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/g1Arguments.hpp"
27 #include "gc/g1/g1CollectedHeap.inline.hpp"
28 #include "gc/g1/g1ConcurrentRefine.hpp"
29 #include "gc/g1/heapRegion.hpp"
30 #include "gc/g1/heapRegionManager.inline.hpp"
31 #include "gc/g1/heapRegionSet.inline.hpp"
32 #include "gc/g1/heterogeneousHeapRegionManager.hpp"
33 #include "memory/allocation.hpp"
34 #include "utilities/bitMap.inline.hpp"
35
36 class MasterFreeRegionListChecker : public HeapRegionSetChecker {
37 public:
38 void check_mt_safety() {
39 // Master Free List MT safety protocol:
40 // (a) If we're at a safepoint, operations on the master free list
41 // should be invoked by either the VM thread (which will serialize
42 // them) or by the GC workers while holding the
43 // FreeList_lock.
44 // (b) If we're not at a safepoint, operations on the master free
45 // list should be invoked while holding the Heap_lock.
46
47 if (SafepointSynchronize::is_at_safepoint()) {
48 guarantee(Thread::current()->is_VM_thread() ||
49 FreeList_lock->owned_by_self(), "master free list MT safety protocol at a safepoint");
50 } else {
51 guarantee(Heap_lock->owned_by_self(), "master free list MT safety protocol outside a safepoint");
52 }
53 }
54 bool is_correct_type(HeapRegion* hr) { return hr->is_free(); }
55 const char* get_description() { return "Free Regions"; }
56 };
57
58 HeapRegionManager::HeapRegionManager() :
59 _bot_mapper(NULL),
60 _cardtable_mapper(NULL),
61 _card_counts_mapper(NULL),
62 _available_map(mtGC),
63 _num_committed(0),
64 _allocated_heapregions_length(0),
65 _regions(), _heap_mapper(NULL),
66 _prev_bitmap_mapper(NULL),
67 _next_bitmap_mapper(NULL),
68 _free_list("Free list", new MasterFreeRegionListChecker())
69 { }
70
71 HeapRegionManager* HeapRegionManager::create_manager(G1CollectedHeap* heap) {
72 if (G1Arguments::is_heterogeneous_heap()) {
73 return new HeterogeneousHeapRegionManager((uint)(G1Arguments::heap_max_size_bytes() / HeapRegion::GrainBytes) /*heap size as num of regions*/);
74 }
75 return new HeapRegionManager();
76 }
77
78 void HeapRegionManager::initialize(G1RegionToSpaceMapper* heap_storage,
79 G1RegionToSpaceMapper* prev_bitmap,
80 G1RegionToSpaceMapper* next_bitmap,
81 G1RegionToSpaceMapper* bot,
82 G1RegionToSpaceMapper* cardtable,
83 G1RegionToSpaceMapper* card_counts) {
84 _allocated_heapregions_length = 0;
85
86 _heap_mapper = heap_storage;
87
88 _prev_bitmap_mapper = prev_bitmap;
89 _next_bitmap_mapper = next_bitmap;
90
91 _bot_mapper = bot;
92 _cardtable_mapper = cardtable;
93
94 _card_counts_mapper = card_counts;
95
96 MemRegion reserved = heap_storage->reserved();
97 _regions.initialize(reserved.start(), reserved.end(), HeapRegion::GrainBytes);
98
99 _available_map.initialize(_regions.length());
100 }
101
102 bool HeapRegionManager::is_available(uint region) const {
103 return _available_map.at(region);
104 }
105
106 #ifdef ASSERT
107 bool HeapRegionManager::is_free(HeapRegion* hr) const {
108 return _free_list.contains(hr);
109 }
110 #endif
111
112 HeapRegion* HeapRegionManager::new_heap_region(uint hrm_index) {
113 G1CollectedHeap* g1h = G1CollectedHeap::heap();
114 HeapWord* bottom = g1h->bottom_addr_for_region(hrm_index);
115 MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
116 assert(reserved().contains(mr), "invariant");
117 return g1h->new_heap_region(hrm_index, mr);
118 }
119
120 void HeapRegionManager::commit_regions(uint index, size_t num_regions, WorkGang* pretouch_gang) {
121 guarantee(num_regions > 0, "Must commit more than zero regions");
122 guarantee(_num_committed + num_regions <= max_length(), "Cannot commit more than the maximum amount of regions");
123
124 _num_committed += (uint)num_regions;
125
126 _heap_mapper->commit_regions(index, num_regions, pretouch_gang);
127
128 // Also commit auxiliary data
129 _prev_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang);
130 _next_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang);
131
132 _bot_mapper->commit_regions(index, num_regions, pretouch_gang);
133 _cardtable_mapper->commit_regions(index, num_regions, pretouch_gang);
134
135 _card_counts_mapper->commit_regions(index, num_regions, pretouch_gang);
136 }
137
138 void HeapRegionManager::uncommit_regions(uint start, size_t num_regions) {
139 guarantee(num_regions >= 1, "Need to specify at least one region to uncommit, tried to uncommit zero regions at %u", start);
140 guarantee(_num_committed >= num_regions, "pre-condition");
141
142 // Print before uncommitting.
143 if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
144 for (uint i = start; i < start + num_regions; i++) {
145 HeapRegion* hr = at(i);
146 G1CollectedHeap::heap()->hr_printer()->uncommit(hr);
147 }
148 }
149
150 _num_committed -= (uint)num_regions;
151
152 _available_map.par_clear_range(start, start + num_regions, BitMap::unknown_range);
153 _heap_mapper->uncommit_regions(start, num_regions);
154
155 // Also uncommit auxiliary data
156 _prev_bitmap_mapper->uncommit_regions(start, num_regions);
157 _next_bitmap_mapper->uncommit_regions(start, num_regions);
158
159 _bot_mapper->uncommit_regions(start, num_regions);
160 _cardtable_mapper->uncommit_regions(start, num_regions);
161
162 _card_counts_mapper->uncommit_regions(start, num_regions);
163 }
164
165 void HeapRegionManager::make_regions_available(uint start, uint num_regions, WorkGang* pretouch_gang) {
166 guarantee(num_regions > 0, "No point in calling this for zero regions");
167 commit_regions(start, num_regions, pretouch_gang);
168 for (uint i = start; i < start + num_regions; i++) {
169 if (_regions.get_by_index(i) == NULL) {
170 HeapRegion* new_hr = new_heap_region(i);
171 OrderAccess::storestore();
172 _regions.set_by_index(i, new_hr);
173 _allocated_heapregions_length = MAX2(_allocated_heapregions_length, i + 1);
174 }
175 }
176
177 _available_map.par_set_range(start, start + num_regions, BitMap::unknown_range);
178
179 for (uint i = start; i < start + num_regions; i++) {
180 assert(is_available(i), "Just made region %u available but is apparently not.", i);
181 HeapRegion* hr = at(i);
182 if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
183 G1CollectedHeap::heap()->hr_printer()->commit(hr);
184 }
185 HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(i);
186 MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
187
188 hr->initialize(mr);
189 insert_into_free_list(at(i));
190 }
191 }
192
193 MemoryUsage HeapRegionManager::get_auxiliary_data_memory_usage() const {
194 size_t used_sz =
195 _prev_bitmap_mapper->committed_size() +
196 _next_bitmap_mapper->committed_size() +
197 _bot_mapper->committed_size() +
198 _cardtable_mapper->committed_size() +
199 _card_counts_mapper->committed_size();
200
201 size_t committed_sz =
202 _prev_bitmap_mapper->reserved_size() +
203 _next_bitmap_mapper->reserved_size() +
204 _bot_mapper->reserved_size() +
205 _cardtable_mapper->reserved_size() +
206 _card_counts_mapper->reserved_size();
207
208 return MemoryUsage(0, used_sz, committed_sz, committed_sz);
209 }
210
211 uint HeapRegionManager::expand_by(uint num_regions, WorkGang* pretouch_workers) {
212 return expand_at(0, num_regions, pretouch_workers);
213 }
214
215 uint HeapRegionManager::expand_at(uint start, uint num_regions, WorkGang* pretouch_workers) {
216 if (num_regions == 0) {
217 return 0;
218 }
219
220 uint cur = start;
221 uint idx_last_found = 0;
222 uint num_last_found = 0;
223
224 uint expanded = 0;
225
226 while (expanded < num_regions &&
227 (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) {
228 uint to_expand = MIN2(num_regions - expanded, num_last_found);
229 make_regions_available(idx_last_found, to_expand, pretouch_workers);
230 expanded += to_expand;
231 cur = idx_last_found + num_last_found + 1;
232 }
233
234 verify_optional();
235 return expanded;
236 }
237
238 uint HeapRegionManager::find_contiguous(size_t num, bool empty_only) {
239 uint found = 0;
240 size_t length_found = 0;
241 uint cur = 0;
242
243 while (length_found < num && cur < max_length()) {
244 HeapRegion* hr = _regions.get_by_index(cur);
245 if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) {
246 // This region is a potential candidate for allocation into.
247 length_found++;
248 } else {
249 // This region is not a candidate. The next region is the next possible one.
250 found = cur + 1;
251 length_found = 0;
252 }
253 cur++;
254 }
255
256 if (length_found == num) {
257 for (uint i = found; i < (found + num); i++) {
258 HeapRegion* hr = _regions.get_by_index(i);
259 // sanity check
260 guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()),
261 "Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT
262 " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr));
263 }
264 return found;
265 } else {
266 return G1_NO_HRM_INDEX;
267 }
268 }
269
270 HeapRegion* HeapRegionManager::next_region_in_heap(const HeapRegion* r) const {
271 guarantee(r != NULL, "Start region must be a valid region");
272 guarantee(is_available(r->hrm_index()), "Trying to iterate starting from region %u which is not in the heap", r->hrm_index());
273 for (uint i = r->hrm_index() + 1; i < _allocated_heapregions_length; i++) {
274 HeapRegion* hr = _regions.get_by_index(i);
275 if (is_available(i)) {
276 return hr;
277 }
278 }
279 return NULL;
280 }
281
282 void HeapRegionManager::iterate(HeapRegionClosure* blk) const {
283 uint len = max_length();
284
285 for (uint i = 0; i < len; i++) {
286 if (!is_available(i)) {
287 continue;
288 }
289 guarantee(at(i) != NULL, "Tried to access region %u that has a NULL HeapRegion*", i);
290 bool res = blk->do_heap_region(at(i));
291 if (res) {
292 blk->set_incomplete();
293 return;
294 }
295 }
296 }
297
298 uint HeapRegionManager::find_unavailable_from_idx(uint start_idx, uint* res_idx) const {
299 guarantee(res_idx != NULL, "checking");
300 guarantee(start_idx <= (max_length() + 1), "checking");
301
302 uint num_regions = 0;
303
304 uint cur = start_idx;
305 while (cur < max_length() && is_available(cur)) {
306 cur++;
307 }
308 if (cur == max_length()) {
309 return num_regions;
310 }
311 *res_idx = cur;
312 while (cur < max_length() && !is_available(cur)) {
313 cur++;
314 }
315 num_regions = cur - *res_idx;
316 #ifdef ASSERT
317 for (uint i = *res_idx; i < (*res_idx + num_regions); i++) {
318 assert(!is_available(i), "just checking");
319 }
320 assert(cur == max_length() || num_regions == 0 || is_available(cur),
321 "The region at the current position %u must be available or at the end of the heap.", cur);
322 #endif
323 return num_regions;
324 }
325
326 uint HeapRegionManager::find_highest_free(bool* expanded) {
327 // Loop downwards from the highest region index, looking for an
328 // entry which is either free or not yet committed. If not yet
329 // committed, expand_at that index.
330 uint curr = max_length() - 1;
331 while (true) {
332 HeapRegion *hr = _regions.get_by_index(curr);
333 if (hr == NULL || !is_available(curr)) {
334 uint res = expand_at(curr, 1, NULL);
335 if (res == 1) {
336 *expanded = true;
337 return curr;
338 }
339 } else {
340 if (hr->is_free()) {
341 *expanded = false;
342 return curr;
343 }
344 }
345 if (curr == 0) {
346 return G1_NO_HRM_INDEX;
347 }
348 curr--;
349 }
350 }
351
352 bool HeapRegionManager::allocate_containing_regions(MemRegion range, size_t* commit_count, WorkGang* pretouch_workers) {
353 size_t commits = 0;
354 uint start_index = (uint)_regions.get_index_by_address(range.start());
355 uint last_index = (uint)_regions.get_index_by_address(range.last());
356
357 // Ensure that each G1 region in the range is free, returning false if not.
358 // Commit those that are not yet available, and keep count.
359 for (uint curr_index = start_index; curr_index <= last_index; curr_index++) {
360 if (!is_available(curr_index)) {
361 commits++;
362 expand_at(curr_index, 1, pretouch_workers);
363 }
364 HeapRegion* curr_region = _regions.get_by_index(curr_index);
365 if (!curr_region->is_free()) {
366 return false;
367 }
368 }
369
370 allocate_free_regions_starting_at(start_index, (last_index - start_index) + 1);
371 *commit_count = commits;
372 return true;
373 }
374
375 void HeapRegionManager::par_iterate(HeapRegionClosure* blk, HeapRegionClaimer* hrclaimer, const uint start_index) const {
376 // Every worker will actually look at all regions, skipping over regions that
377 // are currently not committed.
378 // This also (potentially) iterates over regions newly allocated during GC. This
379 // is no problem except for some extra work.
380 const uint n_regions = hrclaimer->n_regions();
381 for (uint count = 0; count < n_regions; count++) {
382 const uint index = (start_index + count) % n_regions;
383 assert(index < n_regions, "sanity");
384 // Skip over unavailable regions
385 if (!is_available(index)) {
386 continue;
387 }
388 HeapRegion* r = _regions.get_by_index(index);
389 // We'll ignore regions already claimed.
390 // However, if the iteration is specified as concurrent, the values for
391 // is_starts_humongous and is_continues_humongous can not be trusted,
392 // and we should just blindly iterate over regions regardless of their
393 // humongous status.
394 if (hrclaimer->is_region_claimed(index)) {
395 continue;
396 }
397 // OK, try to claim it
398 if (!hrclaimer->claim_region(index)) {
399 continue;
400 }
401 bool res = blk->do_heap_region(r);
402 if (res) {
403 return;
404 }
405 }
406 }
407
408 uint HeapRegionManager::shrink_by(uint num_regions_to_remove) {
409 assert(length() > 0, "the region sequence should not be empty");
410 assert(length() <= _allocated_heapregions_length, "invariant");
411 assert(_allocated_heapregions_length > 0, "we should have at least one region committed");
412 assert(num_regions_to_remove < length(), "We should never remove all regions");
413
414 if (num_regions_to_remove == 0) {
415 return 0;
416 }
417
418 uint removed = 0;
419 uint cur = _allocated_heapregions_length - 1;
420 uint idx_last_found = 0;
421 uint num_last_found = 0;
422
423 while ((removed < num_regions_to_remove) &&
424 (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {
425 uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);
426
427 shrink_at(idx_last_found + num_last_found - to_remove, to_remove);
428
429 cur = idx_last_found;
430 removed += to_remove;
431 }
432
433 verify_optional();
434
435 return removed;
436 }
437
438 void HeapRegionManager::shrink_at(uint index, size_t num_regions) {
439 #ifdef ASSERT
440 for (uint i = index; i < (index + num_regions); i++) {
441 assert(is_available(i), "Expected available region at index %u", i);
442 assert(at(i)->is_empty(), "Expected empty region at index %u", i);
443 assert(at(i)->is_free(), "Expected free region at index %u", i);
444 }
445 #endif
446 uncommit_regions(index, num_regions);
447 }
448
449 uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const {
450 guarantee(start_idx < _allocated_heapregions_length, "checking");
451 guarantee(res_idx != NULL, "checking");
452
453 uint num_regions_found = 0;
454
455 jlong cur = start_idx;
456 while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) {
457 cur--;
458 }
459 if (cur == -1) {
460 return num_regions_found;
461 }
462 jlong old_cur = cur;
463 // cur indexes the first empty region
464 while (cur != -1 && is_available(cur) && at(cur)->is_empty()) {
465 cur--;
466 }
467 *res_idx = cur + 1;
468 num_regions_found = old_cur - cur;
469
470 #ifdef ASSERT
471 for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) {
472 assert(at(i)->is_empty(), "just checking");
473 }
474 #endif
475 return num_regions_found;
476 }
477
478 void HeapRegionManager::verify() {
479 guarantee(length() <= _allocated_heapregions_length,
480 "invariant: _length: %u _allocated_length: %u",
481 length(), _allocated_heapregions_length);
482 guarantee(_allocated_heapregions_length <= max_length(),
483 "invariant: _allocated_length: %u _max_length: %u",
484 _allocated_heapregions_length, max_length());
485
486 bool prev_committed = true;
487 uint num_committed = 0;
488 HeapWord* prev_end = heap_bottom();
489 for (uint i = 0; i < _allocated_heapregions_length; i++) {
490 if (!is_available(i)) {
491 prev_committed = false;
492 continue;
493 }
494 num_committed++;
495 HeapRegion* hr = _regions.get_by_index(i);
496 guarantee(hr != NULL, "invariant: i: %u", i);
497 guarantee(!prev_committed || hr->bottom() == prev_end,
498 "invariant i: %u " HR_FORMAT " prev_end: " PTR_FORMAT,
499 i, HR_FORMAT_PARAMS(hr), p2i(prev_end));
500 guarantee(hr->hrm_index() == i,
501 "invariant: i: %u hrm_index(): %u", i, hr->hrm_index());
502 // Asserts will fire if i is >= _length
503 HeapWord* addr = hr->bottom();
504 guarantee(addr_to_region(addr) == hr, "sanity");
505 // We cannot check whether the region is part of a particular set: at the time
506 // this method may be called, we have only completed allocation of the regions,
507 // but not put into a region set.
508 prev_committed = true;
509 prev_end = hr->end();
510 }
511 for (uint i = _allocated_heapregions_length; i < max_length(); i++) {
512 guarantee(_regions.get_by_index(i) == NULL, "invariant i: %u", i);
513 }
514
515 guarantee(num_committed == _num_committed, "Found %u committed regions, but should be %u", num_committed, _num_committed);
516 _free_list.verify();
517 }
518
519 #ifndef PRODUCT
520 void HeapRegionManager::verify_optional() {
521 verify();
522 }
523 #endif // PRODUCT
524
525 HeapRegionClaimer::HeapRegionClaimer(uint n_workers) :
526 _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm->_allocated_heapregions_length), _claims(NULL) {
527 assert(n_workers > 0, "Need at least one worker.");
528 uint* new_claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC);
529 memset(new_claims, Unclaimed, sizeof(*_claims) * _n_regions);
530 _claims = new_claims;
531 }
532
533 HeapRegionClaimer::~HeapRegionClaimer() {
534 FREE_C_HEAP_ARRAY(uint, _claims);
535 }
536
537 uint HeapRegionClaimer::offset_for_worker(uint worker_id) const {
538 assert(worker_id < _n_workers, "Invalid worker_id.");
539 return _n_regions * worker_id / _n_workers;
540 }
541
542 bool HeapRegionClaimer::is_region_claimed(uint region_index) const {
543 assert(region_index < _n_regions, "Invalid index.");
544 return _claims[region_index] == Claimed;
545 }
546
547 bool HeapRegionClaimer::claim_region(uint region_index) {
548 assert(region_index < _n_regions, "Invalid index.");
549 uint old_val = Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed);
550 return old_val == Unclaimed;
551 }