev = &_fine_grain_regions[ii];
283 PerRegionTable* cur = *prev;
284 while (cur != NULL) {
285 jint cur_occ = cur->occupied();
286 if (max == NULL || cur_occ > max_occ) {
287 max = cur;
288 max_prev = prev;
289 max_ind = i;
290 max_occ = cur_occ;
291 }
292 prev = cur->collision_list_next_addr();
293 cur = cur->collision_list_next();
294 }
295 i = i + _fine_eviction_stride;
296 if (i >= _n_fine_entries) i = i - _n_fine_entries;
297 }
298
299 _fine_eviction_start++;
300
301 if (_fine_eviction_start >= _n_fine_entries) {
302 _fine_eviction_start -= _n_fine_entries;
303 }
304
305 guarantee(max != NULL, "Since _n_fine_entries > 0");
306 guarantee(max_prev != NULL, "Since max != NULL.");
307
308 // Set the corresponding coarse bit.
309 size_t max_hrm_index = (size_t) max->hr()->hrm_index();
310 if (!_coarse_map.at(max_hrm_index)) {
311 _coarse_map.at_put(max_hrm_index, true);
312 _n_coarse_entries++;
313 }
314
315 added_by_deleted = HeapRegion::CardsPerRegion - max_occ;
316 // Unsplice.
317 *max_prev = max->collision_list_next();
318 Atomic::inc(&_n_coarsenings);
319 _n_fine_entries--;
320 return max;
321 }
322
323 bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {
324 return occupied() <= limit;
325 }
326
327 bool OtherRegionsTable::is_empty() const {
328 return occupied() == 0;
329 }
330
331 size_t OtherRegionsTable::occupied() const {
332 return _num_occupied;
333 }
334
335 size_t OtherRegionsTable::mem_size() const {
336 size_t sum = 0;
337 // all PRTs are of the same size so it is sufficient to query only one of them.
338 if (_first_all_fine_prts != NULL) {
339 assert(_last_all_fine_prts != NULL &&
340 _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
341 sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
342 }
343 sum += (sizeof(PerRegionTable*) * _max_fine_entries);
344 sum += (_coarse_map.size_in_words() * HeapWordSize);
345 sum += (_sparse_table.mem_size());
346 sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
347 return sum;
348 }
349
350 size_t OtherRegionsTable::static_mem_size() {
351 return G1FromCardCache::static_mem_size();
352 }
353
354 size_t OtherRegionsTable::fl_mem_size() {
355 return PerRegionTable::fl_mem_size();
356 }
357
358 void OtherRegionsTable::clear() {
359 // if there are no entries, skip this step
360 if (_first_all_fine_prts != NULL) {
361 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
362 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
363 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
364 } else {
365 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
366 }
367
368 _first_all_fine_prts = _last_all_fine_prts = NULL;
369 _sparse_table.clear();
370 if (_n_coarse_entries > 0) {
371 _coarse_map.clear();
372 }
373 _n_fine_entries = 0;
374 _n_coarse_entries = 0;
375
376 _num_occupied = 0;
377 }
378
379 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
380 // Cast away const in this case.
381 MutexLocker x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
382 return contains_reference_locked(from);
383 }
384
385 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
386 HeapRegion* hr = _g1h->heap_region_containing(from);
387 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
388 // Is this region in the coarse map?
389 if (_coarse_map.at(hr_ind)) return true;
390
391 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
392 hr);
393 if (prt != NULL) {
394 return prt->contains_reference(from);
395
396 } else {
397 CardIdx_t card_index = card_within_region(from, hr);
398 return _sparse_table.contains_card(hr_ind, card_index);
399 }
400 }
401
402 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetTable* bot,
403 HeapRegion* hr)
404 : _bot(bot),
405 _code_roots(),
406 _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Mutex::_safepoint_check_never),
407 _other_regions(&_m),
408 _hr(hr),
409 _state(Untracked)
410 {
411 }
412
413 void HeapRegionRemSet::clear_fcc() {
414 G1FromCardCache::clear(_hr->hrm_index());
415 }
416
417 void HeapRegionRemSet::setup_remset_size() {
418 const int LOG_M = 20;
419 guarantee(HeapRegion::LogOfHRGrainBytes >= LOG_M, "Code assumes the region size >= 1M, but is " SIZE_FORMAT "B", HeapRegion::GrainBytes);
420
421 int region_size_log_mb = HeapRegion::LogOfHRGrainBytes - LOG_M;
422 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
423 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * ((size_t)1 << (region_size_log_mb + 1));
424 }
425 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
426 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
427 }
428 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
429 }
430
431 void HeapRegionRemSet::clear(bool only_cardset) {
432 MutexLocker x(&_m, Mutex::_no_safepoint_check_flag);
433 clear_locked(only_cardset);
434 }
435
436 void HeapRegionRemSet::clear_locked(bool only_cardset) {
437 if (!only_cardset) {
438 _code_roots.clear();
439 }
440 clear_fcc();
441 _other_regions.clear();
442 set_state_empty();
443 assert(occupied() == 0, "Should be clear.");
444 }
445
446 // Code roots support
447 //
448 // The code root set is protected by two separate locking schemes
449 // When at safepoint the per-hrrs lock must be held during modifications
450 // except when doing a full gc.
451 // When not at safepoint the CodeCache_lock must be held during modifications.
452 // When concurrent readers access the contains() function
453 // (during the evacuation phase) no removals are allowed.
454
455 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
456 assert(nm != NULL, "sanity");
457 assert((!CodeCache_lock->owned_by_self() || SafepointSynchronize::is_at_safepoint()),
458 "should call add_strong_code_root_locked instead. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s",
459 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()));
460 // Optimistic unlocked contains-check
461 if (!_code_roots.contains(nm)) {
462 MutexLocker ml(&_m, Mutex::_no_safepoint_check_flag);
463 add_strong_code_root_locked(nm);
464 }
465 }
466
467 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
468 assert(nm != NULL, "sanity");
469 assert((CodeCache_lock->owned_by_self() ||
470 (SafepointSynchronize::is_at_safepoint() &&
471 (_m.owned_by_self() || Thread::current()->is_VM_thread()))),
472 "not safely locked. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s, _m.owned_by_self(): %s, Thread::current()->is_VM_thread(): %s",
473 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),
474 BOOL_TO_STR(_m.owned_by_self()), BOOL_TO_STR(Thread::current()->is_VM_thread()));
475 _code_roots.add(nm);
476 }
477
478 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
479 assert(nm != NULL, "sanity");
480 assert_locked_or_safepoint(CodeCache_lock);
481
482 MutexLocker ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
483 _code_roots.remove(nm);
484
485 // Check that there were no duplicates
486 guarantee(!_code_roots.contains(nm), "duplicate entry found");
487 }
488
489 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
490 _code_roots.nmethods_do(blk);
491 }
492
493 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
494 _code_roots.clean(hr);
495 }
496
497 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
498 return _code_roots.mem_size();
499 }