Wed, 03 Oct 2012 20:31:41 +0200
8000351: Tenuring threshold should be unsigned
Summary: Change the flags and variables related to tenuring threshold to be unsigned
Reviewed-by: jmasa, johnc
1 /*
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25 #ifndef SHARE_VM_GC_IMPLEMENTATION_SHARED_ADAPTIVESIZEPOLICY_HPP
26 #define SHARE_VM_GC_IMPLEMENTATION_SHARED_ADAPTIVESIZEPOLICY_HPP
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"
34 // This class keeps statistical information and computes the
35 // size of the heap.
37 // Forward decls
38 class elapsedTimer;
39 class CollectorPolicy;
41 class AdaptiveSizePolicy : public CHeapObj<mtGC> {
42 friend class GCAdaptivePolicyCounters;
43 friend class PSGCAdaptivePolicyCounters;
44 friend class CMSGCAdaptivePolicyCounters;
45 protected:
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; }
54 enum SizePolicyTrueValues {
55 decrease_old_gen_for_throughput_true = -7,
56 decrease_young_gen_for_througput_true = -6,
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,
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,
68 increase_old_gen_for_throughput_true = 4,
69 increase_young_gen_for_througput_true = 5,
71 decrease_young_gen_for_footprint_true = 6,
72 decrease_old_gen_for_footprint_true = 7,
73 decide_at_full_gc_true = 8
74 };
76 // Goal for the fraction of the total time during which application
77 // threads run.
78 const double _throughput_goal;
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
84 size_t _survivor_size; // calculated survivor size in bytes
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.
99 // Minor collection timers used to determine both
100 // pause and interval times for collections.
101 static elapsedTimer _minor_timer;
103 // Major collection timers, used to determine both
104 // pause and interval times for collections
105 static elapsedTimer _major_timer;
107 // Time statistics
108 AdaptivePaddedAverage* _avg_minor_pause;
109 AdaptiveWeightedAverage* _avg_minor_interval;
110 AdaptiveWeightedAverage* _avg_minor_gc_cost;
112 AdaptiveWeightedAverage* _avg_major_interval;
113 AdaptiveWeightedAverage* _avg_major_gc_cost;
115 // Footprint statistics
116 AdaptiveWeightedAverage* _avg_young_live;
117 AdaptiveWeightedAverage* _avg_eden_live;
118 AdaptiveWeightedAverage* _avg_old_live;
120 // Statistics for survivor space calculation for young generation
121 AdaptivePaddedAverage* _avg_survived;
123 // Objects that have been directly allocated in the old generation.
124 AdaptivePaddedNoZeroDevAverage* _avg_pretenured;
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;
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;
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;
145 // Allowed difference between major and minor gc times, used
146 // for computing tenuring_threshold.
147 const double _threshold_tolerance_percent;
149 const double _gc_pause_goal_sec; // goal for maximum gc pause
151 // Flag indicating that the adaptive policy is ready to use
152 bool _young_gen_policy_is_ready;
154 // decrease/increase the young generation for minor pause time
155 int _change_young_gen_for_min_pauses;
157 // decrease/increase the old generation for major pause time
158 int _change_old_gen_for_maj_pauses;
160 // change old geneneration for throughput
161 int _change_old_gen_for_throughput;
163 // change young generation for throughput
164 int _change_young_gen_for_throughput;
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;
176 // decrease generation sizes for footprint
177 int _decrease_for_footprint;
179 // Set if the ergonomic decisions were made at a full GC.
180 int _decide_at_full_gc;
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;
190 static const uint GCWorkersPerJavaThread = 2;
192 // Accessors
194 double gc_pause_goal_sec() const { return _gc_pause_goal_sec; }
195 // The value returned is unitless: it's the proportion of time
196 // spent in a particular collection type.
197 // An interval time will be 0.0 if a collection type hasn't occurred yet.
198 // The 1.4.2 implementation put a floor on the values of major_gc_cost
199 // and minor_gc_cost. This was useful because of the way major_gc_cost
200 // and minor_gc_cost was used in calculating the sizes of the generations.
201 // Do not use a floor in this implementation because any finite value
202 // will put a limit on the throughput that can be achieved and any
203 // throughput goal above that limit will drive the generations sizes
204 // to extremes.
205 double major_gc_cost() const {
206 return MAX2(0.0F, _avg_major_gc_cost->average());
207 }
209 // The value returned is unitless: it's the proportion of time
210 // spent in a particular collection type.
211 // An interval time will be 0.0 if a collection type hasn't occurred yet.
212 // The 1.4.2 implementation put a floor on the values of major_gc_cost
213 // and minor_gc_cost. This was useful because of the way major_gc_cost
214 // and minor_gc_cost was used in calculating the sizes of the generations.
215 // Do not use a floor in this implementation because any finite value
216 // will put a limit on the throughput that can be achieved and any
217 // throughput goal above that limit will drive the generations sizes
218 // to extremes.
220 double minor_gc_cost() const {
221 return MAX2(0.0F, _avg_minor_gc_cost->average());
222 }
224 // Because we're dealing with averages, gc_cost() can be
225 // larger than 1.0 if just the sum of the minor cost the
226 // the major cost is used. Worse than that is the
227 // fact that the minor cost and the major cost each
228 // tend toward 1.0 in the extreme of high gc costs.
229 // Limit the value of gc_cost to 1.0 so that the mutator
230 // cost stays non-negative.
231 virtual double gc_cost() const {
232 double result = MIN2(1.0, minor_gc_cost() + major_gc_cost());
233 assert(result >= 0.0, "Both minor and major costs are non-negative");
234 return result;
235 }
237 // Elapsed time since the last major collection.
238 virtual double time_since_major_gc() const;
240 // Average interval between major collections to be used
241 // in calculating the decaying major gc cost. An overestimate
242 // of this time would be a conservative estimate because
243 // this time is used to decide if the major GC cost
244 // should be decayed (i.e., if the time since the last
245 // major gc is long compared to the time returned here,
246 // then the major GC cost will be decayed). See the
247 // implementations for the specifics.
248 virtual double major_gc_interval_average_for_decay() const {
249 return _avg_major_interval->average();
250 }
252 // Return the cost of the GC where the major gc cost
253 // has been decayed based on the time since the last
254 // major collection.
255 double decaying_gc_cost() const;
257 // Decay the major gc cost. Use this only for decisions on
258 // whether to adjust, not to determine by how much to adjust.
259 // This approximation is crude and may not be good enough for the
260 // latter.
261 double decaying_major_gc_cost() const;
263 // Return the mutator cost using the decayed
264 // GC cost.
265 double adjusted_mutator_cost() const {
266 double result = 1.0 - decaying_gc_cost();
267 assert(result >= 0.0, "adjusted mutator cost calculation is incorrect");
268 return result;
269 }
271 virtual double mutator_cost() const {
272 double result = 1.0 - gc_cost();
273 assert(result >= 0.0, "mutator cost calculation is incorrect");
274 return result;
275 }
278 bool young_gen_policy_is_ready() { return _young_gen_policy_is_ready; }
280 void update_minor_pause_young_estimator(double minor_pause_in_ms);
281 virtual void update_minor_pause_old_estimator(double minor_pause_in_ms) {
282 // This is not meaningful for all policies but needs to be present
283 // to use minor_collection_end() in its current form.
284 }
286 virtual size_t eden_increment(size_t cur_eden);
287 virtual size_t eden_increment(size_t cur_eden, uint percent_change);
288 virtual size_t eden_decrement(size_t cur_eden);
289 virtual size_t promo_increment(size_t cur_eden);
290 virtual size_t promo_increment(size_t cur_eden, uint percent_change);
291 virtual size_t promo_decrement(size_t cur_eden);
293 virtual void clear_generation_free_space_flags();
295 int change_old_gen_for_throughput() const {
296 return _change_old_gen_for_throughput;
297 }
298 void set_change_old_gen_for_throughput(int v) {
299 _change_old_gen_for_throughput = v;
300 }
301 int change_young_gen_for_throughput() const {
302 return _change_young_gen_for_throughput;
303 }
304 void set_change_young_gen_for_throughput(int v) {
305 _change_young_gen_for_throughput = v;
306 }
308 int change_old_gen_for_maj_pauses() const {
309 return _change_old_gen_for_maj_pauses;
310 }
311 void set_change_old_gen_for_maj_pauses(int v) {
312 _change_old_gen_for_maj_pauses = v;
313 }
315 bool decrement_tenuring_threshold_for_gc_cost() const {
316 return _decrement_tenuring_threshold_for_gc_cost;
317 }
318 void set_decrement_tenuring_threshold_for_gc_cost(bool v) {
319 _decrement_tenuring_threshold_for_gc_cost = v;
320 }
321 bool increment_tenuring_threshold_for_gc_cost() const {
322 return _increment_tenuring_threshold_for_gc_cost;
323 }
324 void set_increment_tenuring_threshold_for_gc_cost(bool v) {
325 _increment_tenuring_threshold_for_gc_cost = v;
326 }
327 bool decrement_tenuring_threshold_for_survivor_limit() const {
328 return _decrement_tenuring_threshold_for_survivor_limit;
329 }
330 void set_decrement_tenuring_threshold_for_survivor_limit(bool v) {
331 _decrement_tenuring_threshold_for_survivor_limit = v;
332 }
333 // Return true if the policy suggested a change.
334 bool tenuring_threshold_change() const;
336 static bool _debug_perturbation;
338 public:
339 AdaptiveSizePolicy(size_t init_eden_size,
340 size_t init_promo_size,
341 size_t init_survivor_size,
342 double gc_pause_goal_sec,
343 uint gc_cost_ratio);
345 // Return number default GC threads to use in the next GC.
346 static int calc_default_active_workers(uintx total_workers,
347 const uintx min_workers,
348 uintx active_workers,
349 uintx application_workers);
351 // Return number of GC threads to use in the next GC.
352 // This is called sparingly so as not to change the
353 // number of GC workers gratuitously.
354 // For ParNew collections
355 // For PS scavenge and ParOld collections
356 // For G1 evacuation pauses (subject to update)
357 // Other collection phases inherit the number of
358 // GC workers from the calls above. For example,
359 // a CMS parallel remark uses the same number of GC
360 // workers as the most recent ParNew collection.
361 static int calc_active_workers(uintx total_workers,
362 uintx active_workers,
363 uintx application_workers);
365 // Return number of GC threads to use in the next concurrent GC phase.
366 static int calc_active_conc_workers(uintx total_workers,
367 uintx active_workers,
368 uintx application_workers);
370 bool is_gc_cms_adaptive_size_policy() {
371 return kind() == _gc_cms_adaptive_size_policy;
372 }
373 bool is_gc_ps_adaptive_size_policy() {
374 return kind() == _gc_ps_adaptive_size_policy;
375 }
377 AdaptivePaddedAverage* avg_minor_pause() const { return _avg_minor_pause; }
378 AdaptiveWeightedAverage* avg_minor_interval() const {
379 return _avg_minor_interval;
380 }
381 AdaptiveWeightedAverage* avg_minor_gc_cost() const {
382 return _avg_minor_gc_cost;
383 }
385 AdaptiveWeightedAverage* avg_major_gc_cost() const {
386 return _avg_major_gc_cost;
387 }
389 AdaptiveWeightedAverage* avg_young_live() const { return _avg_young_live; }
390 AdaptiveWeightedAverage* avg_eden_live() const { return _avg_eden_live; }
391 AdaptiveWeightedAverage* avg_old_live() const { return _avg_old_live; }
393 AdaptivePaddedAverage* avg_survived() const { return _avg_survived; }
394 AdaptivePaddedNoZeroDevAverage* avg_pretenured() { return _avg_pretenured; }
396 // Methods indicating events of interest to the adaptive size policy,
397 // called by GC algorithms. It is the responsibility of users of this
398 // policy to call these methods at the correct times!
399 virtual void minor_collection_begin();
400 virtual void minor_collection_end(GCCause::Cause gc_cause);
401 virtual LinearLeastSquareFit* minor_pause_old_estimator() const {
402 return _minor_pause_old_estimator;
403 }
405 LinearLeastSquareFit* minor_pause_young_estimator() {
406 return _minor_pause_young_estimator;
407 }
408 LinearLeastSquareFit* minor_collection_estimator() {
409 return _minor_collection_estimator;
410 }
412 LinearLeastSquareFit* major_collection_estimator() {
413 return _major_collection_estimator;
414 }
416 float minor_pause_young_slope() {
417 return _minor_pause_young_estimator->slope();
418 }
420 float minor_collection_slope() { return _minor_collection_estimator->slope();}
421 float major_collection_slope() { return _major_collection_estimator->slope();}
423 float minor_pause_old_slope() {
424 return _minor_pause_old_estimator->slope();
425 }
427 void set_eden_size(size_t new_size) {
428 _eden_size = new_size;
429 }
430 void set_survivor_size(size_t new_size) {
431 _survivor_size = new_size;
432 }
434 size_t calculated_eden_size_in_bytes() const {
435 return _eden_size;
436 }
438 size_t calculated_promo_size_in_bytes() const {
439 return _promo_size;
440 }
442 size_t calculated_survivor_size_in_bytes() const {
443 return _survivor_size;
444 }
446 // This is a hint for the heap: we've detected that gc times
447 // are taking longer than GCTimeLimit allows.
448 // Most heaps will choose to throw an OutOfMemoryError when
449 // this occurs but it is up to the heap to request this information
450 // of the policy
451 bool gc_overhead_limit_exceeded() {
452 return _gc_overhead_limit_exceeded;
453 }
454 void set_gc_overhead_limit_exceeded(bool v) {
455 _gc_overhead_limit_exceeded = v;
456 }
458 // Tests conditions indicate the GC overhead limit is being approached.
459 bool gc_overhead_limit_near() {
460 return gc_overhead_limit_count() >=
461 (AdaptiveSizePolicyGCTimeLimitThreshold - 1);
462 }
463 uint gc_overhead_limit_count() { return _gc_overhead_limit_count; }
464 void reset_gc_overhead_limit_count() { _gc_overhead_limit_count = 0; }
465 void inc_gc_overhead_limit_count() { _gc_overhead_limit_count++; }
466 // accessors for flags recording the decisions to resize the
467 // generations to meet the pause goal.
469 int change_young_gen_for_min_pauses() const {
470 return _change_young_gen_for_min_pauses;
471 }
472 void set_change_young_gen_for_min_pauses(int v) {
473 _change_young_gen_for_min_pauses = v;
474 }
475 void set_decrease_for_footprint(int v) { _decrease_for_footprint = v; }
476 int decrease_for_footprint() const { return _decrease_for_footprint; }
477 int decide_at_full_gc() { return _decide_at_full_gc; }
478 void set_decide_at_full_gc(int v) { _decide_at_full_gc = v; }
480 // Check the conditions for an out-of-memory due to excessive GC time.
481 // Set _gc_overhead_limit_exceeded if all the conditions have been met.
482 void check_gc_overhead_limit(size_t young_live,
483 size_t eden_live,
484 size_t max_old_gen_size,
485 size_t max_eden_size,
486 bool is_full_gc,
487 GCCause::Cause gc_cause,
488 CollectorPolicy* collector_policy);
490 // Printing support
491 virtual bool print_adaptive_size_policy_on(outputStream* st) const;
492 bool print_adaptive_size_policy_on(outputStream* st,
493 uint tenuring_threshold) const;
494 };
496 // Class that can be used to print information about the
497 // adaptive size policy at intervals specified by
498 // AdaptiveSizePolicyOutputInterval. Only print information
499 // if an adaptive size policy is in use.
500 class AdaptiveSizePolicyOutput : StackObj {
501 AdaptiveSizePolicy* _size_policy;
502 bool _do_print;
503 bool print_test(uint count) {
504 // A count of zero is a special value that indicates that the
505 // interval test should be ignored. An interval is of zero is
506 // a special value that indicates that the interval test should
507 // always fail (never do the print based on the interval test).
508 return PrintGCDetails &&
509 UseAdaptiveSizePolicy &&
510 (UseParallelGC || UseConcMarkSweepGC) &&
511 (AdaptiveSizePolicyOutputInterval > 0) &&
512 ((count == 0) ||
513 ((count % AdaptiveSizePolicyOutputInterval) == 0));
514 }
515 public:
516 // The special value of a zero count can be used to ignore
517 // the count test.
518 AdaptiveSizePolicyOutput(uint count) {
519 if (UseAdaptiveSizePolicy && (AdaptiveSizePolicyOutputInterval > 0)) {
520 CollectedHeap* heap = Universe::heap();
521 _size_policy = heap->size_policy();
522 _do_print = print_test(count);
523 } else {
524 _size_policy = NULL;
525 _do_print = false;
526 }
527 }
528 AdaptiveSizePolicyOutput(AdaptiveSizePolicy* size_policy,
529 uint count) :
530 _size_policy(size_policy) {
531 if (UseAdaptiveSizePolicy && (AdaptiveSizePolicyOutputInterval > 0)) {
532 _do_print = print_test(count);
533 } else {
534 _do_print = false;
535 }
536 }
537 ~AdaptiveSizePolicyOutput() {
538 if (_do_print) {
539 assert(UseAdaptiveSizePolicy, "Should not be in use");
540 _size_policy->print_adaptive_size_policy_on(gclog_or_tty);
541 }
542 }
543 };
545 #endif // SHARE_VM_GC_IMPLEMENTATION_SHARED_ADAPTIVESIZEPOLICY_HPP