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.
8 *
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.
18 *
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.
22 *
23 */
24
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"
34
35 #include <math.h>
36
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 / 100.0),
50 _intra_generation_alignment(intra_generation_alignment),
51 _live_at_last_full_gc(init_promo_size),
52 _gc_minor_pause_goal_sec(gc_minor_pause_goal_sec),
53 _latest_major_mutator_interval_seconds(0),
54 _young_gen_change_for_major_pause_count(0)
55 {
56 // Sizing policy statistics
57 _avg_major_pause =
58 new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding);
59 _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
60 _avg_major_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
61
62 _avg_base_footprint = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
63 _major_pause_old_estimator =
64 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
65 _major_pause_young_estimator =
66 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
67 _major_collection_estimator =
68 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
69
70 _young_gen_size_increment_supplement = YoungGenerationSizeSupplement;
71 _old_gen_size_increment_supplement = TenuredGenerationSizeSupplement;
72
73 // Start the timers
74 _major_timer.start();
75
76 _old_gen_policy_is_ready = false;
77 }
78
79 void PSAdaptiveSizePolicy::major_collection_begin() {
80 // Update the interval time
81 _major_timer.stop();
82 // Save most recent collection time
83 _latest_major_mutator_interval_seconds = _major_timer.seconds();
84 _major_timer.reset();
85 _major_timer.start();
86 }
87
88 void PSAdaptiveSizePolicy::update_minor_pause_old_estimator(
89 double minor_pause_in_ms) {
90 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
91 _minor_pause_old_estimator->update(promo_size_in_mbytes,
92 minor_pause_in_ms);
93 }
94
95 void PSAdaptiveSizePolicy::major_collection_end(size_t amount_live,
96 GCCause::Cause gc_cause) {
97 // Update the pause time.
98 _major_timer.stop();
99
100 if (gc_cause != GCCause::_java_lang_system_gc ||
101 UseAdaptiveSizePolicyWithSystemGC) {
102 double major_pause_in_seconds = _major_timer.seconds();
103 double major_pause_in_ms = major_pause_in_seconds * MILLIUNITS;
104
105 // Sample for performance counter
106 _avg_major_pause->sample(major_pause_in_seconds);
107
108 // Cost of collection (unit-less)
109 double collection_cost = 0.0;
110 if ((_latest_major_mutator_interval_seconds > 0.0) &&
111 (major_pause_in_seconds > 0.0)) {
112 double interval_in_seconds =
113 _latest_major_mutator_interval_seconds + major_pause_in_seconds;
114 collection_cost =
115 major_pause_in_seconds / interval_in_seconds;
116 avg_major_gc_cost()->sample(collection_cost);
117
118 // Sample for performance counter
119 _avg_major_interval->sample(interval_in_seconds);
120 }
121
122 // Calculate variables used to estimate pause time vs. gen sizes
123 double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
124 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
125 _major_pause_old_estimator->update(promo_size_in_mbytes,
126 major_pause_in_ms);
127 _major_pause_young_estimator->update(eden_size_in_mbytes,
128 major_pause_in_ms);
129
130 if (PrintAdaptiveSizePolicy && Verbose) {
131 gclog_or_tty->print("psAdaptiveSizePolicy::major_collection_end: "
132 "major gc cost: %f average: %f", collection_cost,
133 avg_major_gc_cost()->average());
134 gclog_or_tty->print_cr(" major pause: %f major period %f",
135 major_pause_in_ms,
136 _latest_major_mutator_interval_seconds * MILLIUNITS);
137 }
138
139 // Calculate variable used to estimate collection cost vs. gen sizes
140 assert(collection_cost >= 0.0, "Expected to be non-negative");
141 _major_collection_estimator->update(promo_size_in_mbytes,
142 collection_cost);
143 }
144
145 // Update the amount live at the end of a full GC
146 _live_at_last_full_gc = amount_live;
147
148 // The policy does not have enough data until at least some major collections
149 // have been done.
150 if (_avg_major_pause->count() >= AdaptiveSizePolicyReadyThreshold) {
151 _old_gen_policy_is_ready = true;
152 }
153
154 // Interval times use this timer to measure the interval that
155 // the mutator runs. Reset after the GC pause has been measured.
156 _major_timer.reset();
157 _major_timer.start();
158 }
159
160 // If the remaining free space in the old generation is less that
161 // that expected to be needed by the next collection, do a full
162 // collection now.
163 bool PSAdaptiveSizePolicy::should_full_GC(size_t old_free_in_bytes) {
164
165 // A similar test is done in the scavenge's should_attempt_scavenge(). If
166 // this is changed, decide if that test should also be changed.
167 bool result = padded_average_promoted_in_bytes() > (float) old_free_in_bytes;
168 if (PrintGCDetails && Verbose) {
169 if (result) {
170 gclog_or_tty->print(" full after scavenge: ");
171 } else {
172 gclog_or_tty->print(" no full after scavenge: ");
173 }
174 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
175 " padded_average_promoted " SIZE_FORMAT
176 " free in old gen " SIZE_FORMAT,
177 (size_t) average_promoted_in_bytes(),
178 (size_t) padded_average_promoted_in_bytes(),
179 old_free_in_bytes);
180 }
181 return result;
182 }
183
184 void PSAdaptiveSizePolicy::clear_generation_free_space_flags() {
185
186 AdaptiveSizePolicy::clear_generation_free_space_flags();
187
188 set_change_old_gen_for_min_pauses(0);
189
190 set_change_young_gen_for_maj_pauses(0);
191 }
192
193 // If this is not a full GC, only test and modify the young generation.
194
195 void PSAdaptiveSizePolicy::compute_generations_free_space(
196 size_t young_live,
197 size_t eden_live,
198 size_t old_live,
199 size_t cur_eden,
200 size_t max_old_gen_size,
201 size_t max_eden_size,
202 bool is_full_gc) {
203 compute_eden_space_size(young_live,
204 eden_live,
205 cur_eden,
206 max_eden_size,
207 is_full_gc);
208
209 compute_old_gen_free_space(old_live,
210 cur_eden,
211 max_old_gen_size,
212 is_full_gc);
213 }
214
215 void PSAdaptiveSizePolicy::compute_eden_space_size(
216 size_t young_live,
217 size_t eden_live,
218 size_t cur_eden,
219 size_t max_eden_size,
220 bool is_full_gc) {
221
222 // Update statistics
223 // Time statistics are updated as we go, update footprint stats here
224 _avg_base_footprint->sample(BaseFootPrintEstimate);
225 avg_young_live()->sample(young_live);
226 avg_eden_live()->sample(eden_live);
227
228 // This code used to return if the policy was not ready , i.e.,
229 // policy_is_ready() returning false. The intent was that
230 // decisions below needed major collection times and so could
231 // not be made before two major collections. A consequence was
232 // adjustments to the young generation were not done until after
233 // two major collections even if the minor collections times
234 // exceeded the requested goals. Now let the young generation
235 // adjust for the minor collection times. Major collection times
236 // will be zero for the first collection and will naturally be
237 // ignored. Tenured generation adjustments are only made at the
238 // full collections so until the second major collection has
239 // been reached, no tenured generation adjustments will be made.
240
241 // Until we know better, desired promotion size uses the last calculation
242 size_t desired_promo_size = _promo_size;
243
244 // Start eden at the current value. The desired value that is stored
245 // in _eden_size is not bounded by constraints of the heap and can
246 // run away.
247 //
248 // As expected setting desired_eden_size to the current
249 // value of desired_eden_size as a starting point
250 // caused desired_eden_size to grow way too large and caused
251 // an overflow down stream. It may have improved performance in
252 // some case but is dangerous.
253 size_t desired_eden_size = cur_eden;
254
255 // Cache some values. There's a bit of work getting these, so
256 // we might save a little time.
257 const double major_cost = major_gc_cost();
258 const double minor_cost = minor_gc_cost();
259
260 // This method sets the desired eden size. That plus the
261 // desired survivor space sizes sets the desired young generation
262 // size. This methods does not know what the desired survivor
263 // size is but expects that other policy will attempt to make
264 // the survivor sizes compatible with the live data in the
265 // young generation. This limit is an estimate of the space left
266 // in the young generation after the survivor spaces have been
267 // subtracted out.
268 size_t eden_limit = max_eden_size;
269
270 const double gc_cost_limit = GCTimeLimit/100.0;
271
272 // Which way should we go?
273 // if pause requirement is not met
274 // adjust size of any generation with average paus exceeding
275 // the pause limit. Adjust one pause at a time (the larger)
276 // and only make adjustments for the major pause at full collections.
277 // else if throughput requirement not met
278 // adjust the size of the generation with larger gc time. Only
279 // adjust one generation at a time.
280 // else
281 // adjust down the total heap size. Adjust down the larger of the
282 // generations.
283
284 // Add some checks for a threshold for a change. For example,
285 // a change less than the necessary alignment is probably not worth
286 // attempting.
287
288
289 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
290 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
291 //
292 // Check pauses
293 //
294 // Make changes only to affect one of the pauses (the larger)
295 // at a time.
296 adjust_eden_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
297
298 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
299 // Adjust only for the minor pause time goal
300 adjust_eden_for_minor_pause_time(is_full_gc, &desired_eden_size);
301
302 } else if(adjusted_mutator_cost() < _throughput_goal) {
303 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
304 // This sometimes resulted in skipping to the minimize footprint
305 // code. Change this to try and reduce GC time if mutator time is
306 // negative for whatever reason. Or for future consideration,
307 // bail out of the code if mutator time is negative.
308 //
309 // Throughput
310 //
311 assert(major_cost >= 0.0, "major cost is < 0.0");
312 assert(minor_cost >= 0.0, "minor cost is < 0.0");
313 // Try to reduce the GC times.
314 adjust_eden_for_throughput(is_full_gc, &desired_eden_size);
315
316 } else {
317
318 // Be conservative about reducing the footprint.
319 // Do a minimum number of major collections first.
320 // Have reasonable averages for major and minor collections costs.
321 if (UseAdaptiveSizePolicyFootprintGoal &&
322 young_gen_policy_is_ready() &&
323 avg_major_gc_cost()->average() >= 0.0 &&
324 avg_minor_gc_cost()->average() >= 0.0) {
325 size_t desired_sum = desired_eden_size + desired_promo_size;
326 desired_eden_size = adjust_eden_for_footprint(desired_eden_size, desired_sum);
327 }
328 }
329
330 // Note we make the same tests as in the code block below; the code
331 // seems a little easier to read with the printing in another block.
332 if (PrintAdaptiveSizePolicy) {
333 if (desired_eden_size > eden_limit) {
334 gclog_or_tty->print_cr(
335 "PSAdaptiveSizePolicy::compute_eden_space_size limits:"
336 " desired_eden_size: " SIZE_FORMAT
337 " old_eden_size: " SIZE_FORMAT
338 " eden_limit: " SIZE_FORMAT
339 " cur_eden: " SIZE_FORMAT
340 " max_eden_size: " SIZE_FORMAT
341 " avg_young_live: " SIZE_FORMAT,
342 desired_eden_size, _eden_size, eden_limit, cur_eden,
343 max_eden_size, (size_t)avg_young_live()->average());
344 }
345 if (gc_cost() > gc_cost_limit) {
346 gclog_or_tty->print_cr(
347 "PSAdaptiveSizePolicy::compute_eden_space_size: gc time limit"
348 " gc_cost: %f "
349 " GCTimeLimit: %d",
350 gc_cost(), GCTimeLimit);
351 }
352 }
353
354 // Align everything and make a final limit check
355 const size_t alignment = _intra_generation_alignment;
356 desired_eden_size = align_size_up(desired_eden_size, alignment);
357 desired_eden_size = MAX2(desired_eden_size, alignment);
358
359 eden_limit = align_size_down(eden_limit, alignment);
360
361 // And one last limit check, now that we've aligned things.
362 if (desired_eden_size > eden_limit) {
363 // If the policy says to get a larger eden but
364 // is hitting the limit, don't decrease eden.
365 // This can lead to a general drifting down of the
366 // eden size. Let the tenuring calculation push more
367 // into the old gen.
368 desired_eden_size = MAX2(eden_limit, cur_eden);
369 }
370
371 if (PrintAdaptiveSizePolicy) {
372 // Timing stats
373 gclog_or_tty->print(
374 "PSAdaptiveSizePolicy::compute_eden_space_size: costs"
375 " minor_time: %f"
376 " major_cost: %f"
377 " mutator_cost: %f"
378 " throughput_goal: %f",
379 minor_gc_cost(), major_gc_cost(), mutator_cost(),
380 _throughput_goal);
381
382 // We give more details if Verbose is set
383 if (Verbose) {
384 gclog_or_tty->print( " minor_pause: %f"
385 " major_pause: %f"
386 " minor_interval: %f"
387 " major_interval: %f"
388 " pause_goal: %f",
389 _avg_minor_pause->padded_average(),
390 _avg_major_pause->padded_average(),
391 _avg_minor_interval->average(),
392 _avg_major_interval->average(),
393 gc_pause_goal_sec());
394 }
395
396 // Footprint stats
397 gclog_or_tty->print( " live_space: " SIZE_FORMAT
398 " free_space: " SIZE_FORMAT,
399 live_space(), free_space());
400 // More detail
401 if (Verbose) {
402 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
403 " avg_young_live: " SIZE_FORMAT
404 " avg_old_live: " SIZE_FORMAT,
405 (size_t)_avg_base_footprint->average(),
406 (size_t)avg_young_live()->average(),
407 (size_t)avg_old_live()->average());
408 }
409
410 // And finally, our old and new sizes.
411 gclog_or_tty->print(" old_eden_size: " SIZE_FORMAT
412 " desired_eden_size: " SIZE_FORMAT,
413 _eden_size, desired_eden_size);
414 gclog_or_tty->cr();
415 }
416
417 set_eden_size(desired_eden_size);
418 }
419
420 void PSAdaptiveSizePolicy::compute_old_gen_free_space(
421 size_t old_live,
422 size_t cur_eden,
423 size_t max_old_gen_size,
424 bool is_full_gc) {
425
426 // Update statistics
427 // Time statistics are updated as we go, update footprint stats here
428 if (is_full_gc) {
429 // old_live is only accurate after a full gc
430 avg_old_live()->sample(old_live);
431 }
432
433 // This code used to return if the policy was not ready , i.e.,
434 // policy_is_ready() returning false. The intent was that
435 // decisions below needed major collection times and so could
436 // not be made before two major collections. A consequence was
437 // adjustments to the young generation were not done until after
438 // two major collections even if the minor collections times
439 // exceeded the requested goals. Now let the young generation
440 // adjust for the minor collection times. Major collection times
441 // will be zero for the first collection and will naturally be
442 // ignored. Tenured generation adjustments are only made at the
443 // full collections so until the second major collection has
444 // been reached, no tenured generation adjustments will be made.
445
446 // Until we know better, desired promotion size uses the last calculation
447 size_t desired_promo_size = _promo_size;
448
449 // Start eden at the current value. The desired value that is stored
450 // in _eden_size is not bounded by constraints of the heap and can
451 // run away.
452 //
453 // As expected setting desired_eden_size to the current
454 // value of desired_eden_size as a starting point
455 // caused desired_eden_size to grow way too large and caused
456 // an overflow down stream. It may have improved performance in
457 // some case but is dangerous.
458 size_t desired_eden_size = cur_eden;
459
460 // Cache some values. There's a bit of work getting these, so
461 // we might save a little time.
462 const double major_cost = major_gc_cost();
463 const double minor_cost = minor_gc_cost();
464
465 // Limits on our growth
466 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());
467
468 // But don't force a promo size below the current promo size. Otherwise,
469 // the promo size will shrink for no good reason.
470 promo_limit = MAX2(promo_limit, _promo_size);
471
472 const double gc_cost_limit = GCTimeLimit/100.0;
473
474 // Which way should we go?
475 // if pause requirement is not met
476 // adjust size of any generation with average paus exceeding
477 // the pause limit. Adjust one pause at a time (the larger)
478 // and only make adjustments for the major pause at full collections.
479 // else if throughput requirement not met
480 // adjust the size of the generation with larger gc time. Only
481 // adjust one generation at a time.
482 // else
483 // adjust down the total heap size. Adjust down the larger of the
484 // generations.
485
486 // Add some checks for a threshhold for a change. For example,
487 // a change less than the necessary alignment is probably not worth
488 // attempting.
489
490 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
491 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
492 //
493 // Check pauses
494 //
495 // Make changes only to affect one of the pauses (the larger)
496 // at a time.
497 if (is_full_gc) {
498 set_decide_at_full_gc(decide_at_full_gc_true);
499 adjust_promo_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
500 }
501 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
502 // Adjust only for the minor pause time goal
503 adjust_promo_for_minor_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
504 } else if(adjusted_mutator_cost() < _throughput_goal) {
505 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
506 // This sometimes resulted in skipping to the minimize footprint
507 // code. Change this to try and reduce GC time if mutator time is
508 // negative for whatever reason. Or for future consideration,
509 // bail out of the code if mutator time is negative.
510 //
511 // Throughput
512 //
513 assert(major_cost >= 0.0, "major cost is < 0.0");
514 assert(minor_cost >= 0.0, "minor cost is < 0.0");
515 // Try to reduce the GC times.
516 if (is_full_gc) {
517 set_decide_at_full_gc(decide_at_full_gc_true);
518 adjust_promo_for_throughput(is_full_gc, &desired_promo_size);
519 }
520 } else {
521
522 // Be conservative about reducing the footprint.
523 // Do a minimum number of major collections first.
524 // Have reasonable averages for major and minor collections costs.
525 if (UseAdaptiveSizePolicyFootprintGoal &&
526 young_gen_policy_is_ready() &&
527 avg_major_gc_cost()->average() >= 0.0 &&
528 avg_minor_gc_cost()->average() >= 0.0) {
529 if (is_full_gc) {
530 set_decide_at_full_gc(decide_at_full_gc_true);
531 size_t desired_sum = desired_eden_size + desired_promo_size;
532 desired_promo_size = adjust_promo_for_footprint(desired_promo_size, desired_sum);
533 }
534 }
535 }
536
537 // Note we make the same tests as in the code block below; the code
538 // seems a little easier to read with the printing in another block.
539 if (PrintAdaptiveSizePolicy) {
540 if (desired_promo_size > promo_limit) {
541 // "free_in_old_gen" was the original value for used for promo_limit
542 size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());
543 gclog_or_tty->print_cr(
544 "PSAdaptiveSizePolicy::compute_old_gen_free_space limits:"
545 " desired_promo_size: " SIZE_FORMAT
546 " promo_limit: " SIZE_FORMAT
547 " free_in_old_gen: " SIZE_FORMAT
548 " max_old_gen_size: " SIZE_FORMAT
549 " avg_old_live: " SIZE_FORMAT,
550 desired_promo_size, promo_limit, free_in_old_gen,
551 max_old_gen_size, (size_t) avg_old_live()->average());
552 }
553 if (gc_cost() > gc_cost_limit) {
554 gclog_or_tty->print_cr(
555 "PSAdaptiveSizePolicy::compute_old_gen_free_space: gc time limit"
556 " gc_cost: %f "
557 " GCTimeLimit: %d",
558 gc_cost(), GCTimeLimit);
559 }
560 }
561
562 // Align everything and make a final limit check
563 const size_t alignment = _intra_generation_alignment;
564 desired_promo_size = align_size_up(desired_promo_size, alignment);
565 desired_promo_size = MAX2(desired_promo_size, alignment);
566
567 promo_limit = align_size_down(promo_limit, alignment);
568
569 // And one last limit check, now that we've aligned things.
570 desired_promo_size = MIN2(desired_promo_size, promo_limit);
571
572 if (PrintAdaptiveSizePolicy) {
573 // Timing stats
574 gclog_or_tty->print(
575 "PSAdaptiveSizePolicy::compute_old_gen_free_space: costs"
576 " minor_time: %f"
577 " major_cost: %f"
578 " mutator_cost: %f"
579 " throughput_goal: %f",
580 minor_gc_cost(), major_gc_cost(), mutator_cost(),
581 _throughput_goal);
582
583 // We give more details if Verbose is set
584 if (Verbose) {
585 gclog_or_tty->print( " minor_pause: %f"
586 " major_pause: %f"
587 " minor_interval: %f"
588 " major_interval: %f"
589 " pause_goal: %f",
590 _avg_minor_pause->padded_average(),
591 _avg_major_pause->padded_average(),
592 _avg_minor_interval->average(),
593 _avg_major_interval->average(),
594 gc_pause_goal_sec());
595 }
596
597 // Footprint stats
598 gclog_or_tty->print( " live_space: " SIZE_FORMAT
599 " free_space: " SIZE_FORMAT,
600 live_space(), free_space());
601 // More detail
602 if (Verbose) {
603 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
604 " avg_young_live: " SIZE_FORMAT
605 " avg_old_live: " SIZE_FORMAT,
606 (size_t)_avg_base_footprint->average(),
607 (size_t)avg_young_live()->average(),
608 (size_t)avg_old_live()->average());
609 }
610
611 // And finally, our old and new sizes.
612 gclog_or_tty->print(" old_promo_size: " SIZE_FORMAT
613 " desired_promo_size: " SIZE_FORMAT,
614 _promo_size, desired_promo_size);
615 gclog_or_tty->cr();
616 }
617
618 set_promo_size(desired_promo_size);
619 }
620
621 void PSAdaptiveSizePolicy::decay_supplemental_growth(bool is_full_gc) {
622 // Decay the supplemental increment? Decay the supplement growth
623 // factor even if it is not used. It is only meant to give a boost
624 // to the initial growth and if it is not used, then it was not
625 // needed.
626 if (is_full_gc) {
627 // Don't wait for the threshold value for the major collections. If
628 // here, the supplemental growth term was used and should decay.
629 if ((_avg_major_pause->count() % TenuredGenerationSizeSupplementDecay)
630 == 0) {
631 _old_gen_size_increment_supplement =
632 _old_gen_size_increment_supplement >> 1;
633 }
634 } else {
635 if ((_avg_minor_pause->count() >= AdaptiveSizePolicyReadyThreshold) &&
636 (_avg_minor_pause->count() % YoungGenerationSizeSupplementDecay) == 0) {
637 _young_gen_size_increment_supplement =
638 _young_gen_size_increment_supplement >> 1;
639 }
640 }
641 }
642
643 void PSAdaptiveSizePolicy::adjust_promo_for_minor_pause_time(bool is_full_gc,
644 size_t* desired_promo_size_ptr, size_t* desired_eden_size_ptr) {
645
646 if (PSAdjustTenuredGenForMinorPause) {
647 if (is_full_gc) {
648 set_decide_at_full_gc(decide_at_full_gc_true);
649 }
650 // If the desired eden size is as small as it will get,
651 // try to adjust the old gen size.
652 if (*desired_eden_size_ptr <= _intra_generation_alignment) {
653 // Vary the old gen size to reduce the young gen pause. This
654 // may not be a good idea. This is just a test.
655 if (minor_pause_old_estimator()->decrement_will_decrease()) {
656 set_change_old_gen_for_min_pauses(decrease_old_gen_for_min_pauses_true);
657 *desired_promo_size_ptr =
658 _promo_size - promo_decrement_aligned_down(*desired_promo_size_ptr);
659 } else {
660 set_change_old_gen_for_min_pauses(increase_old_gen_for_min_pauses_true);
661 size_t promo_heap_delta =
662 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
663 if ((*desired_promo_size_ptr + promo_heap_delta) >
664 *desired_promo_size_ptr) {
665 *desired_promo_size_ptr =
666 _promo_size + promo_heap_delta;
667 }
668 }
669 }
670 }
671 }
672
673 void PSAdaptiveSizePolicy::adjust_eden_for_minor_pause_time(bool is_full_gc,
674 size_t* desired_eden_size_ptr) {
675
676 // Adjust the young generation size to reduce pause time of
677 // of collections.
678 //
679 // The AdaptiveSizePolicyInitializingSteps test is not used
680 // here. It has not seemed to be needed but perhaps should
681 // be added for consistency.
682 if (minor_pause_young_estimator()->decrement_will_decrease()) {
683 // reduce eden size
684 set_change_young_gen_for_min_pauses(
685 decrease_young_gen_for_min_pauses_true);
686 *desired_eden_size_ptr = *desired_eden_size_ptr -
687 eden_decrement_aligned_down(*desired_eden_size_ptr);
688 } else {
689 // EXPERIMENTAL ADJUSTMENT
690 // Only record that the estimator indicated such an action.
691 // *desired_eden_size_ptr = *desired_eden_size_ptr + eden_heap_delta;
692 set_change_young_gen_for_min_pauses(
693 increase_young_gen_for_min_pauses_true);
694 }
695 }
696
697 void PSAdaptiveSizePolicy::adjust_promo_for_pause_time(bool is_full_gc,
698 size_t* desired_promo_size_ptr,
699 size_t* desired_eden_size_ptr) {
700
701 size_t promo_heap_delta = 0;
702 // Add some checks for a threshold for a change. For example,
703 // a change less than the required alignment is probably not worth
704 // attempting.
705
706 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
707 adjust_promo_for_minor_pause_time(is_full_gc, desired_promo_size_ptr, desired_eden_size_ptr);
708 // major pause adjustments
709 } else if (is_full_gc) {
710 // Adjust for the major pause time only at full gc's because the
711 // affects of a change can only be seen at full gc's.
712
713 // Reduce old generation size to reduce pause?
714 if (major_pause_old_estimator()->decrement_will_decrease()) {
715 // reduce old generation size
716 set_change_old_gen_for_maj_pauses(decrease_old_gen_for_maj_pauses_true);
717 promo_heap_delta = promo_decrement_aligned_down(*desired_promo_size_ptr);
718 *desired_promo_size_ptr = _promo_size - promo_heap_delta;
719 } else {
720 // EXPERIMENTAL ADJUSTMENT
721 // Only record that the estimator indicated such an action.
722 // *desired_promo_size_ptr = _promo_size +
723 // promo_increment_aligned_up(*desired_promo_size_ptr);
724 set_change_old_gen_for_maj_pauses(increase_old_gen_for_maj_pauses_true);
725 }
726 }
727
728 if (PrintAdaptiveSizePolicy && Verbose) {
729 gclog_or_tty->print_cr(
730 "PSAdaptiveSizePolicy::adjust_promo_for_pause_time "
731 "adjusting gen sizes for major pause (avg %f goal %f). "
732 "desired_promo_size " SIZE_FORMAT " promo delta " SIZE_FORMAT,
733 _avg_major_pause->average(), gc_pause_goal_sec(),
734 *desired_promo_size_ptr, promo_heap_delta);
735 }
736 }
737
738 void PSAdaptiveSizePolicy::adjust_eden_for_pause_time(bool is_full_gc,
739 size_t* desired_promo_size_ptr,
740 size_t* desired_eden_size_ptr) {
741
742 size_t eden_heap_delta = 0;
743 // Add some checks for a threshold for a change. For example,
744 // a change less than the required alignment is probably not worth
745 // attempting.
746 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
747 adjust_eden_for_minor_pause_time(is_full_gc,
748 desired_eden_size_ptr);
749 // major pause adjustments
750 } else if (is_full_gc) {
751 // Adjust for the major pause time only at full gc's because the
752 // affects of a change can only be seen at full gc's.
753 if (PSAdjustYoungGenForMajorPause) {
754 // If the promo size is at the minimum (i.e., the old gen
755 // size will not actually decrease), consider changing the
756 // young gen size.
757 if (*desired_promo_size_ptr < _intra_generation_alignment) {
758 // If increasing the young generation will decrease the old gen
759 // pause, do it.
760 // During startup there is noise in the statistics for deciding
761 // on whether to increase or decrease the young gen size. For
762 // some number of iterations, just try to increase the young
763 // gen size if the major pause is too long to try and establish
764 // good statistics for later decisions.
765 if (major_pause_young_estimator()->increment_will_decrease() ||
766 (_young_gen_change_for_major_pause_count
767 <= AdaptiveSizePolicyInitializingSteps)) {
768 set_change_young_gen_for_maj_pauses(
769 increase_young_gen_for_maj_pauses_true);
770 eden_heap_delta = eden_increment_aligned_up(*desired_eden_size_ptr);
771 *desired_eden_size_ptr = _eden_size + eden_heap_delta;
772 _young_gen_change_for_major_pause_count++;
773 } else {
774 // Record that decreasing the young gen size would decrease
775 // the major pause
776 set_change_young_gen_for_maj_pauses(
777 decrease_young_gen_for_maj_pauses_true);
778 eden_heap_delta = eden_decrement_aligned_down(*desired_eden_size_ptr);
779 *desired_eden_size_ptr = _eden_size - eden_heap_delta;
780 }
781 }
782 }
783 }
784
785 if (PrintAdaptiveSizePolicy && Verbose) {
786 gclog_or_tty->print_cr(
787 "PSAdaptiveSizePolicy::adjust_eden_for_pause_time "
788 "adjusting gen sizes for major pause (avg %f goal %f). "
789 "desired_eden_size " SIZE_FORMAT " eden delta " SIZE_FORMAT,
790 _avg_major_pause->average(), gc_pause_goal_sec(),
791 *desired_eden_size_ptr, eden_heap_delta);
792 }
793 }
794
795 void PSAdaptiveSizePolicy::adjust_promo_for_throughput(bool is_full_gc,
796 size_t* desired_promo_size_ptr) {
797
798 // Add some checks for a threshold for a change. For example,
799 // a change less than the required alignment is probably not worth
800 // attempting.
801
802 if ((gc_cost() + mutator_cost()) == 0.0) {
803 return;
804 }
805
806 if (PrintAdaptiveSizePolicy && Verbose) {
807 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_promo_for_throughput("
808 "is_full: %d, promo: " SIZE_FORMAT "): ",
809 is_full_gc, *desired_promo_size_ptr);
810 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
811 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
812 }
813
814 // Tenured generation
815 if (is_full_gc) {
816 // Calculate the change to use for the tenured gen.
817 size_t scaled_promo_heap_delta = 0;
818 // Can the increment to the generation be scaled?
819 if (gc_cost() >= 0.0 && major_gc_cost() >= 0.0) {
820 size_t promo_heap_delta =
821 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
822 double scale_by_ratio = major_gc_cost() / gc_cost();
823 scaled_promo_heap_delta =
824 (size_t) (scale_by_ratio * (double) promo_heap_delta);
825 if (PrintAdaptiveSizePolicy && Verbose) {
826 gclog_or_tty->print_cr(
827 "Scaled tenured increment: " SIZE_FORMAT " by %f down to "
828 SIZE_FORMAT,
829 promo_heap_delta, scale_by_ratio, scaled_promo_heap_delta);
830 }
831 } else if (major_gc_cost() >= 0.0) {
832 // Scaling is not going to work. If the major gc time is the
833 // larger, give it a full increment.
834 if (major_gc_cost() >= minor_gc_cost()) {
835 scaled_promo_heap_delta =
836 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
837 }
838 } else {
839 // Don't expect to get here but it's ok if it does
840 // in the product build since the delta will be 0
841 // and nothing will change.
842 assert(false, "Unexpected value for gc costs");
843 }
844
845 switch (AdaptiveSizeThroughPutPolicy) {
846 case 1:
847 // Early in the run the statistics might not be good. Until
848 // a specific number of collections have been, use the heuristic
849 // that a larger generation size means lower collection costs.
850 if (major_collection_estimator()->increment_will_decrease() ||
851 (_old_gen_change_for_major_throughput
852 <= AdaptiveSizePolicyInitializingSteps)) {
853 // Increase tenured generation size to reduce major collection cost
854 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
855 *desired_promo_size_ptr) {
856 *desired_promo_size_ptr = _promo_size + scaled_promo_heap_delta;
857 }
858 set_change_old_gen_for_throughput(
859 increase_old_gen_for_throughput_true);
860 _old_gen_change_for_major_throughput++;
861 } else {
862 // EXPERIMENTAL ADJUSTMENT
863 // Record that decreasing the old gen size would decrease
864 // the major collection cost but don't do it.
865 // *desired_promo_size_ptr = _promo_size -
866 // promo_decrement_aligned_down(*desired_promo_size_ptr);
867 set_change_old_gen_for_throughput(
868 decrease_old_gen_for_throughput_true);
869 }
870
871 break;
872 default:
873 // Simplest strategy
874 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
875 *desired_promo_size_ptr) {
876 *desired_promo_size_ptr = *desired_promo_size_ptr +
877 scaled_promo_heap_delta;
878 }
879 set_change_old_gen_for_throughput(
880 increase_old_gen_for_throughput_true);
881 _old_gen_change_for_major_throughput++;
882 }
883
884 if (PrintAdaptiveSizePolicy && Verbose) {
885 gclog_or_tty->print_cr(
886 "adjusting tenured gen for throughput (avg %f goal %f). "
887 "desired_promo_size " SIZE_FORMAT " promo_delta " SIZE_FORMAT ,
888 mutator_cost(), _throughput_goal,
889 *desired_promo_size_ptr, scaled_promo_heap_delta);
890 }
891 }
892 }
893
894 void PSAdaptiveSizePolicy::adjust_eden_for_throughput(bool is_full_gc,
895 size_t* desired_eden_size_ptr) {
896
897 // Add some checks for a threshold for a change. For example,
898 // a change less than the required alignment is probably not worth
899 // attempting.
900
901 if ((gc_cost() + mutator_cost()) == 0.0) {
902 return;
903 }
904
905 if (PrintAdaptiveSizePolicy && Verbose) {
906 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_eden_for_throughput("
907 "is_full: %d, cur_eden: " SIZE_FORMAT "): ",
908 is_full_gc, *desired_eden_size_ptr);
909 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
910 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
911 }
912
913 // Young generation
914 size_t scaled_eden_heap_delta = 0;
915 // Can the increment to the generation be scaled?
916 if (gc_cost() >= 0.0 && minor_gc_cost() >= 0.0) {
917 size_t eden_heap_delta =
918 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
919 double scale_by_ratio = minor_gc_cost() / gc_cost();
920 assert(scale_by_ratio <= 1.0 && scale_by_ratio >= 0.0, "Scaling is wrong");
921 scaled_eden_heap_delta =
922 (size_t) (scale_by_ratio * (double) eden_heap_delta);
923 if (PrintAdaptiveSizePolicy && Verbose) {
924 gclog_or_tty->print_cr(
925 "Scaled eden increment: " SIZE_FORMAT " by %f down to "
926 SIZE_FORMAT,
927 eden_heap_delta, scale_by_ratio, scaled_eden_heap_delta);
928 }
929 } else if (minor_gc_cost() >= 0.0) {
930 // Scaling is not going to work. If the minor gc time is the
931 // larger, give it a full increment.
932 if (minor_gc_cost() > major_gc_cost()) {
933 scaled_eden_heap_delta =
934 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
935 }
936 } else {
937 // Don't expect to get here but it's ok if it does
938 // in the product build since the delta will be 0
939 // and nothing will change.
940 assert(false, "Unexpected value for gc costs");
941 }
942
943 // Use a heuristic for some number of collections to give
944 // the averages time to settle down.
945 switch (AdaptiveSizeThroughPutPolicy) {
946 case 1:
947 if (minor_collection_estimator()->increment_will_decrease() ||
948 (_young_gen_change_for_minor_throughput
949 <= AdaptiveSizePolicyInitializingSteps)) {
950 // Expand young generation size to reduce frequency of
951 // of collections.
952 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
953 *desired_eden_size_ptr) {
954 *desired_eden_size_ptr =
955 *desired_eden_size_ptr + scaled_eden_heap_delta;
956 }
957 set_change_young_gen_for_throughput(
958 increase_young_gen_for_througput_true);
959 _young_gen_change_for_minor_throughput++;
960 } else {
961 // EXPERIMENTAL ADJUSTMENT
962 // Record that decreasing the young gen size would decrease
963 // the minor collection cost but don't do it.
964 // *desired_eden_size_ptr = _eden_size -
965 // eden_decrement_aligned_down(*desired_eden_size_ptr);
966 set_change_young_gen_for_throughput(
967 decrease_young_gen_for_througput_true);
968 }
969 break;
970 default:
971 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
972 *desired_eden_size_ptr) {
973 *desired_eden_size_ptr =
974 *desired_eden_size_ptr + scaled_eden_heap_delta;
975 }
976 set_change_young_gen_for_throughput(
977 increase_young_gen_for_througput_true);
978 _young_gen_change_for_minor_throughput++;
979 }
980
981 if (PrintAdaptiveSizePolicy && Verbose) {
982 gclog_or_tty->print_cr(
983 "adjusting eden for throughput (avg %f goal %f). desired_eden_size "
984 SIZE_FORMAT " eden delta " SIZE_FORMAT "\n",
985 mutator_cost(), _throughput_goal,
986 *desired_eden_size_ptr, scaled_eden_heap_delta);
987 }
988 }
989
990 size_t PSAdaptiveSizePolicy::adjust_promo_for_footprint(
991 size_t desired_promo_size, size_t desired_sum) {
992 assert(desired_promo_size <= desired_sum, "Inconsistent parameters");
993 set_decrease_for_footprint(decrease_old_gen_for_footprint_true);
994
995 size_t change = promo_decrement(desired_promo_size);
996 change = scale_down(change, desired_promo_size, desired_sum);
997
998 size_t reduced_size = desired_promo_size - change;
999
1000 if (PrintAdaptiveSizePolicy && Verbose) {
1001 gclog_or_tty->print_cr(
1002 "AdaptiveSizePolicy::adjust_promo_for_footprint "
1003 "adjusting tenured gen for footprint. "
1004 "starting promo size " SIZE_FORMAT
1005 " reduced promo size " SIZE_FORMAT,
1006 " promo delta " SIZE_FORMAT,
1007 desired_promo_size, reduced_size, change );
1008 }
1009
1010 assert(reduced_size <= desired_promo_size, "Inconsistent result");
1011 return reduced_size;
1012 }
1013
1014 size_t PSAdaptiveSizePolicy::adjust_eden_for_footprint(
1015 size_t desired_eden_size, size_t desired_sum) {
1016 assert(desired_eden_size <= desired_sum, "Inconsistent parameters");
1017 set_decrease_for_footprint(decrease_young_gen_for_footprint_true);
1018
1019 size_t change = eden_decrement(desired_eden_size);
1020 change = scale_down(change, desired_eden_size, desired_sum);
1021
1022 size_t reduced_size = desired_eden_size - change;
1023
1024 if (PrintAdaptiveSizePolicy && Verbose) {
1025 gclog_or_tty->print_cr(
1026 "AdaptiveSizePolicy::adjust_eden_for_footprint "
1027 "adjusting eden for footprint. "
1028 " starting eden size " SIZE_FORMAT
1029 " reduced eden size " SIZE_FORMAT
1030 " eden delta " SIZE_FORMAT,
1031 desired_eden_size, reduced_size, change);
1032 }
1033
1034 assert(reduced_size <= desired_eden_size, "Inconsistent result");
1035 return reduced_size;
1036 }
1037
1038 // Scale down "change" by the factor
1039 // part / total
1040 // Don't align the results.
1041
1042 size_t PSAdaptiveSizePolicy::scale_down(size_t change,
1043 double part,
1044 double total) {
1045 assert(part <= total, "Inconsistent input");
1046 size_t reduced_change = change;
1047 if (total > 0) {
1048 double fraction = part / total;
1049 reduced_change = (size_t) (fraction * (double) change);
1050 }
1051 assert(reduced_change <= change, "Inconsistent result");
1052 return reduced_change;
1053 }
1054
1055 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden,
1056 uint percent_change) {
1057 size_t eden_heap_delta;
1058 eden_heap_delta = cur_eden / 100 * percent_change;
1059 return eden_heap_delta;
1060 }
1061
1062 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden) {
1063 return eden_increment(cur_eden, YoungGenerationSizeIncrement);
1064 }
1065
1066 size_t PSAdaptiveSizePolicy::eden_increment_aligned_up(size_t cur_eden) {
1067 size_t result = eden_increment(cur_eden, YoungGenerationSizeIncrement);
1068 return align_size_up(result, _intra_generation_alignment);
1069 }
1070
1071 size_t PSAdaptiveSizePolicy::eden_increment_aligned_down(size_t cur_eden) {
1072 size_t result = eden_increment(cur_eden);
1073 return align_size_down(result, _intra_generation_alignment);
1074 }
1075
1076 size_t PSAdaptiveSizePolicy::eden_increment_with_supplement_aligned_up(
1077 size_t cur_eden) {
1078 size_t result = eden_increment(cur_eden,
1079 YoungGenerationSizeIncrement + _young_gen_size_increment_supplement);
1080 return align_size_up(result, _intra_generation_alignment);
1081 }
1082
1083 size_t PSAdaptiveSizePolicy::eden_decrement_aligned_down(size_t cur_eden) {
1084 size_t eden_heap_delta = eden_decrement(cur_eden);
1085 return align_size_down(eden_heap_delta, _intra_generation_alignment);
1086 }
1087
1088 size_t PSAdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
1089 size_t eden_heap_delta = eden_increment(cur_eden) /
1090 AdaptiveSizeDecrementScaleFactor;
1091 return eden_heap_delta;
1092 }
1093
1094 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo,
1095 uint percent_change) {
1096 size_t promo_heap_delta;
1097 promo_heap_delta = cur_promo / 100 * percent_change;
1098 return promo_heap_delta;
1099 }
1100
1101 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo) {
1102 return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1103 }
1104
1105 size_t PSAdaptiveSizePolicy::promo_increment_aligned_up(size_t cur_promo) {
1106 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1107 return align_size_up(result, _intra_generation_alignment);
1108 }
1109
1110 size_t PSAdaptiveSizePolicy::promo_increment_aligned_down(size_t cur_promo) {
1111 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1112 return align_size_down(result, _intra_generation_alignment);
1113 }
1114
1115 size_t PSAdaptiveSizePolicy::promo_increment_with_supplement_aligned_up(
1116 size_t cur_promo) {
1117 size_t result = promo_increment(cur_promo,
1118 TenuredGenerationSizeIncrement + _old_gen_size_increment_supplement);
1119 return align_size_up(result, _intra_generation_alignment);
1120 }
1121
1122 size_t PSAdaptiveSizePolicy::promo_decrement_aligned_down(size_t cur_promo) {
1123 size_t promo_heap_delta = promo_decrement(cur_promo);
1124 return align_size_down(promo_heap_delta, _intra_generation_alignment);
1125 }
1126
1127 size_t PSAdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
1128 size_t promo_heap_delta = promo_increment(cur_promo);
1129 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
1130 return promo_heap_delta;
1131 }
1132
1133 uint PSAdaptiveSizePolicy::compute_survivor_space_size_and_threshold(
1134 bool is_survivor_overflow,
1135 uint tenuring_threshold,
1136 size_t survivor_limit) {
1137 assert(survivor_limit >= _intra_generation_alignment,
1138 "survivor_limit too small");
1139 assert((size_t)align_size_down(survivor_limit, _intra_generation_alignment)
1140 == survivor_limit, "survivor_limit not aligned");
1141
1142 // This method is called even if the tenuring threshold and survivor
1143 // spaces are not adjusted so that the averages are sampled above.
1144 if (!UsePSAdaptiveSurvivorSizePolicy ||
1145 !young_gen_policy_is_ready()) {
1146 return tenuring_threshold;
1147 }
1148
1149 // We'll decide whether to increase or decrease the tenuring
1150 // threshold based partly on the newly computed survivor size
1151 // (if we hit the maximum limit allowed, we'll always choose to
1152 // decrement the threshold).
1153 bool incr_tenuring_threshold = false;
1154 bool decr_tenuring_threshold = false;
1155
1156 set_decrement_tenuring_threshold_for_gc_cost(false);
1157 set_increment_tenuring_threshold_for_gc_cost(false);
1158 set_decrement_tenuring_threshold_for_survivor_limit(false);
1159
1160 if (!is_survivor_overflow) {
1161 // Keep running averages on how much survived
1162
1163 // We use the tenuring threshold to equalize the cost of major
1164 // and minor collections.
1165 // ThresholdTolerance is used to indicate how sensitive the
1166 // tenuring threshold is to differences in cost betweent the
1167 // collection types.
1168
1169 // Get the times of interest. This involves a little work, so
1170 // we cache the values here.
1171 const double major_cost = major_gc_cost();
1172 const double minor_cost = minor_gc_cost();
1173
1174 if (minor_cost > major_cost * _threshold_tolerance_percent) {
1175 // Minor times are getting too long; lower the threshold so
1176 // less survives and more is promoted.
1177 decr_tenuring_threshold = true;
1178 set_decrement_tenuring_threshold_for_gc_cost(true);
1179 } else if (major_cost > minor_cost * _threshold_tolerance_percent) {
1180 // Major times are too long, so we want less promotion.
1181 incr_tenuring_threshold = true;
1182 set_increment_tenuring_threshold_for_gc_cost(true);
1183 }
1184
1185 } else {
1186 // Survivor space overflow occurred, so promoted and survived are
1187 // not accurate. We'll make our best guess by combining survived
1188 // and promoted and count them as survivors.
1189 //
1190 // We'll lower the tenuring threshold to see if we can correct
1191 // things. Also, set the survivor size conservatively. We're
1192 // trying to avoid many overflows from occurring if defnew size
1193 // is just too small.
1194
1195 decr_tenuring_threshold = true;
1196 }
1197
1198 // The padded average also maintains a deviation from the average;
1199 // we use this to see how good of an estimate we have of what survived.
1200 // We're trying to pad the survivor size as little as possible without
1201 // overflowing the survivor spaces.
1202 size_t target_size = align_size_up((size_t)_avg_survived->padded_average(),
1203 _intra_generation_alignment);
1204 target_size = MAX2(target_size, _intra_generation_alignment);
1205
1206 if (target_size > survivor_limit) {
1207 // Target size is bigger than we can handle. Let's also reduce
1208 // the tenuring threshold.
1209 target_size = survivor_limit;
1210 decr_tenuring_threshold = true;
1211 set_decrement_tenuring_threshold_for_survivor_limit(true);
1212 }
1213
1214 // Finally, increment or decrement the tenuring threshold, as decided above.
1215 // We test for decrementing first, as we might have hit the target size
1216 // limit.
1217 if (decr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1218 if (tenuring_threshold > 1) {
1219 tenuring_threshold--;
1220 }
1221 } else if (incr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1222 if (tenuring_threshold < MaxTenuringThreshold) {
1223 tenuring_threshold++;
1224 }
1225 }
1226
1227 // We keep a running average of the amount promoted which is used
1228 // to decide when we should collect the old generation (when
1229 // the amount of old gen free space is less than what we expect to
1230 // promote).
1231
1232 if (PrintAdaptiveSizePolicy) {
1233 // A little more detail if Verbose is on
1234 if (Verbose) {
1235 gclog_or_tty->print( " avg_survived: %f"
1236 " avg_deviation: %f",
1237 _avg_survived->average(),
1238 _avg_survived->deviation());
1239 }
1240
1241 gclog_or_tty->print( " avg_survived_padded_avg: %f",
1242 _avg_survived->padded_average());
1243
1244 if (Verbose) {
1245 gclog_or_tty->print( " avg_promoted_avg: %f"
1246 " avg_promoted_dev: %f",
1247 avg_promoted()->average(),
1248 avg_promoted()->deviation());
1249 }
1250
1251 gclog_or_tty->print_cr( " avg_promoted_padded_avg: %f"
1252 " avg_pretenured_padded_avg: %f"
1253 " tenuring_thresh: %d"
1254 " target_size: " SIZE_FORMAT,
1255 avg_promoted()->padded_average(),
1256 _avg_pretenured->padded_average(),
1257 tenuring_threshold, target_size);
1258 }
1259
1260 set_survivor_size(target_size);
1261
1262 return tenuring_threshold;
1263 }
1264
1265 void PSAdaptiveSizePolicy::update_averages(bool is_survivor_overflow,
1266 size_t survived,
1267 size_t promoted) {
1268 // Update averages
1269 if (!is_survivor_overflow) {
1270 // Keep running averages on how much survived
1271 _avg_survived->sample(survived);
1272 } else {
1273 size_t survived_guess = survived + promoted;
1274 _avg_survived->sample(survived_guess);
1275 }
1276 avg_promoted()->sample(promoted + _avg_pretenured->padded_average());
1277
1278 if (PrintAdaptiveSizePolicy) {
1279 gclog_or_tty->print_cr(
1280 "AdaptiveSizePolicy::update_averages:"
1281 " survived: " SIZE_FORMAT
1282 " promoted: " SIZE_FORMAT
1283 " overflow: %s",
1284 survived, promoted, is_survivor_overflow ? "true" : "false");
1285 }
1286 }
1287
1288 bool PSAdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st)
1289 const {
1290
1291 if (!UseAdaptiveSizePolicy) return false;
1292
1293 return AdaptiveSizePolicy::print_adaptive_size_policy_on(
1294 st,
1295 PSScavenge::tenuring_threshold());
1296 }