1 /*
2 * Copyright (c) 2016, 2019, 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/g1CollectedHeap.inline.hpp"
27 #include "gc/g1/g1CollectionSet.hpp"
28 #include "gc/g1/g1CollectionSetCandidates.hpp"
29 #include "gc/g1/g1CollectorState.hpp"
30 #include "gc/g1/g1HotCardCache.hpp"
31 #include "gc/g1/g1ParScanThreadState.hpp"
32 #include "gc/g1/g1Policy.hpp"
33 #include "gc/g1/heapRegion.inline.hpp"
34 #include "gc/g1/heapRegionRemSet.hpp"
35 #include "gc/g1/heapRegionSet.hpp"
36 #include "logging/logStream.hpp"
37 #include "utilities/debug.hpp"
38 #include "utilities/globalDefinitions.hpp"
39 #include "utilities/quickSort.hpp"
40
41 G1CollectorState* G1CollectionSet::collector_state() const {
42 return _g1h->collector_state();
43 }
44
45 G1GCPhaseTimes* G1CollectionSet::phase_times() {
46 return _policy->phase_times();
47 }
48
49 double G1CollectionSet::predict_region_non_copy_time_ms(HeapRegion* hr) const {
50 return _policy->predict_region_non_copy_time_ms(hr, collector_state()->in_young_only_phase());
51 }
52
53 G1CollectionSet::G1CollectionSet(G1CollectedHeap* g1h, G1Policy* policy) :
54 _g1h(g1h),
55 _policy(policy),
56 _candidates(NULL),
57 _eden_region_length(0),
58 _survivor_region_length(0),
59 _old_region_length(0),
60 _collection_set_regions(NULL),
61 _collection_set_cur_length(0),
62 _collection_set_max_length(0),
63 _num_optional_regions(0),
64 _bytes_used_before(0),
65 _recorded_rs_length(0),
66 _inc_build_state(Inactive),
67 _inc_part_start(0),
68 _inc_bytes_used_before(0),
69 _inc_recorded_rs_length(0),
70 _inc_recorded_rs_length_diff(0),
71 _inc_predicted_non_copy_time_ms(0.0),
72 _inc_predicted_non_copy_time_ms_diff(0.0) {
73 }
74
75 G1CollectionSet::~G1CollectionSet() {
76 FREE_C_HEAP_ARRAY(uint, _collection_set_regions);
77 free_optional_regions();
78 clear_candidates();
79 }
80
81 void G1CollectionSet::init_region_lengths(uint eden_cset_region_length,
82 uint survivor_cset_region_length) {
83 assert_at_safepoint_on_vm_thread();
84
85 _eden_region_length = eden_cset_region_length;
86 _survivor_region_length = survivor_cset_region_length;
87
88 assert((size_t) young_region_length() == _collection_set_cur_length,
89 "Young region length %u should match collection set length " SIZE_FORMAT, young_region_length(), _collection_set_cur_length);
90
91 _old_region_length = 0;
92 free_optional_regions();
93 }
94
95 void G1CollectionSet::initialize(uint max_region_length) {
96 guarantee(_collection_set_regions == NULL, "Must only initialize once.");
97 _collection_set_max_length = max_region_length;
98 _collection_set_regions = NEW_C_HEAP_ARRAY(uint, max_region_length, mtGC);
99 }
100
101 void G1CollectionSet::free_optional_regions() {
102 _num_optional_regions = 0;
103 }
104
105 void G1CollectionSet::clear_candidates() {
106 delete _candidates;
107 _candidates = NULL;
108 }
109
110 void G1CollectionSet::set_recorded_rs_length(size_t rs_length) {
111 _recorded_rs_length = rs_length;
112 }
113
114 // Add the heap region at the head of the non-incremental collection set
115 void G1CollectionSet::add_old_region(HeapRegion* hr) {
116 assert_at_safepoint_on_vm_thread();
117
118 assert(_inc_build_state == Active,
119 "Precondition, actively building cset or adding optional later on");
120 assert(hr->is_old(), "the region should be old");
121
122 assert(!hr->in_collection_set(), "should not already be in the collection set");
123 _g1h->register_old_region_with_region_attr(hr);
124
125 _collection_set_regions[_collection_set_cur_length++] = hr->hrm_index();
126 assert(_collection_set_cur_length <= _collection_set_max_length, "Collection set now larger than maximum size.");
127
128 _bytes_used_before += hr->used();
129 _recorded_rs_length += hr->rem_set()->occupied();
130 _old_region_length++;
131
132 _g1h->old_set_remove(hr);
133 }
134
135 void G1CollectionSet::add_optional_region(HeapRegion* hr) {
136 assert(hr->is_old(), "the region should be old");
137 assert(!hr->in_collection_set(), "should not already be in the CSet");
138
139 _g1h->register_optional_region_with_region_attr(hr);
140
141 hr->set_index_in_opt_cset(_num_optional_regions++);
142 }
143
144 void G1CollectionSet::start_incremental_building() {
145 assert(_collection_set_cur_length == 0, "Collection set must be empty before starting a new collection set.");
146 assert(_inc_build_state == Inactive, "Precondition");
147
148 _inc_bytes_used_before = 0;
149
150 _inc_recorded_rs_length = 0;
151 _inc_recorded_rs_length_diff = 0;
152 _inc_predicted_non_copy_time_ms = 0.0;
153 _inc_predicted_non_copy_time_ms_diff = 0.0;
154
155 update_incremental_marker();
156 }
157
158 void G1CollectionSet::finalize_incremental_building() {
159 assert(_inc_build_state == Active, "Precondition");
160 assert(SafepointSynchronize::is_at_safepoint(), "should be at a safepoint");
161
162 // The two "main" fields, _inc_recorded_rs_length and
163 // _inc_predicted_non_copy_time_ms, are updated by the thread
164 // that adds a new region to the CSet. Further updates by the
165 // concurrent refinement thread that samples the young RSet lengths
166 // are accumulated in the *_diff fields. Here we add the diffs to
167 // the "main" fields.
168
169 _inc_recorded_rs_length += _inc_recorded_rs_length_diff;
170 _inc_predicted_non_copy_time_ms += _inc_predicted_non_copy_time_ms_diff;
171
172 _inc_recorded_rs_length_diff = 0;
173 _inc_predicted_non_copy_time_ms_diff = 0.0;
174 }
175
176 void G1CollectionSet::clear() {
177 assert_at_safepoint_on_vm_thread();
178 _collection_set_cur_length = 0;
179 }
180
181 void G1CollectionSet::iterate(HeapRegionClosure* cl) const {
182 size_t len = _collection_set_cur_length;
183 OrderAccess::loadload();
184
185 for (uint i = 0; i < len; i++) {
186 HeapRegion* r = _g1h->region_at(_collection_set_regions[i]);
187 bool result = cl->do_heap_region(r);
188 if (result) {
189 cl->set_incomplete();
190 return;
191 }
192 }
193 }
194
195 void G1CollectionSet::iterate_optional(HeapRegionClosure* cl) const {
196 assert_at_safepoint();
197
198 for (uint i = 0; i < _num_optional_regions; i++) {
199 HeapRegion* r = _candidates->at(i);
200 bool result = cl->do_heap_region(r);
201 guarantee(!result, "Must not cancel iteration");
202 }
203 }
204
205 void G1CollectionSet::iterate_incremental_part_from(HeapRegionClosure* cl,
206 HeapRegionClaimer* hr_claimer,
207 uint worker_id,
208 uint total_workers) const {
209 assert_at_safepoint();
210
211 size_t len = increment_length();
212 if (len == 0) {
213 return;
214 }
215
216 size_t start_pos = (worker_id * len) / total_workers;
217 size_t cur_pos = start_pos;
218
219 do {
220 uint region_idx = _collection_set_regions[cur_pos + _inc_part_start];
221 if (hr_claimer == NULL || hr_claimer->claim_region(region_idx)) {
222 HeapRegion* r = _g1h->region_at(region_idx);
223 bool result = cl->do_heap_region(r);
224 guarantee(!result, "Must not cancel iteration");
225 }
226
227 cur_pos++;
228 if (cur_pos == len) {
229 cur_pos = 0;
230 }
231 } while (cur_pos != start_pos);
232 }
233
234 void G1CollectionSet::update_young_region_prediction(HeapRegion* hr,
235 size_t new_rs_length) {
236 // Update the CSet information that is dependent on the new RS length
237 assert(hr->is_young(), "Precondition");
238 assert(!SafepointSynchronize::is_at_safepoint(), "should not be at a safepoint");
239
240 size_t old_rs_length = hr->recorded_rs_length();
241 assert(old_rs_length <= new_rs_length,
242 "Remembered set sizes must increase (changed from " SIZE_FORMAT " to " SIZE_FORMAT " region %u type %s)",
243 old_rs_length, new_rs_length, hr->hrm_index(), hr->get_short_type_str());
244 size_t rs_length_diff = new_rs_length - old_rs_length;
245 hr->set_recorded_rs_length(new_rs_length);
246 _inc_recorded_rs_length_diff += rs_length_diff;
247
248 double old_non_copy_time = hr->predicted_non_copy_time_ms();
249 double new_non_copy_time = predict_region_non_copy_time_ms(hr);
250 double non_copy_time_ms_diff = new_non_copy_time - old_non_copy_time;
251 hr->set_predicted_non_copy_time_ms(new_non_copy_time);
252 _inc_predicted_non_copy_time_ms_diff += non_copy_time_ms_diff;
253 }
254
255 void G1CollectionSet::add_young_region_common(HeapRegion* hr) {
256 assert(hr->is_young(), "invariant");
257 assert(_inc_build_state == Active, "Precondition");
258
259 // This routine is used when:
260 // * adding survivor regions to the incremental cset at the end of an
261 // evacuation pause or
262 // * adding the current allocation region to the incremental cset
263 // when it is retired.
264 // Therefore this routine may be called at a safepoint by the
265 // VM thread, or in-between safepoints by mutator threads (when
266 // retiring the current allocation region)
267 // We need to clear and set the cached recorded/cached collection set
268 // information in the heap region here (before the region gets added
269 // to the collection set). An individual heap region's cached values
270 // are calculated, aggregated with the policy collection set info,
271 // and cached in the heap region here (initially) and (subsequently)
272 // by the Young List sampling code.
273 // Ignore calls to this due to retirement during full gc.
274
275 if (!_g1h->collector_state()->in_full_gc()) {
276 size_t rs_length = hr->rem_set()->occupied();
277 double region_non_copy_time = predict_region_non_copy_time_ms(hr);
278
279 // Cache the values we have added to the aggregated information
280 // in the heap region in case we have to remove this region from
281 // the incremental collection set, or it is updated by the
282 // rset sampling code
283 hr->set_recorded_rs_length(rs_length);
284 hr->set_predicted_non_copy_time_ms(region_non_copy_time);
285
286 _inc_recorded_rs_length += rs_length;
287 _inc_predicted_non_copy_time_ms += region_non_copy_time;
288 _inc_bytes_used_before += hr->used();
289 }
290
291 assert(!hr->in_collection_set(), "invariant");
292 _g1h->register_young_region_with_region_attr(hr);
293
294 size_t collection_set_length = _collection_set_cur_length;
295 // We use UINT_MAX as "invalid" marker in verification.
296 assert(collection_set_length < (UINT_MAX - 1),
297 "Collection set is too large with " SIZE_FORMAT " entries", collection_set_length);
298 hr->set_young_index_in_cset((uint)collection_set_length + 1);
299
300 _collection_set_regions[collection_set_length] = hr->hrm_index();
301 // Concurrent readers must observe the store of the value in the array before an
302 // update to the length field.
303 OrderAccess::storestore();
304 _collection_set_cur_length++;
305 assert(_collection_set_cur_length <= _collection_set_max_length, "Collection set larger than maximum allowed.");
306 }
307
308 void G1CollectionSet::add_survivor_regions(HeapRegion* hr) {
309 assert(hr->is_survivor(), "Must only add survivor regions, but is %s", hr->get_type_str());
310 add_young_region_common(hr);
311 }
312
313 void G1CollectionSet::add_eden_region(HeapRegion* hr) {
314 assert(hr->is_eden(), "Must only add eden regions, but is %s", hr->get_type_str());
315 add_young_region_common(hr);
316 }
317
318 #ifndef PRODUCT
319 class G1VerifyYoungAgesClosure : public HeapRegionClosure {
320 public:
321 bool _valid;
322
323 G1VerifyYoungAgesClosure() : HeapRegionClosure(), _valid(true) { }
324
325 virtual bool do_heap_region(HeapRegion* r) {
326 guarantee(r->is_young(), "Region must be young but is %s", r->get_type_str());
327
328 if (!r->has_surv_rate_group()) {
329 log_error(gc, verify)("## encountered young region without surv_rate_group");
330 _valid = false;
331 }
332
333 if (!r->has_valid_age_in_surv_rate()) {
334 log_error(gc, verify)("## encountered invalid age in young region");
335 _valid = false;
336 }
337
338 return false;
339 }
340
341 bool valid() const { return _valid; }
342 };
343
344 bool G1CollectionSet::verify_young_ages() {
345 assert_at_safepoint_on_vm_thread();
346
347 G1VerifyYoungAgesClosure cl;
348 iterate(&cl);
349
350 if (!cl.valid()) {
351 LogStreamHandle(Error, gc, verify) log;
352 print(&log);
353 }
354
355 return cl.valid();
356 }
357
358 class G1PrintCollectionSetDetailClosure : public HeapRegionClosure {
359 outputStream* _st;
360 public:
361 G1PrintCollectionSetDetailClosure(outputStream* st) : HeapRegionClosure(), _st(st) { }
362
363 virtual bool do_heap_region(HeapRegion* r) {
364 assert(r->in_collection_set(), "Region %u should be in collection set", r->hrm_index());
365 _st->print_cr(" " HR_FORMAT ", P: " PTR_FORMAT "N: " PTR_FORMAT ", age: %4d",
366 HR_FORMAT_PARAMS(r),
367 p2i(r->prev_top_at_mark_start()),
368 p2i(r->next_top_at_mark_start()),
369 r->has_surv_rate_group() ? r->age_in_surv_rate_group() : -1);
370 return false;
371 }
372 };
373
374 void G1CollectionSet::print(outputStream* st) {
375 st->print_cr("\nCollection_set:");
376
377 G1PrintCollectionSetDetailClosure cl(st);
378 iterate(&cl);
379 }
380 #endif // !PRODUCT
381
382 double G1CollectionSet::finalize_young_part(double target_pause_time_ms, G1SurvivorRegions* survivors) {
383 Ticks start_time = Ticks::now();
384
385 finalize_incremental_building();
386
387 guarantee(target_pause_time_ms > 0.0,
388 "target_pause_time_ms = %1.6lf should be positive", target_pause_time_ms);
389
390 size_t pending_cards = _policy->pending_cards_at_gc_start() + _g1h->hot_card_cache()->num_entries();
391
392 log_trace(gc, ergo, cset)("Start choosing CSet. Pending cards: " SIZE_FORMAT " target pause time: %1.2fms",
393 pending_cards, target_pause_time_ms);
394
395 // The young list is laid with the survivor regions from the previous
396 // pause are appended to the RHS of the young list, i.e.
397 // [Newly Young Regions ++ Survivors from last pause].
398
399 uint eden_region_length = _g1h->eden_regions_count();
400 uint survivor_region_length = survivors->length();
401 init_region_lengths(eden_region_length, survivor_region_length);
402
403 verify_young_cset_indices();
404
405 // Clear the fields that point to the survivor list - they are all young now.
406 survivors->convert_to_eden();
407
408 _bytes_used_before = _inc_bytes_used_before;
409
410 // The number of recorded young regions is the incremental
411 // collection set's current size
412 set_recorded_rs_length(_inc_recorded_rs_length);
413
414 double predicted_base_time_ms = _policy->predict_base_elapsed_time_ms(pending_cards);
415 double predicted_eden_time = _inc_predicted_non_copy_time_ms + _policy->predict_eden_copy_time_ms(eden_region_length);
416 double remaining_time_ms = MAX2(target_pause_time_ms - (predicted_base_time_ms + predicted_eden_time), 0.0);
417
418 log_trace(gc, ergo, cset)("Added young regions to CSet. Eden: %u regions, Survivors: %u regions, "
419 "predicted eden time: %1.2fms, predicted base time: %1.2fms, target pause time: %1.2fms, remaining time: %1.2fms",
420 eden_region_length, survivor_region_length,
421 predicted_eden_time, predicted_base_time_ms, target_pause_time_ms, remaining_time_ms);
422
423 phase_times()->record_young_cset_choice_time_ms((Ticks::now() - start_time).seconds() * 1000.0);
424
425 return remaining_time_ms;
426 }
427
428 static int compare_region_idx(const uint a, const uint b) {
429 if (a > b) {
430 return 1;
431 } else if (a == b) {
432 return 0;
433 } else {
434 return -1;
435 }
436 }
437
438 void G1CollectionSet::finalize_old_part(double time_remaining_ms) {
439 double non_young_start_time_sec = os::elapsedTime();
440
441 if (collector_state()->in_mixed_phase()) {
442 candidates()->verify();
443
444 uint num_initial_old_regions;
445 uint num_optional_old_regions;
446
447 _policy->calculate_old_collection_set_regions(candidates(),
448 time_remaining_ms,
449 num_initial_old_regions,
450 num_optional_old_regions);
451
452 // Prepare initial old regions.
453 move_candidates_to_collection_set(num_initial_old_regions);
454
455 // Prepare optional old regions for evacuation.
456 uint candidate_idx = candidates()->cur_idx();
457 for (uint i = 0; i < num_optional_old_regions; i++) {
458 add_optional_region(candidates()->at(candidate_idx + i));
459 }
460
461 candidates()->verify();
462 }
463
464 stop_incremental_building();
465
466 double non_young_end_time_sec = os::elapsedTime();
467 phase_times()->record_non_young_cset_choice_time_ms((non_young_end_time_sec - non_young_start_time_sec) * 1000.0);
468
469 QuickSort::sort(_collection_set_regions, _collection_set_cur_length, compare_region_idx, true);
470 }
471
472 void G1CollectionSet::move_candidates_to_collection_set(uint num_old_candidate_regions) {
473 if (num_old_candidate_regions == 0) {
474 return;
475 }
476 uint candidate_idx = candidates()->cur_idx();
477 for (uint i = 0; i < num_old_candidate_regions; i++) {
478 HeapRegion* r = candidates()->at(candidate_idx + i);
479 // This potentially optional candidate region is going to be an actual collection
480 // set region. Clear cset marker.
481 _g1h->clear_region_attr(r);
482 add_old_region(r);
483 }
484 candidates()->remove(num_old_candidate_regions);
485
486 candidates()->verify();
487 }
488
489 void G1CollectionSet::finalize_initial_collection_set(double target_pause_time_ms, G1SurvivorRegions* survivor) {
490 double time_remaining_ms = finalize_young_part(target_pause_time_ms, survivor);
491 finalize_old_part(time_remaining_ms);
492 }
493
494 bool G1CollectionSet::finalize_optional_for_evacuation(double remaining_pause_time) {
495 update_incremental_marker();
496
497 uint num_selected_regions;
498 _policy->calculate_optional_collection_set_regions(candidates(),
499 _num_optional_regions,
500 remaining_pause_time,
501 num_selected_regions);
502
503 move_candidates_to_collection_set(num_selected_regions);
504
505 _num_optional_regions -= num_selected_regions;
506
507 stop_incremental_building();
508
509 _g1h->verify_region_attr_remset_update();
510
511 return num_selected_regions > 0;
512 }
513
514 void G1CollectionSet::abandon_optional_collection_set(G1ParScanThreadStateSet* pss) {
515 for (uint i = 0; i < _num_optional_regions; i++) {
516 HeapRegion* r = candidates()->at(candidates()->cur_idx() + i);
517 pss->record_unused_optional_region(r);
518 // Clear collection set marker and make sure that the remembered set information
519 // is correct as we still need it later.
520 _g1h->clear_region_attr(r);
521 _g1h->register_region_with_region_attr(r);
522 r->clear_index_in_opt_cset();
523 }
524 free_optional_regions();
525
526 _g1h->verify_region_attr_remset_update();
527 }
528
529 #ifdef ASSERT
530 class G1VerifyYoungCSetIndicesClosure : public HeapRegionClosure {
531 private:
532 size_t _young_length;
533 uint* _heap_region_indices;
534 public:
535 G1VerifyYoungCSetIndicesClosure(size_t young_length) : HeapRegionClosure(), _young_length(young_length) {
536 _heap_region_indices = NEW_C_HEAP_ARRAY(uint, young_length + 1, mtGC);
537 for (size_t i = 0; i < young_length + 1; i++) {
538 _heap_region_indices[i] = UINT_MAX;
539 }
540 }
541 ~G1VerifyYoungCSetIndicesClosure() {
542 FREE_C_HEAP_ARRAY(int, _heap_region_indices);
543 }
544
545 virtual bool do_heap_region(HeapRegion* r) {
546 const uint idx = r->young_index_in_cset();
547
548 assert(idx > 0, "Young index must be set for all regions in the incremental collection set but is not for region %u.", r->hrm_index());
549 assert(idx <= _young_length, "Young cset index %u too large for region %u", idx, r->hrm_index());
550
551 assert(_heap_region_indices[idx] == UINT_MAX,
552 "Index %d used by multiple regions, first use by region %u, second by region %u",
553 idx, _heap_region_indices[idx], r->hrm_index());
554
555 _heap_region_indices[idx] = r->hrm_index();
556
557 return false;
558 }
559 };
560
561 void G1CollectionSet::verify_young_cset_indices() const {
562 assert_at_safepoint_on_vm_thread();
563
564 G1VerifyYoungCSetIndicesClosure cl(_collection_set_cur_length);
565 iterate(&cl);
566 }
567 #endif