1 /*
2 * Copyright (c) 2004, 2010, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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5 * This code is free software; you can redistribute it and/or modify it
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11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_ADAPTIVESIZEPOLICY_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_SHARED_ADAPTIVESIZEPOLICY_HPP
27
28 #include "gc_implementation/shared/gcUtil.hpp"
29 #include "gc_interface/collectedHeap.hpp"
30 #include "gc_interface/gcCause.hpp"
31 #include "memory/allocation.hpp"
32 #include "memory/universe.hpp"
33
34 // This class keeps statistical information and computes the
35 // size of the heap.
36
37 // Forward decls
38 class elapsedTimer;
39 class CollectorPolicy;
40
41 class AdaptiveSizePolicy : public CHeapObj {
42 friend class GCAdaptivePolicyCounters;
43 friend class PSGCAdaptivePolicyCounters;
44 friend class CMSGCAdaptivePolicyCounters;
45 protected:
46
47 enum GCPolicyKind {
48 _gc_adaptive_size_policy,
49 _gc_ps_adaptive_size_policy,
50 _gc_cms_adaptive_size_policy
51 };
52 virtual GCPolicyKind kind() const { return _gc_adaptive_size_policy; }
53
54 enum SizePolicyTrueValues {
55 decrease_old_gen_for_throughput_true = -7,
56 decrease_young_gen_for_througput_true = -6,
57
58 increase_old_gen_for_min_pauses_true = -5,
59 decrease_old_gen_for_min_pauses_true = -4,
60 decrease_young_gen_for_maj_pauses_true = -3,
61 increase_young_gen_for_min_pauses_true = -2,
62 increase_old_gen_for_maj_pauses_true = -1,
63
64 decrease_young_gen_for_min_pauses_true = 1,
65 decrease_old_gen_for_maj_pauses_true = 2,
66 increase_young_gen_for_maj_pauses_true = 3,
67
68 increase_old_gen_for_throughput_true = 4,
69 increase_young_gen_for_througput_true = 5,
70
71 decrease_young_gen_for_footprint_true = 6,
72 decrease_old_gen_for_footprint_true = 7,
73 decide_at_full_gc_true = 8
74 };
75
76 // Goal for the fraction of the total time during which application
77 // threads run.
78 const double _throughput_goal;
79
80 // Last calculated sizes, in bytes, and aligned
81 size_t _eden_size; // calculated eden free space in bytes
82 size_t _promo_size; // calculated cms gen free space in bytes
83
84 size_t _survivor_size; // calculated survivor size in bytes
85
86 // This is a hint for the heap: we've detected that gc times
87 // are taking longer than GCTimeLimit allows.
88 bool _gc_overhead_limit_exceeded;
89 // Use for diagnostics only. If UseGCOverheadLimit is false,
90 // this variable is still set.
91 bool _print_gc_overhead_limit_would_be_exceeded;
92 // Count of consecutive GC that have exceeded the
93 // GC time limit criterion.
94 uint _gc_overhead_limit_count;
95 // This flag signals that GCTimeLimit is being exceeded
96 // but may not have done so for the required number of consequetive
97 // collections.
98
99 // Minor collection timers used to determine both
100 // pause and interval times for collections.
101 static elapsedTimer _minor_timer;
102
103 // Major collection timers, used to determine both
104 // pause and interval times for collections
105 static elapsedTimer _major_timer;
106
107 // Time statistics
108 AdaptivePaddedAverage* _avg_minor_pause;
109 AdaptiveWeightedAverage* _avg_minor_interval;
110 AdaptiveWeightedAverage* _avg_minor_gc_cost;
111
112 AdaptiveWeightedAverage* _avg_major_interval;
113 AdaptiveWeightedAverage* _avg_major_gc_cost;
114
115 // Footprint statistics
116 AdaptiveWeightedAverage* _avg_young_live;
117 AdaptiveWeightedAverage* _avg_eden_live;
118 AdaptiveWeightedAverage* _avg_old_live;
119
120 // Statistics for survivor space calculation for young generation
121 AdaptivePaddedAverage* _avg_survived;
122
123 // Objects that have been directly allocated in the old generation.
124 AdaptivePaddedNoZeroDevAverage* _avg_pretenured;
125
126 // Variable for estimating the major and minor pause times.
127 // These variables represent linear least-squares fits of
128 // the data.
129 // minor pause time vs. old gen size
130 LinearLeastSquareFit* _minor_pause_old_estimator;
131 // minor pause time vs. young gen size
132 LinearLeastSquareFit* _minor_pause_young_estimator;
133
134 // Variables for estimating the major and minor collection costs
135 // minor collection time vs. young gen size
136 LinearLeastSquareFit* _minor_collection_estimator;
137 // major collection time vs. cms gen size
138 LinearLeastSquareFit* _major_collection_estimator;
139
140 // These record the most recent collection times. They
141 // are available as an alternative to using the averages
142 // for making ergonomic decisions.
143 double _latest_minor_mutator_interval_seconds;
144
145 // Allowed difference between major and minor gc times, used
146 // for computing tenuring_threshold.
147 const double _threshold_tolerance_percent;
148
149 const double _gc_pause_goal_sec; // goal for maximum gc pause
150
151 // Flag indicating that the adaptive policy is ready to use
152 bool _young_gen_policy_is_ready;
153
154 // decrease/increase the young generation for minor pause time
155 int _change_young_gen_for_min_pauses;
156
157 // decrease/increase the old generation for major pause time
158 int _change_old_gen_for_maj_pauses;
159
160 // change old geneneration for throughput
161 int _change_old_gen_for_throughput;
162
163 // change young generation for throughput
164 int _change_young_gen_for_throughput;
165
166 // Flag indicating that the policy would
167 // increase the tenuring threshold because of the total major gc cost
168 // is greater than the total minor gc cost
169 bool _increment_tenuring_threshold_for_gc_cost;
170 // decrease the tenuring threshold because of the the total minor gc
171 // cost is greater than the total major gc cost
172 bool _decrement_tenuring_threshold_for_gc_cost;
173 // decrease due to survivor size limit
174 bool _decrement_tenuring_threshold_for_survivor_limit;
175
176 // decrease generation sizes for footprint
177 int _decrease_for_footprint;
178
179 // Set if the ergonomic decisions were made at a full GC.
180 int _decide_at_full_gc;
181
182 // Changing the generation sizing depends on the data that is
183 // gathered about the effects of changes on the pause times and
184 // throughput. These variable count the number of data points
185 // gathered. The policy may use these counters as a threshhold
186 // for reliable data.
187 julong _young_gen_change_for_minor_throughput;
188 julong _old_gen_change_for_major_throughput;
189
190 // Accessors
191
192 double gc_pause_goal_sec() const { return _gc_pause_goal_sec; }
193 // The value returned is unitless: it's the proportion of time
194 // spent in a particular collection type.
195 // An interval time will be 0.0 if a collection type hasn't occurred yet.
196 // The 1.4.2 implementation put a floor on the values of major_gc_cost
197 // and minor_gc_cost. This was useful because of the way major_gc_cost
198 // and minor_gc_cost was used in calculating the sizes of the generations.
199 // Do not use a floor in this implementation because any finite value
200 // will put a limit on the throughput that can be achieved and any
201 // throughput goal above that limit will drive the generations sizes
202 // to extremes.
203 double major_gc_cost() const {
204 return MAX2(0.0F, _avg_major_gc_cost->average());
205 }
206
207 // The value returned is unitless: it's the proportion of time
208 // spent in a particular collection type.
209 // An interval time will be 0.0 if a collection type hasn't occurred yet.
210 // The 1.4.2 implementation put a floor on the values of major_gc_cost
211 // and minor_gc_cost. This was useful because of the way major_gc_cost
212 // and minor_gc_cost was used in calculating the sizes of the generations.
213 // Do not use a floor in this implementation because any finite value
214 // will put a limit on the throughput that can be achieved and any
215 // throughput goal above that limit will drive the generations sizes
216 // to extremes.
217
218 double minor_gc_cost() const {
219 return MAX2(0.0F, _avg_minor_gc_cost->average());
220 }
221
222 // Because we're dealing with averages, gc_cost() can be
223 // larger than 1.0 if just the sum of the minor cost the
224 // the major cost is used. Worse than that is the
225 // fact that the minor cost and the major cost each
226 // tend toward 1.0 in the extreme of high gc costs.
227 // Limit the value of gc_cost to 1.0 so that the mutator
228 // cost stays non-negative.
229 virtual double gc_cost() const {
230 double result = MIN2(1.0, minor_gc_cost() + major_gc_cost());
231 assert(result >= 0.0, "Both minor and major costs are non-negative");
232 return result;
233 }
234
235 // Elapsed time since the last major collection.
236 virtual double time_since_major_gc() const;
237
238 // Average interval between major collections to be used
239 // in calculating the decaying major gc cost. An overestimate
240 // of this time would be a conservative estimate because
241 // this time is used to decide if the major GC cost
242 // should be decayed (i.e., if the time since the last
243 // major gc is long compared to the time returned here,
244 // then the major GC cost will be decayed). See the
245 // implementations for the specifics.
246 virtual double major_gc_interval_average_for_decay() const {
247 return _avg_major_interval->average();
248 }
249
250 // Return the cost of the GC where the major gc cost
251 // has been decayed based on the time since the last
252 // major collection.
253 double decaying_gc_cost() const;
254
255 // Decay the major gc cost. Use this only for decisions on
256 // whether to adjust, not to determine by how much to adjust.
257 // This approximation is crude and may not be good enough for the
258 // latter.
259 double decaying_major_gc_cost() const;
260
261 // Return the mutator cost using the decayed
262 // GC cost.
263 double adjusted_mutator_cost() const {
264 double result = 1.0 - decaying_gc_cost();
265 assert(result >= 0.0, "adjusted mutator cost calculation is incorrect");
266 return result;
267 }
268
269 virtual double mutator_cost() const {
270 double result = 1.0 - gc_cost();
271 assert(result >= 0.0, "mutator cost calculation is incorrect");
272 return result;
273 }
274
275
276 bool young_gen_policy_is_ready() { return _young_gen_policy_is_ready; }
277
278 void update_minor_pause_young_estimator(double minor_pause_in_ms);
279 virtual void update_minor_pause_old_estimator(double minor_pause_in_ms) {
280 // This is not meaningful for all policies but needs to be present
281 // to use minor_collection_end() in its current form.
282 }
283
284 virtual size_t eden_increment(size_t cur_eden);
285 virtual size_t eden_increment(size_t cur_eden, uint percent_change);
286 virtual size_t eden_decrement(size_t cur_eden);
287 virtual size_t promo_increment(size_t cur_eden);
288 virtual size_t promo_increment(size_t cur_eden, uint percent_change);
289 virtual size_t promo_decrement(size_t cur_eden);
290
291 virtual void clear_generation_free_space_flags();
292
293 int change_old_gen_for_throughput() const {
294 return _change_old_gen_for_throughput;
295 }
296 void set_change_old_gen_for_throughput(int v) {
297 _change_old_gen_for_throughput = v;
298 }
299 int change_young_gen_for_throughput() const {
300 return _change_young_gen_for_throughput;
301 }
302 void set_change_young_gen_for_throughput(int v) {
303 _change_young_gen_for_throughput = v;
304 }
305
306 int change_old_gen_for_maj_pauses() const {
307 return _change_old_gen_for_maj_pauses;
308 }
309 void set_change_old_gen_for_maj_pauses(int v) {
310 _change_old_gen_for_maj_pauses = v;
311 }
312
313 bool decrement_tenuring_threshold_for_gc_cost() const {
314 return _decrement_tenuring_threshold_for_gc_cost;
315 }
316 void set_decrement_tenuring_threshold_for_gc_cost(bool v) {
317 _decrement_tenuring_threshold_for_gc_cost = v;
318 }
319 bool increment_tenuring_threshold_for_gc_cost() const {
320 return _increment_tenuring_threshold_for_gc_cost;
321 }
322 void set_increment_tenuring_threshold_for_gc_cost(bool v) {
323 _increment_tenuring_threshold_for_gc_cost = v;
324 }
325 bool decrement_tenuring_threshold_for_survivor_limit() const {
326 return _decrement_tenuring_threshold_for_survivor_limit;
327 }
328 void set_decrement_tenuring_threshold_for_survivor_limit(bool v) {
329 _decrement_tenuring_threshold_for_survivor_limit = v;
330 }
331 // Return true if the policy suggested a change.
332 bool tenuring_threshold_change() const;
333
334 public:
335 AdaptiveSizePolicy(size_t init_eden_size,
336 size_t init_promo_size,
337 size_t init_survivor_size,
338 double gc_pause_goal_sec,
339 uint gc_cost_ratio);
340
341 bool is_gc_cms_adaptive_size_policy() {
342 return kind() == _gc_cms_adaptive_size_policy;
343 }
344 bool is_gc_ps_adaptive_size_policy() {
345 return kind() == _gc_ps_adaptive_size_policy;
346 }
347
348 AdaptivePaddedAverage* avg_minor_pause() const { return _avg_minor_pause; }
349 AdaptiveWeightedAverage* avg_minor_interval() const {
350 return _avg_minor_interval;
351 }
352 AdaptiveWeightedAverage* avg_minor_gc_cost() const {
353 return _avg_minor_gc_cost;
354 }
355
356 AdaptiveWeightedAverage* avg_major_gc_cost() const {
357 return _avg_major_gc_cost;
358 }
359
360 AdaptiveWeightedAverage* avg_young_live() const { return _avg_young_live; }
361 AdaptiveWeightedAverage* avg_eden_live() const { return _avg_eden_live; }
362 AdaptiveWeightedAverage* avg_old_live() const { return _avg_old_live; }
363
364 AdaptivePaddedAverage* avg_survived() const { return _avg_survived; }
365 AdaptivePaddedNoZeroDevAverage* avg_pretenured() { return _avg_pretenured; }
366
367 // Methods indicating events of interest to the adaptive size policy,
368 // called by GC algorithms. It is the responsibility of users of this
369 // policy to call these methods at the correct times!
370 virtual void minor_collection_begin();
371 virtual void minor_collection_end(GCCause::Cause gc_cause);
372 virtual LinearLeastSquareFit* minor_pause_old_estimator() const {
373 return _minor_pause_old_estimator;
374 }
375
376 LinearLeastSquareFit* minor_pause_young_estimator() {
377 return _minor_pause_young_estimator;
378 }
379 LinearLeastSquareFit* minor_collection_estimator() {
380 return _minor_collection_estimator;
381 }
382
383 LinearLeastSquareFit* major_collection_estimator() {
384 return _major_collection_estimator;
385 }
386
387 float minor_pause_young_slope() {
388 return _minor_pause_young_estimator->slope();
389 }
390
391 float minor_collection_slope() { return _minor_collection_estimator->slope();}
392 float major_collection_slope() { return _major_collection_estimator->slope();}
393
394 float minor_pause_old_slope() {
395 return _minor_pause_old_estimator->slope();
396 }
397
398 void set_eden_size(size_t new_size) {
399 _eden_size = new_size;
400 }
401 void set_survivor_size(size_t new_size) {
402 _survivor_size = new_size;
403 }
404
405 size_t calculated_eden_size_in_bytes() const {
406 return _eden_size;
407 }
408
409 size_t calculated_promo_size_in_bytes() const {
410 return _promo_size;
411 }
412
413 size_t calculated_survivor_size_in_bytes() const {
414 return _survivor_size;
415 }
416
417 // This is a hint for the heap: we've detected that gc times
418 // are taking longer than GCTimeLimit allows.
419 // Most heaps will choose to throw an OutOfMemoryError when
420 // this occurs but it is up to the heap to request this information
421 // of the policy
422 bool gc_overhead_limit_exceeded() {
423 return _gc_overhead_limit_exceeded;
424 }
425 void set_gc_overhead_limit_exceeded(bool v) {
426 _gc_overhead_limit_exceeded = v;
427 }
428
429 // Tests conditions indicate the GC overhead limit is being approached.
430 bool gc_overhead_limit_near() {
431 return gc_overhead_limit_count() >=
432 (AdaptiveSizePolicyGCTimeLimitThreshold - 1);
433 }
434 uint gc_overhead_limit_count() { return _gc_overhead_limit_count; }
435 void reset_gc_overhead_limit_count() { _gc_overhead_limit_count = 0; }
436 void inc_gc_overhead_limit_count() { _gc_overhead_limit_count++; }
437 // accessors for flags recording the decisions to resize the
438 // generations to meet the pause goal.
439
440 int change_young_gen_for_min_pauses() const {
441 return _change_young_gen_for_min_pauses;
442 }
443 void set_change_young_gen_for_min_pauses(int v) {
444 _change_young_gen_for_min_pauses = v;
445 }
446 void set_decrease_for_footprint(int v) { _decrease_for_footprint = v; }
447 int decrease_for_footprint() const { return _decrease_for_footprint; }
448 int decide_at_full_gc() { return _decide_at_full_gc; }
449 void set_decide_at_full_gc(int v) { _decide_at_full_gc = v; }
450
451 // Check the conditions for an out-of-memory due to excessive GC time.
452 // Set _gc_overhead_limit_exceeded if all the conditions have been met.
453 void check_gc_overhead_limit(size_t young_live,
454 size_t eden_live,
455 size_t max_old_gen_size,
456 size_t max_eden_size,
457 bool is_full_gc,
458 GCCause::Cause gc_cause,
459 CollectorPolicy* collector_policy);
460
461 // Printing support
462 virtual bool print_adaptive_size_policy_on(outputStream* st) const;
463 bool print_adaptive_size_policy_on(outputStream* st, int
464 tenuring_threshold) const;
465 };
466
467 // Class that can be used to print information about the
468 // adaptive size policy at intervals specified by
469 // AdaptiveSizePolicyOutputInterval. Only print information
470 // if an adaptive size policy is in use.
471 class AdaptiveSizePolicyOutput : StackObj {
472 AdaptiveSizePolicy* _size_policy;
473 bool _do_print;
474 bool print_test(uint count) {
475 // A count of zero is a special value that indicates that the
476 // interval test should be ignored. An interval is of zero is
477 // a special value that indicates that the interval test should
478 // always fail (never do the print based on the interval test).
479 return PrintGCDetails &&
480 UseAdaptiveSizePolicy &&
481 (UseParallelGC || UseConcMarkSweepGC) &&
482 (AdaptiveSizePolicyOutputInterval > 0) &&
483 ((count == 0) ||
484 ((count % AdaptiveSizePolicyOutputInterval) == 0));
485 }
486 public:
487 // The special value of a zero count can be used to ignore
488 // the count test.
489 AdaptiveSizePolicyOutput(uint count) {
490 if (UseAdaptiveSizePolicy && (AdaptiveSizePolicyOutputInterval > 0)) {
491 CollectedHeap* heap = Universe::heap();
492 _size_policy = heap->size_policy();
493 _do_print = print_test(count);
494 } else {
495 _size_policy = NULL;
496 _do_print = false;
497 }
498 }
499 AdaptiveSizePolicyOutput(AdaptiveSizePolicy* size_policy,
500 uint count) :
501 _size_policy(size_policy) {
502 if (UseAdaptiveSizePolicy && (AdaptiveSizePolicyOutputInterval > 0)) {
503 _do_print = print_test(count);
504 } else {
505 _do_print = false;
506 }
507 }
508 ~AdaptiveSizePolicyOutput() {
509 if (_do_print) {
510 assert(UseAdaptiveSizePolicy, "Should not be in use");
511 _size_policy->print_adaptive_size_policy_on(gclog_or_tty);
512 }
513 }
514 };
515
516 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_ADAPTIVESIZEPOLICY_HPP