1 /*
2 * Copyright (c) 2001, 2014, 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 uint HeapRegionManager::expand_by(uint num_regions) {
149 return expand_at(0, num_regions);
150 }
151
152 uint HeapRegionManager::expand_at(uint start, uint num_regions) {
153 if (num_regions == 0) {
154 return 0;
155 }
156
157 uint cur = start;
158 uint idx_last_found = 0;
159 uint num_last_found = 0;
160
161 uint expanded = 0;
162
163 while (expanded < num_regions &&
164 (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) {
165 uint to_expand = MIN2(num_regions - expanded, num_last_found);
166 make_regions_available(idx_last_found, to_expand);
167 expanded += to_expand;
168 cur = idx_last_found + num_last_found + 1;
169 }
170
171 verify_optional();
172 return expanded;
173 }
174
175 uint HeapRegionManager::find_contiguous(size_t num, bool empty_only) {
176 uint found = 0;
177 size_t length_found = 0;
178 uint cur = 0;
179
180 while (length_found < num && cur < max_length()) {
181 HeapRegion* hr = _regions.get_by_index(cur);
182 if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) {
183 // This region is a potential candidate for allocation into.
184 length_found++;
185 } else {
186 // This region is not a candidate. The next region is the next possible one.
187 found = cur + 1;
188 length_found = 0;
189 }
190 cur++;
191 }
192
193 if (length_found == num) {
194 for (uint i = found; i < (found + num); i++) {
195 HeapRegion* hr = _regions.get_by_index(i);
196 // sanity check
197 guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()),
198 err_msg("Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT
199 " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr)));
200 }
201 return found;
202 } else {
203 return G1_NO_HRM_INDEX;
204 }
205 }
206
207 HeapRegion* HeapRegionManager::next_region_in_heap(const HeapRegion* r) const {
208 guarantee(r != NULL, "Start region must be a valid region");
209 guarantee(is_available(r->hrm_index()), err_msg("Trying to iterate starting from region %u which is not in the heap", r->hrm_index()));
210 for (uint i = r->hrm_index() + 1; i < _allocated_heapregions_length; i++) {
211 HeapRegion* hr = _regions.get_by_index(i);
212 if (is_available(i)) {
213 return hr;
214 }
215 }
216 return NULL;
217 }
218
219 void HeapRegionManager::iterate(HeapRegionClosure* blk) const {
220 uint len = max_length();
221
222 for (uint i = 0; i < len; i++) {
223 if (!is_available(i)) {
224 continue;
225 }
226 guarantee(at(i) != NULL, err_msg("Tried to access region %u that has a NULL HeapRegion*", i));
227 bool res = blk->doHeapRegion(at(i));
228 if (res) {
229 blk->incomplete();
230 return;
231 }
232 }
233 }
234
235 uint HeapRegionManager::find_unavailable_from_idx(uint start_idx, uint* res_idx) const {
236 guarantee(res_idx != NULL, "checking");
237 guarantee(start_idx <= (max_length() + 1), "checking");
238
239 uint num_regions = 0;
240
241 uint cur = start_idx;
242 while (cur < max_length() && is_available(cur)) {
243 cur++;
244 }
245 if (cur == max_length()) {
246 return num_regions;
247 }
248 *res_idx = cur;
249 while (cur < max_length() && !is_available(cur)) {
250 cur++;
251 }
252 num_regions = cur - *res_idx;
253 #ifdef ASSERT
254 for (uint i = *res_idx; i < (*res_idx + num_regions); i++) {
255 assert(!is_available(i), "just checking");
256 }
257 assert(cur == max_length() || num_regions == 0 || is_available(cur),
258 err_msg("The region at the current position %u must be available or at the end of the heap.", cur));
259 #endif
260 return num_regions;
261 }
262
263 void HeapRegionManager::par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer, bool concurrent) const {
264 const uint start_index = hrclaimer->start_region_for_worker(worker_id);
265
266 // Every worker will actually look at all regions, skipping over regions that
267 // are currently not committed.
268 // This also (potentially) iterates over regions newly allocated during GC. This
269 // is no problem except for some extra work.
270 const uint n_regions = hrclaimer->n_regions();
271 for (uint count = 0; count < n_regions; count++) {
272 const uint index = (start_index + count) % n_regions;
273 assert(index < n_regions, "sanity");
274 // Skip over unavailable regions
275 if (!is_available(index)) {
276 continue;
277 }
278 HeapRegion* r = _regions.get_by_index(index);
279 // We'll ignore "continues humongous" regions (we'll process them
280 // when we come across their corresponding "start humongous"
281 // region) and regions already claimed.
282 // However, if the iteration is specified as concurrent, the values for
283 // is_starts_humongous and is_continues_humongous can not be trusted,
284 // and we should just blindly iterate over regions regardless of their
285 // humongous status.
286 if (hrclaimer->is_region_claimed(index) || (!concurrent && r->is_continues_humongous())) {
287 continue;
288 }
289 // OK, try to claim it
290 if (!hrclaimer->claim_region(index)) {
291 continue;
292 }
293 // Success!
294 // As mentioned above, special treatment of humongous regions can only be
295 // done if we are iterating non-concurrently.
296 if (!concurrent && r->is_starts_humongous()) {
297 // If the region is "starts humongous" we'll iterate over its
298 // "continues humongous" first; in fact we'll do them
299 // first. The order is important. In one case, calling the
300 // closure on the "starts humongous" region might de-allocate
301 // and clear all its "continues humongous" regions and, as a
302 // result, we might end up processing them twice. So, we'll do
303 // them first (note: most closures will ignore them anyway) and
304 // then we'll do the "starts humongous" region.
305 for (uint ch_index = index + 1; ch_index < index + r->region_num(); ch_index++) {
306 HeapRegion* chr = _regions.get_by_index(ch_index);
307
308 assert(chr->is_continues_humongous(), "Must be humongous region");
309 assert(chr->humongous_start_region() == r,
310 err_msg("Must work on humongous continuation of the original start region "
311 PTR_FORMAT ", but is " PTR_FORMAT, p2i(r), p2i(chr)));
312 assert(!hrclaimer->is_region_claimed(ch_index),
313 "Must not have been claimed yet because claiming of humongous continuation first claims the start region");
314
315 // There's no need to actually claim the continues humongous region, but we can do it in an assert as an extra precaution.
316 assert(hrclaimer->claim_region(ch_index), "We should always be able to claim the continuesHumongous part of the humongous object");
317
318 bool res2 = blk->doHeapRegion(chr);
319 if (res2) {
320 return;
321 }
322
323 // Right now, this holds (i.e., no closure that actually
324 // does something with "continues humongous" regions
325 // clears them). We might have to weaken it in the future,
326 // but let's leave these two asserts here for extra safety.
327 assert(chr->is_continues_humongous(), "should still be the case");
328 assert(chr->humongous_start_region() == r, "sanity");
329 }
330 }
331
332 bool res = blk->doHeapRegion(r);
333 if (res) {
334 return;
335 }
336 }
337 }
338
339 uint HeapRegionManager::shrink_by(uint num_regions_to_remove) {
340 assert(length() > 0, "the region sequence should not be empty");
341 assert(length() <= _allocated_heapregions_length, "invariant");
342 assert(_allocated_heapregions_length > 0, "we should have at least one region committed");
343 assert(num_regions_to_remove < length(), "We should never remove all regions");
344
345 if (num_regions_to_remove == 0) {
346 return 0;
347 }
348
349 uint removed = 0;
350 uint cur = _allocated_heapregions_length - 1;
351 uint idx_last_found = 0;
352 uint num_last_found = 0;
353
354 while ((removed < num_regions_to_remove) &&
355 (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {
356 uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);
357
358 uncommit_regions(idx_last_found + num_last_found - to_remove, to_remove);
359
360 cur -= num_last_found;
361 removed += to_remove;
362 }
363
364 verify_optional();
365
366 return removed;
367 }
368
369 uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const {
370 guarantee(start_idx < _allocated_heapregions_length, "checking");
371 guarantee(res_idx != NULL, "checking");
372
373 uint num_regions_found = 0;
374
375 jlong cur = start_idx;
376 while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) {
377 cur--;
378 }
379 if (cur == -1) {
380 return num_regions_found;
381 }
382 jlong old_cur = cur;
383 // cur indexes the first empty region
384 while (cur != -1 && is_available(cur) && at(cur)->is_empty()) {
385 cur--;
386 }
387 *res_idx = cur + 1;
388 num_regions_found = old_cur - cur;
389
390 #ifdef ASSERT
391 for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) {
392 assert(at(i)->is_empty(), "just checking");
393 }
394 #endif
395 return num_regions_found;
396 }
397
398 void HeapRegionManager::verify() {
399 guarantee(length() <= _allocated_heapregions_length,
400 err_msg("invariant: _length: %u _allocated_length: %u",
401 length(), _allocated_heapregions_length));
402 guarantee(_allocated_heapregions_length <= max_length(),
403 err_msg("invariant: _allocated_length: %u _max_length: %u",
404 _allocated_heapregions_length, max_length()));
405
406 bool prev_committed = true;
407 uint num_committed = 0;
408 HeapWord* prev_end = heap_bottom();
409 for (uint i = 0; i < _allocated_heapregions_length; i++) {
410 if (!is_available(i)) {
411 prev_committed = false;
412 continue;
413 }
414 num_committed++;
415 HeapRegion* hr = _regions.get_by_index(i);
416 guarantee(hr != NULL, err_msg("invariant: i: %u", i));
417 guarantee(!prev_committed || hr->bottom() == prev_end,
418 err_msg("invariant i: %u "HR_FORMAT" prev_end: "PTR_FORMAT,
419 i, HR_FORMAT_PARAMS(hr), p2i(prev_end)));
420 guarantee(hr->hrm_index() == i,
421 err_msg("invariant: i: %u hrm_index(): %u", i, hr->hrm_index()));
422 // Asserts will fire if i is >= _length
423 HeapWord* addr = hr->bottom();
424 guarantee(addr_to_region(addr) == hr, "sanity");
425 // We cannot check whether the region is part of a particular set: at the time
426 // this method may be called, we have only completed allocation of the regions,
427 // but not put into a region set.
428 prev_committed = true;
429 if (hr->is_starts_humongous()) {
430 prev_end = hr->orig_end();
431 } else {
432 prev_end = hr->end();
433 }
434 }
435 for (uint i = _allocated_heapregions_length; i < max_length(); i++) {
436 guarantee(_regions.get_by_index(i) == NULL, err_msg("invariant i: %u", i));
437 }
438
439 guarantee(num_committed == _num_committed, err_msg("Found %u committed regions, but should be %u", num_committed, _num_committed));
440 _free_list.verify();
441 }
442
443 #ifndef PRODUCT
444 void HeapRegionManager::verify_optional() {
445 verify();
446 }
447 #endif // PRODUCT
448
449 HeapRegionClaimer::HeapRegionClaimer(uint n_workers) :
450 _n_workers(n_workers), _n_regions(G1CollectedHeap::heap()->_hrm._allocated_heapregions_length), _claims(NULL) {
451 assert(n_workers > 0, "Need at least one worker.");
452 _claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC);
453 memset(_claims, Unclaimed, sizeof(*_claims) * _n_regions);
454 }
455
456 HeapRegionClaimer::~HeapRegionClaimer() {
457 if (_claims != NULL) {
458 FREE_C_HEAP_ARRAY(uint, _claims);
459 }
460 }
461
462 uint HeapRegionClaimer::start_region_for_worker(uint worker_id) const {
463 assert(worker_id < _n_workers, "Invalid worker_id.");
464 return _n_regions * worker_id / _n_workers;
465 }
466
467 bool HeapRegionClaimer::is_region_claimed(uint region_index) const {
468 assert(region_index < _n_regions, "Invalid index.");
469 return _claims[region_index] == Claimed;
470 }
471
472 bool HeapRegionClaimer::claim_region(uint region_index) {
473 assert(region_index < _n_regions, "Invalid index.");
474 uint old_val = Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed);
475 return old_val == Unclaimed;
476 }