1 /*
2 * Copyright (c) 2001, 2015, 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_implementation/g1/heapRegion.hpp"
27 #include "gc_implementation/g1/heapRegionManager.inline.hpp"
28 #include "gc_implementation/g1/heapRegionSet.inline.hpp"
29 #include "gc_implementation/g1/g1CollectedHeap.inline.hpp"
30 #include "gc_implementation/g1/concurrentG1Refine.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.resize(_regions.length(), false);
55 _available_map.clear();
56 }
57
58 bool HeapRegionManager::is_available(uint region) const {
59 return _available_map.at(region);
60 }
61
62 #ifdef ASSERT
63 bool HeapRegionManager::is_free(HeapRegion* hr) const {
64 return _free_list.contains(hr);
65 }
66 #endif
67
68 HeapRegion* HeapRegionManager::new_heap_region(uint hrm_index) {
69 G1CollectedHeap* g1h = G1CollectedHeap::heap();
70 HeapWord* bottom = g1h->bottom_addr_for_region(hrm_index);
71 MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
72 assert(reserved().contains(mr), "invariant");
73 return g1h->allocator()->new_heap_region(hrm_index, g1h->bot_shared(), mr);
74 }
75
76 void HeapRegionManager::commit_regions(uint index, size_t num_regions) {
77 guarantee(num_regions > 0, "Must commit more than zero regions");
78 guarantee(_num_committed + num_regions <= max_length(), "Cannot commit more than the maximum amount of regions");
79
80 _num_committed += (uint)num_regions;
81
82 _heap_mapper->commit_regions(index, num_regions);
83
84 // Also commit auxiliary data
85 _prev_bitmap_mapper->commit_regions(index, num_regions);
86 _next_bitmap_mapper->commit_regions(index, num_regions);
87
88 _bot_mapper->commit_regions(index, num_regions);
89 _cardtable_mapper->commit_regions(index, num_regions);
90
91 _card_counts_mapper->commit_regions(index, num_regions);
92 }
93
94 void HeapRegionManager::uncommit_regions(uint start, size_t num_regions) {
95 guarantee(num_regions >= 1, err_msg("Need to specify at least one region to uncommit, tried to uncommit zero regions at %u", start));
96 guarantee(_num_committed >= num_regions, "pre-condition");
97
98 // Print before uncommitting.
99 if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
100 for (uint i = start; i < start + num_regions; i++) {
101 HeapRegion* hr = at(i);
102 G1CollectedHeap::heap()->hr_printer()->uncommit(hr->bottom(), hr->end());
103 }
104 }
105
106 _num_committed -= (uint)num_regions;
107
108 _available_map.par_clear_range(start, start + num_regions, BitMap::unknown_range);
109 _heap_mapper->uncommit_regions(start, num_regions);
110
111 // Also uncommit auxiliary data
112 _prev_bitmap_mapper->uncommit_regions(start, num_regions);
113 _next_bitmap_mapper->uncommit_regions(start, num_regions);
114
115 _bot_mapper->uncommit_regions(start, num_regions);
116 _cardtable_mapper->uncommit_regions(start, num_regions);
117
118 _card_counts_mapper->uncommit_regions(start, num_regions);
119 }
120
121 void HeapRegionManager::make_regions_available(uint start, uint num_regions) {
122 guarantee(num_regions > 0, "No point in calling this for zero regions");
123 commit_regions(start, num_regions);
124 for (uint i = start; i < start + num_regions; i++) {
125 if (_regions.get_by_index(i) == NULL) {
126 HeapRegion* new_hr = new_heap_region(i);
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), err_msg("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->bottom(), hr->end());
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 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 return MemoryUsage(0, used_sz, committed_sz, committed_sz);
163 }
164
165 uint HeapRegionManager::expand_by(uint num_regions) {
166 return expand_at(0, num_regions);
167 }
168
169 uint HeapRegionManager::expand_at(uint start, uint num_regions) {
170 if (num_regions == 0) {
171 return 0;
172 }
173
174 uint cur = start;
175 uint idx_last_found = 0;
176 uint num_last_found = 0;
177
178 uint expanded = 0;
179
180 while (expanded < num_regions &&
181 (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) {
182 uint to_expand = MIN2(num_regions - expanded, num_last_found);
183 make_regions_available(idx_last_found, to_expand);
184 expanded += to_expand;
185 cur = idx_last_found + num_last_found + 1;
186 }
187
188 verify_optional();
189 return expanded;
190 }
191
192 uint HeapRegionManager::find_contiguous(size_t num, bool empty_only) {
193 uint found = 0;
194 size_t length_found = 0;
195 uint cur = 0;
196
197 while (length_found < num && cur < max_length()) {
198 HeapRegion* hr = _regions.get_by_index(cur);
199 if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) {
200 // This region is a potential candidate for allocation into.
201 length_found++;
202 } else {
203 // This region is not a candidate. The next region is the next possible one.
204 found = cur + 1;
205 length_found = 0;
206 }
207 cur++;
208 }
209
210 if (length_found == num) {
211 for (uint i = found; i < (found + num); i++) {
212 HeapRegion* hr = _regions.get_by_index(i);
213 // sanity check
214 guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()),
215 err_msg("Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT
216 " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr)));
217 }
218 return found;
219 } else {
220 return G1_NO_HRM_INDEX;
221 }
222 }
223
224 HeapRegion* HeapRegionManager::next_region_in_heap(const HeapRegion* r) const {
225 guarantee(r != NULL, "Start region must be a valid region");
226 guarantee(is_available(r->hrm_index()), err_msg("Trying to iterate starting from region %u which is not in the heap", r->hrm_index()));
227 for (uint i = r->hrm_index() + 1; i < _allocated_heapregions_length; i++) {
228 HeapRegion* hr = _regions.get_by_index(i);
229 if (is_available(i)) {
230 return hr;
231 }
232 }
233 return NULL;
234 }
235
236 void HeapRegionManager::iterate(HeapRegionClosure* blk) const {
237 uint len = max_length();
238
239 for (uint i = 0; i < len; i++) {
240 if (!is_available(i)) {
241 continue;
242 }
243 guarantee(at(i) != NULL, err_msg("Tried to access region %u that has a NULL HeapRegion*", i));
244 bool res = blk->doHeapRegion(at(i));
245 if (res) {
246 blk->incomplete();
247 return;
248 }
249 }
250 }
251
252 uint HeapRegionManager::find_unavailable_from_idx(uint start_idx, uint* res_idx) const {
253 guarantee(res_idx != NULL, "checking");
254 guarantee(start_idx <= (max_length() + 1), "checking");
255
256 uint num_regions = 0;
257
258 uint cur = start_idx;
259 while (cur < max_length() && is_available(cur)) {
260 cur++;
261 }
262 if (cur == max_length()) {
263 return num_regions;
264 }
265 *res_idx = cur;
266 while (cur < max_length() && !is_available(cur)) {
267 cur++;
268 }
269 num_regions = cur - *res_idx;
270 #ifdef ASSERT
271 for (uint i = *res_idx; i < (*res_idx + num_regions); i++) {
272 assert(!is_available(i), "just checking");
273 }
274 assert(cur == max_length() || num_regions == 0 || is_available(cur),
275 err_msg("The region at the current position %u must be available or at the end of the heap.", cur));
276 #endif
277 return num_regions;
278 }
279
280 void HeapRegionManager::par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer, bool concurrent) const {
281 const uint start_index = hrclaimer->start_region_for_worker(worker_id);
282
283 // Every worker will actually look at all regions, skipping over regions that
284 // are currently not committed.
285 // This also (potentially) iterates over regions newly allocated during GC. This
286 // is no problem except for some extra work.
287 const uint n_regions = hrclaimer->n_regions();
288 for (uint count = 0; count < n_regions; count++) {
289 const uint index = (start_index + count) % n_regions;
290 assert(0 <= index && index < n_regions, "sanity");
291 // Skip over unavailable regions
292 if (!is_available(index)) {
293 continue;
294 }
295 HeapRegion* r = _regions.get_by_index(index);
296 // We'll ignore "continues humongous" regions (we'll process them
297 // when we come across their corresponding "start humongous"
298 // region) and regions already claimed.
299 // However, if the iteration is specified as concurrent, the values for
300 // is_starts_humongous and is_continues_humongous can not be trusted,
301 // and we should just blindly iterate over regions regardless of their
302 // humongous status.
303 if (hrclaimer->is_region_claimed(index) || (!concurrent && r->is_continues_humongous())) {
304 continue;
305 }
306 // OK, try to claim it
307 if (!hrclaimer->claim_region(index)) {
308 continue;
309 }
310 // Success!
311 // As mentioned above, special treatment of humongous regions can only be
312 // done if we are iterating non-concurrently.
313 if (!concurrent && r->is_starts_humongous()) {
314 // If the region is "starts humongous" we'll iterate over its
315 // "continues humongous" first; in fact we'll do them
316 // first. The order is important. In one case, calling the
317 // closure on the "starts humongous" region might de-allocate
318 // and clear all its "continues humongous" regions and, as a
319 // result, we might end up processing them twice. So, we'll do
320 // them first (note: most closures will ignore them anyway) and
321 // then we'll do the "starts humongous" region.
322 for (uint ch_index = index + 1; ch_index < index + r->region_num(); ch_index++) {
323 HeapRegion* chr = _regions.get_by_index(ch_index);
324
325 assert(chr->is_continues_humongous(), "Must be humongous region");
326 assert(chr->humongous_start_region() == r,
327 err_msg("Must work on humongous continuation of the original start region "
328 PTR_FORMAT ", but is " PTR_FORMAT, p2i(r), p2i(chr)));
329 assert(!hrclaimer->is_region_claimed(ch_index),
330 "Must not have been claimed yet because claiming of humongous continuation first claims the start region");
331
332 // There's no need to actually claim the continues humongous region, but we can do it in an assert as an extra precaution.
333 assert(hrclaimer->claim_region(ch_index), "We should always be able to claim the continuesHumongous part of the humongous object");
334
335 bool res2 = blk->doHeapRegion(chr);
336 if (res2) {
337 return;
338 }
339
340 // Right now, this holds (i.e., no closure that actually
341 // does something with "continues humongous" regions
342 // clears them). We might have to weaken it in the future,
343 // but let's leave these two asserts here for extra safety.
344 assert(chr->is_continues_humongous(), "should still be the case");
345 assert(chr->humongous_start_region() == r, "sanity");
346 }
347 }
348
349 bool res = blk->doHeapRegion(r);
350 if (res) {
351 return;
352 }
353 }
354 }
355
356 uint HeapRegionManager::shrink_by(uint num_regions_to_remove) {
357 assert(length() > 0, "the region sequence should not be empty");
358 assert(length() <= _allocated_heapregions_length, "invariant");
359 assert(_allocated_heapregions_length > 0, "we should have at least one region committed");
360 assert(num_regions_to_remove < length(), "We should never remove all regions");
361
362 if (num_regions_to_remove == 0) {
363 return 0;
364 }
365
366 uint removed = 0;
367 uint cur = _allocated_heapregions_length - 1;
368 uint idx_last_found = 0;
369 uint num_last_found = 0;
370
371 while ((removed < num_regions_to_remove) &&
372 (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {
373 uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);
374
375 uncommit_regions(idx_last_found + num_last_found - to_remove, to_remove);
376
377 cur -= num_last_found;
378 removed += to_remove;
379 }
380
381 verify_optional();
382
383 return removed;
384 }
385
386 uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const {
387 guarantee(start_idx < _allocated_heapregions_length, "checking");
388 guarantee(res_idx != NULL, "checking");
389
390 uint num_regions_found = 0;
391
392 jlong cur = start_idx;
393 while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) {
394 cur--;
395 }
396 if (cur == -1) {
397 return num_regions_found;
398 }
399 jlong old_cur = cur;
400 // cur indexes the first empty region
401 while (cur != -1 && is_available(cur) && at(cur)->is_empty()) {
402 cur--;
403 }
404 *res_idx = cur + 1;
405 num_regions_found = old_cur - cur;
406
407 #ifdef ASSERT
408 for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) {
409 assert(at(i)->is_empty(), "just checking");
410 }
411 #endif
412 return num_regions_found;
413 }
414
415 void HeapRegionManager::verify() {
416 guarantee(length() <= _allocated_heapregions_length,
417 err_msg("invariant: _length: %u _allocated_length: %u",
418 length(), _allocated_heapregions_length));
419 guarantee(_allocated_heapregions_length <= max_length(),
420 err_msg("invariant: _allocated_length: %u _max_length: %u",
421 _allocated_heapregions_length, max_length()));
422
423 bool prev_committed = true;
424 uint num_committed = 0;
425 HeapWord* prev_end = heap_bottom();
426 for (uint i = 0; i < _allocated_heapregions_length; i++) {
427 if (!is_available(i)) {
428 prev_committed = false;
429 continue;
430 }
431 num_committed++;
432 HeapRegion* hr = _regions.get_by_index(i);
433 guarantee(hr != NULL, err_msg("invariant: i: %u", i));
434 guarantee(!prev_committed || hr->bottom() == prev_end,
435 err_msg("invariant i: %u "HR_FORMAT" prev_end: "PTR_FORMAT,
436 i, HR_FORMAT_PARAMS(hr), p2i(prev_end)));
437 guarantee(hr->hrm_index() == i,
438 err_msg("invariant: i: %u hrm_index(): %u", i, hr->hrm_index()));
439 // Asserts will fire if i is >= _length
440 HeapWord* addr = hr->bottom();
441 guarantee(addr_to_region(addr) == hr, "sanity");
442 // We cannot check whether the region is part of a particular set: at the time
443 // this method may be called, we have only completed allocation of the regions,
444 // but not put into a region set.
445 prev_committed = true;
446 if (hr->is_starts_humongous()) {
447 prev_end = hr->orig_end();
448 } else {
449 prev_end = hr->end();
450 }
451 }
452 for (uint i = _allocated_heapregions_length; i < max_length(); i++) {
453 guarantee(_regions.get_by_index(i) == NULL, err_msg("invariant i: %u", i));
454 }
455
456 guarantee(num_committed == _num_committed, err_msg("Found %u committed regions, but should be %u", num_committed, _num_committed));
457 _free_list.verify();
458 }
459
460 #ifndef PRODUCT
461 void HeapRegionManager::verify_optional() {
462 verify();
463 }
464 #endif // PRODUCT
465
466 HeapRegionClaimer::HeapRegionClaimer(uint n_workers) :
467 _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm._allocated_heapregions_length), _claims(NULL) {
468 assert(n_workers > 0, "Need at least one worker.");
469 _claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC);
470 memset(_claims, Unclaimed, sizeof(*_claims) * _n_regions);
471 }
472
473 HeapRegionClaimer::~HeapRegionClaimer() {
474 if (_claims != NULL) {
475 FREE_C_HEAP_ARRAY(uint, _claims);
476 }
477 }
478
479 uint HeapRegionClaimer::start_region_for_worker(uint worker_id) const {
480 assert(worker_id < _n_workers, "Invalid worker_id.");
481 return _n_regions * worker_id / _n_workers;
482 }
483
484 bool HeapRegionClaimer::is_region_claimed(uint region_index) const {
485 assert(region_index < _n_regions, "Invalid index.");
486 return _claims[region_index] == Claimed;
487 }
488
489 bool HeapRegionClaimer::claim_region(uint region_index) {
490 assert(region_index < _n_regions, "Invalid index.");
491 uint old_val = Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed);
492 return old_val == Unclaimed;
493 }