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G1: Use SoftMaxHeapSize to guide GC heuristics
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--- old/src/hotspot/share/gc/g1/g1Policy.hpp
+++ new/src/hotspot/share/gc/g1/g1Policy.hpp
1 1 /*
2 2 * Copyright (c) 2016, 2019, Oracle and/or its affiliates. All rights reserved.
3 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 4 *
5 5 * This code is free software; you can redistribute it and/or modify it
6 6 * under the terms of the GNU General Public License version 2 only, as
7 7 * published by the Free Software Foundation.
8 8 *
9 9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 12 * version 2 for more details (a copy is included in the LICENSE file that
13 13 * accompanied this code).
14 14 *
15 15 * You should have received a copy of the GNU General Public License version
16 16 * 2 along with this work; if not, write to the Free Software Foundation,
17 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 18 *
19 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 20 * or visit www.oracle.com if you need additional information or have any
21 21 * questions.
22 22 *
23 23 */
24 24
25 25 #ifndef SHARE_GC_G1_G1POLICY_HPP
26 26 #define SHARE_GC_G1_G1POLICY_HPP
27 27
28 28 #include "gc/g1/g1CollectorState.hpp"
29 29 #include "gc/g1/g1GCPhaseTimes.hpp"
30 30 #include "gc/g1/g1HeapRegionAttr.hpp"
31 31 #include "gc/g1/g1InitialMarkToMixedTimeTracker.hpp"
32 32 #include "gc/g1/g1MMUTracker.hpp"
33 33 #include "gc/g1/g1RemSetTrackingPolicy.hpp"
34 34 #include "gc/g1/g1Predictions.hpp"
35 35 #include "gc/g1/g1YoungGenSizer.hpp"
36 36 #include "gc/shared/gcCause.hpp"
37 37 #include "utilities/pair.hpp"
38 38
39 39 // A G1Policy makes policy decisions that determine the
40 40 // characteristics of the collector. Examples include:
41 41 // * choice of collection set.
42 42 // * when to collect.
43 43
44 44 class HeapRegion;
45 45 class G1CollectionSet;
46 46 class G1CollectionSetCandidates;
47 47 class G1CollectionSetChooser;
48 48 class G1IHOPControl;
49 49 class G1Analytics;
50 50 class G1SurvivorRegions;
51 51 class G1YoungGenSizer;
52 52 class GCPolicyCounters;
53 53 class STWGCTimer;
54 54
55 55 class G1Policy: public CHeapObj<mtGC> {
56 56 private:
57 57
58 58 static G1IHOPControl* create_ihop_control(const G1Predictions* predictor);
59 59 // Update the IHOP control with necessary statistics.
60 60 void update_ihop_prediction(double mutator_time_s,
61 61 size_t mutator_alloc_bytes,
62 62 size_t young_gen_size,
63 63 bool this_gc_was_young_only);
64 64 void report_ihop_statistics();
65 65
66 66 G1Predictions _predictor;
67 67 G1Analytics* _analytics;
68 68 G1RemSetTrackingPolicy _remset_tracker;
69 69 G1MMUTracker* _mmu_tracker;
70 70 G1IHOPControl* _ihop_control;
71 71
72 72 GCPolicyCounters* _policy_counters;
73 73
74 74 double _full_collection_start_sec;
75 75
76 76 jlong _collection_pause_end_millis;
77 77
78 78 uint _young_list_target_length;
79 79 uint _young_list_fixed_length;
80 80
81 81 // The max number of regions we can extend the eden by while the GC
82 82 // locker is active. This should be >= _young_list_target_length;
83 83 uint _young_list_max_length;
84 84
85 85 // The survivor rate groups below must be initialized after the predictor because they
86 86 // indirectly use it through the "this" object passed to their constructor.
87 87 G1SurvRateGroup* _eden_surv_rate_group;
88 88 G1SurvRateGroup* _survivor_surv_rate_group;
89 89
90 90 double _reserve_factor;
91 91 // This will be set when the heap is expanded
92 92 // for the first time during initialization.
93 93 uint _reserve_regions;
94 94
95 95 G1YoungGenSizer* _young_gen_sizer;
96 96
97 97 uint _free_regions_at_end_of_collection;
98 98
99 99 size_t _rs_length;
100 100
101 101 size_t _rs_length_prediction;
102 102
103 103 size_t _pending_cards_at_gc_start;
104 104 size_t _pending_cards_at_prev_gc_end;
105 105 size_t _total_mutator_refined_cards;
106 106 size_t _total_concurrent_refined_cards;
107 107 Tickspan _total_concurrent_refinement_time;
108 108
109 109 // The amount of allocated bytes in old gen during the last mutator and the following
110 110 // young GC phase.
111 111 size_t _bytes_allocated_in_old_since_last_gc;
112 112
113 113 G1InitialMarkToMixedTimeTracker _initial_mark_to_mixed;
114 114
115 115 bool should_update_surv_rate_group_predictors() {
116 116 return collector_state()->in_young_only_phase() && !collector_state()->mark_or_rebuild_in_progress();
117 117 }
118 118
119 119 double logged_cards_processing_time() const;
120 120 public:
121 121 const G1Predictions& predictor() const { return _predictor; }
122 122 const G1Analytics* analytics() const { return const_cast<const G1Analytics*>(_analytics); }
123 123
124 124 G1RemSetTrackingPolicy* remset_tracker() { return &_remset_tracker; }
125 125
126 126 // Add the given number of bytes to the total number of allocated bytes in the old gen.
127 127 void add_bytes_allocated_in_old_since_last_gc(size_t bytes) { _bytes_allocated_in_old_since_last_gc += bytes; }
128 128
129 129 void set_region_eden(HeapRegion* hr) {
130 130 hr->set_eden();
131 131 hr->install_surv_rate_group(_eden_surv_rate_group);
132 132 }
133 133
134 134 void set_region_survivor(HeapRegion* hr) {
135 135 assert(hr->is_survivor(), "pre-condition");
136 136 hr->install_surv_rate_group(_survivor_surv_rate_group);
137 137 }
138 138
139 139 void record_rs_length(size_t rs_length) {
140 140 _rs_length = rs_length;
141 141 }
142 142
143 143 double predict_base_elapsed_time_ms(size_t num_pending_cards) const;
144 144
145 145 private:
146 146 double predict_base_elapsed_time_ms(size_t num_pending_cards, size_t rs_length) const;
147 147
148 148 double predict_region_copy_time_ms(HeapRegion* hr) const;
149 149
150 150 public:
151 151
152 152 double predict_eden_copy_time_ms(uint count, size_t* bytes_to_copy = NULL) const;
153 153 double predict_region_non_copy_time_ms(HeapRegion* hr, bool for_young_gc) const;
154 154 double predict_region_total_time_ms(HeapRegion* hr, bool for_young_gc) const;
155 155
156 156 void cset_regions_freed() {
157 157 bool update = should_update_surv_rate_group_predictors();
158 158
159 159 _eden_surv_rate_group->all_surviving_words_recorded(predictor(), update);
160 160 _survivor_surv_rate_group->all_surviving_words_recorded(predictor(), update);
161 161 }
162 162
163 163 G1MMUTracker* mmu_tracker() {
164 164 return _mmu_tracker;
165 165 }
166 166
167 167 const G1MMUTracker* mmu_tracker() const {
168 168 return _mmu_tracker;
169 169 }
170 170
171 171 double max_pause_time_ms() const {
172 172 return _mmu_tracker->max_gc_time() * 1000.0;
173 173 }
174 174
175 175 private:
176 176 G1CollectionSet* _collection_set;
177 177 double average_time_ms(G1GCPhaseTimes::GCParPhases phase) const;
178 178 double other_time_ms(double pause_time_ms) const;
179 179
180 180 double young_other_time_ms() const;
181 181 double non_young_other_time_ms() const;
182 182 double constant_other_time_ms(double pause_time_ms) const;
183 183
184 184 G1CollectionSetChooser* cset_chooser() const;
185 185
186 186 // Stash a pointer to the g1 heap.
187 187 G1CollectedHeap* _g1h;
188 188
189 189 G1GCPhaseTimes* _phase_times;
190 190
191 191 // This set of variables tracks the collector efficiency, in order to
192 192 // determine whether we should initiate a new marking.
193 193 double _mark_remark_start_sec;
194 194 double _mark_cleanup_start_sec;
195 195
196 196 // Updates the internal young list maximum and target lengths. Returns the
197 197 // unbounded young list target length. If no rs_length parameter is passed,
198 198 // predict the RS length using the prediction model, otherwise use the
199 199 // given rs_length as the prediction.
200 200 uint update_young_list_max_and_target_length();
201 201 uint update_young_list_max_and_target_length(size_t rs_length);
202 202
203 203 // Update the young list target length either by setting it to the
204 204 // desired fixed value or by calculating it using G1's pause
205 205 // prediction model.
206 206 // Returns the unbounded young list target length.
207 207 uint update_young_list_target_length(size_t rs_length);
208 208
209 209 // Calculate and return the minimum desired young list target
210 210 // length. This is the minimum desired young list length according
211 211 // to the user's inputs.
212 212 uint calculate_young_list_desired_min_length(uint base_min_length) const;
213 213
214 214 // Calculate and return the maximum desired young list target
215 215 // length. This is the maximum desired young list length according
216 216 // to the user's inputs.
217 217 uint calculate_young_list_desired_max_length() const;
218 218
219 219 // Calculate and return the maximum young list target length that
220 220 // can fit into the pause time goal. The parameters are: rs_length
221 221 // represent the prediction of how large the young RSet lengths will
222 222 // be, base_min_length is the already existing number of regions in
223 223 // the young list, min_length and max_length are the desired min and
224 224 // max young list length according to the user's inputs.
225 225 uint calculate_young_list_target_length(size_t rs_length,
226 226 uint base_min_length,
227 227 uint desired_min_length,
228 228 uint desired_max_length) const;
229 229
230 230 // Result of the bounded_young_list_target_length() method, containing both the
231 231 // bounded as well as the unbounded young list target lengths in this order.
232 232 typedef Pair<uint, uint, StackObj> YoungTargetLengths;
233 233 YoungTargetLengths young_list_target_lengths(size_t rs_length) const;
234 234
235 235 void update_rs_length_prediction();
236 236 void update_rs_length_prediction(size_t prediction);
237 237
238 238 size_t predict_bytes_to_copy(HeapRegion* hr) const;
239 239 double predict_survivor_regions_evac_time() const;
240 240
241 241 // Check whether a given young length (young_length) fits into the
242 242 // given target pause time and whether the prediction for the amount
243 243 // of objects to be copied for the given length will fit into the
244 244 // given free space (expressed by base_free_regions). It is used by
245 245 // calculate_young_list_target_length().
246 246 bool predict_will_fit(uint young_length, double base_time_ms,
247 247 uint base_free_regions, double target_pause_time_ms) const;
248 248
249 249 public:
250 250 size_t pending_cards_at_gc_start() const { return _pending_cards_at_gc_start; }
251 251
252 252 // Calculate the minimum number of old regions we'll add to the CSet
253 253 // during a mixed GC.
254 254 uint calc_min_old_cset_length() const;
255 255
256 256 // Calculate the maximum number of old regions we'll add to the CSet
257 257 // during a mixed GC.
258 258 uint calc_max_old_cset_length() const;
259 259
260 260 // Returns the given amount of reclaimable bytes (that represents
261 261 // the amount of reclaimable space still to be collected) as a
262 262 // percentage of the current heap capacity.
263 263 double reclaimable_bytes_percent(size_t reclaimable_bytes) const;
264 264
265 265 jlong collection_pause_end_millis() { return _collection_pause_end_millis; }
266 266
267 267 private:
268 268 void clear_collection_set_candidates();
269 269 // Sets up marking if proper conditions are met.
270 270 void maybe_start_marking();
271 271
272 272 // The kind of STW pause.
273 273 enum PauseKind {
274 274 FullGC,
275 275 YoungOnlyGC,
276 276 MixedGC,
277 277 LastYoungGC,
278 278 InitialMarkGC,
279 279 Cleanup,
280 280 Remark
281 281 };
282 282
283 283 // Calculate PauseKind from internal state.
284 284 PauseKind young_gc_pause_kind() const;
285 285 // Record the given STW pause with the given start and end times (in s).
286 286 void record_pause(PauseKind kind, double start, double end);
287 287 // Indicate that we aborted marking before doing any mixed GCs.
288 288 void abort_time_to_mixed_tracking();
289 289
290 290 void record_concurrent_refinement_data(bool is_full_collection);
291 291
292 292 public:
293 293
294 294 G1Policy(STWGCTimer* gc_timer);
295 295
296 296 virtual ~G1Policy();
297 297
298 298 static G1Policy* create_policy(STWGCTimer* gc_timer_stw);
299 299
300 300 G1CollectorState* collector_state() const;
301 301
302 302 G1GCPhaseTimes* phase_times() const { return _phase_times; }
303 303
304 304 // Check the current value of the young list RSet length and
305 305 // compare it against the last prediction. If the current value is
306 306 // higher, recalculate the young list target length prediction.
307 307 void revise_young_list_target_length_if_necessary(size_t rs_length);
308 308
309 309 // This should be called after the heap is resized.
310 310 void record_new_heap_size(uint new_number_of_regions);
311 311
312 312 virtual void init(G1CollectedHeap* g1h, G1CollectionSet* collection_set);
313 313
314 314 void note_gc_start();
315 315
316 316 bool need_to_start_conc_mark(const char* source, size_t alloc_word_size = 0);
317 317
318 318 bool about_to_start_mixed_phase() const;
319 319
320 320 // Record the start and end of an evacuation pause.
321 321 void record_collection_pause_start(double start_time_sec);
322 322 virtual void record_collection_pause_end(double pause_time_ms);
323 323
324 324 // Record the start and end of a full collection.
325 325 void record_full_collection_start();
326 326 virtual void record_full_collection_end();
327 327
328 328 // Must currently be called while the world is stopped.
329 329 void record_concurrent_mark_init_end(double mark_init_elapsed_time_ms);
330 330
331 331 // Record start and end of remark.
332 332 void record_concurrent_mark_remark_start();
333 333 void record_concurrent_mark_remark_end();
334 334
335 335 // Record start, end, and completion of cleanup.
336 336 void record_concurrent_mark_cleanup_start();
337 337 void record_concurrent_mark_cleanup_end();
338 338
339 339 void print_phases();
340 340
341 341 bool next_gc_should_be_mixed(const char* true_action_str,
342 342 const char* false_action_str) const;
343 343
344 344 // Calculate and return the number of initial and optional old gen regions from
345 345 // the given collection set candidates and the remaining time.
346 346 void calculate_old_collection_set_regions(G1CollectionSetCandidates* candidates,
347 347 double time_remaining_ms,
348 348 uint& num_initial_regions,
349 349 uint& num_optional_regions);
350 350
351 351 // Calculate the number of optional regions from the given collection set candidates,
352 352 // the remaining time and the maximum number of these regions and return the number
353 353 // of actually selected regions in num_optional_regions.
354 354 void calculate_optional_collection_set_regions(G1CollectionSetCandidates* candidates,
355 355 uint const max_optional_regions,
356 356 double time_remaining_ms,
357 357 uint& num_optional_regions);
358 358
359 359 private:
360 360 // Set the state to start a concurrent marking cycle and clear
361 361 // _initiate_conc_mark_if_possible because it has now been
362 362 // acted on.
363 363 void initiate_conc_mark();
364 364
365 365 public:
366 366 // This sets the initiate_conc_mark_if_possible() flag to start a
367 367 // new cycle, as long as we are not already in one. It's best if it
368 368 // is called during a safepoint when the test whether a cycle is in
369 369 // progress or not is stable.
370 370 bool force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause);
371 371
372 372 // This is called at the very beginning of an evacuation pause (it
373 373 // has to be the first thing that the pause does). If
374 374 // initiate_conc_mark_if_possible() is true, and the concurrent
375 375 // marking thread has completed its work during the previous cycle,
376 376 // it will set in_initial_mark_gc() to so that the pause does
377 377 // the initial-mark work and start a marking cycle.
378 378 void decide_on_conc_mark_initiation();
379 379
380 380 size_t young_list_target_length() const { return _young_list_target_length; }
381 381
382 382 bool should_allocate_mutator_region() const;
383 383
384 384 bool can_expand_young_list() const;
385 385
386 386 uint young_list_max_length() const {
387 387 return _young_list_max_length;
388 388 }
389 389
390 390 bool use_adaptive_young_list_length() const;
391 391
392 392 void transfer_survivors_to_cset(const G1SurvivorRegions* survivors);
393 393
394 394 private:
395 395 //
396 396 // Survivor regions policy.
397 397 //
398 398
399 399 // Current tenuring threshold, set to 0 if the collector reaches the
400 400 // maximum amount of survivors regions.
401 401 uint _tenuring_threshold;
402 402
403 403 // The limit on the number of regions allocated for survivors.
404 404 uint _max_survivor_regions;
405 405
406 406 AgeTable _survivors_age_table;
407 407
408 408 size_t desired_survivor_size(uint max_regions) const;
409 409
410 410 // Fraction used when predicting how many optional regions to include in
411 411 // the CSet. This fraction of the available time is used for optional regions,
412 412 // the rest is used to add old regions to the normal CSet.
413 413 double optional_prediction_fraction() { return 0.2; }
414 414
415 415 public:
416 416 // Fraction used when evacuating the optional regions. This fraction of the
417 417 // remaining time is used to choose what regions to include in the evacuation.
418 418 double optional_evacuation_fraction() { return 0.75; }
419 419
420 420 uint tenuring_threshold() const { return _tenuring_threshold; }
421 421
422 422 uint max_survivor_regions() {
423 423 return _max_survivor_regions;
424 424 }
425 425
426 426 void note_start_adding_survivor_regions() {
427 427 _survivor_surv_rate_group->start_adding_regions();
428 428 }
429 429
430 430 void note_stop_adding_survivor_regions() {
431 431 _survivor_surv_rate_group->stop_adding_regions();
432 432 }
433 433
434 434 void record_age_table(AgeTable* age_table) {
435 435 _survivors_age_table.merge(age_table);
436 436 }
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437 437
438 438 void print_age_table();
439 439
440 440 void update_max_gc_locker_expansion();
441 441
442 442 void update_survivors_policy();
443 443
444 444 virtual bool force_upgrade_to_full() {
445 445 return false;
446 446 }
447 + size_t minimum_desired_bytes_after_concurrent_mark(size_t used_bytes);
447 448 };
448 449
449 450 #endif // SHARE_GC_G1_G1POLICY_HPP
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