Thu, 03 Oct 2013 17:16:23 +0200
8025853: Remove unnecessary uses of GenerationSizer
Summary: Removed stray includes and some minor cleanup of GenerationSizer
Reviewed-by: tschatzl, jcoomes
1 /*
2 * Copyright (c) 2002, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
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9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
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23 */
25 #include "precompiled.hpp"
26 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
27 #include "gc_implementation/parallelScavenge/psGCAdaptivePolicyCounters.hpp"
28 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
29 #include "gc_implementation/shared/gcPolicyCounters.hpp"
30 #include "gc_interface/gcCause.hpp"
31 #include "memory/collectorPolicy.hpp"
32 #include "runtime/timer.hpp"
33 #include "utilities/top.hpp"
35 #include <math.h>
37 PSAdaptiveSizePolicy::PSAdaptiveSizePolicy(size_t init_eden_size,
38 size_t init_promo_size,
39 size_t init_survivor_size,
40 size_t intra_generation_alignment,
41 double gc_pause_goal_sec,
42 double gc_minor_pause_goal_sec,
43 uint gc_cost_ratio) :
44 AdaptiveSizePolicy(init_eden_size,
45 init_promo_size,
46 init_survivor_size,
47 gc_pause_goal_sec,
48 gc_cost_ratio),
49 _collection_cost_margin_fraction(AdaptiveSizePolicyCollectionCostMargin/
50 100.0),
51 _intra_generation_alignment(intra_generation_alignment),
52 _live_at_last_full_gc(init_promo_size),
53 _gc_minor_pause_goal_sec(gc_minor_pause_goal_sec),
54 _latest_major_mutator_interval_seconds(0),
55 _young_gen_change_for_major_pause_count(0)
56 {
57 // Sizing policy statistics
58 _avg_major_pause =
59 new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding);
60 _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
61 _avg_major_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
63 _avg_base_footprint = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
64 _major_pause_old_estimator =
65 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
66 _major_pause_young_estimator =
67 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
68 _major_collection_estimator =
69 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
71 _young_gen_size_increment_supplement = YoungGenerationSizeSupplement;
72 _old_gen_size_increment_supplement = TenuredGenerationSizeSupplement;
74 // Start the timers
75 _major_timer.start();
77 _old_gen_policy_is_ready = false;
78 }
80 void PSAdaptiveSizePolicy::major_collection_begin() {
81 // Update the interval time
82 _major_timer.stop();
83 // Save most recent collection time
84 _latest_major_mutator_interval_seconds = _major_timer.seconds();
85 _major_timer.reset();
86 _major_timer.start();
87 }
89 void PSAdaptiveSizePolicy::update_minor_pause_old_estimator(
90 double minor_pause_in_ms) {
91 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
92 _minor_pause_old_estimator->update(promo_size_in_mbytes,
93 minor_pause_in_ms);
94 }
96 void PSAdaptiveSizePolicy::major_collection_end(size_t amount_live,
97 GCCause::Cause gc_cause) {
98 // Update the pause time.
99 _major_timer.stop();
101 if (gc_cause != GCCause::_java_lang_system_gc ||
102 UseAdaptiveSizePolicyWithSystemGC) {
103 double major_pause_in_seconds = _major_timer.seconds();
104 double major_pause_in_ms = major_pause_in_seconds * MILLIUNITS;
106 // Sample for performance counter
107 _avg_major_pause->sample(major_pause_in_seconds);
109 // Cost of collection (unit-less)
110 double collection_cost = 0.0;
111 if ((_latest_major_mutator_interval_seconds > 0.0) &&
112 (major_pause_in_seconds > 0.0)) {
113 double interval_in_seconds =
114 _latest_major_mutator_interval_seconds + major_pause_in_seconds;
115 collection_cost =
116 major_pause_in_seconds / interval_in_seconds;
117 avg_major_gc_cost()->sample(collection_cost);
119 // Sample for performance counter
120 _avg_major_interval->sample(interval_in_seconds);
121 }
123 // Calculate variables used to estimate pause time vs. gen sizes
124 double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
125 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
126 _major_pause_old_estimator->update(promo_size_in_mbytes,
127 major_pause_in_ms);
128 _major_pause_young_estimator->update(eden_size_in_mbytes,
129 major_pause_in_ms);
131 if (PrintAdaptiveSizePolicy && Verbose) {
132 gclog_or_tty->print("psAdaptiveSizePolicy::major_collection_end: "
133 "major gc cost: %f average: %f", collection_cost,
134 avg_major_gc_cost()->average());
135 gclog_or_tty->print_cr(" major pause: %f major period %f",
136 major_pause_in_ms,
137 _latest_major_mutator_interval_seconds * MILLIUNITS);
138 }
140 // Calculate variable used to estimate collection cost vs. gen sizes
141 assert(collection_cost >= 0.0, "Expected to be non-negative");
142 _major_collection_estimator->update(promo_size_in_mbytes,
143 collection_cost);
144 }
146 // Update the amount live at the end of a full GC
147 _live_at_last_full_gc = amount_live;
149 // The policy does not have enough data until at least some major collections
150 // have been done.
151 if (_avg_major_pause->count() >= AdaptiveSizePolicyReadyThreshold) {
152 _old_gen_policy_is_ready = true;
153 }
155 // Interval times use this timer to measure the interval that
156 // the mutator runs. Reset after the GC pause has been measured.
157 _major_timer.reset();
158 _major_timer.start();
159 }
161 // If the remaining free space in the old generation is less that
162 // that expected to be needed by the next collection, do a full
163 // collection now.
164 bool PSAdaptiveSizePolicy::should_full_GC(size_t old_free_in_bytes) {
166 // A similar test is done in the scavenge's should_attempt_scavenge(). If
167 // this is changed, decide if that test should also be changed.
168 bool result = padded_average_promoted_in_bytes() > (float) old_free_in_bytes;
169 if (PrintGCDetails && Verbose) {
170 if (result) {
171 gclog_or_tty->print(" full after scavenge: ");
172 } else {
173 gclog_or_tty->print(" no full after scavenge: ");
174 }
175 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
176 " padded_average_promoted " SIZE_FORMAT
177 " free in old gen " SIZE_FORMAT,
178 (size_t) average_promoted_in_bytes(),
179 (size_t) padded_average_promoted_in_bytes(),
180 old_free_in_bytes);
181 }
182 return result;
183 }
185 void PSAdaptiveSizePolicy::clear_generation_free_space_flags() {
187 AdaptiveSizePolicy::clear_generation_free_space_flags();
189 set_change_old_gen_for_min_pauses(0);
191 set_change_young_gen_for_maj_pauses(0);
192 }
194 // If this is not a full GC, only test and modify the young generation.
196 void PSAdaptiveSizePolicy::compute_generations_free_space(
197 size_t young_live,
198 size_t eden_live,
199 size_t old_live,
200 size_t cur_eden,
201 size_t max_old_gen_size,
202 size_t max_eden_size,
203 bool is_full_gc) {
204 compute_eden_space_size(young_live,
205 eden_live,
206 cur_eden,
207 max_eden_size,
208 is_full_gc);
210 compute_old_gen_free_space(old_live,
211 cur_eden,
212 max_old_gen_size,
213 is_full_gc);
214 }
216 void PSAdaptiveSizePolicy::compute_eden_space_size(
217 size_t young_live,
218 size_t eden_live,
219 size_t cur_eden,
220 size_t max_eden_size,
221 bool is_full_gc) {
223 // Update statistics
224 // Time statistics are updated as we go, update footprint stats here
225 _avg_base_footprint->sample(BaseFootPrintEstimate);
226 avg_young_live()->sample(young_live);
227 avg_eden_live()->sample(eden_live);
229 // This code used to return if the policy was not ready , i.e.,
230 // policy_is_ready() returning false. The intent was that
231 // decisions below needed major collection times and so could
232 // not be made before two major collections. A consequence was
233 // adjustments to the young generation were not done until after
234 // two major collections even if the minor collections times
235 // exceeded the requested goals. Now let the young generation
236 // adjust for the minor collection times. Major collection times
237 // will be zero for the first collection and will naturally be
238 // ignored. Tenured generation adjustments are only made at the
239 // full collections so until the second major collection has
240 // been reached, no tenured generation adjustments will be made.
242 // Until we know better, desired promotion size uses the last calculation
243 size_t desired_promo_size = _promo_size;
245 // Start eden at the current value. The desired value that is stored
246 // in _eden_size is not bounded by constraints of the heap and can
247 // run away.
248 //
249 // As expected setting desired_eden_size to the current
250 // value of desired_eden_size as a starting point
251 // caused desired_eden_size to grow way too large and caused
252 // an overflow down stream. It may have improved performance in
253 // some case but is dangerous.
254 size_t desired_eden_size = cur_eden;
256 // Cache some values. There's a bit of work getting these, so
257 // we might save a little time.
258 const double major_cost = major_gc_cost();
259 const double minor_cost = minor_gc_cost();
261 // This method sets the desired eden size. That plus the
262 // desired survivor space sizes sets the desired young generation
263 // size. This methods does not know what the desired survivor
264 // size is but expects that other policy will attempt to make
265 // the survivor sizes compatible with the live data in the
266 // young generation. This limit is an estimate of the space left
267 // in the young generation after the survivor spaces have been
268 // subtracted out.
269 size_t eden_limit = max_eden_size;
271 const double gc_cost_limit = GCTimeLimit/100.0;
273 // Which way should we go?
274 // if pause requirement is not met
275 // adjust size of any generation with average paus exceeding
276 // the pause limit. Adjust one pause at a time (the larger)
277 // and only make adjustments for the major pause at full collections.
278 // else if throughput requirement not met
279 // adjust the size of the generation with larger gc time. Only
280 // adjust one generation at a time.
281 // else
282 // adjust down the total heap size. Adjust down the larger of the
283 // generations.
285 // Add some checks for a threshold for a change. For example,
286 // a change less than the necessary alignment is probably not worth
287 // attempting.
290 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
291 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
292 //
293 // Check pauses
294 //
295 // Make changes only to affect one of the pauses (the larger)
296 // at a time.
297 adjust_eden_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
299 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
300 // Adjust only for the minor pause time goal
301 adjust_eden_for_minor_pause_time(is_full_gc, &desired_eden_size);
303 } else if(adjusted_mutator_cost() < _throughput_goal) {
304 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
305 // This sometimes resulted in skipping to the minimize footprint
306 // code. Change this to try and reduce GC time if mutator time is
307 // negative for whatever reason. Or for future consideration,
308 // bail out of the code if mutator time is negative.
309 //
310 // Throughput
311 //
312 assert(major_cost >= 0.0, "major cost is < 0.0");
313 assert(minor_cost >= 0.0, "minor cost is < 0.0");
314 // Try to reduce the GC times.
315 adjust_eden_for_throughput(is_full_gc, &desired_eden_size);
317 } else {
319 // Be conservative about reducing the footprint.
320 // Do a minimum number of major collections first.
321 // Have reasonable averages for major and minor collections costs.
322 if (UseAdaptiveSizePolicyFootprintGoal &&
323 young_gen_policy_is_ready() &&
324 avg_major_gc_cost()->average() >= 0.0 &&
325 avg_minor_gc_cost()->average() >= 0.0) {
326 size_t desired_sum = desired_eden_size + desired_promo_size;
327 desired_eden_size = adjust_eden_for_footprint(desired_eden_size, desired_sum);
328 }
329 }
331 // Note we make the same tests as in the code block below; the code
332 // seems a little easier to read with the printing in another block.
333 if (PrintAdaptiveSizePolicy) {
334 if (desired_eden_size > eden_limit) {
335 gclog_or_tty->print_cr(
336 "PSAdaptiveSizePolicy::compute_eden_space_size limits:"
337 " desired_eden_size: " SIZE_FORMAT
338 " old_eden_size: " SIZE_FORMAT
339 " eden_limit: " SIZE_FORMAT
340 " cur_eden: " SIZE_FORMAT
341 " max_eden_size: " SIZE_FORMAT
342 " avg_young_live: " SIZE_FORMAT,
343 desired_eden_size, _eden_size, eden_limit, cur_eden,
344 max_eden_size, (size_t)avg_young_live()->average());
345 }
346 if (gc_cost() > gc_cost_limit) {
347 gclog_or_tty->print_cr(
348 "PSAdaptiveSizePolicy::compute_eden_space_size: gc time limit"
349 " gc_cost: %f "
350 " GCTimeLimit: %d",
351 gc_cost(), GCTimeLimit);
352 }
353 }
355 // Align everything and make a final limit check
356 const size_t alignment = _intra_generation_alignment;
357 desired_eden_size = align_size_up(desired_eden_size, alignment);
358 desired_eden_size = MAX2(desired_eden_size, alignment);
360 eden_limit = align_size_down(eden_limit, alignment);
362 // And one last limit check, now that we've aligned things.
363 if (desired_eden_size > eden_limit) {
364 // If the policy says to get a larger eden but
365 // is hitting the limit, don't decrease eden.
366 // This can lead to a general drifting down of the
367 // eden size. Let the tenuring calculation push more
368 // into the old gen.
369 desired_eden_size = MAX2(eden_limit, cur_eden);
370 }
372 if (PrintAdaptiveSizePolicy) {
373 // Timing stats
374 gclog_or_tty->print(
375 "PSAdaptiveSizePolicy::compute_eden_space_size: costs"
376 " minor_time: %f"
377 " major_cost: %f"
378 " mutator_cost: %f"
379 " throughput_goal: %f",
380 minor_gc_cost(), major_gc_cost(), mutator_cost(),
381 _throughput_goal);
383 // We give more details if Verbose is set
384 if (Verbose) {
385 gclog_or_tty->print( " minor_pause: %f"
386 " major_pause: %f"
387 " minor_interval: %f"
388 " major_interval: %f"
389 " pause_goal: %f",
390 _avg_minor_pause->padded_average(),
391 _avg_major_pause->padded_average(),
392 _avg_minor_interval->average(),
393 _avg_major_interval->average(),
394 gc_pause_goal_sec());
395 }
397 // Footprint stats
398 gclog_or_tty->print( " live_space: " SIZE_FORMAT
399 " free_space: " SIZE_FORMAT,
400 live_space(), free_space());
401 // More detail
402 if (Verbose) {
403 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
404 " avg_young_live: " SIZE_FORMAT
405 " avg_old_live: " SIZE_FORMAT,
406 (size_t)_avg_base_footprint->average(),
407 (size_t)avg_young_live()->average(),
408 (size_t)avg_old_live()->average());
409 }
411 // And finally, our old and new sizes.
412 gclog_or_tty->print(" old_eden_size: " SIZE_FORMAT
413 " desired_eden_size: " SIZE_FORMAT,
414 _eden_size, desired_eden_size);
415 gclog_or_tty->cr();
416 }
418 set_eden_size(desired_eden_size);
419 }
421 void PSAdaptiveSizePolicy::compute_old_gen_free_space(
422 size_t old_live,
423 size_t cur_eden,
424 size_t max_old_gen_size,
425 bool is_full_gc) {
427 // Update statistics
428 // Time statistics are updated as we go, update footprint stats here
429 if (is_full_gc) {
430 // old_live is only accurate after a full gc
431 avg_old_live()->sample(old_live);
432 }
434 // This code used to return if the policy was not ready , i.e.,
435 // policy_is_ready() returning false. The intent was that
436 // decisions below needed major collection times and so could
437 // not be made before two major collections. A consequence was
438 // adjustments to the young generation were not done until after
439 // two major collections even if the minor collections times
440 // exceeded the requested goals. Now let the young generation
441 // adjust for the minor collection times. Major collection times
442 // will be zero for the first collection and will naturally be
443 // ignored. Tenured generation adjustments are only made at the
444 // full collections so until the second major collection has
445 // been reached, no tenured generation adjustments will be made.
447 // Until we know better, desired promotion size uses the last calculation
448 size_t desired_promo_size = _promo_size;
450 // Start eden at the current value. The desired value that is stored
451 // in _eden_size is not bounded by constraints of the heap and can
452 // run away.
453 //
454 // As expected setting desired_eden_size to the current
455 // value of desired_eden_size as a starting point
456 // caused desired_eden_size to grow way too large and caused
457 // an overflow down stream. It may have improved performance in
458 // some case but is dangerous.
459 size_t desired_eden_size = cur_eden;
461 // Cache some values. There's a bit of work getting these, so
462 // we might save a little time.
463 const double major_cost = major_gc_cost();
464 const double minor_cost = minor_gc_cost();
466 // Limits on our growth
467 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());
469 // But don't force a promo size below the current promo size. Otherwise,
470 // the promo size will shrink for no good reason.
471 promo_limit = MAX2(promo_limit, _promo_size);
473 const double gc_cost_limit = GCTimeLimit/100.0;
475 // Which way should we go?
476 // if pause requirement is not met
477 // adjust size of any generation with average paus exceeding
478 // the pause limit. Adjust one pause at a time (the larger)
479 // and only make adjustments for the major pause at full collections.
480 // else if throughput requirement not met
481 // adjust the size of the generation with larger gc time. Only
482 // adjust one generation at a time.
483 // else
484 // adjust down the total heap size. Adjust down the larger of the
485 // generations.
487 // Add some checks for a threshhold for a change. For example,
488 // a change less than the necessary alignment is probably not worth
489 // attempting.
491 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
492 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
493 //
494 // Check pauses
495 //
496 // Make changes only to affect one of the pauses (the larger)
497 // at a time.
498 if (is_full_gc) {
499 set_decide_at_full_gc(decide_at_full_gc_true);
500 adjust_promo_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
501 }
502 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
503 // Adjust only for the minor pause time goal
504 adjust_promo_for_minor_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
505 } else if(adjusted_mutator_cost() < _throughput_goal) {
506 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
507 // This sometimes resulted in skipping to the minimize footprint
508 // code. Change this to try and reduce GC time if mutator time is
509 // negative for whatever reason. Or for future consideration,
510 // bail out of the code if mutator time is negative.
511 //
512 // Throughput
513 //
514 assert(major_cost >= 0.0, "major cost is < 0.0");
515 assert(minor_cost >= 0.0, "minor cost is < 0.0");
516 // Try to reduce the GC times.
517 if (is_full_gc) {
518 set_decide_at_full_gc(decide_at_full_gc_true);
519 adjust_promo_for_throughput(is_full_gc, &desired_promo_size);
520 }
521 } else {
523 // Be conservative about reducing the footprint.
524 // Do a minimum number of major collections first.
525 // Have reasonable averages for major and minor collections costs.
526 if (UseAdaptiveSizePolicyFootprintGoal &&
527 young_gen_policy_is_ready() &&
528 avg_major_gc_cost()->average() >= 0.0 &&
529 avg_minor_gc_cost()->average() >= 0.0) {
530 if (is_full_gc) {
531 set_decide_at_full_gc(decide_at_full_gc_true);
532 size_t desired_sum = desired_eden_size + desired_promo_size;
533 desired_promo_size = adjust_promo_for_footprint(desired_promo_size, desired_sum);
534 }
535 }
536 }
538 // Note we make the same tests as in the code block below; the code
539 // seems a little easier to read with the printing in another block.
540 if (PrintAdaptiveSizePolicy) {
541 if (desired_promo_size > promo_limit) {
542 // "free_in_old_gen" was the original value for used for promo_limit
543 size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());
544 gclog_or_tty->print_cr(
545 "PSAdaptiveSizePolicy::compute_old_gen_free_space limits:"
546 " desired_promo_size: " SIZE_FORMAT
547 " promo_limit: " SIZE_FORMAT
548 " free_in_old_gen: " SIZE_FORMAT
549 " max_old_gen_size: " SIZE_FORMAT
550 " avg_old_live: " SIZE_FORMAT,
551 desired_promo_size, promo_limit, free_in_old_gen,
552 max_old_gen_size, (size_t) avg_old_live()->average());
553 }
554 if (gc_cost() > gc_cost_limit) {
555 gclog_or_tty->print_cr(
556 "PSAdaptiveSizePolicy::compute_old_gen_free_space: gc time limit"
557 " gc_cost: %f "
558 " GCTimeLimit: %d",
559 gc_cost(), GCTimeLimit);
560 }
561 }
563 // Align everything and make a final limit check
564 const size_t alignment = _intra_generation_alignment;
565 desired_promo_size = align_size_up(desired_promo_size, alignment);
566 desired_promo_size = MAX2(desired_promo_size, alignment);
568 promo_limit = align_size_down(promo_limit, alignment);
570 // And one last limit check, now that we've aligned things.
571 desired_promo_size = MIN2(desired_promo_size, promo_limit);
573 if (PrintAdaptiveSizePolicy) {
574 // Timing stats
575 gclog_or_tty->print(
576 "PSAdaptiveSizePolicy::compute_old_gen_free_space: costs"
577 " minor_time: %f"
578 " major_cost: %f"
579 " mutator_cost: %f"
580 " throughput_goal: %f",
581 minor_gc_cost(), major_gc_cost(), mutator_cost(),
582 _throughput_goal);
584 // We give more details if Verbose is set
585 if (Verbose) {
586 gclog_or_tty->print( " minor_pause: %f"
587 " major_pause: %f"
588 " minor_interval: %f"
589 " major_interval: %f"
590 " pause_goal: %f",
591 _avg_minor_pause->padded_average(),
592 _avg_major_pause->padded_average(),
593 _avg_minor_interval->average(),
594 _avg_major_interval->average(),
595 gc_pause_goal_sec());
596 }
598 // Footprint stats
599 gclog_or_tty->print( " live_space: " SIZE_FORMAT
600 " free_space: " SIZE_FORMAT,
601 live_space(), free_space());
602 // More detail
603 if (Verbose) {
604 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
605 " avg_young_live: " SIZE_FORMAT
606 " avg_old_live: " SIZE_FORMAT,
607 (size_t)_avg_base_footprint->average(),
608 (size_t)avg_young_live()->average(),
609 (size_t)avg_old_live()->average());
610 }
612 // And finally, our old and new sizes.
613 gclog_or_tty->print(" old_promo_size: " SIZE_FORMAT
614 " desired_promo_size: " SIZE_FORMAT,
615 _promo_size, desired_promo_size);
616 gclog_or_tty->cr();
617 }
619 set_promo_size(desired_promo_size);
620 }
622 void PSAdaptiveSizePolicy::decay_supplemental_growth(bool is_full_gc) {
623 // Decay the supplemental increment? Decay the supplement growth
624 // factor even if it is not used. It is only meant to give a boost
625 // to the initial growth and if it is not used, then it was not
626 // needed.
627 if (is_full_gc) {
628 // Don't wait for the threshold value for the major collections. If
629 // here, the supplemental growth term was used and should decay.
630 if ((_avg_major_pause->count() % TenuredGenerationSizeSupplementDecay)
631 == 0) {
632 _old_gen_size_increment_supplement =
633 _old_gen_size_increment_supplement >> 1;
634 }
635 } else {
636 if ((_avg_minor_pause->count() >= AdaptiveSizePolicyReadyThreshold) &&
637 (_avg_minor_pause->count() % YoungGenerationSizeSupplementDecay) == 0) {
638 _young_gen_size_increment_supplement =
639 _young_gen_size_increment_supplement >> 1;
640 }
641 }
642 }
644 void PSAdaptiveSizePolicy::adjust_promo_for_minor_pause_time(bool is_full_gc,
645 size_t* desired_promo_size_ptr, size_t* desired_eden_size_ptr) {
647 if (PSAdjustTenuredGenForMinorPause) {
648 if (is_full_gc) {
649 set_decide_at_full_gc(decide_at_full_gc_true);
650 }
651 // If the desired eden size is as small as it will get,
652 // try to adjust the old gen size.
653 if (*desired_eden_size_ptr <= _intra_generation_alignment) {
654 // Vary the old gen size to reduce the young gen pause. This
655 // may not be a good idea. This is just a test.
656 if (minor_pause_old_estimator()->decrement_will_decrease()) {
657 set_change_old_gen_for_min_pauses(decrease_old_gen_for_min_pauses_true);
658 *desired_promo_size_ptr =
659 _promo_size - promo_decrement_aligned_down(*desired_promo_size_ptr);
660 } else {
661 set_change_old_gen_for_min_pauses(increase_old_gen_for_min_pauses_true);
662 size_t promo_heap_delta =
663 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
664 if ((*desired_promo_size_ptr + promo_heap_delta) >
665 *desired_promo_size_ptr) {
666 *desired_promo_size_ptr =
667 _promo_size + promo_heap_delta;
668 }
669 }
670 }
671 }
672 }
674 void PSAdaptiveSizePolicy::adjust_eden_for_minor_pause_time(bool is_full_gc,
675 size_t* desired_eden_size_ptr) {
677 // Adjust the young generation size to reduce pause time of
678 // of collections.
679 //
680 // The AdaptiveSizePolicyInitializingSteps test is not used
681 // here. It has not seemed to be needed but perhaps should
682 // be added for consistency.
683 if (minor_pause_young_estimator()->decrement_will_decrease()) {
684 // reduce eden size
685 set_change_young_gen_for_min_pauses(
686 decrease_young_gen_for_min_pauses_true);
687 *desired_eden_size_ptr = *desired_eden_size_ptr -
688 eden_decrement_aligned_down(*desired_eden_size_ptr);
689 } else {
690 // EXPERIMENTAL ADJUSTMENT
691 // Only record that the estimator indicated such an action.
692 // *desired_eden_size_ptr = *desired_eden_size_ptr + eden_heap_delta;
693 set_change_young_gen_for_min_pauses(
694 increase_young_gen_for_min_pauses_true);
695 }
696 }
698 void PSAdaptiveSizePolicy::adjust_promo_for_pause_time(bool is_full_gc,
699 size_t* desired_promo_size_ptr,
700 size_t* desired_eden_size_ptr) {
702 size_t promo_heap_delta = 0;
703 // Add some checks for a threshold for a change. For example,
704 // a change less than the required alignment is probably not worth
705 // attempting.
707 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
708 adjust_promo_for_minor_pause_time(is_full_gc, desired_promo_size_ptr, desired_eden_size_ptr);
709 // major pause adjustments
710 } else if (is_full_gc) {
711 // Adjust for the major pause time only at full gc's because the
712 // affects of a change can only be seen at full gc's.
714 // Reduce old generation size to reduce pause?
715 if (major_pause_old_estimator()->decrement_will_decrease()) {
716 // reduce old generation size
717 set_change_old_gen_for_maj_pauses(decrease_old_gen_for_maj_pauses_true);
718 promo_heap_delta = promo_decrement_aligned_down(*desired_promo_size_ptr);
719 *desired_promo_size_ptr = _promo_size - promo_heap_delta;
720 } else {
721 // EXPERIMENTAL ADJUSTMENT
722 // Only record that the estimator indicated such an action.
723 // *desired_promo_size_ptr = _promo_size +
724 // promo_increment_aligned_up(*desired_promo_size_ptr);
725 set_change_old_gen_for_maj_pauses(increase_old_gen_for_maj_pauses_true);
726 }
727 }
729 if (PrintAdaptiveSizePolicy && Verbose) {
730 gclog_or_tty->print_cr(
731 "PSAdaptiveSizePolicy::adjust_promo_for_pause_time "
732 "adjusting gen sizes for major pause (avg %f goal %f). "
733 "desired_promo_size " SIZE_FORMAT " promo delta " SIZE_FORMAT,
734 _avg_major_pause->average(), gc_pause_goal_sec(),
735 *desired_promo_size_ptr, promo_heap_delta);
736 }
737 }
739 void PSAdaptiveSizePolicy::adjust_eden_for_pause_time(bool is_full_gc,
740 size_t* desired_promo_size_ptr,
741 size_t* desired_eden_size_ptr) {
743 size_t eden_heap_delta = 0;
744 // Add some checks for a threshold for a change. For example,
745 // a change less than the required alignment is probably not worth
746 // attempting.
747 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
748 adjust_eden_for_minor_pause_time(is_full_gc,
749 desired_eden_size_ptr);
750 // major pause adjustments
751 } else if (is_full_gc) {
752 // Adjust for the major pause time only at full gc's because the
753 // affects of a change can only be seen at full gc's.
754 if (PSAdjustYoungGenForMajorPause) {
755 // If the promo size is at the minimum (i.e., the old gen
756 // size will not actually decrease), consider changing the
757 // young gen size.
758 if (*desired_promo_size_ptr < _intra_generation_alignment) {
759 // If increasing the young generation will decrease the old gen
760 // pause, do it.
761 // During startup there is noise in the statistics for deciding
762 // on whether to increase or decrease the young gen size. For
763 // some number of iterations, just try to increase the young
764 // gen size if the major pause is too long to try and establish
765 // good statistics for later decisions.
766 if (major_pause_young_estimator()->increment_will_decrease() ||
767 (_young_gen_change_for_major_pause_count
768 <= AdaptiveSizePolicyInitializingSteps)) {
769 set_change_young_gen_for_maj_pauses(
770 increase_young_gen_for_maj_pauses_true);
771 eden_heap_delta = eden_increment_aligned_up(*desired_eden_size_ptr);
772 *desired_eden_size_ptr = _eden_size + eden_heap_delta;
773 _young_gen_change_for_major_pause_count++;
774 } else {
775 // Record that decreasing the young gen size would decrease
776 // the major pause
777 set_change_young_gen_for_maj_pauses(
778 decrease_young_gen_for_maj_pauses_true);
779 eden_heap_delta = eden_decrement_aligned_down(*desired_eden_size_ptr);
780 *desired_eden_size_ptr = _eden_size - eden_heap_delta;
781 }
782 }
783 }
784 }
786 if (PrintAdaptiveSizePolicy && Verbose) {
787 gclog_or_tty->print_cr(
788 "PSAdaptiveSizePolicy::adjust_eden_for_pause_time "
789 "adjusting gen sizes for major pause (avg %f goal %f). "
790 "desired_eden_size " SIZE_FORMAT " eden delta " SIZE_FORMAT,
791 _avg_major_pause->average(), gc_pause_goal_sec(),
792 *desired_eden_size_ptr, eden_heap_delta);
793 }
794 }
796 void PSAdaptiveSizePolicy::adjust_promo_for_throughput(bool is_full_gc,
797 size_t* desired_promo_size_ptr) {
799 // Add some checks for a threshold for a change. For example,
800 // a change less than the required alignment is probably not worth
801 // attempting.
803 if ((gc_cost() + mutator_cost()) == 0.0) {
804 return;
805 }
807 if (PrintAdaptiveSizePolicy && Verbose) {
808 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_promo_for_throughput("
809 "is_full: %d, promo: " SIZE_FORMAT "): ",
810 is_full_gc, *desired_promo_size_ptr);
811 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
812 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
813 }
815 // Tenured generation
816 if (is_full_gc) {
817 // Calculate the change to use for the tenured gen.
818 size_t scaled_promo_heap_delta = 0;
819 // Can the increment to the generation be scaled?
820 if (gc_cost() >= 0.0 && major_gc_cost() >= 0.0) {
821 size_t promo_heap_delta =
822 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
823 double scale_by_ratio = major_gc_cost() / gc_cost();
824 scaled_promo_heap_delta =
825 (size_t) (scale_by_ratio * (double) promo_heap_delta);
826 if (PrintAdaptiveSizePolicy && Verbose) {
827 gclog_or_tty->print_cr(
828 "Scaled tenured increment: " SIZE_FORMAT " by %f down to "
829 SIZE_FORMAT,
830 promo_heap_delta, scale_by_ratio, scaled_promo_heap_delta);
831 }
832 } else if (major_gc_cost() >= 0.0) {
833 // Scaling is not going to work. If the major gc time is the
834 // larger, give it a full increment.
835 if (major_gc_cost() >= minor_gc_cost()) {
836 scaled_promo_heap_delta =
837 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
838 }
839 } else {
840 // Don't expect to get here but it's ok if it does
841 // in the product build since the delta will be 0
842 // and nothing will change.
843 assert(false, "Unexpected value for gc costs");
844 }
846 switch (AdaptiveSizeThroughPutPolicy) {
847 case 1:
848 // Early in the run the statistics might not be good. Until
849 // a specific number of collections have been, use the heuristic
850 // that a larger generation size means lower collection costs.
851 if (major_collection_estimator()->increment_will_decrease() ||
852 (_old_gen_change_for_major_throughput
853 <= AdaptiveSizePolicyInitializingSteps)) {
854 // Increase tenured generation size to reduce major collection cost
855 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
856 *desired_promo_size_ptr) {
857 *desired_promo_size_ptr = _promo_size + scaled_promo_heap_delta;
858 }
859 set_change_old_gen_for_throughput(
860 increase_old_gen_for_throughput_true);
861 _old_gen_change_for_major_throughput++;
862 } else {
863 // EXPERIMENTAL ADJUSTMENT
864 // Record that decreasing the old gen size would decrease
865 // the major collection cost but don't do it.
866 // *desired_promo_size_ptr = _promo_size -
867 // promo_decrement_aligned_down(*desired_promo_size_ptr);
868 set_change_old_gen_for_throughput(
869 decrease_old_gen_for_throughput_true);
870 }
872 break;
873 default:
874 // Simplest strategy
875 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
876 *desired_promo_size_ptr) {
877 *desired_promo_size_ptr = *desired_promo_size_ptr +
878 scaled_promo_heap_delta;
879 }
880 set_change_old_gen_for_throughput(
881 increase_old_gen_for_throughput_true);
882 _old_gen_change_for_major_throughput++;
883 }
885 if (PrintAdaptiveSizePolicy && Verbose) {
886 gclog_or_tty->print_cr(
887 "adjusting tenured gen for throughput (avg %f goal %f). "
888 "desired_promo_size " SIZE_FORMAT " promo_delta " SIZE_FORMAT ,
889 mutator_cost(), _throughput_goal,
890 *desired_promo_size_ptr, scaled_promo_heap_delta);
891 }
892 }
893 }
895 void PSAdaptiveSizePolicy::adjust_eden_for_throughput(bool is_full_gc,
896 size_t* desired_eden_size_ptr) {
898 // Add some checks for a threshold for a change. For example,
899 // a change less than the required alignment is probably not worth
900 // attempting.
902 if ((gc_cost() + mutator_cost()) == 0.0) {
903 return;
904 }
906 if (PrintAdaptiveSizePolicy && Verbose) {
907 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_eden_for_throughput("
908 "is_full: %d, cur_eden: " SIZE_FORMAT "): ",
909 is_full_gc, *desired_eden_size_ptr);
910 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
911 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
912 }
914 // Young generation
915 size_t scaled_eden_heap_delta = 0;
916 // Can the increment to the generation be scaled?
917 if (gc_cost() >= 0.0 && minor_gc_cost() >= 0.0) {
918 size_t eden_heap_delta =
919 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
920 double scale_by_ratio = minor_gc_cost() / gc_cost();
921 assert(scale_by_ratio <= 1.0 && scale_by_ratio >= 0.0, "Scaling is wrong");
922 scaled_eden_heap_delta =
923 (size_t) (scale_by_ratio * (double) eden_heap_delta);
924 if (PrintAdaptiveSizePolicy && Verbose) {
925 gclog_or_tty->print_cr(
926 "Scaled eden increment: " SIZE_FORMAT " by %f down to "
927 SIZE_FORMAT,
928 eden_heap_delta, scale_by_ratio, scaled_eden_heap_delta);
929 }
930 } else if (minor_gc_cost() >= 0.0) {
931 // Scaling is not going to work. If the minor gc time is the
932 // larger, give it a full increment.
933 if (minor_gc_cost() > major_gc_cost()) {
934 scaled_eden_heap_delta =
935 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
936 }
937 } else {
938 // Don't expect to get here but it's ok if it does
939 // in the product build since the delta will be 0
940 // and nothing will change.
941 assert(false, "Unexpected value for gc costs");
942 }
944 // Use a heuristic for some number of collections to give
945 // the averages time to settle down.
946 switch (AdaptiveSizeThroughPutPolicy) {
947 case 1:
948 if (minor_collection_estimator()->increment_will_decrease() ||
949 (_young_gen_change_for_minor_throughput
950 <= AdaptiveSizePolicyInitializingSteps)) {
951 // Expand young generation size to reduce frequency of
952 // of collections.
953 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
954 *desired_eden_size_ptr) {
955 *desired_eden_size_ptr =
956 *desired_eden_size_ptr + scaled_eden_heap_delta;
957 }
958 set_change_young_gen_for_throughput(
959 increase_young_gen_for_througput_true);
960 _young_gen_change_for_minor_throughput++;
961 } else {
962 // EXPERIMENTAL ADJUSTMENT
963 // Record that decreasing the young gen size would decrease
964 // the minor collection cost but don't do it.
965 // *desired_eden_size_ptr = _eden_size -
966 // eden_decrement_aligned_down(*desired_eden_size_ptr);
967 set_change_young_gen_for_throughput(
968 decrease_young_gen_for_througput_true);
969 }
970 break;
971 default:
972 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
973 *desired_eden_size_ptr) {
974 *desired_eden_size_ptr =
975 *desired_eden_size_ptr + scaled_eden_heap_delta;
976 }
977 set_change_young_gen_for_throughput(
978 increase_young_gen_for_througput_true);
979 _young_gen_change_for_minor_throughput++;
980 }
982 if (PrintAdaptiveSizePolicy && Verbose) {
983 gclog_or_tty->print_cr(
984 "adjusting eden for throughput (avg %f goal %f). desired_eden_size "
985 SIZE_FORMAT " eden delta " SIZE_FORMAT "\n",
986 mutator_cost(), _throughput_goal,
987 *desired_eden_size_ptr, scaled_eden_heap_delta);
988 }
989 }
991 size_t PSAdaptiveSizePolicy::adjust_promo_for_footprint(
992 size_t desired_promo_size, size_t desired_sum) {
993 assert(desired_promo_size <= desired_sum, "Inconsistent parameters");
994 set_decrease_for_footprint(decrease_old_gen_for_footprint_true);
996 size_t change = promo_decrement(desired_promo_size);
997 change = scale_down(change, desired_promo_size, desired_sum);
999 size_t reduced_size = desired_promo_size - change;
1001 if (PrintAdaptiveSizePolicy && Verbose) {
1002 gclog_or_tty->print_cr(
1003 "AdaptiveSizePolicy::adjust_promo_for_footprint "
1004 "adjusting tenured gen for footprint. "
1005 "starting promo size " SIZE_FORMAT
1006 " reduced promo size " SIZE_FORMAT,
1007 " promo delta " SIZE_FORMAT,
1008 desired_promo_size, reduced_size, change );
1009 }
1011 assert(reduced_size <= desired_promo_size, "Inconsistent result");
1012 return reduced_size;
1013 }
1015 size_t PSAdaptiveSizePolicy::adjust_eden_for_footprint(
1016 size_t desired_eden_size, size_t desired_sum) {
1017 assert(desired_eden_size <= desired_sum, "Inconsistent parameters");
1018 set_decrease_for_footprint(decrease_young_gen_for_footprint_true);
1020 size_t change = eden_decrement(desired_eden_size);
1021 change = scale_down(change, desired_eden_size, desired_sum);
1023 size_t reduced_size = desired_eden_size - change;
1025 if (PrintAdaptiveSizePolicy && Verbose) {
1026 gclog_or_tty->print_cr(
1027 "AdaptiveSizePolicy::adjust_eden_for_footprint "
1028 "adjusting eden for footprint. "
1029 " starting eden size " SIZE_FORMAT
1030 " reduced eden size " SIZE_FORMAT
1031 " eden delta " SIZE_FORMAT,
1032 desired_eden_size, reduced_size, change);
1033 }
1035 assert(reduced_size <= desired_eden_size, "Inconsistent result");
1036 return reduced_size;
1037 }
1039 // Scale down "change" by the factor
1040 // part / total
1041 // Don't align the results.
1043 size_t PSAdaptiveSizePolicy::scale_down(size_t change,
1044 double part,
1045 double total) {
1046 assert(part <= total, "Inconsistent input");
1047 size_t reduced_change = change;
1048 if (total > 0) {
1049 double fraction = part / total;
1050 reduced_change = (size_t) (fraction * (double) change);
1051 }
1052 assert(reduced_change <= change, "Inconsistent result");
1053 return reduced_change;
1054 }
1056 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden,
1057 uint percent_change) {
1058 size_t eden_heap_delta;
1059 eden_heap_delta = cur_eden / 100 * percent_change;
1060 return eden_heap_delta;
1061 }
1063 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden) {
1064 return eden_increment(cur_eden, YoungGenerationSizeIncrement);
1065 }
1067 size_t PSAdaptiveSizePolicy::eden_increment_aligned_up(size_t cur_eden) {
1068 size_t result = eden_increment(cur_eden, YoungGenerationSizeIncrement);
1069 return align_size_up(result, _intra_generation_alignment);
1070 }
1072 size_t PSAdaptiveSizePolicy::eden_increment_aligned_down(size_t cur_eden) {
1073 size_t result = eden_increment(cur_eden);
1074 return align_size_down(result, _intra_generation_alignment);
1075 }
1077 size_t PSAdaptiveSizePolicy::eden_increment_with_supplement_aligned_up(
1078 size_t cur_eden) {
1079 size_t result = eden_increment(cur_eden,
1080 YoungGenerationSizeIncrement + _young_gen_size_increment_supplement);
1081 return align_size_up(result, _intra_generation_alignment);
1082 }
1084 size_t PSAdaptiveSizePolicy::eden_decrement_aligned_down(size_t cur_eden) {
1085 size_t eden_heap_delta = eden_decrement(cur_eden);
1086 return align_size_down(eden_heap_delta, _intra_generation_alignment);
1087 }
1089 size_t PSAdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
1090 size_t eden_heap_delta = eden_increment(cur_eden) /
1091 AdaptiveSizeDecrementScaleFactor;
1092 return eden_heap_delta;
1093 }
1095 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo,
1096 uint percent_change) {
1097 size_t promo_heap_delta;
1098 promo_heap_delta = cur_promo / 100 * percent_change;
1099 return promo_heap_delta;
1100 }
1102 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo) {
1103 return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1104 }
1106 size_t PSAdaptiveSizePolicy::promo_increment_aligned_up(size_t cur_promo) {
1107 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1108 return align_size_up(result, _intra_generation_alignment);
1109 }
1111 size_t PSAdaptiveSizePolicy::promo_increment_aligned_down(size_t cur_promo) {
1112 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1113 return align_size_down(result, _intra_generation_alignment);
1114 }
1116 size_t PSAdaptiveSizePolicy::promo_increment_with_supplement_aligned_up(
1117 size_t cur_promo) {
1118 size_t result = promo_increment(cur_promo,
1119 TenuredGenerationSizeIncrement + _old_gen_size_increment_supplement);
1120 return align_size_up(result, _intra_generation_alignment);
1121 }
1123 size_t PSAdaptiveSizePolicy::promo_decrement_aligned_down(size_t cur_promo) {
1124 size_t promo_heap_delta = promo_decrement(cur_promo);
1125 return align_size_down(promo_heap_delta, _intra_generation_alignment);
1126 }
1128 size_t PSAdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
1129 size_t promo_heap_delta = promo_increment(cur_promo);
1130 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
1131 return promo_heap_delta;
1132 }
1134 uint PSAdaptiveSizePolicy::compute_survivor_space_size_and_threshold(
1135 bool is_survivor_overflow,
1136 uint tenuring_threshold,
1137 size_t survivor_limit) {
1138 assert(survivor_limit >= _intra_generation_alignment,
1139 "survivor_limit too small");
1140 assert((size_t)align_size_down(survivor_limit, _intra_generation_alignment)
1141 == survivor_limit, "survivor_limit not aligned");
1143 // This method is called even if the tenuring threshold and survivor
1144 // spaces are not adjusted so that the averages are sampled above.
1145 if (!UsePSAdaptiveSurvivorSizePolicy ||
1146 !young_gen_policy_is_ready()) {
1147 return tenuring_threshold;
1148 }
1150 // We'll decide whether to increase or decrease the tenuring
1151 // threshold based partly on the newly computed survivor size
1152 // (if we hit the maximum limit allowed, we'll always choose to
1153 // decrement the threshold).
1154 bool incr_tenuring_threshold = false;
1155 bool decr_tenuring_threshold = false;
1157 set_decrement_tenuring_threshold_for_gc_cost(false);
1158 set_increment_tenuring_threshold_for_gc_cost(false);
1159 set_decrement_tenuring_threshold_for_survivor_limit(false);
1161 if (!is_survivor_overflow) {
1162 // Keep running averages on how much survived
1164 // We use the tenuring threshold to equalize the cost of major
1165 // and minor collections.
1166 // ThresholdTolerance is used to indicate how sensitive the
1167 // tenuring threshold is to differences in cost betweent the
1168 // collection types.
1170 // Get the times of interest. This involves a little work, so
1171 // we cache the values here.
1172 const double major_cost = major_gc_cost();
1173 const double minor_cost = minor_gc_cost();
1175 if (minor_cost > major_cost * _threshold_tolerance_percent) {
1176 // Minor times are getting too long; lower the threshold so
1177 // less survives and more is promoted.
1178 decr_tenuring_threshold = true;
1179 set_decrement_tenuring_threshold_for_gc_cost(true);
1180 } else if (major_cost > minor_cost * _threshold_tolerance_percent) {
1181 // Major times are too long, so we want less promotion.
1182 incr_tenuring_threshold = true;
1183 set_increment_tenuring_threshold_for_gc_cost(true);
1184 }
1186 } else {
1187 // Survivor space overflow occurred, so promoted and survived are
1188 // not accurate. We'll make our best guess by combining survived
1189 // and promoted and count them as survivors.
1190 //
1191 // We'll lower the tenuring threshold to see if we can correct
1192 // things. Also, set the survivor size conservatively. We're
1193 // trying to avoid many overflows from occurring if defnew size
1194 // is just too small.
1196 decr_tenuring_threshold = true;
1197 }
1199 // The padded average also maintains a deviation from the average;
1200 // we use this to see how good of an estimate we have of what survived.
1201 // We're trying to pad the survivor size as little as possible without
1202 // overflowing the survivor spaces.
1203 size_t target_size = align_size_up((size_t)_avg_survived->padded_average(),
1204 _intra_generation_alignment);
1205 target_size = MAX2(target_size, _intra_generation_alignment);
1207 if (target_size > survivor_limit) {
1208 // Target size is bigger than we can handle. Let's also reduce
1209 // the tenuring threshold.
1210 target_size = survivor_limit;
1211 decr_tenuring_threshold = true;
1212 set_decrement_tenuring_threshold_for_survivor_limit(true);
1213 }
1215 // Finally, increment or decrement the tenuring threshold, as decided above.
1216 // We test for decrementing first, as we might have hit the target size
1217 // limit.
1218 if (decr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1219 if (tenuring_threshold > 1) {
1220 tenuring_threshold--;
1221 }
1222 } else if (incr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1223 if (tenuring_threshold < MaxTenuringThreshold) {
1224 tenuring_threshold++;
1225 }
1226 }
1228 // We keep a running average of the amount promoted which is used
1229 // to decide when we should collect the old generation (when
1230 // the amount of old gen free space is less than what we expect to
1231 // promote).
1233 if (PrintAdaptiveSizePolicy) {
1234 // A little more detail if Verbose is on
1235 if (Verbose) {
1236 gclog_or_tty->print( " avg_survived: %f"
1237 " avg_deviation: %f",
1238 _avg_survived->average(),
1239 _avg_survived->deviation());
1240 }
1242 gclog_or_tty->print( " avg_survived_padded_avg: %f",
1243 _avg_survived->padded_average());
1245 if (Verbose) {
1246 gclog_or_tty->print( " avg_promoted_avg: %f"
1247 " avg_promoted_dev: %f",
1248 avg_promoted()->average(),
1249 avg_promoted()->deviation());
1250 }
1252 gclog_or_tty->print_cr( " avg_promoted_padded_avg: %f"
1253 " avg_pretenured_padded_avg: %f"
1254 " tenuring_thresh: %d"
1255 " target_size: " SIZE_FORMAT,
1256 avg_promoted()->padded_average(),
1257 _avg_pretenured->padded_average(),
1258 tenuring_threshold, target_size);
1259 }
1261 set_survivor_size(target_size);
1263 return tenuring_threshold;
1264 }
1266 void PSAdaptiveSizePolicy::update_averages(bool is_survivor_overflow,
1267 size_t survived,
1268 size_t promoted) {
1269 // Update averages
1270 if (!is_survivor_overflow) {
1271 // Keep running averages on how much survived
1272 _avg_survived->sample(survived);
1273 } else {
1274 size_t survived_guess = survived + promoted;
1275 _avg_survived->sample(survived_guess);
1276 }
1277 avg_promoted()->sample(promoted + _avg_pretenured->padded_average());
1279 if (PrintAdaptiveSizePolicy) {
1280 gclog_or_tty->print_cr(
1281 "AdaptiveSizePolicy::update_averages:"
1282 " survived: " SIZE_FORMAT
1283 " promoted: " SIZE_FORMAT
1284 " overflow: %s",
1285 survived, promoted, is_survivor_overflow ? "true" : "false");
1286 }
1287 }
1289 bool PSAdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st)
1290 const {
1292 if (!UseAdaptiveSizePolicy) return false;
1294 return AdaptiveSizePolicy::print_adaptive_size_policy_on(
1295 st,
1296 PSScavenge::tenuring_threshold());
1297 }