Wed, 15 May 2013 10:41:22 -0700
8007763: Refactoring: split up compute_generation_free_space() into two functions for class PSAdaptiveSizePolicy
Summary: split up compute_generation_free_space() into two functions: compute_eden_space_size() + compute_old_gen_free_space(), each of which (if needed) can be reused without executing an overhead of the other.
Reviewed-by: jmasa, tschatzl
Contributed-by: tamao <tao.mao@oracle.com>
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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23 */
25 #include "precompiled.hpp"
26 #include "gc_implementation/parallelScavenge/generationSizer.hpp"
27 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
28 #include "gc_implementation/parallelScavenge/psGCAdaptivePolicyCounters.hpp"
29 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
30 #include "gc_implementation/shared/gcPolicyCounters.hpp"
31 #include "gc_interface/gcCause.hpp"
32 #include "memory/collectorPolicy.hpp"
33 #include "runtime/timer.hpp"
34 #include "utilities/top.hpp"
36 #include <math.h>
38 PSAdaptiveSizePolicy::PSAdaptiveSizePolicy(size_t init_eden_size,
39 size_t init_promo_size,
40 size_t init_survivor_size,
41 size_t intra_generation_alignment,
42 double gc_pause_goal_sec,
43 double gc_minor_pause_goal_sec,
44 uint gc_cost_ratio) :
45 AdaptiveSizePolicy(init_eden_size,
46 init_promo_size,
47 init_survivor_size,
48 gc_pause_goal_sec,
49 gc_cost_ratio),
50 _collection_cost_margin_fraction(AdaptiveSizePolicyCollectionCostMargin/
51 100.0),
52 _intra_generation_alignment(intra_generation_alignment),
53 _live_at_last_full_gc(init_promo_size),
54 _gc_minor_pause_goal_sec(gc_minor_pause_goal_sec),
55 _latest_major_mutator_interval_seconds(0),
56 _young_gen_change_for_major_pause_count(0)
57 {
58 // Sizing policy statistics
59 _avg_major_pause =
60 new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding);
61 _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
62 _avg_major_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
64 _avg_base_footprint = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
65 _major_pause_old_estimator =
66 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
67 _major_pause_young_estimator =
68 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
69 _major_collection_estimator =
70 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
72 _young_gen_size_increment_supplement = YoungGenerationSizeSupplement;
73 _old_gen_size_increment_supplement = TenuredGenerationSizeSupplement;
75 // Start the timers
76 _major_timer.start();
78 _old_gen_policy_is_ready = false;
79 }
81 void PSAdaptiveSizePolicy::major_collection_begin() {
82 // Update the interval time
83 _major_timer.stop();
84 // Save most recent collection time
85 _latest_major_mutator_interval_seconds = _major_timer.seconds();
86 _major_timer.reset();
87 _major_timer.start();
88 }
90 void PSAdaptiveSizePolicy::update_minor_pause_old_estimator(
91 double minor_pause_in_ms) {
92 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
93 _minor_pause_old_estimator->update(promo_size_in_mbytes,
94 minor_pause_in_ms);
95 }
97 void PSAdaptiveSizePolicy::major_collection_end(size_t amount_live,
98 GCCause::Cause gc_cause) {
99 // Update the pause time.
100 _major_timer.stop();
102 if (gc_cause != GCCause::_java_lang_system_gc ||
103 UseAdaptiveSizePolicyWithSystemGC) {
104 double major_pause_in_seconds = _major_timer.seconds();
105 double major_pause_in_ms = major_pause_in_seconds * MILLIUNITS;
107 // Sample for performance counter
108 _avg_major_pause->sample(major_pause_in_seconds);
110 // Cost of collection (unit-less)
111 double collection_cost = 0.0;
112 if ((_latest_major_mutator_interval_seconds > 0.0) &&
113 (major_pause_in_seconds > 0.0)) {
114 double interval_in_seconds =
115 _latest_major_mutator_interval_seconds + major_pause_in_seconds;
116 collection_cost =
117 major_pause_in_seconds / interval_in_seconds;
118 avg_major_gc_cost()->sample(collection_cost);
120 // Sample for performance counter
121 _avg_major_interval->sample(interval_in_seconds);
122 }
124 // Calculate variables used to estimate pause time vs. gen sizes
125 double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
126 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
127 _major_pause_old_estimator->update(promo_size_in_mbytes,
128 major_pause_in_ms);
129 _major_pause_young_estimator->update(eden_size_in_mbytes,
130 major_pause_in_ms);
132 if (PrintAdaptiveSizePolicy && Verbose) {
133 gclog_or_tty->print("psAdaptiveSizePolicy::major_collection_end: "
134 "major gc cost: %f average: %f", collection_cost,
135 avg_major_gc_cost()->average());
136 gclog_or_tty->print_cr(" major pause: %f major period %f",
137 major_pause_in_ms,
138 _latest_major_mutator_interval_seconds * MILLIUNITS);
139 }
141 // Calculate variable used to estimate collection cost vs. gen sizes
142 assert(collection_cost >= 0.0, "Expected to be non-negative");
143 _major_collection_estimator->update(promo_size_in_mbytes,
144 collection_cost);
145 }
147 // Update the amount live at the end of a full GC
148 _live_at_last_full_gc = amount_live;
150 // The policy does not have enough data until at least some major collections
151 // have been done.
152 if (_avg_major_pause->count() >= AdaptiveSizePolicyReadyThreshold) {
153 _old_gen_policy_is_ready = true;
154 }
156 // Interval times use this timer to measure the interval that
157 // the mutator runs. Reset after the GC pause has been measured.
158 _major_timer.reset();
159 _major_timer.start();
160 }
162 // If the remaining free space in the old generation is less that
163 // that expected to be needed by the next collection, do a full
164 // collection now.
165 bool PSAdaptiveSizePolicy::should_full_GC(size_t old_free_in_bytes) {
167 // A similar test is done in the scavenge's should_attempt_scavenge(). If
168 // this is changed, decide if that test should also be changed.
169 bool result = padded_average_promoted_in_bytes() > (float) old_free_in_bytes;
170 if (PrintGCDetails && Verbose) {
171 if (result) {
172 gclog_or_tty->print(" full after scavenge: ");
173 } else {
174 gclog_or_tty->print(" no full after scavenge: ");
175 }
176 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
177 " padded_average_promoted " SIZE_FORMAT
178 " free in old gen " SIZE_FORMAT,
179 (size_t) average_promoted_in_bytes(),
180 (size_t) padded_average_promoted_in_bytes(),
181 old_free_in_bytes);
182 }
183 return result;
184 }
186 void PSAdaptiveSizePolicy::clear_generation_free_space_flags() {
188 AdaptiveSizePolicy::clear_generation_free_space_flags();
190 set_change_old_gen_for_min_pauses(0);
192 set_change_young_gen_for_maj_pauses(0);
193 }
195 // If this is not a full GC, only test and modify the young generation.
197 void PSAdaptiveSizePolicy::compute_generation_free_space(
198 size_t young_live,
199 size_t eden_live,
200 size_t old_live,
201 size_t cur_eden,
202 size_t max_old_gen_size,
203 size_t max_eden_size,
204 bool is_full_gc) {
205 compute_eden_space_size(young_live,
206 eden_live,
207 cur_eden,
208 max_eden_size,
209 is_full_gc);
211 compute_old_gen_free_space(old_live,
212 cur_eden,
213 max_old_gen_size,
214 is_full_gc);
215 }
217 void PSAdaptiveSizePolicy::compute_eden_space_size(
218 size_t young_live,
219 size_t eden_live,
220 size_t cur_eden,
221 size_t max_eden_size,
222 bool is_full_gc) {
224 // Update statistics
225 // Time statistics are updated as we go, update footprint stats here
226 _avg_base_footprint->sample(BaseFootPrintEstimate);
227 avg_young_live()->sample(young_live);
228 avg_eden_live()->sample(eden_live);
230 // This code used to return if the policy was not ready , i.e.,
231 // policy_is_ready() returning false. The intent was that
232 // decisions below needed major collection times and so could
233 // not be made before two major collections. A consequence was
234 // adjustments to the young generation were not done until after
235 // two major collections even if the minor collections times
236 // exceeded the requested goals. Now let the young generation
237 // adjust for the minor collection times. Major collection times
238 // will be zero for the first collection and will naturally be
239 // ignored. Tenured generation adjustments are only made at the
240 // full collections so until the second major collection has
241 // been reached, no tenured generation adjustments will be made.
243 // Until we know better, desired promotion size uses the last calculation
244 size_t desired_promo_size = _promo_size;
246 // Start eden at the current value. The desired value that is stored
247 // in _eden_size is not bounded by constraints of the heap and can
248 // run away.
249 //
250 // As expected setting desired_eden_size to the current
251 // value of desired_eden_size as a starting point
252 // caused desired_eden_size to grow way too large and caused
253 // an overflow down stream. It may have improved performance in
254 // some case but is dangerous.
255 size_t desired_eden_size = cur_eden;
257 // Cache some values. There's a bit of work getting these, so
258 // we might save a little time.
259 const double major_cost = major_gc_cost();
260 const double minor_cost = minor_gc_cost();
262 // This method sets the desired eden size. That plus the
263 // desired survivor space sizes sets the desired young generation
264 // size. This methods does not know what the desired survivor
265 // size is but expects that other policy will attempt to make
266 // the survivor sizes compatible with the live data in the
267 // young generation. This limit is an estimate of the space left
268 // in the young generation after the survivor spaces have been
269 // subtracted out.
270 size_t eden_limit = max_eden_size;
272 const double gc_cost_limit = GCTimeLimit/100.0;
274 // Which way should we go?
275 // if pause requirement is not met
276 // adjust size of any generation with average paus exceeding
277 // the pause limit. Adjust one pause at a time (the larger)
278 // and only make adjustments for the major pause at full collections.
279 // else if throughput requirement not met
280 // adjust the size of the generation with larger gc time. Only
281 // adjust one generation at a time.
282 // else
283 // adjust down the total heap size. Adjust down the larger of the
284 // generations.
286 // Add some checks for a threshold for a change. For example,
287 // a change less than the necessary alignment is probably not worth
288 // attempting.
291 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
292 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
293 //
294 // Check pauses
295 //
296 // Make changes only to affect one of the pauses (the larger)
297 // at a time.
298 adjust_eden_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
300 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
301 // Adjust only for the minor pause time goal
302 adjust_eden_for_minor_pause_time(is_full_gc, &desired_eden_size);
304 } else if(adjusted_mutator_cost() < _throughput_goal) {
305 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
306 // This sometimes resulted in skipping to the minimize footprint
307 // code. Change this to try and reduce GC time if mutator time is
308 // negative for whatever reason. Or for future consideration,
309 // bail out of the code if mutator time is negative.
310 //
311 // Throughput
312 //
313 assert(major_cost >= 0.0, "major cost is < 0.0");
314 assert(minor_cost >= 0.0, "minor cost is < 0.0");
315 // Try to reduce the GC times.
316 adjust_eden_for_throughput(is_full_gc, &desired_eden_size);
318 } else {
320 // Be conservative about reducing the footprint.
321 // Do a minimum number of major collections first.
322 // Have reasonable averages for major and minor collections costs.
323 if (UseAdaptiveSizePolicyFootprintGoal &&
324 young_gen_policy_is_ready() &&
325 avg_major_gc_cost()->average() >= 0.0 &&
326 avg_minor_gc_cost()->average() >= 0.0) {
327 size_t desired_sum = desired_eden_size + desired_promo_size;
328 desired_eden_size = adjust_eden_for_footprint(desired_eden_size, desired_sum);
329 }
330 }
332 // Note we make the same tests as in the code block below; the code
333 // seems a little easier to read with the printing in another block.
334 if (PrintAdaptiveSizePolicy) {
335 if (desired_eden_size > eden_limit) {
336 gclog_or_tty->print_cr(
337 "PSAdaptiveSizePolicy::compute_eden_space_size limits:"
338 " desired_eden_size: " SIZE_FORMAT
339 " old_eden_size: " SIZE_FORMAT
340 " eden_limit: " SIZE_FORMAT
341 " cur_eden: " SIZE_FORMAT
342 " max_eden_size: " SIZE_FORMAT
343 " avg_young_live: " SIZE_FORMAT,
344 desired_eden_size, _eden_size, eden_limit, cur_eden,
345 max_eden_size, (size_t)avg_young_live()->average());
346 }
347 if (gc_cost() > gc_cost_limit) {
348 gclog_or_tty->print_cr(
349 "PSAdaptiveSizePolicy::compute_eden_space_size: gc time limit"
350 " gc_cost: %f "
351 " GCTimeLimit: %d",
352 gc_cost(), GCTimeLimit);
353 }
354 }
356 // Align everything and make a final limit check
357 const size_t alignment = _intra_generation_alignment;
358 desired_eden_size = align_size_up(desired_eden_size, alignment);
359 desired_eden_size = MAX2(desired_eden_size, alignment);
361 eden_limit = align_size_down(eden_limit, alignment);
363 // And one last limit check, now that we've aligned things.
364 if (desired_eden_size > eden_limit) {
365 // If the policy says to get a larger eden but
366 // is hitting the limit, don't decrease eden.
367 // This can lead to a general drifting down of the
368 // eden size. Let the tenuring calculation push more
369 // into the old gen.
370 desired_eden_size = MAX2(eden_limit, cur_eden);
371 }
373 if (PrintAdaptiveSizePolicy) {
374 // Timing stats
375 gclog_or_tty->print(
376 "PSAdaptiveSizePolicy::compute_eden_space_size: costs"
377 " minor_time: %f"
378 " major_cost: %f"
379 " mutator_cost: %f"
380 " throughput_goal: %f",
381 minor_gc_cost(), major_gc_cost(), mutator_cost(),
382 _throughput_goal);
384 // We give more details if Verbose is set
385 if (Verbose) {
386 gclog_or_tty->print( " minor_pause: %f"
387 " major_pause: %f"
388 " minor_interval: %f"
389 " major_interval: %f"
390 " pause_goal: %f",
391 _avg_minor_pause->padded_average(),
392 _avg_major_pause->padded_average(),
393 _avg_minor_interval->average(),
394 _avg_major_interval->average(),
395 gc_pause_goal_sec());
396 }
398 // Footprint stats
399 gclog_or_tty->print( " live_space: " SIZE_FORMAT
400 " free_space: " SIZE_FORMAT,
401 live_space(), free_space());
402 // More detail
403 if (Verbose) {
404 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
405 " avg_young_live: " SIZE_FORMAT
406 " avg_old_live: " SIZE_FORMAT,
407 (size_t)_avg_base_footprint->average(),
408 (size_t)avg_young_live()->average(),
409 (size_t)avg_old_live()->average());
410 }
412 // And finally, our old and new sizes.
413 gclog_or_tty->print(" old_eden_size: " SIZE_FORMAT
414 " desired_eden_size: " SIZE_FORMAT,
415 _eden_size, desired_eden_size);
416 gclog_or_tty->cr();
417 }
419 set_eden_size(desired_eden_size);
420 }
422 void PSAdaptiveSizePolicy::compute_old_gen_free_space(
423 size_t old_live,
424 size_t cur_eden,
425 size_t max_old_gen_size,
426 bool is_full_gc) {
428 // Update statistics
429 // Time statistics are updated as we go, update footprint stats here
430 if (is_full_gc) {
431 // old_live is only accurate after a full gc
432 avg_old_live()->sample(old_live);
433 }
435 // This code used to return if the policy was not ready , i.e.,
436 // policy_is_ready() returning false. The intent was that
437 // decisions below needed major collection times and so could
438 // not be made before two major collections. A consequence was
439 // adjustments to the young generation were not done until after
440 // two major collections even if the minor collections times
441 // exceeded the requested goals. Now let the young generation
442 // adjust for the minor collection times. Major collection times
443 // will be zero for the first collection and will naturally be
444 // ignored. Tenured generation adjustments are only made at the
445 // full collections so until the second major collection has
446 // been reached, no tenured generation adjustments will be made.
448 // Until we know better, desired promotion size uses the last calculation
449 size_t desired_promo_size = _promo_size;
451 // Start eden at the current value. The desired value that is stored
452 // in _eden_size is not bounded by constraints of the heap and can
453 // run away.
454 //
455 // As expected setting desired_eden_size to the current
456 // value of desired_eden_size as a starting point
457 // caused desired_eden_size to grow way too large and caused
458 // an overflow down stream. It may have improved performance in
459 // some case but is dangerous.
460 size_t desired_eden_size = cur_eden;
462 // Cache some values. There's a bit of work getting these, so
463 // we might save a little time.
464 const double major_cost = major_gc_cost();
465 const double minor_cost = minor_gc_cost();
467 // Limits on our growth
468 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());
470 // But don't force a promo size below the current promo size. Otherwise,
471 // the promo size will shrink for no good reason.
472 promo_limit = MAX2(promo_limit, _promo_size);
474 const double gc_cost_limit = GCTimeLimit/100.0;
476 // Which way should we go?
477 // if pause requirement is not met
478 // adjust size of any generation with average paus exceeding
479 // the pause limit. Adjust one pause at a time (the larger)
480 // and only make adjustments for the major pause at full collections.
481 // else if throughput requirement not met
482 // adjust the size of the generation with larger gc time. Only
483 // adjust one generation at a time.
484 // else
485 // adjust down the total heap size. Adjust down the larger of the
486 // generations.
488 // Add some checks for a threshhold for a change. For example,
489 // a change less than the necessary alignment is probably not worth
490 // attempting.
492 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
493 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
494 //
495 // Check pauses
496 //
497 // Make changes only to affect one of the pauses (the larger)
498 // at a time.
499 if (is_full_gc) {
500 set_decide_at_full_gc(decide_at_full_gc_true);
501 adjust_promo_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
502 }
503 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
504 // Adjust only for the minor pause time goal
505 adjust_promo_for_minor_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
506 } else if(adjusted_mutator_cost() < _throughput_goal) {
507 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
508 // This sometimes resulted in skipping to the minimize footprint
509 // code. Change this to try and reduce GC time if mutator time is
510 // negative for whatever reason. Or for future consideration,
511 // bail out of the code if mutator time is negative.
512 //
513 // Throughput
514 //
515 assert(major_cost >= 0.0, "major cost is < 0.0");
516 assert(minor_cost >= 0.0, "minor cost is < 0.0");
517 // Try to reduce the GC times.
518 if (is_full_gc) {
519 set_decide_at_full_gc(decide_at_full_gc_true);
520 adjust_promo_for_throughput(is_full_gc, &desired_promo_size);
521 }
522 } else {
524 // Be conservative about reducing the footprint.
525 // Do a minimum number of major collections first.
526 // Have reasonable averages for major and minor collections costs.
527 if (UseAdaptiveSizePolicyFootprintGoal &&
528 young_gen_policy_is_ready() &&
529 avg_major_gc_cost()->average() >= 0.0 &&
530 avg_minor_gc_cost()->average() >= 0.0) {
531 if (is_full_gc) {
532 set_decide_at_full_gc(decide_at_full_gc_true);
533 size_t desired_sum = desired_eden_size + desired_promo_size;
534 desired_promo_size = adjust_promo_for_footprint(desired_promo_size, desired_sum);
535 }
536 }
537 }
539 // Note we make the same tests as in the code block below; the code
540 // seems a little easier to read with the printing in another block.
541 if (PrintAdaptiveSizePolicy) {
542 if (desired_promo_size > promo_limit) {
543 // "free_in_old_gen" was the original value for used for promo_limit
544 size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());
545 gclog_or_tty->print_cr(
546 "PSAdaptiveSizePolicy::compute_old_gen_free_space limits:"
547 " desired_promo_size: " SIZE_FORMAT
548 " promo_limit: " SIZE_FORMAT
549 " free_in_old_gen: " SIZE_FORMAT
550 " max_old_gen_size: " SIZE_FORMAT
551 " avg_old_live: " SIZE_FORMAT,
552 desired_promo_size, promo_limit, free_in_old_gen,
553 max_old_gen_size, (size_t) avg_old_live()->average());
554 }
555 if (gc_cost() > gc_cost_limit) {
556 gclog_or_tty->print_cr(
557 "PSAdaptiveSizePolicy::compute_old_gen_free_space: gc time limit"
558 " gc_cost: %f "
559 " GCTimeLimit: %d",
560 gc_cost(), GCTimeLimit);
561 }
562 }
564 // Align everything and make a final limit check
565 const size_t alignment = _intra_generation_alignment;
566 desired_promo_size = align_size_up(desired_promo_size, alignment);
567 desired_promo_size = MAX2(desired_promo_size, alignment);
569 promo_limit = align_size_down(promo_limit, alignment);
571 // And one last limit check, now that we've aligned things.
572 desired_promo_size = MIN2(desired_promo_size, promo_limit);
574 if (PrintAdaptiveSizePolicy) {
575 // Timing stats
576 gclog_or_tty->print(
577 "PSAdaptiveSizePolicy::compute_old_gen_free_space: costs"
578 " minor_time: %f"
579 " major_cost: %f"
580 " mutator_cost: %f"
581 " throughput_goal: %f",
582 minor_gc_cost(), major_gc_cost(), mutator_cost(),
583 _throughput_goal);
585 // We give more details if Verbose is set
586 if (Verbose) {
587 gclog_or_tty->print( " minor_pause: %f"
588 " major_pause: %f"
589 " minor_interval: %f"
590 " major_interval: %f"
591 " pause_goal: %f",
592 _avg_minor_pause->padded_average(),
593 _avg_major_pause->padded_average(),
594 _avg_minor_interval->average(),
595 _avg_major_interval->average(),
596 gc_pause_goal_sec());
597 }
599 // Footprint stats
600 gclog_or_tty->print( " live_space: " SIZE_FORMAT
601 " free_space: " SIZE_FORMAT,
602 live_space(), free_space());
603 // More detail
604 if (Verbose) {
605 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
606 " avg_young_live: " SIZE_FORMAT
607 " avg_old_live: " SIZE_FORMAT,
608 (size_t)_avg_base_footprint->average(),
609 (size_t)avg_young_live()->average(),
610 (size_t)avg_old_live()->average());
611 }
613 // And finally, our old and new sizes.
614 gclog_or_tty->print(" old_promo_size: " SIZE_FORMAT
615 " desired_promo_size: " SIZE_FORMAT,
616 _promo_size, desired_promo_size);
617 gclog_or_tty->cr();
618 }
620 set_promo_size(desired_promo_size);
621 }
623 void PSAdaptiveSizePolicy::decay_supplemental_growth(bool is_full_gc) {
624 // Decay the supplemental increment? Decay the supplement growth
625 // factor even if it is not used. It is only meant to give a boost
626 // to the initial growth and if it is not used, then it was not
627 // needed.
628 if (is_full_gc) {
629 // Don't wait for the threshold value for the major collections. If
630 // here, the supplemental growth term was used and should decay.
631 if ((_avg_major_pause->count() % TenuredGenerationSizeSupplementDecay)
632 == 0) {
633 _old_gen_size_increment_supplement =
634 _old_gen_size_increment_supplement >> 1;
635 }
636 } else {
637 if ((_avg_minor_pause->count() >= AdaptiveSizePolicyReadyThreshold) &&
638 (_avg_minor_pause->count() % YoungGenerationSizeSupplementDecay) == 0) {
639 _young_gen_size_increment_supplement =
640 _young_gen_size_increment_supplement >> 1;
641 }
642 }
643 }
645 void PSAdaptiveSizePolicy::adjust_promo_for_minor_pause_time(bool is_full_gc,
646 size_t* desired_promo_size_ptr, size_t* desired_eden_size_ptr) {
648 if (PSAdjustTenuredGenForMinorPause) {
649 if (is_full_gc) {
650 set_decide_at_full_gc(decide_at_full_gc_true);
651 }
652 // If the desired eden size is as small as it will get,
653 // try to adjust the old gen size.
654 if (*desired_eden_size_ptr <= _intra_generation_alignment) {
655 // Vary the old gen size to reduce the young gen pause. This
656 // may not be a good idea. This is just a test.
657 if (minor_pause_old_estimator()->decrement_will_decrease()) {
658 set_change_old_gen_for_min_pauses(decrease_old_gen_for_min_pauses_true);
659 *desired_promo_size_ptr =
660 _promo_size - promo_decrement_aligned_down(*desired_promo_size_ptr);
661 } else {
662 set_change_old_gen_for_min_pauses(increase_old_gen_for_min_pauses_true);
663 size_t promo_heap_delta =
664 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
665 if ((*desired_promo_size_ptr + promo_heap_delta) >
666 *desired_promo_size_ptr) {
667 *desired_promo_size_ptr =
668 _promo_size + promo_heap_delta;
669 }
670 }
671 }
672 }
673 }
675 void PSAdaptiveSizePolicy::adjust_eden_for_minor_pause_time(bool is_full_gc,
676 size_t* desired_eden_size_ptr) {
678 // Adjust the young generation size to reduce pause time of
679 // of collections.
680 //
681 // The AdaptiveSizePolicyInitializingSteps test is not used
682 // here. It has not seemed to be needed but perhaps should
683 // be added for consistency.
684 if (minor_pause_young_estimator()->decrement_will_decrease()) {
685 // reduce eden size
686 set_change_young_gen_for_min_pauses(
687 decrease_young_gen_for_min_pauses_true);
688 *desired_eden_size_ptr = *desired_eden_size_ptr -
689 eden_decrement_aligned_down(*desired_eden_size_ptr);
690 } else {
691 // EXPERIMENTAL ADJUSTMENT
692 // Only record that the estimator indicated such an action.
693 // *desired_eden_size_ptr = *desired_eden_size_ptr + eden_heap_delta;
694 set_change_young_gen_for_min_pauses(
695 increase_young_gen_for_min_pauses_true);
696 }
697 }
699 void PSAdaptiveSizePolicy::adjust_promo_for_pause_time(bool is_full_gc,
700 size_t* desired_promo_size_ptr,
701 size_t* desired_eden_size_ptr) {
703 size_t promo_heap_delta = 0;
704 // Add some checks for a threshold for a change. For example,
705 // a change less than the required alignment is probably not worth
706 // attempting.
708 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
709 adjust_promo_for_minor_pause_time(is_full_gc, desired_promo_size_ptr, desired_eden_size_ptr);
710 // major pause adjustments
711 } else if (is_full_gc) {
712 // Adjust for the major pause time only at full gc's because the
713 // affects of a change can only be seen at full gc's.
715 // Reduce old generation size to reduce pause?
716 if (major_pause_old_estimator()->decrement_will_decrease()) {
717 // reduce old generation size
718 set_change_old_gen_for_maj_pauses(decrease_old_gen_for_maj_pauses_true);
719 promo_heap_delta = promo_decrement_aligned_down(*desired_promo_size_ptr);
720 *desired_promo_size_ptr = _promo_size - promo_heap_delta;
721 } else {
722 // EXPERIMENTAL ADJUSTMENT
723 // Only record that the estimator indicated such an action.
724 // *desired_promo_size_ptr = _promo_size +
725 // promo_increment_aligned_up(*desired_promo_size_ptr);
726 set_change_old_gen_for_maj_pauses(increase_old_gen_for_maj_pauses_true);
727 }
728 }
730 if (PrintAdaptiveSizePolicy && Verbose) {
731 gclog_or_tty->print_cr(
732 "PSAdaptiveSizePolicy::compute_old_gen_free_space "
733 "adjusting gen sizes for major pause (avg %f goal %f). "
734 "desired_promo_size " SIZE_FORMAT " promo delta " SIZE_FORMAT,
735 _avg_major_pause->average(), gc_pause_goal_sec(),
736 *desired_promo_size_ptr, promo_heap_delta);
737 }
738 }
740 void PSAdaptiveSizePolicy::adjust_eden_for_pause_time(bool is_full_gc,
741 size_t* desired_promo_size_ptr,
742 size_t* desired_eden_size_ptr) {
744 size_t eden_heap_delta = 0;
745 // Add some checks for a threshold for a change. For example,
746 // a change less than the required alignment is probably not worth
747 // attempting.
748 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
749 adjust_eden_for_minor_pause_time(is_full_gc,
750 desired_eden_size_ptr);
751 // major pause adjustments
752 } else if (is_full_gc) {
753 // Adjust for the major pause time only at full gc's because the
754 // affects of a change can only be seen at full gc's.
755 if (PSAdjustYoungGenForMajorPause) {
756 // If the promo size is at the minimum (i.e., the old gen
757 // size will not actually decrease), consider changing the
758 // young gen size.
759 if (*desired_promo_size_ptr < _intra_generation_alignment) {
760 // If increasing the young generation will decrease the old gen
761 // pause, do it.
762 // During startup there is noise in the statistics for deciding
763 // on whether to increase or decrease the young gen size. For
764 // some number of iterations, just try to increase the young
765 // gen size if the major pause is too long to try and establish
766 // good statistics for later decisions.
767 if (major_pause_young_estimator()->increment_will_decrease() ||
768 (_young_gen_change_for_major_pause_count
769 <= AdaptiveSizePolicyInitializingSteps)) {
770 set_change_young_gen_for_maj_pauses(
771 increase_young_gen_for_maj_pauses_true);
772 eden_heap_delta = eden_increment_aligned_up(*desired_eden_size_ptr);
773 *desired_eden_size_ptr = _eden_size + eden_heap_delta;
774 _young_gen_change_for_major_pause_count++;
775 } else {
776 // Record that decreasing the young gen size would decrease
777 // the major pause
778 set_change_young_gen_for_maj_pauses(
779 decrease_young_gen_for_maj_pauses_true);
780 eden_heap_delta = eden_decrement_aligned_down(*desired_eden_size_ptr);
781 *desired_eden_size_ptr = _eden_size - eden_heap_delta;
782 }
783 }
784 }
785 }
787 if (PrintAdaptiveSizePolicy && Verbose) {
788 gclog_or_tty->print_cr(
789 "PSAdaptiveSizePolicy::compute_eden_space_size "
790 "adjusting gen sizes for major pause (avg %f goal %f). "
791 "desired_eden_size " SIZE_FORMAT " eden delta " SIZE_FORMAT,
792 _avg_major_pause->average(), gc_pause_goal_sec(),
793 *desired_eden_size_ptr, eden_heap_delta);
794 }
795 }
797 void PSAdaptiveSizePolicy::adjust_promo_for_throughput(bool is_full_gc,
798 size_t* desired_promo_size_ptr) {
800 // Add some checks for a threshold for a change. For example,
801 // a change less than the required alignment is probably not worth
802 // attempting.
804 if ((gc_cost() + mutator_cost()) == 0.0) {
805 return;
806 }
808 if (PrintAdaptiveSizePolicy && Verbose) {
809 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_promo_for_throughput("
810 "is_full: %d, promo: " SIZE_FORMAT "): ",
811 is_full_gc, *desired_promo_size_ptr);
812 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
813 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
814 }
816 // Tenured generation
817 if (is_full_gc) {
818 // Calculate the change to use for the tenured gen.
819 size_t scaled_promo_heap_delta = 0;
820 // Can the increment to the generation be scaled?
821 if (gc_cost() >= 0.0 && major_gc_cost() >= 0.0) {
822 size_t promo_heap_delta =
823 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
824 double scale_by_ratio = major_gc_cost() / gc_cost();
825 scaled_promo_heap_delta =
826 (size_t) (scale_by_ratio * (double) promo_heap_delta);
827 if (PrintAdaptiveSizePolicy && Verbose) {
828 gclog_or_tty->print_cr(
829 "Scaled tenured increment: " SIZE_FORMAT " by %f down to "
830 SIZE_FORMAT,
831 promo_heap_delta, scale_by_ratio, scaled_promo_heap_delta);
832 }
833 } else if (major_gc_cost() >= 0.0) {
834 // Scaling is not going to work. If the major gc time is the
835 // larger, give it a full increment.
836 if (major_gc_cost() >= minor_gc_cost()) {
837 scaled_promo_heap_delta =
838 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
839 }
840 } else {
841 // Don't expect to get here but it's ok if it does
842 // in the product build since the delta will be 0
843 // and nothing will change.
844 assert(false, "Unexpected value for gc costs");
845 }
847 switch (AdaptiveSizeThroughPutPolicy) {
848 case 1:
849 // Early in the run the statistics might not be good. Until
850 // a specific number of collections have been, use the heuristic
851 // that a larger generation size means lower collection costs.
852 if (major_collection_estimator()->increment_will_decrease() ||
853 (_old_gen_change_for_major_throughput
854 <= AdaptiveSizePolicyInitializingSteps)) {
855 // Increase tenured generation size to reduce major collection cost
856 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
857 *desired_promo_size_ptr) {
858 *desired_promo_size_ptr = _promo_size + scaled_promo_heap_delta;
859 }
860 set_change_old_gen_for_throughput(
861 increase_old_gen_for_throughput_true);
862 _old_gen_change_for_major_throughput++;
863 } else {
864 // EXPERIMENTAL ADJUSTMENT
865 // Record that decreasing the old gen size would decrease
866 // the major collection cost but don't do it.
867 // *desired_promo_size_ptr = _promo_size -
868 // promo_decrement_aligned_down(*desired_promo_size_ptr);
869 set_change_old_gen_for_throughput(
870 decrease_old_gen_for_throughput_true);
871 }
873 break;
874 default:
875 // Simplest strategy
876 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
877 *desired_promo_size_ptr) {
878 *desired_promo_size_ptr = *desired_promo_size_ptr +
879 scaled_promo_heap_delta;
880 }
881 set_change_old_gen_for_throughput(
882 increase_old_gen_for_throughput_true);
883 _old_gen_change_for_major_throughput++;
884 }
886 if (PrintAdaptiveSizePolicy && Verbose) {
887 gclog_or_tty->print_cr(
888 "adjusting tenured gen for throughput (avg %f goal %f). "
889 "desired_promo_size " SIZE_FORMAT " promo_delta " SIZE_FORMAT ,
890 mutator_cost(), _throughput_goal,
891 *desired_promo_size_ptr, scaled_promo_heap_delta);
892 }
893 }
894 }
896 void PSAdaptiveSizePolicy::adjust_eden_for_throughput(bool is_full_gc,
897 size_t* desired_eden_size_ptr) {
899 // Add some checks for a threshold for a change. For example,
900 // a change less than the required alignment is probably not worth
901 // attempting.
903 if ((gc_cost() + mutator_cost()) == 0.0) {
904 return;
905 }
907 if (PrintAdaptiveSizePolicy && Verbose) {
908 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_eden_for_throughput("
909 "is_full: %d, cur_eden: " SIZE_FORMAT "): ",
910 is_full_gc, *desired_eden_size_ptr);
911 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
912 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
913 }
915 // Young generation
916 size_t scaled_eden_heap_delta = 0;
917 // Can the increment to the generation be scaled?
918 if (gc_cost() >= 0.0 && minor_gc_cost() >= 0.0) {
919 size_t eden_heap_delta =
920 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
921 double scale_by_ratio = minor_gc_cost() / gc_cost();
922 assert(scale_by_ratio <= 1.0 && scale_by_ratio >= 0.0, "Scaling is wrong");
923 scaled_eden_heap_delta =
924 (size_t) (scale_by_ratio * (double) eden_heap_delta);
925 if (PrintAdaptiveSizePolicy && Verbose) {
926 gclog_or_tty->print_cr(
927 "Scaled eden increment: " SIZE_FORMAT " by %f down to "
928 SIZE_FORMAT,
929 eden_heap_delta, scale_by_ratio, scaled_eden_heap_delta);
930 }
931 } else if (minor_gc_cost() >= 0.0) {
932 // Scaling is not going to work. If the minor gc time is the
933 // larger, give it a full increment.
934 if (minor_gc_cost() > major_gc_cost()) {
935 scaled_eden_heap_delta =
936 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
937 }
938 } else {
939 // Don't expect to get here but it's ok if it does
940 // in the product build since the delta will be 0
941 // and nothing will change.
942 assert(false, "Unexpected value for gc costs");
943 }
945 // Use a heuristic for some number of collections to give
946 // the averages time to settle down.
947 switch (AdaptiveSizeThroughPutPolicy) {
948 case 1:
949 if (minor_collection_estimator()->increment_will_decrease() ||
950 (_young_gen_change_for_minor_throughput
951 <= AdaptiveSizePolicyInitializingSteps)) {
952 // Expand young generation size to reduce frequency of
953 // of collections.
954 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
955 *desired_eden_size_ptr) {
956 *desired_eden_size_ptr =
957 *desired_eden_size_ptr + scaled_eden_heap_delta;
958 }
959 set_change_young_gen_for_throughput(
960 increase_young_gen_for_througput_true);
961 _young_gen_change_for_minor_throughput++;
962 } else {
963 // EXPERIMENTAL ADJUSTMENT
964 // Record that decreasing the young gen size would decrease
965 // the minor collection cost but don't do it.
966 // *desired_eden_size_ptr = _eden_size -
967 // eden_decrement_aligned_down(*desired_eden_size_ptr);
968 set_change_young_gen_for_throughput(
969 decrease_young_gen_for_througput_true);
970 }
971 break;
972 default:
973 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
974 *desired_eden_size_ptr) {
975 *desired_eden_size_ptr =
976 *desired_eden_size_ptr + scaled_eden_heap_delta;
977 }
978 set_change_young_gen_for_throughput(
979 increase_young_gen_for_througput_true);
980 _young_gen_change_for_minor_throughput++;
981 }
983 if (PrintAdaptiveSizePolicy && Verbose) {
984 gclog_or_tty->print_cr(
985 "adjusting eden for throughput (avg %f goal %f). desired_eden_size "
986 SIZE_FORMAT " eden delta " SIZE_FORMAT "\n",
987 mutator_cost(), _throughput_goal,
988 *desired_eden_size_ptr, scaled_eden_heap_delta);
989 }
990 }
992 size_t PSAdaptiveSizePolicy::adjust_promo_for_footprint(
993 size_t desired_promo_size, size_t desired_sum) {
994 assert(desired_promo_size <= desired_sum, "Inconsistent parameters");
995 set_decrease_for_footprint(decrease_old_gen_for_footprint_true);
997 size_t change = promo_decrement(desired_promo_size);
998 change = scale_down(change, desired_promo_size, desired_sum);
1000 size_t reduced_size = desired_promo_size - change;
1002 if (PrintAdaptiveSizePolicy && Verbose) {
1003 gclog_or_tty->print_cr(
1004 "AdaptiveSizePolicy::compute_generation_free_space "
1005 "adjusting tenured gen for footprint. "
1006 "starting promo size " SIZE_FORMAT
1007 " reduced promo size " SIZE_FORMAT,
1008 " promo delta " SIZE_FORMAT,
1009 desired_promo_size, reduced_size, change );
1010 }
1012 assert(reduced_size <= desired_promo_size, "Inconsistent result");
1013 return reduced_size;
1014 }
1016 size_t PSAdaptiveSizePolicy::adjust_eden_for_footprint(
1017 size_t desired_eden_size, size_t desired_sum) {
1018 assert(desired_eden_size <= desired_sum, "Inconsistent parameters");
1019 set_decrease_for_footprint(decrease_young_gen_for_footprint_true);
1021 size_t change = eden_decrement(desired_eden_size);
1022 change = scale_down(change, desired_eden_size, desired_sum);
1024 size_t reduced_size = desired_eden_size - change;
1026 if (PrintAdaptiveSizePolicy && Verbose) {
1027 gclog_or_tty->print_cr(
1028 "AdaptiveSizePolicy::compute_generation_free_space "
1029 "adjusting eden for footprint. "
1030 " starting eden size " SIZE_FORMAT
1031 " reduced eden size " SIZE_FORMAT
1032 " eden delta " SIZE_FORMAT,
1033 desired_eden_size, reduced_size, change);
1034 }
1036 assert(reduced_size <= desired_eden_size, "Inconsistent result");
1037 return reduced_size;
1038 }
1040 // Scale down "change" by the factor
1041 // part / total
1042 // Don't align the results.
1044 size_t PSAdaptiveSizePolicy::scale_down(size_t change,
1045 double part,
1046 double total) {
1047 assert(part <= total, "Inconsistent input");
1048 size_t reduced_change = change;
1049 if (total > 0) {
1050 double fraction = part / total;
1051 reduced_change = (size_t) (fraction * (double) change);
1052 }
1053 assert(reduced_change <= change, "Inconsistent result");
1054 return reduced_change;
1055 }
1057 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden,
1058 uint percent_change) {
1059 size_t eden_heap_delta;
1060 eden_heap_delta = cur_eden / 100 * percent_change;
1061 return eden_heap_delta;
1062 }
1064 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden) {
1065 return eden_increment(cur_eden, YoungGenerationSizeIncrement);
1066 }
1068 size_t PSAdaptiveSizePolicy::eden_increment_aligned_up(size_t cur_eden) {
1069 size_t result = eden_increment(cur_eden, YoungGenerationSizeIncrement);
1070 return align_size_up(result, _intra_generation_alignment);
1071 }
1073 size_t PSAdaptiveSizePolicy::eden_increment_aligned_down(size_t cur_eden) {
1074 size_t result = eden_increment(cur_eden);
1075 return align_size_down(result, _intra_generation_alignment);
1076 }
1078 size_t PSAdaptiveSizePolicy::eden_increment_with_supplement_aligned_up(
1079 size_t cur_eden) {
1080 size_t result = eden_increment(cur_eden,
1081 YoungGenerationSizeIncrement + _young_gen_size_increment_supplement);
1082 return align_size_up(result, _intra_generation_alignment);
1083 }
1085 size_t PSAdaptiveSizePolicy::eden_decrement_aligned_down(size_t cur_eden) {
1086 size_t eden_heap_delta = eden_decrement(cur_eden);
1087 return align_size_down(eden_heap_delta, _intra_generation_alignment);
1088 }
1090 size_t PSAdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
1091 size_t eden_heap_delta = eden_increment(cur_eden) /
1092 AdaptiveSizeDecrementScaleFactor;
1093 return eden_heap_delta;
1094 }
1096 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo,
1097 uint percent_change) {
1098 size_t promo_heap_delta;
1099 promo_heap_delta = cur_promo / 100 * percent_change;
1100 return promo_heap_delta;
1101 }
1103 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo) {
1104 return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1105 }
1107 size_t PSAdaptiveSizePolicy::promo_increment_aligned_up(size_t cur_promo) {
1108 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1109 return align_size_up(result, _intra_generation_alignment);
1110 }
1112 size_t PSAdaptiveSizePolicy::promo_increment_aligned_down(size_t cur_promo) {
1113 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1114 return align_size_down(result, _intra_generation_alignment);
1115 }
1117 size_t PSAdaptiveSizePolicy::promo_increment_with_supplement_aligned_up(
1118 size_t cur_promo) {
1119 size_t result = promo_increment(cur_promo,
1120 TenuredGenerationSizeIncrement + _old_gen_size_increment_supplement);
1121 return align_size_up(result, _intra_generation_alignment);
1122 }
1124 size_t PSAdaptiveSizePolicy::promo_decrement_aligned_down(size_t cur_promo) {
1125 size_t promo_heap_delta = promo_decrement(cur_promo);
1126 return align_size_down(promo_heap_delta, _intra_generation_alignment);
1127 }
1129 size_t PSAdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
1130 size_t promo_heap_delta = promo_increment(cur_promo);
1131 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
1132 return promo_heap_delta;
1133 }
1135 uint PSAdaptiveSizePolicy::compute_survivor_space_size_and_threshold(
1136 bool is_survivor_overflow,
1137 uint tenuring_threshold,
1138 size_t survivor_limit) {
1139 assert(survivor_limit >= _intra_generation_alignment,
1140 "survivor_limit too small");
1141 assert((size_t)align_size_down(survivor_limit, _intra_generation_alignment)
1142 == survivor_limit, "survivor_limit not aligned");
1144 // This method is called even if the tenuring threshold and survivor
1145 // spaces are not adjusted so that the averages are sampled above.
1146 if (!UsePSAdaptiveSurvivorSizePolicy ||
1147 !young_gen_policy_is_ready()) {
1148 return tenuring_threshold;
1149 }
1151 // We'll decide whether to increase or decrease the tenuring
1152 // threshold based partly on the newly computed survivor size
1153 // (if we hit the maximum limit allowed, we'll always choose to
1154 // decrement the threshold).
1155 bool incr_tenuring_threshold = false;
1156 bool decr_tenuring_threshold = false;
1158 set_decrement_tenuring_threshold_for_gc_cost(false);
1159 set_increment_tenuring_threshold_for_gc_cost(false);
1160 set_decrement_tenuring_threshold_for_survivor_limit(false);
1162 if (!is_survivor_overflow) {
1163 // Keep running averages on how much survived
1165 // We use the tenuring threshold to equalize the cost of major
1166 // and minor collections.
1167 // ThresholdTolerance is used to indicate how sensitive the
1168 // tenuring threshold is to differences in cost betweent the
1169 // collection types.
1171 // Get the times of interest. This involves a little work, so
1172 // we cache the values here.
1173 const double major_cost = major_gc_cost();
1174 const double minor_cost = minor_gc_cost();
1176 if (minor_cost > major_cost * _threshold_tolerance_percent) {
1177 // Minor times are getting too long; lower the threshold so
1178 // less survives and more is promoted.
1179 decr_tenuring_threshold = true;
1180 set_decrement_tenuring_threshold_for_gc_cost(true);
1181 } else if (major_cost > minor_cost * _threshold_tolerance_percent) {
1182 // Major times are too long, so we want less promotion.
1183 incr_tenuring_threshold = true;
1184 set_increment_tenuring_threshold_for_gc_cost(true);
1185 }
1187 } else {
1188 // Survivor space overflow occurred, so promoted and survived are
1189 // not accurate. We'll make our best guess by combining survived
1190 // and promoted and count them as survivors.
1191 //
1192 // We'll lower the tenuring threshold to see if we can correct
1193 // things. Also, set the survivor size conservatively. We're
1194 // trying to avoid many overflows from occurring if defnew size
1195 // is just too small.
1197 decr_tenuring_threshold = true;
1198 }
1200 // The padded average also maintains a deviation from the average;
1201 // we use this to see how good of an estimate we have of what survived.
1202 // We're trying to pad the survivor size as little as possible without
1203 // overflowing the survivor spaces.
1204 size_t target_size = align_size_up((size_t)_avg_survived->padded_average(),
1205 _intra_generation_alignment);
1206 target_size = MAX2(target_size, _intra_generation_alignment);
1208 if (target_size > survivor_limit) {
1209 // Target size is bigger than we can handle. Let's also reduce
1210 // the tenuring threshold.
1211 target_size = survivor_limit;
1212 decr_tenuring_threshold = true;
1213 set_decrement_tenuring_threshold_for_survivor_limit(true);
1214 }
1216 // Finally, increment or decrement the tenuring threshold, as decided above.
1217 // We test for decrementing first, as we might have hit the target size
1218 // limit.
1219 if (decr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1220 if (tenuring_threshold > 1) {
1221 tenuring_threshold--;
1222 }
1223 } else if (incr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1224 if (tenuring_threshold < MaxTenuringThreshold) {
1225 tenuring_threshold++;
1226 }
1227 }
1229 // We keep a running average of the amount promoted which is used
1230 // to decide when we should collect the old generation (when
1231 // the amount of old gen free space is less than what we expect to
1232 // promote).
1234 if (PrintAdaptiveSizePolicy) {
1235 // A little more detail if Verbose is on
1236 if (Verbose) {
1237 gclog_or_tty->print( " avg_survived: %f"
1238 " avg_deviation: %f",
1239 _avg_survived->average(),
1240 _avg_survived->deviation());
1241 }
1243 gclog_or_tty->print( " avg_survived_padded_avg: %f",
1244 _avg_survived->padded_average());
1246 if (Verbose) {
1247 gclog_or_tty->print( " avg_promoted_avg: %f"
1248 " avg_promoted_dev: %f",
1249 avg_promoted()->average(),
1250 avg_promoted()->deviation());
1251 }
1253 gclog_or_tty->print( " avg_promoted_padded_avg: %f"
1254 " avg_pretenured_padded_avg: %f"
1255 " tenuring_thresh: %d"
1256 " target_size: " SIZE_FORMAT,
1257 avg_promoted()->padded_average(),
1258 _avg_pretenured->padded_average(),
1259 tenuring_threshold, target_size);
1260 tty->cr();
1261 }
1263 set_survivor_size(target_size);
1265 return tenuring_threshold;
1266 }
1268 void PSAdaptiveSizePolicy::update_averages(bool is_survivor_overflow,
1269 size_t survived,
1270 size_t promoted) {
1271 // Update averages
1272 if (!is_survivor_overflow) {
1273 // Keep running averages on how much survived
1274 _avg_survived->sample(survived);
1275 } else {
1276 size_t survived_guess = survived + promoted;
1277 _avg_survived->sample(survived_guess);
1278 }
1279 avg_promoted()->sample(promoted + _avg_pretenured->padded_average());
1281 if (PrintAdaptiveSizePolicy) {
1282 gclog_or_tty->print(
1283 "AdaptiveSizePolicy::compute_survivor_space_size_and_thresh:"
1284 " survived: " SIZE_FORMAT
1285 " promoted: " SIZE_FORMAT
1286 " overflow: %s",
1287 survived, promoted, is_survivor_overflow ? "true" : "false");
1288 }
1289 }
1291 bool PSAdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st)
1292 const {
1294 if (!UseAdaptiveSizePolicy) return false;
1296 return AdaptiveSizePolicy::print_adaptive_size_policy_on(
1297 st,
1298 PSScavenge::tenuring_threshold());
1299 }