1 /*
2 * Copyright (c) 2001, 2020, 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/g1NUMAStats.hpp"
30 #include "gc/g1/heapRegion.hpp"
31 #include "gc/g1/heapRegionManager.inline.hpp"
32 #include "gc/g1/heapRegionSet.inline.hpp"
33 #include "gc/g1/heterogeneousHeapRegionManager.hpp"
34 #include "jfr/jfrEvents.hpp"
35 #include "logging/logStream.hpp"
36 #include "memory/allocation.hpp"
37 #include "runtime/atomic.hpp"
38 #include "runtime/orderAccess.hpp"
39 #include "utilities/bitMap.inline.hpp"
40
41 class MasterFreeRegionListChecker : public HeapRegionSetChecker {
42 public:
43 void check_mt_safety() {
44 // Master Free List MT safety protocol:
45 // (a) If we're at a safepoint, operations on the master free list
46 // should be invoked by either the VM thread (which will serialize
47 // them) or by the GC workers while holding the
48 // FreeList_lock.
49 // (b) If we're not at a safepoint, operations on the master free
50 // list should be invoked while holding the Heap_lock.
51
52 if (SafepointSynchronize::is_at_safepoint()) {
53 guarantee(Thread::current()->is_VM_thread() ||
54 FreeList_lock->owned_by_self(), "master free list MT safety protocol at a safepoint");
55 } else {
56 guarantee(Heap_lock->owned_by_self(), "master free list MT safety protocol outside a safepoint");
57 }
58 }
59 bool is_correct_type(HeapRegion* hr) { return hr->is_free(); }
60 const char* get_description() { return "Free Regions"; }
61 };
62
63 HeapRegionRange::HeapRegionRange(uint start, uint end) : _start(start), _end(end) {
64 assert(start <= end, "Invariant");
65 }
66
67 HeapRegionManager::HeapRegionManager() :
68 _bot_mapper(NULL),
69 _cardtable_mapper(NULL),
70 _card_counts_mapper(NULL),
71 _available_map(mtGC),
72 _num_committed(0),
73 _allocated_heapregions_length(0),
74 _regions(), _heap_mapper(NULL),
75 _prev_bitmap_mapper(NULL),
76 _next_bitmap_mapper(NULL),
77 _free_list("Free list", new MasterFreeRegionListChecker())
78 { }
79
80 HeapRegionManager* HeapRegionManager::create_manager(G1CollectedHeap* heap) {
81 if (G1Arguments::is_heterogeneous_heap()) {
82 return new HeterogeneousHeapRegionManager((uint)(G1Arguments::heap_max_size_bytes() / HeapRegion::GrainBytes) /*heap size as num of regions*/);
83 }
84 return new HeapRegionManager();
85 }
86
87 void HeapRegionManager::initialize(G1RegionToSpaceMapper* heap_storage,
88 G1RegionToSpaceMapper* prev_bitmap,
89 G1RegionToSpaceMapper* next_bitmap,
90 G1RegionToSpaceMapper* bot,
91 G1RegionToSpaceMapper* cardtable,
92 G1RegionToSpaceMapper* card_counts) {
93 _allocated_heapregions_length = 0;
94
95 _heap_mapper = heap_storage;
96
97 _prev_bitmap_mapper = prev_bitmap;
98 _next_bitmap_mapper = next_bitmap;
99
100 _bot_mapper = bot;
101 _cardtable_mapper = cardtable;
102
103 _card_counts_mapper = card_counts;
104
105 MemRegion reserved = heap_storage->reserved();
106 _regions.initialize(reserved.start(), reserved.end(), HeapRegion::GrainBytes);
107
108 _available_map.initialize(_regions.length());
109 }
110
111 bool HeapRegionManager::is_available(uint region) const {
112 return _available_map.at(region);
113 }
114
115 HeapRegion* HeapRegionManager::allocate_free_region(HeapRegionType type, uint requested_node_index) {
116 HeapRegion* hr = NULL;
117 bool from_head = !type.is_young();
118 G1NUMA* numa = G1NUMA::numa();
119
120 if (requested_node_index != G1NUMA::AnyNodeIndex && numa->is_enabled()) {
121 // Try to allocate with requested node index.
122 hr = _free_list.remove_region_with_node_index(from_head, requested_node_index);
123 }
124
125 if (hr == NULL) {
126 // If there's a single active node or we did not get a region from our requested node,
127 // try without requested node index.
128 hr = _free_list.remove_region(from_head);
129 }
130
131 if (hr != NULL) {
132 assert(hr->next() == NULL, "Single region should not have next");
133 assert(is_available(hr->hrm_index()), "Must be committed");
134
135 if (numa->is_enabled() && hr->node_index() < numa->num_active_nodes()) {
136 numa->update_statistics(G1NUMAStats::NewRegionAlloc, requested_node_index, hr->node_index());
137 }
138 }
139
140 return hr;
141 }
142
143 HeapRegion* HeapRegionManager::allocate_humongous_from_free_list(uint num_regions) {
144 uint candidate = find_contiguous_in_free_list(num_regions);
145 if (candidate == G1_NO_HRM_INDEX) {
146 return NULL;
147 }
148 return allocate_free_regions_starting_at(candidate, num_regions);
149 }
150
151 HeapRegion* HeapRegionManager::allocate_humongous_allow_expand(uint num_regions) {
152 uint candidate = find_contiguous_allow_expand(num_regions);
153 if (candidate == G1_NO_HRM_INDEX) {
154 return NULL;
155 }
156 expand_exact(candidate, num_regions, G1CollectedHeap::heap()->workers());
157 return allocate_free_regions_starting_at(candidate, num_regions);
158 }
159
160 HeapRegion* HeapRegionManager::allocate_humongous(uint num_regions) {
161 // Special case a single region to avoid expensive search.
162 if (num_regions == 1) {
163 return allocate_free_region(HeapRegionType::Humongous, G1NUMA::AnyNodeIndex);
164 }
165 return allocate_humongous_from_free_list(num_regions);
166 }
167
168 HeapRegion* HeapRegionManager::expand_and_allocate_humongous(uint num_regions) {
169 return allocate_humongous_allow_expand(num_regions);
170 }
171
172 #ifdef ASSERT
173 bool HeapRegionManager::is_free(HeapRegion* hr) const {
174 return _free_list.contains(hr);
175 }
176 #endif
177
178 HeapRegion* HeapRegionManager::new_heap_region(uint hrm_index) {
179 G1CollectedHeap* g1h = G1CollectedHeap::heap();
180 HeapWord* bottom = g1h->bottom_addr_for_region(hrm_index);
181 MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
182 assert(reserved().contains(mr), "invariant");
183 return g1h->new_heap_region(hrm_index, mr);
184 }
185
186 void HeapRegionManager::commit_regions(uint index, size_t num_regions, WorkGang* pretouch_gang) {
187 guarantee(num_regions > 0, "Must commit more than zero regions");
188 guarantee(_num_committed + num_regions <= max_length(), "Cannot commit more than the maximum amount of regions");
189
190 _num_committed += (uint)num_regions;
191
192 _heap_mapper->commit_regions(index, num_regions, pretouch_gang);
193
194 // Also commit auxiliary data
195 _prev_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang);
196 _next_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang);
197
198 _bot_mapper->commit_regions(index, num_regions, pretouch_gang);
199 _cardtable_mapper->commit_regions(index, num_regions, pretouch_gang);
200
201 _card_counts_mapper->commit_regions(index, num_regions, pretouch_gang);
202 }
203
204 void HeapRegionManager::uncommit_regions(uint start, size_t num_regions) {
205 guarantee(num_regions >= 1, "Need to specify at least one region to uncommit, tried to uncommit zero regions at %u", start);
206 guarantee(_num_committed >= num_regions, "pre-condition");
207
208 // Reset node index to distinguish with committed regions.
209 for (uint i = start; i < start + num_regions; i++) {
210 at(i)->set_node_index(G1NUMA::UnknownNodeIndex);
211 }
212
213 // Print before uncommitting.
214 if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
215 for (uint i = start; i < start + num_regions; i++) {
216 HeapRegion* hr = at(i);
217 G1CollectedHeap::heap()->hr_printer()->uncommit(hr);
218 }
219 }
220
221 _num_committed -= (uint)num_regions;
222
223 _available_map.par_clear_range(start, start + num_regions, BitMap::unknown_range);
224 _heap_mapper->uncommit_regions(start, num_regions);
225
226 // Also uncommit auxiliary data
227 _prev_bitmap_mapper->uncommit_regions(start, num_regions);
228 _next_bitmap_mapper->uncommit_regions(start, num_regions);
229
230 _bot_mapper->uncommit_regions(start, num_regions);
231 _cardtable_mapper->uncommit_regions(start, num_regions);
232
233 _card_counts_mapper->uncommit_regions(start, num_regions);
234 }
235
236 void HeapRegionManager::make_regions_available(uint start, uint num_regions, WorkGang* pretouch_gang) {
237 guarantee(num_regions > 0, "No point in calling this for zero regions");
238 commit_regions(start, num_regions, pretouch_gang);
239 for (uint i = start; i < start + num_regions; i++) {
240 if (_regions.get_by_index(i) == NULL) {
241 HeapRegion* new_hr = new_heap_region(i);
242 OrderAccess::storestore();
243 _regions.set_by_index(i, new_hr);
244 _allocated_heapregions_length = MAX2(_allocated_heapregions_length, i + 1);
245 }
246 }
247
248 _available_map.par_set_range(start, start + num_regions, BitMap::unknown_range);
249
250 for (uint i = start; i < start + num_regions; i++) {
251 assert(is_available(i), "Just made region %u available but is apparently not.", i);
252 HeapRegion* hr = at(i);
253 if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
254 G1CollectedHeap::heap()->hr_printer()->commit(hr);
255 }
256
257 hr->initialize();
258 hr->set_node_index(G1NUMA::numa()->index_for_region(hr));
259 insert_into_free_list(at(i));
260 }
261 }
262
263 MemoryUsage HeapRegionManager::get_auxiliary_data_memory_usage() const {
264 size_t used_sz =
265 _prev_bitmap_mapper->committed_size() +
266 _next_bitmap_mapper->committed_size() +
267 _bot_mapper->committed_size() +
268 _cardtable_mapper->committed_size() +
269 _card_counts_mapper->committed_size();
270
271 size_t committed_sz =
272 _prev_bitmap_mapper->reserved_size() +
273 _next_bitmap_mapper->reserved_size() +
274 _bot_mapper->reserved_size() +
275 _cardtable_mapper->reserved_size() +
276 _card_counts_mapper->reserved_size();
277
278 return MemoryUsage(0, used_sz, committed_sz, committed_sz);
279 }
280
281 uint HeapRegionManager::expand_by(uint num_regions, WorkGang* pretouch_workers) {
282 return expand_at(0, num_regions, pretouch_workers);
283 }
284
285 uint HeapRegionManager::expand_at(uint start, uint num_regions, WorkGang* pretouch_workers) {
286 if (num_regions == 0) {
287 return 0;
288 }
289
290 uint offset = start;
291 uint expanded = 0;
292
293 do {
294 HeapRegionRange regions = find_unavailable_from_idx(offset);
295 if (regions.length() == 0) {
296 // No more unavailable regions.
297 break;
298 }
299
300 uint to_expand = MIN2(num_regions - expanded, regions.length());
301 make_regions_available(regions.start(), to_expand, pretouch_workers);
302 expanded += to_expand;
303 offset = regions.end();
304 } while (expanded < num_regions);
305
306 verify_optional();
307 return expanded;
308 }
309
310 void HeapRegionManager::expand_exact(uint start, uint num_regions, WorkGang* pretouch_workers) {
311 assert(num_regions != 0, "Need to request at least one region");
312 uint end = start + num_regions;
313
314 for (uint i = start; i < end; i++) {
315 if (!is_available(i)) {
316 make_regions_available(i, 1, pretouch_workers);
317 }
318 }
319
320 verify_optional();
321 }
322
323 uint HeapRegionManager::expand_on_preferred_node(uint preferred_index) {
324 uint expand_candidate = UINT_MAX;
325 for (uint i = 0; i < max_length(); i++) {
326 if (is_available(i)) {
327 // Already in use continue
328 continue;
329 }
330 // Always save the candidate so we can expand later on.
331 expand_candidate = i;
332 if (is_on_preferred_index(expand_candidate, preferred_index)) {
333 // We have found a candidate on the preffered node, break.
334 break;
335 }
336 }
337
338 if (expand_candidate == UINT_MAX) {
339 // No regions left, expand failed.
340 return 0;
341 }
342
343 expand_exact(expand_candidate, 1, NULL);
344 return 1;
345 }
346
347 bool HeapRegionManager::is_on_preferred_index(uint region_index, uint preferred_node_index) {
348 uint region_node_index = G1NUMA::numa()->preferred_node_index_for_index(region_index);
349 return region_node_index == preferred_node_index;
350 }
351
352 #ifdef ASSERT
353 void HeapRegionManager::assert_contiguous_range(uint start, uint num_regions) {
354 // General sanity check, regions found should either be available and empty
355 // or not available so that we can make them available and use them.
356 for (uint i = start; i < (start + num_regions); i++) {
357 HeapRegion* hr = _regions.get_by_index(i);
358 assert(!is_available(i) || hr->is_free(),
359 "Found region sequence starting at " UINT32_FORMAT ", length " UINT32_FORMAT
360 " that is not free at " UINT32_FORMAT ". Hr is " PTR_FORMAT ", type is %s",
361 start, num_regions, i, p2i(hr), hr->get_type_str());
362 }
363 }
364 #endif
365
366 uint HeapRegionManager::find_contiguous_in_range(uint start, uint end, uint num_regions) {
367 assert(start <= end, "precondition");
368 assert(num_regions >= 1, "precondition");
369 uint candidate = start; // First region in candidate sequence.
370 uint unchecked = candidate; // First unchecked region in candidate.
371 // While the candidate sequence fits in the range...
372 while (num_regions <= (end - candidate)) {
373 // Walk backward over the regions for the current candidate.
374 for (uint i = candidate + num_regions - 1; true; --i) {
375 if (is_available(i) && !at(i)->is_free()) {
376 // Region i can't be used, so restart with i+1 as the start
377 // of a new candidate sequence, and with the region after the
378 // old candidate sequence being the first unchecked region.
379 unchecked = candidate + num_regions;
380 candidate = i + 1;
381 break;
382 } else if (i == unchecked) {
383 // All regions of candidate sequence have passed check.
384 assert_contiguous_range(candidate, num_regions);
385 return candidate;
386 }
387 }
388 }
389 return G1_NO_HRM_INDEX;
390 }
391
392 uint HeapRegionManager::find_contiguous_in_free_list(uint num_regions) {
393 BitMap::idx_t range_start = 0;
394 BitMap::idx_t range_end = range_start;
395 uint candidate = G1_NO_HRM_INDEX;
396
397 do {
398 range_start = _available_map.get_next_one_offset(range_end);
399 range_end = _available_map.get_next_zero_offset(range_start);
400 candidate = find_contiguous_in_range((uint) range_start, (uint) range_end, num_regions);
401 } while (candidate == G1_NO_HRM_INDEX && range_end < max_length());
402
403 return candidate;
404 }
405
406 uint HeapRegionManager::find_contiguous_allow_expand(uint num_regions) {
407 // Find any candidate.
408 return find_contiguous_in_range(0, max_length(), num_regions);
409 }
410
411 HeapRegion* HeapRegionManager::next_region_in_heap(const HeapRegion* r) const {
412 guarantee(r != NULL, "Start region must be a valid region");
413 guarantee(is_available(r->hrm_index()), "Trying to iterate starting from region %u which is not in the heap", r->hrm_index());
414 for (uint i = r->hrm_index() + 1; i < _allocated_heapregions_length; i++) {
415 HeapRegion* hr = _regions.get_by_index(i);
416 if (is_available(i)) {
417 return hr;
418 }
419 }
420 return NULL;
421 }
422
423 void HeapRegionManager::iterate(HeapRegionClosure* blk) const {
424 uint len = max_length();
425
426 for (uint i = 0; i < len; i++) {
427 if (!is_available(i)) {
428 continue;
429 }
430 guarantee(at(i) != NULL, "Tried to access region %u that has a NULL HeapRegion*", i);
431 bool res = blk->do_heap_region(at(i));
432 if (res) {
433 blk->set_incomplete();
434 return;
435 }
436 }
437 }
438
439 HeapRegionRange HeapRegionManager::find_unavailable_from_idx(uint index) const {
440 guarantee(index <= max_length(), "checking");
441
442 // Find first unavailable region from offset.
443 BitMap::idx_t start = _available_map.get_next_zero_offset(index);
444 if (start == _available_map.size()) {
445 // No unavailable regions found.
446 return HeapRegionRange(max_length(), max_length());
447 }
448
449 // The end of the range is the next available region.
450 BitMap::idx_t end = _available_map.get_next_one_offset(start);
451
452 assert(!_available_map.at(start), "Found region (" SIZE_FORMAT ") is not unavailable", start);
453 assert(!_available_map.at(end - 1), "Last region (" SIZE_FORMAT ") in range is not unavailable", end - 1);
454 assert(end == _available_map.size() || _available_map.at(end), "Region (" SIZE_FORMAT ") is not available", end);
455
456 return HeapRegionRange((uint) start, (uint) end);
457 }
458
459 uint HeapRegionManager::find_highest_free(bool* expanded) {
460 // Loop downwards from the highest region index, looking for an
461 // entry which is either free or not yet committed. If not yet
462 // committed, expand_at that index.
463 uint curr = max_length() - 1;
464 while (true) {
465 HeapRegion *hr = _regions.get_by_index(curr);
466 if (hr == NULL || !is_available(curr)) {
467 uint res = expand_at(curr, 1, NULL);
468 if (res == 1) {
469 *expanded = true;
470 return curr;
471 }
472 } else {
473 if (hr->is_free()) {
474 *expanded = false;
475 return curr;
476 }
477 }
478 if (curr == 0) {
479 return G1_NO_HRM_INDEX;
480 }
481 curr--;
482 }
483 }
484
485 bool HeapRegionManager::allocate_containing_regions(MemRegion range, size_t* commit_count, WorkGang* pretouch_workers) {
486 size_t commits = 0;
487 uint start_index = (uint)_regions.get_index_by_address(range.start());
488 uint last_index = (uint)_regions.get_index_by_address(range.last());
489
490 // Ensure that each G1 region in the range is free, returning false if not.
491 // Commit those that are not yet available, and keep count.
492 for (uint curr_index = start_index; curr_index <= last_index; curr_index++) {
493 if (!is_available(curr_index)) {
494 commits++;
495 expand_at(curr_index, 1, pretouch_workers);
496 }
497 HeapRegion* curr_region = _regions.get_by_index(curr_index);
498 if (!curr_region->is_free()) {
499 return false;
500 }
501 }
502
503 allocate_free_regions_starting_at(start_index, (last_index - start_index) + 1);
504 *commit_count = commits;
505 return true;
506 }
507
508 void HeapRegionManager::par_iterate(HeapRegionClosure* blk, HeapRegionClaimer* hrclaimer, const uint start_index) const {
509 // Every worker will actually look at all regions, skipping over regions that
510 // are currently not committed.
511 // This also (potentially) iterates over regions newly allocated during GC. This
512 // is no problem except for some extra work.
513 const uint n_regions = hrclaimer->n_regions();
514 for (uint count = 0; count < n_regions; count++) {
515 const uint index = (start_index + count) % n_regions;
516 assert(index < n_regions, "sanity");
517 // Skip over unavailable regions
518 if (!is_available(index)) {
519 continue;
520 }
521 HeapRegion* r = _regions.get_by_index(index);
522 // We'll ignore regions already claimed.
523 // However, if the iteration is specified as concurrent, the values for
524 // is_starts_humongous and is_continues_humongous can not be trusted,
525 // and we should just blindly iterate over regions regardless of their
526 // humongous status.
527 if (hrclaimer->is_region_claimed(index)) {
528 continue;
529 }
530 // OK, try to claim it
531 if (!hrclaimer->claim_region(index)) {
532 continue;
533 }
534 bool res = blk->do_heap_region(r);
535 if (res) {
536 return;
537 }
538 }
539 }
540
541 uint HeapRegionManager::shrink_by(uint num_regions_to_remove) {
542 assert(length() > 0, "the region sequence should not be empty");
543 assert(length() <= _allocated_heapregions_length, "invariant");
544 assert(_allocated_heapregions_length > 0, "we should have at least one region committed");
545 assert(num_regions_to_remove < length(), "We should never remove all regions");
546
547 if (num_regions_to_remove == 0) {
548 return 0;
549 }
550
551 uint removed = 0;
552 uint cur = _allocated_heapregions_length - 1;
553 uint idx_last_found = 0;
554 uint num_last_found = 0;
555
556 while ((removed < num_regions_to_remove) &&
557 (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {
558 uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);
559
560 shrink_at(idx_last_found + num_last_found - to_remove, to_remove);
561
562 cur = idx_last_found;
563 removed += to_remove;
564 }
565
566 verify_optional();
567
568 return removed;
569 }
570
571 void HeapRegionManager::shrink_at(uint index, size_t num_regions) {
572 #ifdef ASSERT
573 for (uint i = index; i < (index + num_regions); i++) {
574 assert(is_available(i), "Expected available region at index %u", i);
575 assert(at(i)->is_empty(), "Expected empty region at index %u", i);
576 assert(at(i)->is_free(), "Expected free region at index %u", i);
577 }
578 #endif
579 uncommit_regions(index, num_regions);
580 }
581
582 uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const {
583 guarantee(start_idx < _allocated_heapregions_length, "checking");
584 guarantee(res_idx != NULL, "checking");
585
586 uint num_regions_found = 0;
587
588 jlong cur = start_idx;
589 while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) {
590 cur--;
591 }
592 if (cur == -1) {
593 return num_regions_found;
594 }
595 jlong old_cur = cur;
596 // cur indexes the first empty region
597 while (cur != -1 && is_available(cur) && at(cur)->is_empty()) {
598 cur--;
599 }
600 *res_idx = cur + 1;
601 num_regions_found = old_cur - cur;
602
603 #ifdef ASSERT
604 for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) {
605 assert(at(i)->is_empty(), "just checking");
606 }
607 #endif
608 return num_regions_found;
609 }
610
611 void HeapRegionManager::verify() {
612 guarantee(length() <= _allocated_heapregions_length,
613 "invariant: _length: %u _allocated_length: %u",
614 length(), _allocated_heapregions_length);
615 guarantee(_allocated_heapregions_length <= max_length(),
616 "invariant: _allocated_length: %u _max_length: %u",
617 _allocated_heapregions_length, max_length());
618
619 bool prev_committed = true;
620 uint num_committed = 0;
621 HeapWord* prev_end = heap_bottom();
622 for (uint i = 0; i < _allocated_heapregions_length; i++) {
623 if (!is_available(i)) {
624 prev_committed = false;
625 continue;
626 }
627 num_committed++;
628 HeapRegion* hr = _regions.get_by_index(i);
629 guarantee(hr != NULL, "invariant: i: %u", i);
630 guarantee(!prev_committed || hr->bottom() == prev_end,
631 "invariant i: %u " HR_FORMAT " prev_end: " PTR_FORMAT,
632 i, HR_FORMAT_PARAMS(hr), p2i(prev_end));
633 guarantee(hr->hrm_index() == i,
634 "invariant: i: %u hrm_index(): %u", i, hr->hrm_index());
635 // Asserts will fire if i is >= _length
636 HeapWord* addr = hr->bottom();
637 guarantee(addr_to_region(addr) == hr, "sanity");
638 // We cannot check whether the region is part of a particular set: at the time
639 // this method may be called, we have only completed allocation of the regions,
640 // but not put into a region set.
641 prev_committed = true;
642 prev_end = hr->end();
643 }
644 for (uint i = _allocated_heapregions_length; i < max_length(); i++) {
645 guarantee(_regions.get_by_index(i) == NULL, "invariant i: %u", i);
646 }
647
648 guarantee(num_committed == _num_committed, "Found %u committed regions, but should be %u", num_committed, _num_committed);
649 _free_list.verify();
650 }
651
652 #ifndef PRODUCT
653 void HeapRegionManager::verify_optional() {
654 verify();
655 }
656 #endif // PRODUCT
657
658 HeapRegionClaimer::HeapRegionClaimer(uint n_workers) :
659 _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm->_allocated_heapregions_length), _claims(NULL) {
660 assert(n_workers > 0, "Need at least one worker.");
661 uint* new_claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC);
662 memset(new_claims, Unclaimed, sizeof(*_claims) * _n_regions);
663 _claims = new_claims;
664 }
665
666 HeapRegionClaimer::~HeapRegionClaimer() {
667 FREE_C_HEAP_ARRAY(uint, _claims);
668 }
669
670 uint HeapRegionClaimer::offset_for_worker(uint worker_id) const {
671 assert(worker_id < _n_workers, "Invalid worker_id.");
672 return _n_regions * worker_id / _n_workers;
673 }
674
675 bool HeapRegionClaimer::is_region_claimed(uint region_index) const {
676 assert(region_index < _n_regions, "Invalid index.");
677 return _claims[region_index] == Claimed;
678 }
679
680 bool HeapRegionClaimer::claim_region(uint region_index) {
681 assert(region_index < _n_regions, "Invalid index.");
682 uint old_val = Atomic::cmpxchg(&_claims[region_index], Unclaimed, Claimed);
683 return old_val == Unclaimed;
684 }
685
686 class G1RebuildFreeListTask : public AbstractGangTask {
687 HeapRegionManager* _hrm;
688 FreeRegionList* _worker_freelists;
689 uint _worker_chunk_size;
690 uint _num_workers;
691
692 public:
693 G1RebuildFreeListTask(HeapRegionManager* hrm, uint num_workers) :
694 AbstractGangTask("G1 Rebuild Free List Task"),
695 _hrm(hrm),
696 _worker_freelists(NEW_C_HEAP_ARRAY(FreeRegionList, num_workers, mtGC)),
697 _worker_chunk_size((_hrm->max_length() + num_workers - 1) / num_workers),
698 _num_workers(num_workers) {
699 for (uint worker = 0; worker < _num_workers; worker++) {
700 ::new (&_worker_freelists[worker]) FreeRegionList("Appendable Worker Free List");
701 }
702 }
703
704 ~G1RebuildFreeListTask() {
705 for (uint worker = 0; worker < _num_workers; worker++) {
706 _worker_freelists[worker].~FreeRegionList();
707 }
708 FREE_C_HEAP_ARRAY(FreeRegionList, _worker_freelists);
709 }
710
711 FreeRegionList* worker_freelist(uint worker) {
712 return &_worker_freelists[worker];
713 }
714
715 // Each worker creates a free list for a chunk of the heap. The chunks won't
716 // be overlapping so we don't need to do any claiming.
717 void work(uint worker_id) {
718 Ticks start_time = Ticks::now();
719 EventGCPhaseParallel event;
720
721 uint start = worker_id * _worker_chunk_size;
722 uint end = MIN2(start + _worker_chunk_size, _hrm->max_length());
723
724 // If start is outside the heap, this worker has nothing to do.
725 if (start > end) {
726 return;
727 }
728
729 FreeRegionList *free_list = worker_freelist(worker_id);
730 for (uint i = start; i < end; i++) {
731 HeapRegion *region = _hrm->at_or_null(i);
732 if (region != NULL && region->is_free()) {
733 // Need to clear old links to allow to be added to new freelist.
734 region->unlink_from_list();
735 free_list->add_to_tail(region);
736 }
737 }
738
739 event.commit(GCId::current(), worker_id, G1GCPhaseTimes::phase_name(G1GCPhaseTimes::RebuildFreeList));
740 G1CollectedHeap::heap()->phase_times()->record_time_secs(G1GCPhaseTimes::RebuildFreeList, worker_id, (Ticks::now() - start_time).seconds());
741 }
742 };
743
744 void HeapRegionManager::rebuild_free_list(WorkGang* workers) {
745 // Abandon current free list to allow a rebuild.
746 _free_list.abandon();
747
748 uint const num_workers = clamp(max_length(), 1u, workers->active_workers());
749 G1RebuildFreeListTask task(this, num_workers);
750
751 log_debug(gc, ergo)("Running %s using %u workers for rebuilding free list of regions",
752 task.name(), num_workers);
753 workers->run_task(&task, num_workers);
754
755 // Link the partial free lists together.
756 Ticks serial_time = Ticks::now();
757 for (uint worker = 0; worker < num_workers; worker++) {
758 _free_list.append_ordered(task.worker_freelist(worker));
759 }
760 G1CollectedHeap::heap()->phase_times()->record_serial_rebuild_freelist_time_ms((Ticks::now() - serial_time).seconds() * 1000.0);
761 }