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 "logging/logStream.hpp"
34 #include "memory/allocation.hpp"
35 #include "utilities/bitMap.inline.hpp"
36
37 class MasterFreeRegionListChecker : public HeapRegionSetChecker {
38 public:
39 void check_mt_safety() {
40 // Master Free List MT safety protocol:
41 // (a) If we're at a safepoint, operations on the master free list
42 // should be invoked by either the VM thread (which will serialize
43 // them) or by the GC workers while holding the
44 // FreeList_lock.
45 // (b) If we're not at a safepoint, operations on the master free
46 // list should be invoked while holding the Heap_lock.
47
48 if (SafepointSynchronize::is_at_safepoint()) {
49 guarantee(Thread::current()->is_VM_thread() ||
50 FreeList_lock->owned_by_self(), "master free list MT safety protocol at a safepoint");
51 } else {
52 guarantee(Heap_lock->owned_by_self(), "master free list MT safety protocol outside a safepoint");
53 }
54 }
55 bool is_correct_type(HeapRegion* hr) { return hr->is_free(); }
56 const char* get_description() { return "Free Regions"; }
57 };
58
59 HeapRegionManager::HeapRegionManager() :
60 _bot_mapper(NULL),
61 _cardtable_mapper(NULL),
62 _card_counts_mapper(NULL),
63 _available_map(mtGC),
64 _num_committed(0),
65 _allocated_heapregions_length(0),
66 _regions(), _heap_mapper(NULL),
67 _prev_bitmap_mapper(NULL),
68 _next_bitmap_mapper(NULL),
69 _free_list("Free list", new MasterFreeRegionListChecker())
70 { }
71
72 HeapRegionManager* HeapRegionManager::create_manager(G1CollectedHeap* heap) {
73 if (G1Arguments::is_heterogeneous_heap()) {
74 return new HeterogeneousHeapRegionManager((uint)(G1Arguments::heap_max_size_bytes() / HeapRegion::GrainBytes) /*heap size as num of regions*/);
75 }
76 return new HeapRegionManager();
77 }
78
79 void HeapRegionManager::initialize(G1RegionToSpaceMapper* heap_storage,
80 G1RegionToSpaceMapper* prev_bitmap,
81 G1RegionToSpaceMapper* next_bitmap,
82 G1RegionToSpaceMapper* bot,
83 G1RegionToSpaceMapper* cardtable,
84 G1RegionToSpaceMapper* card_counts) {
85 _allocated_heapregions_length = 0;
86
87 _heap_mapper = heap_storage;
88
89 _prev_bitmap_mapper = prev_bitmap;
90 _next_bitmap_mapper = next_bitmap;
91
92 _bot_mapper = bot;
93 _cardtable_mapper = cardtable;
94
95 _card_counts_mapper = card_counts;
96
97 MemRegion reserved = heap_storage->reserved();
98 _regions.initialize(reserved.start(), reserved.end(), HeapRegion::GrainBytes);
99
100 _available_map.initialize(_regions.length());
101 }
102
103 bool HeapRegionManager::is_available(uint region) const {
104 return _available_map.at(region);
105 }
106
107 HeapRegion* HeapRegionManager::allocate_free_region(HeapRegionType type, uint requested_node_index) {
108 HeapRegion* hr = NULL;
109 bool from_head = !type.is_young();
110
111 if (requested_node_index != G1NUMA::AnyNodeIndex && G1NUMA::numa()->is_enabled()) {
112 // Try to allocate with requested node index.
113 hr = _free_list.remove_region_with_node_index(from_head, requested_node_index, NULL);
114 }
115
116 if (hr == NULL) {
117 // If there's a single active node or we did not get a region from our requested node,
118 // try without requested node index.
119 hr = _free_list.remove_region(from_head);
120 }
121
122 if (hr != NULL) {
123 assert(hr->next() == NULL, "Single region should not have next");
124 assert(is_available(hr->hrm_index()), "Must be committed");
125 }
126
127 return hr;
128 }
129
130 #ifdef ASSERT
131 bool HeapRegionManager::is_free(HeapRegion* hr) const {
132 return _free_list.contains(hr);
133 }
134 #endif
135
136 HeapRegion* HeapRegionManager::new_heap_region(uint hrm_index) {
137 G1CollectedHeap* g1h = G1CollectedHeap::heap();
138 HeapWord* bottom = g1h->bottom_addr_for_region(hrm_index);
139 MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
140 assert(reserved().contains(mr), "invariant");
141 return g1h->new_heap_region(hrm_index, mr);
142 }
143
144 void HeapRegionManager::commit_regions(uint index, size_t num_regions, WorkGang* pretouch_gang) {
145 guarantee(num_regions > 0, "Must commit more than zero regions");
146 guarantee(_num_committed + num_regions <= max_length(), "Cannot commit more than the maximum amount of regions");
147
148 _num_committed += (uint)num_regions;
149
150 _heap_mapper->commit_regions(index, num_regions, pretouch_gang);
151
152 // Also commit auxiliary data
153 _prev_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang);
154 _next_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang);
155
156 _bot_mapper->commit_regions(index, num_regions, pretouch_gang);
157 _cardtable_mapper->commit_regions(index, num_regions, pretouch_gang);
158
159 _card_counts_mapper->commit_regions(index, num_regions, pretouch_gang);
160 }
161
162 void HeapRegionManager::uncommit_regions(uint start, size_t num_regions) {
163 guarantee(num_regions >= 1, "Need to specify at least one region to uncommit, tried to uncommit zero regions at %u", start);
164 guarantee(_num_committed >= num_regions, "pre-condition");
165
166 // Reset node index to distinguish with committed regions.
167 for (uint i = start; i < start + num_regions; i++) {
168 at(i)->set_node_index(G1NUMA::UnknownNodeIndex);
169 }
170
171 // Print before uncommitting.
172 if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
173 for (uint i = start; i < start + num_regions; i++) {
174 HeapRegion* hr = at(i);
175 G1CollectedHeap::heap()->hr_printer()->uncommit(hr);
176 }
177 }
178
179 _num_committed -= (uint)num_regions;
180
181 _available_map.par_clear_range(start, start + num_regions, BitMap::unknown_range);
182 _heap_mapper->uncommit_regions(start, num_regions);
183
184 // Also uncommit auxiliary data
185 _prev_bitmap_mapper->uncommit_regions(start, num_regions);
186 _next_bitmap_mapper->uncommit_regions(start, num_regions);
187
188 _bot_mapper->uncommit_regions(start, num_regions);
189 _cardtable_mapper->uncommit_regions(start, num_regions);
190
191 _card_counts_mapper->uncommit_regions(start, num_regions);
192 }
193
194 void HeapRegionManager::make_regions_available(uint start, uint num_regions, WorkGang* pretouch_gang) {
195 guarantee(num_regions > 0, "No point in calling this for zero regions");
196 commit_regions(start, num_regions, pretouch_gang);
197 for (uint i = start; i < start + num_regions; i++) {
198 if (_regions.get_by_index(i) == NULL) {
199 HeapRegion* new_hr = new_heap_region(i);
200 OrderAccess::storestore();
201 _regions.set_by_index(i, new_hr);
202 _allocated_heapregions_length = MAX2(_allocated_heapregions_length, i + 1);
203 }
204 }
205
206 _available_map.par_set_range(start, start + num_regions, BitMap::unknown_range);
207
208 for (uint i = start; i < start + num_regions; i++) {
209 assert(is_available(i), "Just made region %u available but is apparently not.", i);
210 HeapRegion* hr = at(i);
211 if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
212 G1CollectedHeap::heap()->hr_printer()->commit(hr);
213 }
214 HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(i);
215 MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
216
217 hr->initialize(mr);
218 hr->set_node_index(G1NUMA::numa()->index_for_region(hr));
219 insert_into_free_list(at(i));
220 }
221 }
222
223 MemoryUsage HeapRegionManager::get_auxiliary_data_memory_usage() const {
224 size_t used_sz =
225 _prev_bitmap_mapper->committed_size() +
226 _next_bitmap_mapper->committed_size() +
227 _bot_mapper->committed_size() +
228 _cardtable_mapper->committed_size() +
229 _card_counts_mapper->committed_size();
230
231 size_t committed_sz =
232 _prev_bitmap_mapper->reserved_size() +
233 _next_bitmap_mapper->reserved_size() +
234 _bot_mapper->reserved_size() +
235 _cardtable_mapper->reserved_size() +
236 _card_counts_mapper->reserved_size();
237
238 return MemoryUsage(0, used_sz, committed_sz, committed_sz);
239 }
240
241 uint HeapRegionManager::expand_by(uint num_regions, WorkGang* pretouch_workers) {
242 return expand_at(0, num_regions, pretouch_workers);
243 }
244
245 uint HeapRegionManager::expand_at(uint start, uint num_regions, WorkGang* pretouch_workers) {
246 if (num_regions == 0) {
247 return 0;
248 }
249
250 uint cur = start;
251 uint idx_last_found = 0;
252 uint num_last_found = 0;
253
254 uint expanded = 0;
255
256 while (expanded < num_regions &&
257 (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) {
258 uint to_expand = MIN2(num_regions - expanded, num_last_found);
259 make_regions_available(idx_last_found, to_expand, pretouch_workers);
260 expanded += to_expand;
261 cur = idx_last_found + num_last_found + 1;
262 }
263
264 verify_optional();
265 return expanded;
266 }
267
268 uint HeapRegionManager::expand_on_preferred_node(uint preferred_index) {
269 uint expand_candidate = UINT_MAX;
270 for (uint i = 0; i < max_length(); i++) {
271 if (is_available(i)) {
272 // Already in use continue
273 continue;
274 }
275 // Always save the candidate so we can expand later on.
276 expand_candidate = i;
277 if (is_on_preferred_index(expand_candidate, preferred_index)) {
278 // We have found a candidate on the preffered node, break.
279 break;
280 }
281 }
282
283 if (expand_candidate == UINT_MAX) {
284 // No regions left, expand failed.
285 return 0;
286 }
287
288 make_regions_available(expand_candidate, 1, NULL);
289 return 1;
290 }
291
292 bool HeapRegionManager::is_on_preferred_index(uint region_index, uint preferred_node_index) {
293 uint region_node_index = G1NUMA::numa()->preferred_node_index_for_index(region_index);
294 return region_node_index == preferred_node_index;
295 }
296
297 uint HeapRegionManager::find_contiguous(size_t num, bool empty_only) {
298 uint found = 0;
299 size_t length_found = 0;
300 uint cur = 0;
301
302 while (length_found < num && cur < max_length()) {
303 HeapRegion* hr = _regions.get_by_index(cur);
304 if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) {
305 // This region is a potential candidate for allocation into.
306 length_found++;
307 } else {
308 // This region is not a candidate. The next region is the next possible one.
309 found = cur + 1;
310 length_found = 0;
311 }
312 cur++;
313 }
314
315 if (length_found == num) {
316 for (uint i = found; i < (found + num); i++) {
317 HeapRegion* hr = _regions.get_by_index(i);
318 // sanity check
319 guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()),
320 "Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT
321 " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr));
322 }
323 return found;
324 } else {
325 return G1_NO_HRM_INDEX;
326 }
327 }
328
329 HeapRegion* HeapRegionManager::next_region_in_heap(const HeapRegion* r) const {
330 guarantee(r != NULL, "Start region must be a valid region");
331 guarantee(is_available(r->hrm_index()), "Trying to iterate starting from region %u which is not in the heap", r->hrm_index());
332 for (uint i = r->hrm_index() + 1; i < _allocated_heapregions_length; i++) {
333 HeapRegion* hr = _regions.get_by_index(i);
334 if (is_available(i)) {
335 return hr;
336 }
337 }
338 return NULL;
339 }
340
341 void HeapRegionManager::iterate(HeapRegionClosure* blk) const {
342 uint len = max_length();
343
344 for (uint i = 0; i < len; i++) {
345 if (!is_available(i)) {
346 continue;
347 }
348 guarantee(at(i) != NULL, "Tried to access region %u that has a NULL HeapRegion*", i);
349 bool res = blk->do_heap_region(at(i));
350 if (res) {
351 blk->set_incomplete();
352 return;
353 }
354 }
355 }
356
357 uint HeapRegionManager::find_unavailable_from_idx(uint start_idx, uint* res_idx) const {
358 guarantee(res_idx != NULL, "checking");
359 guarantee(start_idx <= (max_length() + 1), "checking");
360
361 uint num_regions = 0;
362
363 uint cur = start_idx;
364 while (cur < max_length() && is_available(cur)) {
365 cur++;
366 }
367 if (cur == max_length()) {
368 return num_regions;
369 }
370 *res_idx = cur;
371 while (cur < max_length() && !is_available(cur)) {
372 cur++;
373 }
374 num_regions = cur - *res_idx;
375 #ifdef ASSERT
376 for (uint i = *res_idx; i < (*res_idx + num_regions); i++) {
377 assert(!is_available(i), "just checking");
378 }
379 assert(cur == max_length() || num_regions == 0 || is_available(cur),
380 "The region at the current position %u must be available or at the end of the heap.", cur);
381 #endif
382 return num_regions;
383 }
384
385 uint HeapRegionManager::find_highest_free(bool* expanded) {
386 // Loop downwards from the highest region index, looking for an
387 // entry which is either free or not yet committed. If not yet
388 // committed, expand_at that index.
389 uint curr = max_length() - 1;
390 while (true) {
391 HeapRegion *hr = _regions.get_by_index(curr);
392 if (hr == NULL || !is_available(curr)) {
393 uint res = expand_at(curr, 1, NULL);
394 if (res == 1) {
395 *expanded = true;
396 return curr;
397 }
398 } else {
399 if (hr->is_free()) {
400 *expanded = false;
401 return curr;
402 }
403 }
404 if (curr == 0) {
405 return G1_NO_HRM_INDEX;
406 }
407 curr--;
408 }
409 }
410
411 bool HeapRegionManager::allocate_containing_regions(MemRegion range, size_t* commit_count, WorkGang* pretouch_workers) {
412 size_t commits = 0;
413 uint start_index = (uint)_regions.get_index_by_address(range.start());
414 uint last_index = (uint)_regions.get_index_by_address(range.last());
415
416 // Ensure that each G1 region in the range is free, returning false if not.
417 // Commit those that are not yet available, and keep count.
418 for (uint curr_index = start_index; curr_index <= last_index; curr_index++) {
419 if (!is_available(curr_index)) {
420 commits++;
421 expand_at(curr_index, 1, pretouch_workers);
422 }
423 HeapRegion* curr_region = _regions.get_by_index(curr_index);
424 if (!curr_region->is_free()) {
425 return false;
426 }
427 }
428
429 allocate_free_regions_starting_at(start_index, (last_index - start_index) + 1);
430 *commit_count = commits;
431 return true;
432 }
433
434 void HeapRegionManager::par_iterate(HeapRegionClosure* blk, HeapRegionClaimer* hrclaimer, const uint start_index) const {
435 // Every worker will actually look at all regions, skipping over regions that
436 // are currently not committed.
437 // This also (potentially) iterates over regions newly allocated during GC. This
438 // is no problem except for some extra work.
439 const uint n_regions = hrclaimer->n_regions();
440 for (uint count = 0; count < n_regions; count++) {
441 const uint index = (start_index + count) % n_regions;
442 assert(index < n_regions, "sanity");
443 // Skip over unavailable regions
444 if (!is_available(index)) {
445 continue;
446 }
447 HeapRegion* r = _regions.get_by_index(index);
448 // We'll ignore regions already claimed.
449 // However, if the iteration is specified as concurrent, the values for
450 // is_starts_humongous and is_continues_humongous can not be trusted,
451 // and we should just blindly iterate over regions regardless of their
452 // humongous status.
453 if (hrclaimer->is_region_claimed(index)) {
454 continue;
455 }
456 // OK, try to claim it
457 if (!hrclaimer->claim_region(index)) {
458 continue;
459 }
460 bool res = blk->do_heap_region(r);
461 if (res) {
462 return;
463 }
464 }
465 }
466
467 uint HeapRegionManager::shrink_by(uint num_regions_to_remove) {
468 assert(length() > 0, "the region sequence should not be empty");
469 assert(length() <= _allocated_heapregions_length, "invariant");
470 assert(_allocated_heapregions_length > 0, "we should have at least one region committed");
471 assert(num_regions_to_remove < length(), "We should never remove all regions");
472
473 if (num_regions_to_remove == 0) {
474 return 0;
475 }
476
477 uint removed = 0;
478 uint cur = _allocated_heapregions_length - 1;
479 uint idx_last_found = 0;
480 uint num_last_found = 0;
481
482 while ((removed < num_regions_to_remove) &&
483 (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {
484 uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);
485
486 shrink_at(idx_last_found + num_last_found - to_remove, to_remove);
487
488 cur = idx_last_found;
489 removed += to_remove;
490 }
491
492 verify_optional();
493
494 return removed;
495 }
496
497 void HeapRegionManager::shrink_at(uint index, size_t num_regions) {
498 #ifdef ASSERT
499 for (uint i = index; i < (index + num_regions); i++) {
500 assert(is_available(i), "Expected available region at index %u", i);
501 assert(at(i)->is_empty(), "Expected empty region at index %u", i);
502 assert(at(i)->is_free(), "Expected free region at index %u", i);
503 }
504 #endif
505 uncommit_regions(index, num_regions);
506 }
507
508 uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const {
509 guarantee(start_idx < _allocated_heapregions_length, "checking");
510 guarantee(res_idx != NULL, "checking");
511
512 uint num_regions_found = 0;
513
514 jlong cur = start_idx;
515 while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) {
516 cur--;
517 }
518 if (cur == -1) {
519 return num_regions_found;
520 }
521 jlong old_cur = cur;
522 // cur indexes the first empty region
523 while (cur != -1 && is_available(cur) && at(cur)->is_empty()) {
524 cur--;
525 }
526 *res_idx = cur + 1;
527 num_regions_found = old_cur - cur;
528
529 #ifdef ASSERT
530 for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) {
531 assert(at(i)->is_empty(), "just checking");
532 }
533 #endif
534 return num_regions_found;
535 }
536
537 void HeapRegionManager::verify() {
538 guarantee(length() <= _allocated_heapregions_length,
539 "invariant: _length: %u _allocated_length: %u",
540 length(), _allocated_heapregions_length);
541 guarantee(_allocated_heapregions_length <= max_length(),
542 "invariant: _allocated_length: %u _max_length: %u",
543 _allocated_heapregions_length, max_length());
544
545 bool prev_committed = true;
546 uint num_committed = 0;
547 HeapWord* prev_end = heap_bottom();
548 for (uint i = 0; i < _allocated_heapregions_length; i++) {
549 if (!is_available(i)) {
550 prev_committed = false;
551 continue;
552 }
553 num_committed++;
554 HeapRegion* hr = _regions.get_by_index(i);
555 guarantee(hr != NULL, "invariant: i: %u", i);
556 guarantee(!prev_committed || hr->bottom() == prev_end,
557 "invariant i: %u " HR_FORMAT " prev_end: " PTR_FORMAT,
558 i, HR_FORMAT_PARAMS(hr), p2i(prev_end));
559 guarantee(hr->hrm_index() == i,
560 "invariant: i: %u hrm_index(): %u", i, hr->hrm_index());
561 // Asserts will fire if i is >= _length
562 HeapWord* addr = hr->bottom();
563 guarantee(addr_to_region(addr) == hr, "sanity");
564 // We cannot check whether the region is part of a particular set: at the time
565 // this method may be called, we have only completed allocation of the regions,
566 // but not put into a region set.
567 prev_committed = true;
568 prev_end = hr->end();
569 }
570 for (uint i = _allocated_heapregions_length; i < max_length(); i++) {
571 guarantee(_regions.get_by_index(i) == NULL, "invariant i: %u", i);
572 }
573
574 guarantee(num_committed == _num_committed, "Found %u committed regions, but should be %u", num_committed, _num_committed);
575 _free_list.verify();
576 }
577
578 #ifndef PRODUCT
579 void HeapRegionManager::verify_optional() {
580 verify();
581 }
582 #endif // PRODUCT
583
584 HeapRegionClaimer::HeapRegionClaimer(uint n_workers) :
585 _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm->_allocated_heapregions_length), _claims(NULL) {
586 assert(n_workers > 0, "Need at least one worker.");
587 uint* new_claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC);
588 memset(new_claims, Unclaimed, sizeof(*_claims) * _n_regions);
589 _claims = new_claims;
590 }
591
592 HeapRegionClaimer::~HeapRegionClaimer() {
593 FREE_C_HEAP_ARRAY(uint, _claims);
594 }
595
596 uint HeapRegionClaimer::offset_for_worker(uint worker_id) const {
597 assert(worker_id < _n_workers, "Invalid worker_id.");
598 return _n_regions * worker_id / _n_workers;
599 }
600
601 bool HeapRegionClaimer::is_region_claimed(uint region_index) const {
602 assert(region_index < _n_regions, "Invalid index.");
603 return _claims[region_index] == Claimed;
604 }
605
606 bool HeapRegionClaimer::claim_region(uint region_index) {
607 assert(region_index < _n_regions, "Invalid index.");
608 uint old_val = Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed);
609 return old_val == Unclaimed;
610 }