1 /*
2 * Copyright (c) 2001, 2016, 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/concurrentG1Refine.hpp"
27 #include "gc/g1/g1CollectedHeap.inline.hpp"
28 #include "gc/g1/heapRegion.hpp"
29 #include "gc/g1/heapRegionManager.inline.hpp"
30 #include "gc/g1/heapRegionSet.inline.hpp"
31 #include "memory/allocation.hpp"
32
33 void HeapRegionManager::initialize(G1RegionToSpaceMapper* heap_storage,
34 G1RegionToSpaceMapper* prev_bitmap,
35 G1RegionToSpaceMapper* next_bitmap,
36 G1RegionToSpaceMapper* bot,
37 G1RegionToSpaceMapper* cardtable,
38 G1RegionToSpaceMapper* card_counts) {
39 _allocated_heapregions_length = 0;
40
41 _heap_mapper = heap_storage;
42
43 _prev_bitmap_mapper = prev_bitmap;
44 _next_bitmap_mapper = next_bitmap;
45
46 _bot_mapper = bot;
47 _cardtable_mapper = cardtable;
48
49 _card_counts_mapper = card_counts;
50
51 MemRegion reserved = heap_storage->reserved();
52 _regions.initialize(reserved.start(), reserved.end(), HeapRegion::GrainBytes);
53
54 _available_map.initialize(_regions.length());
55 }
56
57 bool HeapRegionManager::is_available(uint region) const {
58 return _available_map.at(region);
59 }
60
61 #ifdef ASSERT
62 bool HeapRegionManager::is_free(HeapRegion* hr) const {
63 return _free_list.contains(hr);
64 }
65 #endif
66
67 HeapRegion* HeapRegionManager::new_heap_region(uint hrm_index) {
68 G1CollectedHeap* g1h = G1CollectedHeap::heap();
69 HeapWord* bottom = g1h->bottom_addr_for_region(hrm_index);
70 MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
71 assert(reserved().contains(mr), "invariant");
72 return g1h->new_heap_region(hrm_index, mr);
73 }
74
75 void HeapRegionManager::commit_regions(uint index, size_t num_regions, WorkGang* pretouch_gang) {
76 guarantee(num_regions > 0, "Must commit more than zero regions");
77 guarantee(_num_committed + num_regions <= max_length(), "Cannot commit more than the maximum amount of regions");
78
79 _num_committed += (uint)num_regions;
80
81 _heap_mapper->commit_regions(index, num_regions, pretouch_gang);
82
83 // Also commit auxiliary data
84 _prev_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang);
85 _next_bitmap_mapper->commit_regions(index, num_regions, pretouch_gang);
86
87 _bot_mapper->commit_regions(index, num_regions, pretouch_gang);
88 _cardtable_mapper->commit_regions(index, num_regions, pretouch_gang);
89
90 _card_counts_mapper->commit_regions(index, num_regions, pretouch_gang);
91 }
92
93 void HeapRegionManager::uncommit_regions(uint start, size_t num_regions) {
94 guarantee(num_regions >= 1, "Need to specify at least one region to uncommit, tried to uncommit zero regions at %u", start);
95 guarantee(_num_committed >= num_regions, "pre-condition");
96
97 // Print before uncommitting.
98 if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
99 for (uint i = start; i < start + num_regions; i++) {
100 HeapRegion* hr = at(i);
101 G1CollectedHeap::heap()->hr_printer()->uncommit(hr);
102 }
103 }
104
105 _num_committed -= (uint)num_regions;
106
107 _available_map.par_clear_range(start, start + num_regions, BitMap::unknown_range);
108 _heap_mapper->uncommit_regions(start, num_regions);
109
110 // Also uncommit auxiliary data
111 _prev_bitmap_mapper->uncommit_regions(start, num_regions);
112 _next_bitmap_mapper->uncommit_regions(start, num_regions);
113
114 _bot_mapper->uncommit_regions(start, num_regions);
115 _cardtable_mapper->uncommit_regions(start, num_regions);
116
117 _card_counts_mapper->uncommit_regions(start, num_regions);
118 }
119
120 void HeapRegionManager::make_regions_available(uint start, uint num_regions, WorkGang* pretouch_gang) {
121 guarantee(num_regions > 0, "No point in calling this for zero regions");
122 commit_regions(start, num_regions, pretouch_gang);
123 for (uint i = start; i < start + num_regions; i++) {
124 if (_regions.get_by_index(i) == NULL) {
125 HeapRegion* new_hr = new_heap_region(i);
126 OrderAccess::storestore();
127 _regions.set_by_index(i, new_hr);
128 _allocated_heapregions_length = MAX2(_allocated_heapregions_length, i + 1);
129 }
130 }
131
132 _available_map.par_set_range(start, start + num_regions, BitMap::unknown_range);
133
134 for (uint i = start; i < start + num_regions; i++) {
135 assert(is_available(i), "Just made region %u available but is apparently not.", i);
136 HeapRegion* hr = at(i);
137 if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
138 G1CollectedHeap::heap()->hr_printer()->commit(hr);
139 }
140 HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(i);
141 MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
142
143 hr->initialize(mr);
144 insert_into_free_list(at(i));
145 }
146 }
147
148 MemoryUsage HeapRegionManager::get_auxiliary_data_memory_usage() const {
149 size_t used_sz =
150 _prev_bitmap_mapper->committed_size() +
151 _next_bitmap_mapper->committed_size() +
152 _bot_mapper->committed_size() +
153 _cardtable_mapper->committed_size() +
154 _card_counts_mapper->committed_size();
155
156 size_t committed_sz =
157 _prev_bitmap_mapper->reserved_size() +
158 _next_bitmap_mapper->reserved_size() +
159 _bot_mapper->reserved_size() +
160 _cardtable_mapper->reserved_size() +
161 _card_counts_mapper->reserved_size();
162
163 return MemoryUsage(0, used_sz, committed_sz, committed_sz);
164 }
165
166 uint HeapRegionManager::expand_by(uint num_regions, WorkGang* pretouch_workers) {
167 return expand_at(0, num_regions, pretouch_workers);
168 }
169
170 uint HeapRegionManager::expand_at(uint start, uint num_regions, WorkGang* pretouch_workers) {
171 if (num_regions == 0) {
172 return 0;
173 }
174
175 uint cur = start;
176 uint idx_last_found = 0;
177 uint num_last_found = 0;
178
179 uint expanded = 0;
180
181 while (expanded < num_regions &&
182 (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) {
183 uint to_expand = MIN2(num_regions - expanded, num_last_found);
184 make_regions_available(idx_last_found, to_expand, pretouch_workers);
185 expanded += to_expand;
186 cur = idx_last_found + num_last_found + 1;
187 }
188
189 verify_optional();
190 return expanded;
191 }
192
193 uint HeapRegionManager::find_contiguous(size_t num, bool empty_only) {
194 uint found = 0;
195 size_t length_found = 0;
196 uint cur = 0;
197
198 while (length_found < num && cur < max_length()) {
199 HeapRegion* hr = _regions.get_by_index(cur);
200 if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) {
201 // This region is a potential candidate for allocation into.
202 length_found++;
203 } else {
204 // This region is not a candidate. The next region is the next possible one.
205 found = cur + 1;
206 length_found = 0;
207 }
208 cur++;
209 }
210
211 if (length_found == num) {
212 for (uint i = found; i < (found + num); i++) {
213 HeapRegion* hr = _regions.get_by_index(i);
214 // sanity check
215 guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()),
216 "Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT
217 " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr));
218 }
219 return found;
220 } else {
221 return G1_NO_HRM_INDEX;
222 }
223 }
224
225 HeapRegion* HeapRegionManager::next_region_in_heap(const HeapRegion* r) const {
226 guarantee(r != NULL, "Start region must be a valid region");
227 guarantee(is_available(r->hrm_index()), "Trying to iterate starting from region %u which is not in the heap", r->hrm_index());
228 for (uint i = r->hrm_index() + 1; i < _allocated_heapregions_length; i++) {
229 HeapRegion* hr = _regions.get_by_index(i);
230 if (is_available(i)) {
231 return hr;
232 }
233 }
234 return NULL;
235 }
236
237 void HeapRegionManager::iterate(HeapRegionClosure* blk) const {
238 uint len = max_length();
239
240 for (uint i = 0; i < len; i++) {
241 if (!is_available(i)) {
242 continue;
243 }
244 guarantee(at(i) != NULL, "Tried to access region %u that has a NULL HeapRegion*", i);
245 bool res = blk->doHeapRegion(at(i));
246 if (res) {
247 blk->incomplete();
248 return;
249 }
250 }
251 }
252
253 uint HeapRegionManager::find_unavailable_from_idx(uint start_idx, uint* res_idx) const {
254 guarantee(res_idx != NULL, "checking");
255 guarantee(start_idx <= (max_length() + 1), "checking");
256
257 uint num_regions = 0;
258
259 uint cur = start_idx;
260 while (cur < max_length() && is_available(cur)) {
261 cur++;
262 }
263 if (cur == max_length()) {
264 return num_regions;
265 }
266 *res_idx = cur;
267 while (cur < max_length() && !is_available(cur)) {
268 cur++;
269 }
270 num_regions = cur - *res_idx;
271 #ifdef ASSERT
272 for (uint i = *res_idx; i < (*res_idx + num_regions); i++) {
273 assert(!is_available(i), "just checking");
274 }
275 assert(cur == max_length() || num_regions == 0 || is_available(cur),
276 "The region at the current position %u must be available or at the end of the heap.", cur);
277 #endif
278 return num_regions;
279 }
280
281 uint HeapRegionManager::find_highest_free(bool* expanded) {
282 // Loop downwards from the highest region index, looking for an
283 // entry which is either free or not yet committed. If not yet
284 // committed, expand_at that index.
285 uint curr = max_length() - 1;
286 while (true) {
287 HeapRegion *hr = _regions.get_by_index(curr);
288 if (hr == NULL) {
289 uint res = expand_at(curr, 1);
290 if (res == 1) {
291 *expanded = true;
292 return curr;
293 }
294 } else {
295 if (hr->is_free()) {
296 *expanded = false;
297 return curr;
298 }
299 }
300 if (curr == 0) {
301 return G1_NO_HRM_INDEX;
302 }
303 curr--;
304 }
305 }
306
307 bool HeapRegionManager::allocate_containing_regions(MemRegion range, size_t* commit_count) {
308 size_t commits = 0;
309 uint start_index = (uint)_regions.get_index_by_address(range.start());
310 uint last_index = (uint)_regions.get_index_by_address(range.last());
311
312 // Ensure that each G1 region in the range is free, returning false if not.
313 // Commit those that are not yet available, and keep count.
314 for (uint curr_index = start_index; curr_index <= last_index; curr_index++) {
315 if (!is_available(curr_index)) {
316 commits++;
317 expand_at(curr_index, 1);
318 }
319 HeapRegion* curr_region = _regions.get_by_index(curr_index);
320 if (!curr_region->is_free()) {
321 return false;
322 }
323 }
324
325 allocate_free_regions_starting_at(start_index, (last_index - start_index) + 1);
326 *commit_count = commits;
327 return true;
328 }
329
330 void HeapRegionManager::par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer, bool concurrent) const {
331 const uint start_index = hrclaimer->start_region_for_worker(worker_id);
332
333 // Every worker will actually look at all regions, skipping over regions that
334 // are currently not committed.
335 // This also (potentially) iterates over regions newly allocated during GC. This
336 // is no problem except for some extra work.
337 const uint n_regions = hrclaimer->n_regions();
338 for (uint count = 0; count < n_regions; count++) {
339 const uint index = (start_index + count) % n_regions;
340 assert(index < n_regions, "sanity");
341 // Skip over unavailable regions
342 if (!is_available(index)) {
343 continue;
344 }
345 HeapRegion* r = _regions.get_by_index(index);
346 // We'll ignore regions already claimed.
347 // However, if the iteration is specified as concurrent, the values for
348 // is_starts_humongous and is_continues_humongous can not be trusted,
349 // and we should just blindly iterate over regions regardless of their
350 // humongous status.
351 if (hrclaimer->is_region_claimed(index)) {
352 continue;
353 }
354 // OK, try to claim it
355 if (!hrclaimer->claim_region(index)) {
356 continue;
357 }
358 bool res = blk->doHeapRegion(r);
359 if (res) {
360 return;
361 }
362 }
363 }
364
365 uint HeapRegionManager::shrink_by(uint num_regions_to_remove) {
366 assert(length() > 0, "the region sequence should not be empty");
367 assert(length() <= _allocated_heapregions_length, "invariant");
368 assert(_allocated_heapregions_length > 0, "we should have at least one region committed");
369 assert(num_regions_to_remove < length(), "We should never remove all regions");
370
371 if (num_regions_to_remove == 0) {
372 return 0;
373 }
374
375 uint removed = 0;
376 uint cur = _allocated_heapregions_length - 1;
377 uint idx_last_found = 0;
378 uint num_last_found = 0;
379
380 while ((removed < num_regions_to_remove) &&
381 (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {
382 uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);
383
384 shrink_at(idx_last_found + num_last_found - to_remove, to_remove);
385
386 cur = idx_last_found;
387 removed += to_remove;
388 }
389
390 verify_optional();
391
392 return removed;
393 }
394
395 void HeapRegionManager::shrink_at(uint index, size_t num_regions) {
396 #ifdef ASSERT
397 for (uint i = index; i < (index + num_regions); i++) {
398 assert(is_available(i), "Expected available region at index %u", i);
399 assert(at(i)->is_empty(), "Expected empty region at index %u", i);
400 assert(at(i)->is_free(), "Expected free region at index %u", i);
401 }
402 #endif
403 uncommit_regions(index, num_regions);
404 }
405
406 uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const {
407 guarantee(start_idx < _allocated_heapregions_length, "checking");
408 guarantee(res_idx != NULL, "checking");
409
410 uint num_regions_found = 0;
411
412 jlong cur = start_idx;
413 while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) {
414 cur--;
415 }
416 if (cur == -1) {
417 return num_regions_found;
418 }
419 jlong old_cur = cur;
420 // cur indexes the first empty region
421 while (cur != -1 && is_available(cur) && at(cur)->is_empty()) {
422 cur--;
423 }
424 *res_idx = cur + 1;
425 num_regions_found = old_cur - cur;
426
427 #ifdef ASSERT
428 for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) {
429 assert(at(i)->is_empty(), "just checking");
430 }
431 #endif
432 return num_regions_found;
433 }
434
435 void HeapRegionManager::verify() {
436 guarantee(length() <= _allocated_heapregions_length,
437 "invariant: _length: %u _allocated_length: %u",
438 length(), _allocated_heapregions_length);
439 guarantee(_allocated_heapregions_length <= max_length(),
440 "invariant: _allocated_length: %u _max_length: %u",
441 _allocated_heapregions_length, max_length());
442
443 bool prev_committed = true;
444 uint num_committed = 0;
445 HeapWord* prev_end = heap_bottom();
446 for (uint i = 0; i < _allocated_heapregions_length; i++) {
447 if (!is_available(i)) {
448 prev_committed = false;
449 continue;
450 }
451 num_committed++;
452 HeapRegion* hr = _regions.get_by_index(i);
453 guarantee(hr != NULL, "invariant: i: %u", i);
454 guarantee(!prev_committed || hr->bottom() == prev_end,
455 "invariant i: %u " HR_FORMAT " prev_end: " PTR_FORMAT,
456 i, HR_FORMAT_PARAMS(hr), p2i(prev_end));
457 guarantee(hr->hrm_index() == i,
458 "invariant: i: %u hrm_index(): %u", i, hr->hrm_index());
459 // Asserts will fire if i is >= _length
460 HeapWord* addr = hr->bottom();
461 guarantee(addr_to_region(addr) == hr, "sanity");
462 // We cannot check whether the region is part of a particular set: at the time
463 // this method may be called, we have only completed allocation of the regions,
464 // but not put into a region set.
465 prev_committed = true;
466 prev_end = hr->end();
467 }
468 for (uint i = _allocated_heapregions_length; i < max_length(); i++) {
469 guarantee(_regions.get_by_index(i) == NULL, "invariant i: %u", i);
470 }
471
472 guarantee(num_committed == _num_committed, "Found %u committed regions, but should be %u", num_committed, _num_committed);
473 _free_list.verify();
474 }
475
476 #ifndef PRODUCT
477 void HeapRegionManager::verify_optional() {
478 verify();
479 }
480 #endif // PRODUCT
481
482 HeapRegionClaimer::HeapRegionClaimer(uint n_workers) :
483 _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm._allocated_heapregions_length), _claims(NULL) {
484 assert(n_workers > 0, "Need at least one worker.");
485 uint* new_claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC);
486 memset(new_claims, Unclaimed, sizeof(*_claims) * _n_regions);
487 _claims = new_claims;
488 }
489
490 HeapRegionClaimer::~HeapRegionClaimer() {
491 if (_claims != NULL) {
492 FREE_C_HEAP_ARRAY(uint, _claims);
493 }
494 }
495
496 uint HeapRegionClaimer::start_region_for_worker(uint worker_id) const {
497 assert(worker_id < _n_workers, "Invalid worker_id.");
498 return _n_regions * worker_id / _n_workers;
499 }
500
501 bool HeapRegionClaimer::is_region_claimed(uint region_index) const {
502 assert(region_index < _n_regions, "Invalid index.");
503 return _claims[region_index] == Claimed;
504 }
505
506 bool HeapRegionClaimer::claim_region(uint region_index) {
507 assert(region_index < _n_regions, "Invalid index.");
508 uint old_val = Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed);
509 return old_val == Unclaimed;
510 }