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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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24
25 #ifndef SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_CMSADAPTIVESIZEPOLICY_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_CMSADAPTIVESIZEPOLICY_HPP
27
28 #include "gc_implementation/shared/adaptiveSizePolicy.hpp"
29 #include "runtime/timer.hpp"
30
31 // This class keeps statistical information and computes the
32 // size of the heap for the concurrent mark sweep collector.
33 //
34 // Cost for garbage collector include cost for
35 // minor collection
36 // concurrent collection
37 // stop-the-world component
38 // concurrent component
39 // major compacting collection
40 // uses decaying cost
41
42 // Forward decls
43 class elapsedTimer;
44
45 class CMSAdaptiveSizePolicy : public AdaptiveSizePolicy {
46 friend class CMSGCAdaptivePolicyCounters;
47 friend class CMSCollector;
48 private:
49
50 // Total number of processors available
51 int _processor_count;
52 // Number of processors used by the concurrent phases of GC
53 // This number is assumed to be the same for all concurrent
54 // phases.
55 int _concurrent_processor_count;
56
57 // Time that the mutators run exclusive of a particular
58 // phase. For example, the time the mutators run excluding
59 // the time during which the cms collector runs concurrently
60 // with the mutators.
61 // Between end of most recent cms reset and start of initial mark
62 // This may be redundant
63 double _latest_cms_reset_end_to_initial_mark_start_secs;
64 // Between end of the most recent initial mark and start of remark
65 double _latest_cms_initial_mark_end_to_remark_start_secs;
66 // Between end of most recent collection and start of
67 // a concurrent collection
68 double _latest_cms_collection_end_to_collection_start_secs;
69 // Times of the concurrent phases of the most recent
70 // concurrent collection
71 double _latest_cms_concurrent_marking_time_secs;
72 double _latest_cms_concurrent_precleaning_time_secs;
73 double _latest_cms_concurrent_sweeping_time_secs;
74 // Between end of most recent STW MSC and start of next STW MSC
75 double _latest_cms_msc_end_to_msc_start_time_secs;
76 // Between end of most recent MS and start of next MS
77 // This does not include any time spent during a concurrent
78 // collection.
79 double _latest_cms_ms_end_to_ms_start;
80 // Between start and end of the initial mark of the most recent
81 // concurrent collection.
82 double _latest_cms_initial_mark_start_to_end_time_secs;
83 // Between start and end of the remark phase of the most recent
84 // concurrent collection
85 double _latest_cms_remark_start_to_end_time_secs;
86 // Between start and end of the most recent MS STW marking phase
87 double _latest_cms_ms_marking_start_to_end_time_secs;
88
89 // Pause time timers
90 static elapsedTimer _STW_timer;
91 // Concurrent collection timer. Used for total of all concurrent phases
92 // during 1 collection cycle.
93 static elapsedTimer _concurrent_timer;
94
95 // When the size of the generation is changed, the size
96 // of the change will rounded up or down (depending on the
97 // type of change) by this value.
98 size_t _generation_alignment;
99
100 // If this variable is true, the size of the young generation
101 // may be changed in order to reduce the pause(s) of the
102 // collection of the tenured generation in order to meet the
103 // pause time goal. It is common to change the size of the
104 // tenured generation in order to meet the pause time goal
105 // for the tenured generation. With the CMS collector for
106 // the tenured generation, the size of the young generation
107 // can have an significant affect on the pause times for collecting the
108 // tenured generation.
109 // This is a duplicate of a variable in PSAdaptiveSizePolicy. It
110 // is duplicated because it is not clear that it is general enough
111 // to go into AdaptiveSizePolicy.
112 int _change_young_gen_for_maj_pauses;
113
114 // Variable that is set to true after a collection.
115 bool _first_after_collection;
116
117 // Fraction of collections that are of each type
118 double concurrent_fraction() const;
119 double STW_msc_fraction() const;
120 double STW_ms_fraction() const;
121
122 // This call cannot be put into the epilogue as long as some
123 // of the counters can be set during concurrent phases.
124 virtual void clear_generation_free_space_flags();
125
126 void set_first_after_collection() { _first_after_collection = true; }
127
128 protected:
129 // Average of the sum of the concurrent times for
130 // one collection in seconds.
131 AdaptiveWeightedAverage* _avg_concurrent_time;
132 // Average time between concurrent collections in seconds.
133 AdaptiveWeightedAverage* _avg_concurrent_interval;
134 // Average cost of the concurrent part of a collection
135 // in seconds.
136 AdaptiveWeightedAverage* _avg_concurrent_gc_cost;
137
138 // Average of the initial pause of a concurrent collection in seconds.
139 AdaptivePaddedAverage* _avg_initial_pause;
140 // Average of the remark pause of a concurrent collection in seconds.
141 AdaptivePaddedAverage* _avg_remark_pause;
142
143 // Average of the stop-the-world (STW) (initial mark + remark)
144 // times in seconds for concurrent collections.
145 AdaptiveWeightedAverage* _avg_cms_STW_time;
146 // Average of the STW collection cost for concurrent collections.
147 AdaptiveWeightedAverage* _avg_cms_STW_gc_cost;
148
149 // Average of the bytes free at the start of the sweep.
150 AdaptiveWeightedAverage* _avg_cms_free_at_sweep;
151 // Average of the bytes free at the end of the collection.
152 AdaptiveWeightedAverage* _avg_cms_free;
153 // Average of the bytes promoted between cms collections.
154 AdaptiveWeightedAverage* _avg_cms_promo;
155
156 // stop-the-world (STW) mark-sweep-compact
157 // Average of the pause time in seconds for STW mark-sweep-compact
158 // collections.
159 AdaptiveWeightedAverage* _avg_msc_pause;
160 // Average of the interval in seconds between STW mark-sweep-compact
161 // collections.
162 AdaptiveWeightedAverage* _avg_msc_interval;
163 // Average of the collection costs for STW mark-sweep-compact
164 // collections.
165 AdaptiveWeightedAverage* _avg_msc_gc_cost;
166
167 // Averages for mark-sweep collections.
168 // The collection may have started as a background collection
169 // that completes in a stop-the-world (STW) collection.
170 // Average of the pause time in seconds for mark-sweep
171 // collections.
172 AdaptiveWeightedAverage* _avg_ms_pause;
173 // Average of the interval in seconds between mark-sweep
174 // collections.
175 AdaptiveWeightedAverage* _avg_ms_interval;
176 // Average of the collection costs for mark-sweep
177 // collections.
178 AdaptiveWeightedAverage* _avg_ms_gc_cost;
179
180 // These variables contain a linear fit of
181 // a generation size as the independent variable
182 // and a pause time as the dependent variable.
183 // For example _remark_pause_old_estimator
184 // is a fit of the old generation size as the
185 // independent variable and the remark pause
186 // as the dependent variable.
187 // remark pause time vs. cms gen size
188 LinearLeastSquareFit* _remark_pause_old_estimator;
189 // initial pause time vs. cms gen size
190 LinearLeastSquareFit* _initial_pause_old_estimator;
191 // remark pause time vs. young gen size
192 LinearLeastSquareFit* _remark_pause_young_estimator;
193 // initial pause time vs. young gen size
194 LinearLeastSquareFit* _initial_pause_young_estimator;
195
196 // Accessors
197 int processor_count() const { return _processor_count; }
198 int concurrent_processor_count() const { return _concurrent_processor_count; }
199
200 AdaptiveWeightedAverage* avg_concurrent_time() const {
201 return _avg_concurrent_time;
202 }
203
204 AdaptiveWeightedAverage* avg_concurrent_interval() const {
205 return _avg_concurrent_interval;
206 }
207
208 AdaptiveWeightedAverage* avg_concurrent_gc_cost() const {
209 return _avg_concurrent_gc_cost;
210 }
211
212 AdaptiveWeightedAverage* avg_cms_STW_time() const {
213 return _avg_cms_STW_time;
214 }
215
216 AdaptiveWeightedAverage* avg_cms_STW_gc_cost() const {
217 return _avg_cms_STW_gc_cost;
218 }
219
220 AdaptivePaddedAverage* avg_initial_pause() const {
221 return _avg_initial_pause;
222 }
223
224 AdaptivePaddedAverage* avg_remark_pause() const {
225 return _avg_remark_pause;
226 }
227
228 AdaptiveWeightedAverage* avg_cms_free() const {
229 return _avg_cms_free;
230 }
231
232 AdaptiveWeightedAverage* avg_cms_free_at_sweep() const {
233 return _avg_cms_free_at_sweep;
234 }
235
236 AdaptiveWeightedAverage* avg_msc_pause() const {
237 return _avg_msc_pause;
238 }
239
240 AdaptiveWeightedAverage* avg_msc_interval() const {
241 return _avg_msc_interval;
242 }
243
244 AdaptiveWeightedAverage* avg_msc_gc_cost() const {
245 return _avg_msc_gc_cost;
246 }
247
248 AdaptiveWeightedAverage* avg_ms_pause() const {
249 return _avg_ms_pause;
250 }
251
252 AdaptiveWeightedAverage* avg_ms_interval() const {
253 return _avg_ms_interval;
254 }
255
256 AdaptiveWeightedAverage* avg_ms_gc_cost() const {
257 return _avg_ms_gc_cost;
258 }
259
260 LinearLeastSquareFit* remark_pause_old_estimator() {
261 return _remark_pause_old_estimator;
262 }
263 LinearLeastSquareFit* initial_pause_old_estimator() {
264 return _initial_pause_old_estimator;
265 }
266 LinearLeastSquareFit* remark_pause_young_estimator() {
267 return _remark_pause_young_estimator;
268 }
269 LinearLeastSquareFit* initial_pause_young_estimator() {
270 return _initial_pause_young_estimator;
271 }
272
273 // These *slope() methods return the slope
274 // m for the linear fit of an independent
275 // variable vs. a dependent variable. For
276 // example
277 // remark_pause = m * old_generation_size + c
278 // These may be used to determine if an
279 // adjustment should be made to achieve a goal.
280 // For example, if remark_pause_old_slope() is
281 // positive, a reduction of the old generation
282 // size has on average resulted in the reduction
283 // of the remark pause.
284 float remark_pause_old_slope() {
285 return _remark_pause_old_estimator->slope();
286 }
287
288 float initial_pause_old_slope() {
289 return _initial_pause_old_estimator->slope();
290 }
291
292 float remark_pause_young_slope() {
293 return _remark_pause_young_estimator->slope();
294 }
295
296 float initial_pause_young_slope() {
297 return _initial_pause_young_estimator->slope();
298 }
299
300 // Update estimators
301 void update_minor_pause_old_estimator(double minor_pause_in_ms);
302
303 // Fraction of processors used by the concurrent phases.
304 double concurrent_processor_fraction();
305
306 // Returns the total times for the concurrent part of the
307 // latest collection in seconds.
308 double concurrent_collection_time();
309
310 // Return the total times for the concurrent part of the
311 // latest collection in seconds where the times of the various
312 // concurrent phases are scaled by the processor fraction used
313 // during the phase.
314 double scaled_concurrent_collection_time();
315
316 // Dimensionless concurrent GC cost for all the concurrent phases.
317 double concurrent_collection_cost(double interval_in_seconds);
318
319 // Dimensionless GC cost
320 double collection_cost(double pause_in_seconds, double interval_in_seconds);
321
322 virtual GCPolicyKind kind() const { return _gc_cms_adaptive_size_policy; }
323
324 virtual double time_since_major_gc() const;
325
326 // This returns the maximum average for the concurrent, ms, and
327 // msc collections. This is meant to be used for the calculation
328 // of the decayed major gc cost and is not in general the
329 // average of all the different types of major collections.
330 virtual double major_gc_interval_average_for_decay() const;
331
332 public:
333 CMSAdaptiveSizePolicy(size_t init_eden_size,
334 size_t init_promo_size,
335 size_t init_survivor_size,
336 double max_gc_minor_pause_sec,
337 double max_gc_pause_sec,
338 uint gc_cost_ratio);
339
340 // The timers for the stop-the-world phases measure a total
341 // stop-the-world time. The timer is started and stopped
342 // for each phase but is only reset after the final checkpoint.
343 void checkpoint_roots_initial_begin();
344 void checkpoint_roots_initial_end(GCCause::Cause gc_cause);
345 void checkpoint_roots_final_begin();
346 void checkpoint_roots_final_end(GCCause::Cause gc_cause);
347
348 // Methods for gathering information about the
349 // concurrent marking phase of the collection.
350 // Records the mutator times and
351 // resets the concurrent timer.
352 void concurrent_marking_begin();
353 // Resets concurrent phase timer in the begin methods and
354 // saves the time for a phase in the end methods.
355 void concurrent_marking_end();
356 void concurrent_sweeping_begin();
357 void concurrent_sweeping_end();
358 // Similar to the above (e.g., concurrent_marking_end()) and
359 // is used for both the precleaning an abortable precleaing
360 // phases.
361 void concurrent_precleaning_begin();
362 void concurrent_precleaning_end();
363 // Stops the concurrent phases time. Gathers
364 // information and resets the timer.
365 void concurrent_phases_end(GCCause::Cause gc_cause,
366 size_t cur_eden,
367 size_t cur_promo);
368
369 // Methods for gather information about STW Mark-Sweep-Compact
370 void msc_collection_begin();
371 void msc_collection_end(GCCause::Cause gc_cause);
372
373 // Methods for gather information about Mark-Sweep done
374 // in the foreground.
375 void ms_collection_begin();
376 void ms_collection_end(GCCause::Cause gc_cause);
377
378 // Cost for a mark-sweep tenured gen collection done in the foreground
379 double ms_gc_cost() const {
380 return MAX2(0.0F, _avg_ms_gc_cost->average());
381 }
382
383 // Cost of collecting the tenured generation. Includes
384 // concurrent collection and STW collection costs
385 double cms_gc_cost() const;
386
387 // Cost of STW mark-sweep-compact tenured gen collection.
388 double msc_gc_cost() const {
389 return MAX2(0.0F, _avg_msc_gc_cost->average());
390 }
391
392 //
393 double compacting_gc_cost() const {
394 double result = MIN2(1.0, minor_gc_cost() + msc_gc_cost());
395 assert(result >= 0.0, "Both minor and major costs are non-negative");
396 return result;
397 }
398
399 // Restarts the concurrent phases timer.
400 void concurrent_phases_resume();
401
402 // Time beginning and end of the marking phase for
403 // a synchronous MS collection. A MS collection
404 // that finishes in the foreground can have started
405 // in the background. These methods capture the
406 // completion of the marking (after the initial
407 // marking) that is done in the foreground.
408 void ms_collection_marking_begin();
409 void ms_collection_marking_end(GCCause::Cause gc_cause);
410
411 static elapsedTimer* concurrent_timer_ptr() {
412 return &_concurrent_timer;
413 }
414
415 AdaptiveWeightedAverage* avg_cms_promo() const {
416 return _avg_cms_promo;
417 }
418
419 int change_young_gen_for_maj_pauses() {
420 return _change_young_gen_for_maj_pauses;
421 }
422 void set_change_young_gen_for_maj_pauses(int v) {
423 _change_young_gen_for_maj_pauses = v;
424 }
425
426 void clear_internal_time_intervals();
427
428
429 // Either calculated_promo_size_in_bytes() or promo_size()
430 // should be deleted.
431 size_t promo_size() { return _promo_size; }
432 void set_promo_size(size_t v) { _promo_size = v; }
433
434 // Cost of GC for all types of collections.
435 virtual double gc_cost() const;
436
437 size_t generation_alignment() { return _generation_alignment; }
438
439 virtual void compute_eden_space_size(size_t cur_eden,
440 size_t max_eden_size);
441 // Calculates new survivor space size; returns a new tenuring threshold
442 // value. Stores new survivor size in _survivor_size.
443 virtual uint compute_survivor_space_size_and_threshold(
444 bool is_survivor_overflow,
445 uint tenuring_threshold,
446 size_t survivor_limit);
447
448 virtual void compute_tenured_generation_free_space(size_t cur_tenured_free,
449 size_t max_tenured_available,
450 size_t cur_eden);
451
452 size_t eden_decrement_aligned_down(size_t cur_eden);
453 size_t eden_increment_aligned_up(size_t cur_eden);
454
455 size_t adjust_eden_for_pause_time(size_t cur_eden);
456 size_t adjust_eden_for_throughput(size_t cur_eden);
457 size_t adjust_eden_for_footprint(size_t cur_eden);
458
459 size_t promo_decrement_aligned_down(size_t cur_promo);
460 size_t promo_increment_aligned_up(size_t cur_promo);
461
462 size_t adjust_promo_for_pause_time(size_t cur_promo);
463 size_t adjust_promo_for_throughput(size_t cur_promo);
464 size_t adjust_promo_for_footprint(size_t cur_promo, size_t cur_eden);
465
466 // Scale down the input size by the ratio of the cost to collect the
467 // generation to the total GC cost.
468 size_t scale_by_gen_gc_cost(size_t base_change, double gen_gc_cost);
469
470 // Return the value and clear it.
471 bool get_and_clear_first_after_collection();
472
473 // Printing support
474 virtual bool print_adaptive_size_policy_on(outputStream* st) const;
475 };
476
477 #endif // SHARE_VM_GC_IMPLEMENTATION_CONCURRENTMARKSWEEP_CMSADAPTIVESIZEPOLICY_HPP