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
alloc(HeapRegion * hr)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
OtherRegionsTable(Mutex * m)68 OtherRegionsTable::OtherRegionsTable(Mutex* m) :
69 _g1h(G1CollectedHeap::heap()),
70 _m(m),
71 _num_occupied(0),
72 _coarse_map(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
link_to_all(PerRegionTable * prt)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 prt->set_next(_first_all_fine_prts);
106 } else {
107 // this is the first element we insert. Adjust the "last" pointer
108 _last_all_fine_prts = prt;
109 assert(prt->next() == NULL, "just checking");
110 }
111 _first_all_fine_prts = prt;
112
113 assert(_first_all_fine_prts == prt, "just checking");
114 assert((_first_all_fine_prts == NULL && _last_all_fine_prts == NULL) ||
115 (_first_all_fine_prts != NULL && _last_all_fine_prts != NULL),
116 "just checking");
117 assert(_last_all_fine_prts == NULL || _last_all_fine_prts->next() == NULL,
118 "just checking");
119 }
120
card_within_region(OopOrNarrowOopStar within_region,HeapRegion * hr)121 CardIdx_t OtherRegionsTable::card_within_region(OopOrNarrowOopStar within_region, HeapRegion* hr) {
122 assert(hr->is_in_reserved(within_region),
123 "HeapWord " PTR_FORMAT " is outside of region %u [" PTR_FORMAT ", " PTR_FORMAT ")",
124 p2i(within_region), hr->hrm_index(), p2i(hr->bottom()), p2i(hr->end()));
125 CardIdx_t result = (CardIdx_t)(pointer_delta((HeapWord*)within_region, hr->bottom()) >> (CardTable::card_shift - LogHeapWordSize));
126 return result;
127 }
128
add_reference(OopOrNarrowOopStar from,uint tid)129 void OtherRegionsTable::add_reference(OopOrNarrowOopStar from, uint tid) {
130 // Note that this may be a continued H region.
131 HeapRegion* from_hr = _g1h->heap_region_containing(from);
132 RegionIdx_t from_hrm_ind = (RegionIdx_t) from_hr->hrm_index();
133
134 // If the region is already coarsened, return.
135 if (is_region_coarsened(from_hrm_ind)) {
136 assert(contains_reference(from), "We just found " PTR_FORMAT " in the Coarse table", p2i(from));
137 return;
138 }
139
140 size_t num_added_by_coarsening = 0;
141 // Otherwise find a per-region table to add it to.
142 size_t ind = from_hrm_ind & _mod_max_fine_entries_mask;
143 PerRegionTable* prt = find_region_table(ind, from_hr);
144 if (prt == NULL) {
145 MutexLocker x(_m, Mutex::_no_safepoint_check_flag);
146 // Confirm that it's really not there...
147 prt = find_region_table(ind, from_hr);
148 if (prt == NULL) {
149
150 CardIdx_t card_index = card_within_region(from, from_hr);
151
152 SparsePRT::AddCardResult result = _sparse_table.add_card(from_hrm_ind, card_index);
153 if (result != SparsePRT::overflow) {
154 if (result == SparsePRT::added) {
155 Atomic::inc(&_num_occupied, memory_order_relaxed);
156 }
157 assert(contains_reference_locked(from), "We just added " PTR_FORMAT " to the Sparse table", p2i(from));
158 return;
159 }
160
161 if (_n_fine_entries == _max_fine_entries) {
162 prt = delete_region_table(num_added_by_coarsening);
163 // There is no need to clear the links to the 'all' list here:
164 // prt will be reused immediately, i.e. remain in the 'all' list.
165 prt->init(from_hr, false /* clear_links_to_all_list */);
166 } else {
167 prt = PerRegionTable::alloc(from_hr);
168 link_to_all(prt);
169 }
170
171 PerRegionTable* first_prt = _fine_grain_regions[ind];
172 prt->set_collision_list_next(first_prt);
173 // The assignment into _fine_grain_regions allows the prt to
174 // start being used concurrently. In addition to
175 // collision_list_next which must be visible (else concurrent
176 // parsing of the list, if any, may fail to see other entries),
177 // the content of the prt must be visible (else for instance
178 // some mark bits may not yet seem cleared or a 'later' update
179 // performed by a concurrent thread could be undone when the
180 // zeroing becomes visible). This requires store ordering.
181 Atomic::release_store(&_fine_grain_regions[ind], prt);
182 _n_fine_entries++;
183
184 // Transfer from sparse to fine-grain. The cards from the sparse table
185 // were already added to the total in _num_occupied.
186 SparsePRTEntry *sprt_entry = _sparse_table.get_entry(from_hrm_ind);
187 assert(sprt_entry != NULL, "There should have been an entry");
188 for (int i = 0; i < sprt_entry->num_valid_cards(); i++) {
189 CardIdx_t c = sprt_entry->card(i);
190 prt->add_card(c);
191 }
192 // Now we can delete the sparse entry.
193 bool res = _sparse_table.delete_entry(from_hrm_ind);
194 assert(res, "It should have been there.");
195 }
196 assert(prt != NULL && prt->hr() == from_hr, "consequence");
197 }
198 // Note that we can't assert "prt->hr() == from_hr", because of the
199 // possibility of concurrent reuse. But see head comment of
200 // OtherRegionsTable for why this is OK.
201 assert(prt != NULL, "Inv");
202
203 if (prt->add_reference(from)) {
204 num_added_by_coarsening++;
205 }
206 Atomic::add(&_num_occupied, num_added_by_coarsening, memory_order_relaxed);
207 assert(contains_reference(from), "We just added " PTR_FORMAT " to the PRT (%d)", p2i(from), prt->contains_reference(from));
208 }
209
210 PerRegionTable*
find_region_table(size_t ind,HeapRegion * hr) const211 OtherRegionsTable::find_region_table(size_t ind, HeapRegion* hr) const {
212 assert(ind < _max_fine_entries, "Preconditions.");
213 PerRegionTable* prt = _fine_grain_regions[ind];
214 while (prt != NULL && prt->hr() != hr) {
215 prt = prt->collision_list_next();
216 }
217 // Loop postcondition is the method postcondition.
218 return prt;
219 }
220
221 jint OtherRegionsTable::_n_coarsenings = 0;
222
delete_region_table(size_t & added_by_deleted)223 PerRegionTable* OtherRegionsTable::delete_region_table(size_t& added_by_deleted) {
224 assert(_m->owned_by_self(), "Precondition");
225 assert(_n_fine_entries == _max_fine_entries, "Precondition");
226 PerRegionTable* max = NULL;
227 jint max_occ = 0;
228 PerRegionTable** max_prev = NULL;
229
230 size_t i = _fine_eviction_start;
231 for (size_t k = 0; k < _fine_eviction_sample_size; k++) {
232 size_t ii = i;
233 // Make sure we get a non-NULL sample.
234 while (_fine_grain_regions[ii] == NULL) {
235 ii++;
236 if (ii == _max_fine_entries) ii = 0;
237 guarantee(ii != i, "We must find one.");
238 }
239 PerRegionTable** prev = &_fine_grain_regions[ii];
240 PerRegionTable* cur = *prev;
241 while (cur != NULL) {
242 jint cur_occ = cur->occupied();
243 if (max == NULL || cur_occ > max_occ) {
244 max = cur;
245 max_prev = prev;
246 max_occ = cur_occ;
247 }
248 prev = cur->collision_list_next_addr();
249 cur = cur->collision_list_next();
250 }
251 i = i + _fine_eviction_stride;
252 if (i >= _n_fine_entries) i = i - _n_fine_entries;
253 }
254
255 _fine_eviction_start++;
256
257 if (_fine_eviction_start >= _n_fine_entries) {
258 _fine_eviction_start -= _n_fine_entries;
259 }
260
261 guarantee(max != NULL, "Since _n_fine_entries > 0");
262 guarantee(max_prev != NULL, "Since max != NULL.");
263
264 // Set the corresponding coarse bit.
265 size_t max_hrm_index = (size_t) max->hr()->hrm_index();
266 if (_n_coarse_entries == 0) {
267 // This will lazily initialize an uninitialized bitmap
268 _coarse_map.reinitialize(G1CollectedHeap::heap()->max_regions());
269 _coarse_map.at_put(max_hrm_index, true);
270 // Release store guarantees that the bitmap has initialized before any
271 // concurrent reader will ever see a non-zero value for _n_coarse_entries
272 // (when read with load_acquire)
273 Atomic::release_store(&_n_coarse_entries, _n_coarse_entries + 1);
274 } else if (!_coarse_map.at(max_hrm_index)) {
275 _coarse_map.at_put(max_hrm_index, true);
276 _n_coarse_entries++;
277 }
278
279 added_by_deleted = HeapRegion::CardsPerRegion - max_occ;
280 // Unsplice.
281 *max_prev = max->collision_list_next();
282 Atomic::inc(&_n_coarsenings);
283 _n_fine_entries--;
284 return max;
285 }
286
occupancy_less_or_equal_than(size_t limit) const287 bool OtherRegionsTable::occupancy_less_or_equal_than(size_t limit) const {
288 return occupied() <= limit;
289 }
290
is_empty() const291 bool OtherRegionsTable::is_empty() const {
292 return occupied() == 0;
293 }
294
occupied() const295 size_t OtherRegionsTable::occupied() const {
296 return _num_occupied;
297 }
298
mem_size() const299 size_t OtherRegionsTable::mem_size() const {
300 size_t sum = 0;
301 // all PRTs are of the same size so it is sufficient to query only one of them.
302 if (_first_all_fine_prts != NULL) {
303 assert(_last_all_fine_prts != NULL &&
304 _first_all_fine_prts->mem_size() == _last_all_fine_prts->mem_size(), "check that mem_size() is constant");
305 sum += _first_all_fine_prts->mem_size() * _n_fine_entries;
306 }
307 sum += (sizeof(PerRegionTable*) * _max_fine_entries);
308 sum += (_coarse_map.size_in_words() * HeapWordSize);
309 sum += (_sparse_table.mem_size());
310 sum += sizeof(OtherRegionsTable) - sizeof(_sparse_table); // Avoid double counting above.
311 return sum;
312 }
313
static_mem_size()314 size_t OtherRegionsTable::static_mem_size() {
315 return G1FromCardCache::static_mem_size();
316 }
317
fl_mem_size()318 size_t OtherRegionsTable::fl_mem_size() {
319 return PerRegionTable::fl_mem_size();
320 }
321
clear()322 void OtherRegionsTable::clear() {
323 // if there are no entries, skip this step
324 if (_first_all_fine_prts != NULL) {
325 guarantee(_first_all_fine_prts != NULL && _last_all_fine_prts != NULL, "just checking");
326 PerRegionTable::bulk_free(_first_all_fine_prts, _last_all_fine_prts);
327 memset(_fine_grain_regions, 0, _max_fine_entries * sizeof(_fine_grain_regions[0]));
328 } else {
329 guarantee(_first_all_fine_prts == NULL && _last_all_fine_prts == NULL, "just checking");
330 }
331
332 _first_all_fine_prts = _last_all_fine_prts = NULL;
333 _sparse_table.clear();
334 if (_n_coarse_entries > 0) {
335 _coarse_map.clear();
336 }
337 _n_fine_entries = 0;
338 _n_coarse_entries = 0;
339
340 _num_occupied = 0;
341 }
342
contains_reference(OopOrNarrowOopStar from) const343 bool OtherRegionsTable::contains_reference(OopOrNarrowOopStar from) const {
344 // Cast away const in this case.
345 MutexLocker x((Mutex*)_m, Mutex::_no_safepoint_check_flag);
346 return contains_reference_locked(from);
347 }
348
contains_reference_locked(OopOrNarrowOopStar from) const349 bool OtherRegionsTable::contains_reference_locked(OopOrNarrowOopStar from) const {
350 HeapRegion* hr = _g1h->heap_region_containing(from);
351 RegionIdx_t hr_ind = (RegionIdx_t) hr->hrm_index();
352 // Is this region in the coarse map?
353 if (is_region_coarsened(hr_ind)) return true;
354
355 PerRegionTable* prt = find_region_table(hr_ind & _mod_max_fine_entries_mask,
356 hr);
357 if (prt != NULL) {
358 return prt->contains_reference(from);
359 } else {
360 CardIdx_t card_index = card_within_region(from, hr);
361 return _sparse_table.contains_card(hr_ind, card_index);
362 }
363 }
364
365 // A load_acquire on _n_coarse_entries - coupled with the release_store in
366 // delete_region_table - guarantees we don't access _coarse_map before
367 // it's been properly initialized.
is_region_coarsened(RegionIdx_t from_hrm_ind) const368 bool OtherRegionsTable::is_region_coarsened(RegionIdx_t from_hrm_ind) const {
369 return Atomic::load_acquire(&_n_coarse_entries) > 0 && _coarse_map.at(from_hrm_ind);
370 }
371
HeapRegionRemSet(G1BlockOffsetTable * bot,HeapRegion * hr)372 HeapRegionRemSet::HeapRegionRemSet(G1BlockOffsetTable* bot,
373 HeapRegion* hr)
374 : _bot(bot),
375 _code_roots(),
376 _m(Mutex::leaf, FormatBuffer<128>("HeapRegionRemSet lock #%u", hr->hrm_index()), true, Mutex::_safepoint_check_never),
377 _other_regions(&_m),
378 _hr(hr),
379 _state(Untracked)
380 {
381 }
382
clear_fcc()383 void HeapRegionRemSet::clear_fcc() {
384 G1FromCardCache::clear(_hr->hrm_index());
385 }
386
setup_remset_size()387 void HeapRegionRemSet::setup_remset_size() {
388 const int LOG_M = 20;
389 guarantee(HeapRegion::LogOfHRGrainBytes >= LOG_M, "Code assumes the region size >= 1M, but is " SIZE_FORMAT "B", HeapRegion::GrainBytes);
390
391 int region_size_log_mb = HeapRegion::LogOfHRGrainBytes - LOG_M;
392 if (FLAG_IS_DEFAULT(G1RSetSparseRegionEntries)) {
393 G1RSetSparseRegionEntries = G1RSetSparseRegionEntriesBase * ((size_t)1 << (region_size_log_mb + 1));
394 }
395 if (FLAG_IS_DEFAULT(G1RSetRegionEntries)) {
396 G1RSetRegionEntries = G1RSetRegionEntriesBase * (region_size_log_mb + 1);
397 }
398 guarantee(G1RSetSparseRegionEntries > 0 && G1RSetRegionEntries > 0 , "Sanity");
399 }
400
clear(bool only_cardset)401 void HeapRegionRemSet::clear(bool only_cardset) {
402 MutexLocker x(&_m, Mutex::_no_safepoint_check_flag);
403 clear_locked(only_cardset);
404 }
405
clear_locked(bool only_cardset)406 void HeapRegionRemSet::clear_locked(bool only_cardset) {
407 if (!only_cardset) {
408 _code_roots.clear();
409 }
410 clear_fcc();
411 _other_regions.clear();
412 set_state_empty();
413 assert(occupied() == 0, "Should be clear.");
414 }
415
416 // Code roots support
417 //
418 // The code root set is protected by two separate locking schemes
419 // When at safepoint the per-hrrs lock must be held during modifications
420 // except when doing a full gc.
421 // When not at safepoint the CodeCache_lock must be held during modifications.
422 // When concurrent readers access the contains() function
423 // (during the evacuation phase) no removals are allowed.
424
add_strong_code_root(nmethod * nm)425 void HeapRegionRemSet::add_strong_code_root(nmethod* nm) {
426 assert(nm != NULL, "sanity");
427 assert((!CodeCache_lock->owned_by_self() || SafepointSynchronize::is_at_safepoint()),
428 "should call add_strong_code_root_locked instead. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s",
429 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()));
430 // Optimistic unlocked contains-check
431 if (!_code_roots.contains(nm)) {
432 MutexLocker ml(&_m, Mutex::_no_safepoint_check_flag);
433 add_strong_code_root_locked(nm);
434 }
435 }
436
add_strong_code_root_locked(nmethod * nm)437 void HeapRegionRemSet::add_strong_code_root_locked(nmethod* nm) {
438 assert(nm != NULL, "sanity");
439 assert((CodeCache_lock->owned_by_self() ||
440 (SafepointSynchronize::is_at_safepoint() &&
441 (_m.owned_by_self() || Thread::current()->is_VM_thread()))),
442 "not safely locked. CodeCache_lock->owned_by_self(): %s, is_at_safepoint(): %s, _m.owned_by_self(): %s, Thread::current()->is_VM_thread(): %s",
443 BOOL_TO_STR(CodeCache_lock->owned_by_self()), BOOL_TO_STR(SafepointSynchronize::is_at_safepoint()),
444 BOOL_TO_STR(_m.owned_by_self()), BOOL_TO_STR(Thread::current()->is_VM_thread()));
445 _code_roots.add(nm);
446 }
447
remove_strong_code_root(nmethod * nm)448 void HeapRegionRemSet::remove_strong_code_root(nmethod* nm) {
449 assert(nm != NULL, "sanity");
450 assert_locked_or_safepoint(CodeCache_lock);
451
452 MutexLocker ml(CodeCache_lock->owned_by_self() ? NULL : &_m, Mutex::_no_safepoint_check_flag);
453 _code_roots.remove(nm);
454
455 // Check that there were no duplicates
456 guarantee(!_code_roots.contains(nm), "duplicate entry found");
457 }
458
strong_code_roots_do(CodeBlobClosure * blk) const459 void HeapRegionRemSet::strong_code_roots_do(CodeBlobClosure* blk) const {
460 _code_roots.nmethods_do(blk);
461 }
462
clean_strong_code_roots(HeapRegion * hr)463 void HeapRegionRemSet::clean_strong_code_roots(HeapRegion* hr) {
464 _code_roots.clean(hr);
465 }
466
strong_code_roots_mem_size()467 size_t HeapRegionRemSet::strong_code_roots_mem_size() {
468 return _code_roots.mem_size();
469 }
470