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