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 HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(hrm_index);
70 MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
71 assert(reserved().contains(mr), "invariant");
72 return new HeapRegion(hrm_index, G1CollectedHeap::heap()->bot_shared(), mr);
73 }
74
75 void HeapRegionManager::commit_regions(uint index, size_t num_regions) {
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);
82
83 // Also commit auxiliary data
84 _prev_bitmap_mapper->commit_regions(index, num_regions);
85 _next_bitmap_mapper->commit_regions(index, num_regions);
86
87 _bot_mapper->commit_regions(index, num_regions);
88 _cardtable_mapper->commit_regions(index, num_regions);
89
90 _card_counts_mapper->commit_regions(index, num_regions);
91 }
92
93 void HeapRegionManager::uncommit_regions(uint start, size_t num_regions) {
94 guarantee(num_regions >= 1, err_msg("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->bottom(), hr->end());
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) {
121 guarantee(num_regions > 0, "No point in calling this for zero regions");
122 commit_regions(start, num_regions);
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 _regions.set_by_index(i, new_hr);
127 _allocated_heapregions_length = MAX2(_allocated_heapregions_length, i + 1);
128 }
129 }
130
131 _available_map.par_set_range(start, start + num_regions, BitMap::unknown_range);
132
133 for (uint i = start; i < start + num_regions; i++) {
134 assert(is_available(i), err_msg("Just made region %u available but is apparently not.", i));
135 HeapRegion* hr = at(i);
136 if (G1CollectedHeap::heap()->hr_printer()->is_active()) {
137 G1CollectedHeap::heap()->hr_printer()->commit(hr->bottom(), hr->end());
138 }
139 HeapWord* bottom = G1CollectedHeap::heap()->bottom_addr_for_region(i);
140 MemRegion mr(bottom, bottom + HeapRegion::GrainWords);
141
142 hr->initialize(mr);
143 insert_into_free_list(at(i));
144 }
145 }
146
147 uint HeapRegionManager::expand_by(uint num_regions) {
148 return expand_at(0, num_regions);
149 }
150
151 uint HeapRegionManager::expand_at(uint start, uint num_regions) {
152 if (num_regions == 0) {
153 return 0;
154 }
155
156 uint cur = start;
157 uint idx_last_found = 0;
158 uint num_last_found = 0;
159
160 uint expanded = 0;
161
162 while (expanded < num_regions &&
163 (num_last_found = find_unavailable_from_idx(cur, &idx_last_found)) > 0) {
164 uint to_expand = MIN2(num_regions - expanded, num_last_found);
165 make_regions_available(idx_last_found, to_expand);
166 expanded += to_expand;
167 cur = idx_last_found + num_last_found + 1;
168 }
169
170 verify_optional();
171 return expanded;
172 }
173
174 uint HeapRegionManager::find_contiguous(size_t num, bool empty_only) {
175 uint found = 0;
176 size_t length_found = 0;
177 uint cur = 0;
178
179 while (length_found < num && cur < max_length()) {
180 HeapRegion* hr = _regions.get_by_index(cur);
181 if ((!empty_only && !is_available(cur)) || (is_available(cur) && hr != NULL && hr->is_empty())) {
182 // This region is a potential candidate for allocation into.
183 length_found++;
184 } else {
185 // This region is not a candidate. The next region is the next possible one.
186 found = cur + 1;
187 length_found = 0;
188 }
189 cur++;
190 }
191
192 if (length_found == num) {
193 for (uint i = found; i < (found + num); i++) {
194 HeapRegion* hr = _regions.get_by_index(i);
195 // sanity check
196 guarantee((!empty_only && !is_available(i)) || (is_available(i) && hr != NULL && hr->is_empty()),
197 err_msg("Found region sequence starting at " UINT32_FORMAT ", length " SIZE_FORMAT
198 " that is not empty at " UINT32_FORMAT ". Hr is " PTR_FORMAT, found, num, i, p2i(hr)));
199 }
200 return found;
201 } else {
202 return G1_NO_HRM_INDEX;
203 }
204 }
205
206 HeapRegion* HeapRegionManager::next_region_in_heap(const HeapRegion* r) const {
207 guarantee(r != NULL, "Start region must be a valid region");
208 guarantee(is_available(r->hrm_index()), err_msg("Trying to iterate starting from region %u which is not in the heap", r->hrm_index()));
209 for (uint i = r->hrm_index() + 1; i < _allocated_heapregions_length; i++) {
210 HeapRegion* hr = _regions.get_by_index(i);
211 if (is_available(i)) {
212 return hr;
213 }
214 }
215 return NULL;
216 }
217
218 void HeapRegionManager::iterate(HeapRegionClosure* blk) const {
219 uint len = max_length();
220
221 for (uint i = 0; i < len; i++) {
222 if (!is_available(i)) {
223 continue;
224 }
225 guarantee(at(i) != NULL, err_msg("Tried to access region %u that has a NULL HeapRegion*", i));
226 bool res = blk->doHeapRegion(at(i));
227 if (res) {
228 blk->incomplete();
229 return;
230 }
231 }
232 }
233
234 uint HeapRegionManager::find_unavailable_from_idx(uint start_idx, uint* res_idx) const {
235 guarantee(res_idx != NULL, "checking");
236 guarantee(start_idx <= (max_length() + 1), "checking");
237
238 uint num_regions = 0;
239
240 uint cur = start_idx;
241 while (cur < max_length() && is_available(cur)) {
242 cur++;
243 }
244 if (cur == max_length()) {
245 return num_regions;
246 }
247 *res_idx = cur;
248 while (cur < max_length() && !is_available(cur)) {
249 cur++;
250 }
251 num_regions = cur - *res_idx;
252 #ifdef ASSERT
253 for (uint i = *res_idx; i < (*res_idx + num_regions); i++) {
254 assert(!is_available(i), "just checking");
255 }
256 assert(cur == max_length() || num_regions == 0 || is_available(cur),
257 err_msg("The region at the current position %u must be available or at the end of the heap.", cur));
258 #endif
259 return num_regions;
260 }
261
262 void HeapRegionManager::par_iterate(HeapRegionClosure* blk, uint worker_id, HeapRegionClaimer* hrclaimer) const {
263 const uint start_index = hrclaimer->start_region_for_worker(worker_id);
264
265 // Every worker will actually look at all regions, skipping over regions that
266 // are currently not committed.
267 // This also (potentially) iterates over regions newly allocated during GC. This
268 // is no problem except for some extra work.
269 const uint n_regions = hrclaimer->n_regions();
270 for (uint count = 0; count < n_regions; count++) {
271 const uint index = (start_index + count) % n_regions;
272 assert(0 <= index && index < n_regions, "sanity");
273 // Skip over unavailable regions
274 if (!is_available(index)) {
275 continue;
276 }
277 HeapRegion* r = _regions.get_by_index(index);
278 // We'll ignore "continues humongous" regions (we'll process them
279 // when we come across their corresponding "start humongous"
280 // region) and regions already claimed.
281 if (hrclaimer->is_region_claimed(index) || r->continuesHumongous()) {
282 continue;
283 }
284 // OK, try to claim it
285 if (!hrclaimer->claim_region(index)) {
286 continue;
287 }
288 // Success!
289 if (r->startsHumongous()) {
290 // If the region is "starts humongous" we'll iterate over its
291 // "continues humongous" first; in fact we'll do them
292 // first. The order is important. In one case, calling the
293 // closure on the "starts humongous" region might de-allocate
294 // and clear all its "continues humongous" regions and, as a
295 // result, we might end up processing them twice. So, we'll do
296 // them first (note: most closures will ignore them anyway) and
297 // then we'll do the "starts humongous" region.
298 for (uint ch_index = index + 1; ch_index < index + r->region_num(); ch_index++) {
299 HeapRegion* chr = _regions.get_by_index(ch_index);
300
301 assert(chr->continuesHumongous(), "Must be humongous region");
302 assert(chr->humongous_start_region() == r,
303 err_msg("Must work on humongous continuation of the original start region "
304 PTR_FORMAT ", but is " PTR_FORMAT, p2i(r), p2i(chr)));
305 assert(!hrclaimer->is_region_claimed(ch_index),
306 "Must not have been claimed yet because claiming of humongous continuation first claims the start region");
307
308 // There's no need to actually claim the continues humongous region, but we can do it in an assert as an extra precaution.
309 assert(hrclaimer->claim_region(ch_index), "We should always be able to claim the continuesHumongous part of the humongous object");
310
311 bool res2 = blk->doHeapRegion(chr);
312 if (res2) {
313 return;
314 }
315
316 // Right now, this holds (i.e., no closure that actually
317 // does something with "continues humongous" regions
318 // clears them). We might have to weaken it in the future,
319 // but let's leave these two asserts here for extra safety.
320 assert(chr->continuesHumongous(), "should still be the case");
321 assert(chr->humongous_start_region() == r, "sanity");
322 }
323 }
324
325 bool res = blk->doHeapRegion(r);
326 if (res) {
327 return;
328 }
329 }
330 }
331
332 uint HeapRegionManager::shrink_by(uint num_regions_to_remove) {
333 assert(length() > 0, "the region sequence should not be empty");
334 assert(length() <= _allocated_heapregions_length, "invariant");
335 assert(_allocated_heapregions_length > 0, "we should have at least one region committed");
336 assert(num_regions_to_remove < length(), "We should never remove all regions");
337
338 if (num_regions_to_remove == 0) {
339 return 0;
340 }
341
342 uint removed = 0;
343 uint cur = _allocated_heapregions_length - 1;
344 uint idx_last_found = 0;
345 uint num_last_found = 0;
346
347 while ((removed < num_regions_to_remove) &&
348 (num_last_found = find_empty_from_idx_reverse(cur, &idx_last_found)) > 0) {
349 uint to_remove = MIN2(num_regions_to_remove - removed, num_last_found);
350
351 uncommit_regions(idx_last_found + num_last_found - to_remove, to_remove);
352
353 cur -= num_last_found;
354 removed += to_remove;
355 }
356
357 verify_optional();
358
359 return removed;
360 }
361
362 uint HeapRegionManager::find_empty_from_idx_reverse(uint start_idx, uint* res_idx) const {
363 guarantee(start_idx < _allocated_heapregions_length, "checking");
364 guarantee(res_idx != NULL, "checking");
365
366 uint num_regions_found = 0;
367
368 jlong cur = start_idx;
369 while (cur != -1 && !(is_available(cur) && at(cur)->is_empty())) {
370 cur--;
371 }
372 if (cur == -1) {
373 return num_regions_found;
374 }
375 jlong old_cur = cur;
376 // cur indexes the first empty region
377 while (cur != -1 && is_available(cur) && at(cur)->is_empty()) {
378 cur--;
379 }
380 *res_idx = cur + 1;
381 num_regions_found = old_cur - cur;
382
383 #ifdef ASSERT
384 for (uint i = *res_idx; i < (*res_idx + num_regions_found); i++) {
385 assert(at(i)->is_empty(), "just checking");
386 }
387 #endif
388 return num_regions_found;
389 }
390
391 void HeapRegionManager::verify() {
392 guarantee(length() <= _allocated_heapregions_length,
393 err_msg("invariant: _length: %u _allocated_length: %u",
394 length(), _allocated_heapregions_length));
395 guarantee(_allocated_heapregions_length <= max_length(),
396 err_msg("invariant: _allocated_length: %u _max_length: %u",
397 _allocated_heapregions_length, max_length()));
398
399 bool prev_committed = true;
400 uint num_committed = 0;
401 HeapWord* prev_end = heap_bottom();
402 for (uint i = 0; i < _allocated_heapregions_length; i++) {
403 if (!is_available(i)) {
404 prev_committed = false;
405 continue;
406 }
407 num_committed++;
408 HeapRegion* hr = _regions.get_by_index(i);
409 guarantee(hr != NULL, err_msg("invariant: i: %u", i));
410 guarantee(!prev_committed || hr->bottom() == prev_end,
411 err_msg("invariant i: %u "HR_FORMAT" prev_end: "PTR_FORMAT,
412 i, HR_FORMAT_PARAMS(hr), p2i(prev_end)));
413 guarantee(hr->hrm_index() == i,
414 err_msg("invariant: i: %u hrm_index(): %u", i, hr->hrm_index()));
415 // Asserts will fire if i is >= _length
416 HeapWord* addr = hr->bottom();
417 guarantee(addr_to_region(addr) == hr, "sanity");
418 // We cannot check whether the region is part of a particular set: at the time
419 // this method may be called, we have only completed allocation of the regions,
420 // but not put into a region set.
421 prev_committed = true;
422 if (hr->startsHumongous()) {
423 prev_end = hr->orig_end();
424 } else {
425 prev_end = hr->end();
426 }
427 }
428 for (uint i = _allocated_heapregions_length; i < max_length(); i++) {
429 guarantee(_regions.get_by_index(i) == NULL, err_msg("invariant i: %u", i));
430 }
431
432 guarantee(num_committed == _num_committed, err_msg("Found %u committed regions, but should be %u", num_committed, _num_committed));
433 _free_list.verify();
434 }
435
436 #ifndef PRODUCT
437 void HeapRegionManager::verify_optional() {
438 verify();
439 }
440 #endif // PRODUCT
441
442 void HeapRegionClaimer::initialize(uint n_workers) {
443 assert(n_workers > 0, "Need at least one worker.");
444 assert(_claims == NULL, "Must initialize only once.");
445 _n_workers = n_workers;
446 _n_regions = G1CollectedHeap::heap()->_hrm._allocated_heapregions_length;
447 _claims = NEW_C_HEAP_ARRAY(uint, _n_regions, mtGC);
448 memset(_claims, Unclaimed, sizeof(*_claims) * _n_regions);
449 }
450
451 uint HeapRegionClaimer::start_region_for_worker(uint worker_id) const {
452 assert(_n_workers != 0, "Must initialize before use.");
453 assert(worker_id < _n_workers, "Invalid worker_id.");
454 return _n_regions * worker_id / _n_workers;
455 }
456
457 bool HeapRegionClaimer::is_region_claimed(uint region_index) const {
458 assert(_claims != NULL, "Must initialize before use.");
459 assert(region_index < _n_regions, "Invalid index.");
460 return _claims[region_index] == Claimed;
461 }
462
463 bool HeapRegionClaimer::claim_region(uint region_index) {
464 assert(_claims != NULL, "Must initialize before use.");
465 assert(region_index < _n_regions, "Invalid index.");
466 if (Atomic::cmpxchg(Claimed, &_claims[region_index], Unclaimed) == Unclaimed) {
467 return true;
468 }
469 return false;
470 }