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 space_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 _space_alignment(space_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 desired_eden_size = align_size_up(desired_eden_size, _space_alignment);
356 desired_eden_size = MAX2(desired_eden_size, _space_alignment);
357
358 eden_limit = align_size_down(eden_limit, _space_alignment);
359
360 // And one last limit check, now that we've aligned things.
361 if (desired_eden_size > eden_limit) {
362 // If the policy says to get a larger eden but
363 // is hitting the limit, don't decrease eden.
364 // This can lead to a general drifting down of the
365 // eden size. Let the tenuring calculation push more
366 // into the old gen.
367 desired_eden_size = MAX2(eden_limit, cur_eden);
368 }
369
370 if (PrintAdaptiveSizePolicy) {
371 // Timing stats
372 gclog_or_tty->print(
373 "PSAdaptiveSizePolicy::compute_eden_space_size: costs"
374 " minor_time: %f"
375 " major_cost: %f"
376 " mutator_cost: %f"
377 " throughput_goal: %f",
378 minor_gc_cost(), major_gc_cost(), mutator_cost(),
379 _throughput_goal);
380
381 // We give more details if Verbose is set
382 if (Verbose) {
383 gclog_or_tty->print( " minor_pause: %f"
384 " major_pause: %f"
385 " minor_interval: %f"
386 " major_interval: %f"
387 " pause_goal: %f",
388 _avg_minor_pause->padded_average(),
389 _avg_major_pause->padded_average(),
390 _avg_minor_interval->average(),
391 _avg_major_interval->average(),
392 gc_pause_goal_sec());
393 }
394
395 // Footprint stats
396 gclog_or_tty->print( " live_space: " SIZE_FORMAT
397 " free_space: " SIZE_FORMAT,
398 live_space(), free_space());
399 // More detail
400 if (Verbose) {
401 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
402 " avg_young_live: " SIZE_FORMAT
403 " avg_old_live: " SIZE_FORMAT,
404 (size_t)_avg_base_footprint->average(),
405 (size_t)avg_young_live()->average(),
406 (size_t)avg_old_live()->average());
407 }
408
409 // And finally, our old and new sizes.
410 gclog_or_tty->print(" old_eden_size: " SIZE_FORMAT
411 " desired_eden_size: " SIZE_FORMAT,
412 _eden_size, desired_eden_size);
413 gclog_or_tty->cr();
414 }
415
416 set_eden_size(desired_eden_size);
417 }
418
419 void PSAdaptiveSizePolicy::compute_old_gen_free_space(
420 size_t old_live,
421 size_t cur_eden,
422 size_t max_old_gen_size,
423 bool is_full_gc) {
424
425 // Update statistics
426 // Time statistics are updated as we go, update footprint stats here
427 if (is_full_gc) {
428 // old_live is only accurate after a full gc
429 avg_old_live()->sample(old_live);
430 }
431
432 // This code used to return if the policy was not ready , i.e.,
433 // policy_is_ready() returning false. The intent was that
434 // decisions below needed major collection times and so could
435 // not be made before two major collections. A consequence was
436 // adjustments to the young generation were not done until after
437 // two major collections even if the minor collections times
438 // exceeded the requested goals. Now let the young generation
439 // adjust for the minor collection times. Major collection times
440 // will be zero for the first collection and will naturally be
441 // ignored. Tenured generation adjustments are only made at the
442 // full collections so until the second major collection has
443 // been reached, no tenured generation adjustments will be made.
444
445 // Until we know better, desired promotion size uses the last calculation
446 size_t desired_promo_size = _promo_size;
447
448 // Start eden at the current value. The desired value that is stored
449 // in _eden_size is not bounded by constraints of the heap and can
450 // run away.
451 //
452 // As expected setting desired_eden_size to the current
453 // value of desired_eden_size as a starting point
454 // caused desired_eden_size to grow way too large and caused
455 // an overflow down stream. It may have improved performance in
456 // some case but is dangerous.
457 size_t desired_eden_size = cur_eden;
458
459 // Cache some values. There's a bit of work getting these, so
460 // we might save a little time.
461 const double major_cost = major_gc_cost();
462 const double minor_cost = minor_gc_cost();
463
464 // Limits on our growth
465 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());
466
467 // But don't force a promo size below the current promo size. Otherwise,
468 // the promo size will shrink for no good reason.
469 promo_limit = MAX2(promo_limit, _promo_size);
470
471 const double gc_cost_limit = GCTimeLimit/100.0;
472
473 // Which way should we go?
474 // if pause requirement is not met
475 // adjust size of any generation with average paus exceeding
476 // the pause limit. Adjust one pause at a time (the larger)
477 // and only make adjustments for the major pause at full collections.
478 // else if throughput requirement not met
479 // adjust the size of the generation with larger gc time. Only
480 // adjust one generation at a time.
481 // else
482 // adjust down the total heap size. Adjust down the larger of the
483 // generations.
484
485 // Add some checks for a threshold for a change. For example,
486 // a change less than the necessary alignment is probably not worth
487 // attempting.
488
489 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
490 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
491 //
492 // Check pauses
493 //
494 // Make changes only to affect one of the pauses (the larger)
495 // at a time.
496 if (is_full_gc) {
497 set_decide_at_full_gc(decide_at_full_gc_true);
498 adjust_promo_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
499 }
500 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
501 // Adjust only for the minor pause time goal
502 adjust_promo_for_minor_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
503 } else if(adjusted_mutator_cost() < _throughput_goal) {
504 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
505 // This sometimes resulted in skipping to the minimize footprint
506 // code. Change this to try and reduce GC time if mutator time is
507 // negative for whatever reason. Or for future consideration,
508 // bail out of the code if mutator time is negative.
509 //
510 // Throughput
511 //
512 assert(major_cost >= 0.0, "major cost is < 0.0");
513 assert(minor_cost >= 0.0, "minor cost is < 0.0");
514 // Try to reduce the GC times.
515 if (is_full_gc) {
516 set_decide_at_full_gc(decide_at_full_gc_true);
517 adjust_promo_for_throughput(is_full_gc, &desired_promo_size);
518 }
519 } else {
520
521 // Be conservative about reducing the footprint.
522 // Do a minimum number of major collections first.
523 // Have reasonable averages for major and minor collections costs.
524 if (UseAdaptiveSizePolicyFootprintGoal &&
525 young_gen_policy_is_ready() &&
526 avg_major_gc_cost()->average() >= 0.0 &&
527 avg_minor_gc_cost()->average() >= 0.0) {
528 if (is_full_gc) {
529 set_decide_at_full_gc(decide_at_full_gc_true);
530 size_t desired_sum = desired_eden_size + desired_promo_size;
531 desired_promo_size = adjust_promo_for_footprint(desired_promo_size, desired_sum);
532 }
533 }
534 }
535
536 // Note we make the same tests as in the code block below; the code
537 // seems a little easier to read with the printing in another block.
538 if (PrintAdaptiveSizePolicy) {
539 if (desired_promo_size > promo_limit) {
540 // "free_in_old_gen" was the original value for used for promo_limit
541 size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());
542 gclog_or_tty->print_cr(
543 "PSAdaptiveSizePolicy::compute_old_gen_free_space limits:"
544 " desired_promo_size: " SIZE_FORMAT
545 " promo_limit: " SIZE_FORMAT
546 " free_in_old_gen: " SIZE_FORMAT
547 " max_old_gen_size: " SIZE_FORMAT
548 " avg_old_live: " SIZE_FORMAT,
549 desired_promo_size, promo_limit, free_in_old_gen,
550 max_old_gen_size, (size_t) avg_old_live()->average());
551 }
552 if (gc_cost() > gc_cost_limit) {
553 gclog_or_tty->print_cr(
554 "PSAdaptiveSizePolicy::compute_old_gen_free_space: gc time limit"
555 " gc_cost: %f "
556 " GCTimeLimit: %d",
557 gc_cost(), GCTimeLimit);
558 }
559 }
560
561 // Align everything and make a final limit check
562 desired_promo_size = align_size_up(desired_promo_size, _space_alignment);
563 desired_promo_size = MAX2(desired_promo_size, _space_alignment);
564
565 promo_limit = align_size_down(promo_limit, _space_alignment);
566
567 // And one last limit check, now that we've aligned things.
568 desired_promo_size = MIN2(desired_promo_size, promo_limit);
569
570 if (PrintAdaptiveSizePolicy) {
571 // Timing stats
572 gclog_or_tty->print(
573 "PSAdaptiveSizePolicy::compute_old_gen_free_space: costs"
574 " minor_time: %f"
575 " major_cost: %f"
576 " mutator_cost: %f"
577 " throughput_goal: %f",
578 minor_gc_cost(), major_gc_cost(), mutator_cost(),
579 _throughput_goal);
580
581 // We give more details if Verbose is set
582 if (Verbose) {
583 gclog_or_tty->print( " minor_pause: %f"
584 " major_pause: %f"
585 " minor_interval: %f"
586 " major_interval: %f"
587 " pause_goal: %f",
588 _avg_minor_pause->padded_average(),
589 _avg_major_pause->padded_average(),
590 _avg_minor_interval->average(),
591 _avg_major_interval->average(),
592 gc_pause_goal_sec());
593 }
594
595 // Footprint stats
596 gclog_or_tty->print( " live_space: " SIZE_FORMAT
597 " free_space: " SIZE_FORMAT,
598 live_space(), free_space());
599 // More detail
600 if (Verbose) {
601 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
602 " avg_young_live: " SIZE_FORMAT
603 " avg_old_live: " SIZE_FORMAT,
604 (size_t)_avg_base_footprint->average(),
605 (size_t)avg_young_live()->average(),
606 (size_t)avg_old_live()->average());
607 }
608
609 // And finally, our old and new sizes.
610 gclog_or_tty->print(" old_promo_size: " SIZE_FORMAT
611 " desired_promo_size: " SIZE_FORMAT,
612 _promo_size, desired_promo_size);
613 gclog_or_tty->cr();
614 }
615
616 set_promo_size(desired_promo_size);
617 }
618
619 void PSAdaptiveSizePolicy::decay_supplemental_growth(bool is_full_gc) {
620 // Decay the supplemental increment? Decay the supplement growth
621 // factor even if it is not used. It is only meant to give a boost
622 // to the initial growth and if it is not used, then it was not
623 // needed.
624 if (is_full_gc) {
625 // Don't wait for the threshold value for the major collections. If
626 // here, the supplemental growth term was used and should decay.
627 if ((_avg_major_pause->count() % TenuredGenerationSizeSupplementDecay)
628 == 0) {
629 _old_gen_size_increment_supplement =
630 _old_gen_size_increment_supplement >> 1;
631 }
632 } else {
633 if ((_avg_minor_pause->count() >= AdaptiveSizePolicyReadyThreshold) &&
634 (_avg_minor_pause->count() % YoungGenerationSizeSupplementDecay) == 0) {
635 _young_gen_size_increment_supplement =
636 _young_gen_size_increment_supplement >> 1;
637 }
638 }
639 }
640
641 void PSAdaptiveSizePolicy::adjust_promo_for_minor_pause_time(bool is_full_gc,
642 size_t* desired_promo_size_ptr, size_t* desired_eden_size_ptr) {
643
644 if (PSAdjustTenuredGenForMinorPause) {
645 if (is_full_gc) {
646 set_decide_at_full_gc(decide_at_full_gc_true);
647 }
648 // If the desired eden size is as small as it will get,
649 // try to adjust the old gen size.
650 if (*desired_eden_size_ptr <= _space_alignment) {
651 // Vary the old gen size to reduce the young gen pause. This
652 // may not be a good idea. This is just a test.
653 if (minor_pause_old_estimator()->decrement_will_decrease()) {
654 set_change_old_gen_for_min_pauses(decrease_old_gen_for_min_pauses_true);
655 *desired_promo_size_ptr =
656 _promo_size - promo_decrement_aligned_down(*desired_promo_size_ptr);
657 } else {
658 set_change_old_gen_for_min_pauses(increase_old_gen_for_min_pauses_true);
659 size_t promo_heap_delta =
660 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
661 if ((*desired_promo_size_ptr + promo_heap_delta) >
662 *desired_promo_size_ptr) {
663 *desired_promo_size_ptr =
664 _promo_size + promo_heap_delta;
665 }
666 }
667 }
668 }
669 }
670
671 void PSAdaptiveSizePolicy::adjust_eden_for_minor_pause_time(bool is_full_gc,
672 size_t* desired_eden_size_ptr) {
673
674 // Adjust the young generation size to reduce pause time of
675 // of collections.
676 //
677 // The AdaptiveSizePolicyInitializingSteps test is not used
678 // here. It has not seemed to be needed but perhaps should
679 // be added for consistency.
680 if (minor_pause_young_estimator()->decrement_will_decrease()) {
681 // reduce eden size
682 set_change_young_gen_for_min_pauses(
683 decrease_young_gen_for_min_pauses_true);
684 *desired_eden_size_ptr = *desired_eden_size_ptr -
685 eden_decrement_aligned_down(*desired_eden_size_ptr);
686 } else {
687 // EXPERIMENTAL ADJUSTMENT
688 // Only record that the estimator indicated such an action.
689 // *desired_eden_size_ptr = *desired_eden_size_ptr + eden_heap_delta;
690 set_change_young_gen_for_min_pauses(
691 increase_young_gen_for_min_pauses_true);
692 }
693 }
694
695 void PSAdaptiveSizePolicy::adjust_promo_for_pause_time(bool is_full_gc,
696 size_t* desired_promo_size_ptr,
697 size_t* desired_eden_size_ptr) {
698
699 size_t promo_heap_delta = 0;
700 // Add some checks for a threshold for a change. For example,
701 // a change less than the required alignment is probably not worth
702 // attempting.
703
704 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
705 adjust_promo_for_minor_pause_time(is_full_gc, desired_promo_size_ptr, desired_eden_size_ptr);
706 // major pause adjustments
707 } else if (is_full_gc) {
708 // Adjust for the major pause time only at full gc's because the
709 // affects of a change can only be seen at full gc's.
710
711 // Reduce old generation size to reduce pause?
712 if (major_pause_old_estimator()->decrement_will_decrease()) {
713 // reduce old generation size
714 set_change_old_gen_for_maj_pauses(decrease_old_gen_for_maj_pauses_true);
715 promo_heap_delta = promo_decrement_aligned_down(*desired_promo_size_ptr);
716 *desired_promo_size_ptr = _promo_size - promo_heap_delta;
717 } else {
718 // EXPERIMENTAL ADJUSTMENT
719 // Only record that the estimator indicated such an action.
720 // *desired_promo_size_ptr = _promo_size +
721 // promo_increment_aligned_up(*desired_promo_size_ptr);
722 set_change_old_gen_for_maj_pauses(increase_old_gen_for_maj_pauses_true);
723 }
724 }
725
726 if (PrintAdaptiveSizePolicy && Verbose) {
727 gclog_or_tty->print_cr(
728 "PSAdaptiveSizePolicy::adjust_promo_for_pause_time "
729 "adjusting gen sizes for major pause (avg %f goal %f). "
730 "desired_promo_size " SIZE_FORMAT " promo delta " SIZE_FORMAT,
731 _avg_major_pause->average(), gc_pause_goal_sec(),
732 *desired_promo_size_ptr, promo_heap_delta);
733 }
734 }
735
736 void PSAdaptiveSizePolicy::adjust_eden_for_pause_time(bool is_full_gc,
737 size_t* desired_promo_size_ptr,
738 size_t* desired_eden_size_ptr) {
739
740 size_t eden_heap_delta = 0;
741 // Add some checks for a threshold for a change. For example,
742 // a change less than the required alignment is probably not worth
743 // attempting.
744 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
745 adjust_eden_for_minor_pause_time(is_full_gc,
746 desired_eden_size_ptr);
747 // major pause adjustments
748 } else if (is_full_gc) {
749 // Adjust for the major pause time only at full gc's because the
750 // affects of a change can only be seen at full gc's.
751 if (PSAdjustYoungGenForMajorPause) {
752 // If the promo size is at the minimum (i.e., the old gen
753 // size will not actually decrease), consider changing the
754 // young gen size.
755 if (*desired_promo_size_ptr < _space_alignment) {
756 // If increasing the young generation will decrease the old gen
757 // pause, do it.
758 // During startup there is noise in the statistics for deciding
759 // on whether to increase or decrease the young gen size. For
760 // some number of iterations, just try to increase the young
761 // gen size if the major pause is too long to try and establish
762 // good statistics for later decisions.
763 if (major_pause_young_estimator()->increment_will_decrease() ||
764 (_young_gen_change_for_major_pause_count
765 <= AdaptiveSizePolicyInitializingSteps)) {
766 set_change_young_gen_for_maj_pauses(
767 increase_young_gen_for_maj_pauses_true);
768 eden_heap_delta = eden_increment_aligned_up(*desired_eden_size_ptr);
769 *desired_eden_size_ptr = _eden_size + eden_heap_delta;
770 _young_gen_change_for_major_pause_count++;
771 } else {
772 // Record that decreasing the young gen size would decrease
773 // the major pause
774 set_change_young_gen_for_maj_pauses(
775 decrease_young_gen_for_maj_pauses_true);
776 eden_heap_delta = eden_decrement_aligned_down(*desired_eden_size_ptr);
777 *desired_eden_size_ptr = _eden_size - eden_heap_delta;
778 }
779 }
780 }
781 }
782
783 if (PrintAdaptiveSizePolicy && Verbose) {
784 gclog_or_tty->print_cr(
785 "PSAdaptiveSizePolicy::adjust_eden_for_pause_time "
786 "adjusting gen sizes for major pause (avg %f goal %f). "
787 "desired_eden_size " SIZE_FORMAT " eden delta " SIZE_FORMAT,
788 _avg_major_pause->average(), gc_pause_goal_sec(),
789 *desired_eden_size_ptr, eden_heap_delta);
790 }
791 }
792
793 void PSAdaptiveSizePolicy::adjust_promo_for_throughput(bool is_full_gc,
794 size_t* desired_promo_size_ptr) {
795
796 // Add some checks for a threshold for a change. For example,
797 // a change less than the required alignment is probably not worth
798 // attempting.
799
800 if ((gc_cost() + mutator_cost()) == 0.0) {
801 return;
802 }
803
804 if (PrintAdaptiveSizePolicy && Verbose) {
805 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_promo_for_throughput("
806 "is_full: %d, promo: " SIZE_FORMAT "): ",
807 is_full_gc, *desired_promo_size_ptr);
808 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
809 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
810 }
811
812 // Tenured generation
813 if (is_full_gc) {
814 // Calculate the change to use for the tenured gen.
815 size_t scaled_promo_heap_delta = 0;
816 // Can the increment to the generation be scaled?
817 if (gc_cost() >= 0.0 && major_gc_cost() >= 0.0) {
818 size_t promo_heap_delta =
819 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
820 double scale_by_ratio = major_gc_cost() / gc_cost();
821 scaled_promo_heap_delta =
822 (size_t) (scale_by_ratio * (double) promo_heap_delta);
823 if (PrintAdaptiveSizePolicy && Verbose) {
824 gclog_or_tty->print_cr(
825 "Scaled tenured increment: " SIZE_FORMAT " by %f down to "
826 SIZE_FORMAT,
827 promo_heap_delta, scale_by_ratio, scaled_promo_heap_delta);
828 }
829 } else if (major_gc_cost() >= 0.0) {
830 // Scaling is not going to work. If the major gc time is the
831 // larger, give it a full increment.
832 if (major_gc_cost() >= minor_gc_cost()) {
833 scaled_promo_heap_delta =
834 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
835 }
836 } else {
837 // Don't expect to get here but it's ok if it does
838 // in the product build since the delta will be 0
839 // and nothing will change.
840 assert(false, "Unexpected value for gc costs");
841 }
842
843 switch (AdaptiveSizeThroughPutPolicy) {
844 case 1:
845 // Early in the run the statistics might not be good. Until
846 // a specific number of collections have been, use the heuristic
847 // that a larger generation size means lower collection costs.
848 if (major_collection_estimator()->increment_will_decrease() ||
849 (_old_gen_change_for_major_throughput
850 <= AdaptiveSizePolicyInitializingSteps)) {
851 // Increase tenured generation size to reduce major collection cost
852 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
853 *desired_promo_size_ptr) {
854 *desired_promo_size_ptr = _promo_size + scaled_promo_heap_delta;
855 }
856 set_change_old_gen_for_throughput(
857 increase_old_gen_for_throughput_true);
858 _old_gen_change_for_major_throughput++;
859 } else {
860 // EXPERIMENTAL ADJUSTMENT
861 // Record that decreasing the old gen size would decrease
862 // the major collection cost but don't do it.
863 // *desired_promo_size_ptr = _promo_size -
864 // promo_decrement_aligned_down(*desired_promo_size_ptr);
865 set_change_old_gen_for_throughput(
866 decrease_old_gen_for_throughput_true);
867 }
868
869 break;
870 default:
871 // Simplest strategy
872 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
873 *desired_promo_size_ptr) {
874 *desired_promo_size_ptr = *desired_promo_size_ptr +
875 scaled_promo_heap_delta;
876 }
877 set_change_old_gen_for_throughput(
878 increase_old_gen_for_throughput_true);
879 _old_gen_change_for_major_throughput++;
880 }
881
882 if (PrintAdaptiveSizePolicy && Verbose) {
883 gclog_or_tty->print_cr(
884 "adjusting tenured gen for throughput (avg %f goal %f). "
885 "desired_promo_size " SIZE_FORMAT " promo_delta " SIZE_FORMAT ,
886 mutator_cost(), _throughput_goal,
887 *desired_promo_size_ptr, scaled_promo_heap_delta);
888 }
889 }
890 }
891
892 void PSAdaptiveSizePolicy::adjust_eden_for_throughput(bool is_full_gc,
893 size_t* desired_eden_size_ptr) {
894
895 // Add some checks for a threshold for a change. For example,
896 // a change less than the required alignment is probably not worth
897 // attempting.
898
899 if ((gc_cost() + mutator_cost()) == 0.0) {
900 return;
901 }
902
903 if (PrintAdaptiveSizePolicy && Verbose) {
904 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_eden_for_throughput("
905 "is_full: %d, cur_eden: " SIZE_FORMAT "): ",
906 is_full_gc, *desired_eden_size_ptr);
907 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
908 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
909 }
910
911 // Young generation
912 size_t scaled_eden_heap_delta = 0;
913 // Can the increment to the generation be scaled?
914 if (gc_cost() >= 0.0 && minor_gc_cost() >= 0.0) {
915 size_t eden_heap_delta =
916 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
917 double scale_by_ratio = minor_gc_cost() / gc_cost();
918 assert(scale_by_ratio <= 1.0 && scale_by_ratio >= 0.0, "Scaling is wrong");
919 scaled_eden_heap_delta =
920 (size_t) (scale_by_ratio * (double) eden_heap_delta);
921 if (PrintAdaptiveSizePolicy && Verbose) {
922 gclog_or_tty->print_cr(
923 "Scaled eden increment: " SIZE_FORMAT " by %f down to "
924 SIZE_FORMAT,
925 eden_heap_delta, scale_by_ratio, scaled_eden_heap_delta);
926 }
927 } else if (minor_gc_cost() >= 0.0) {
928 // Scaling is not going to work. If the minor gc time is the
929 // larger, give it a full increment.
930 if (minor_gc_cost() > major_gc_cost()) {
931 scaled_eden_heap_delta =
932 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
933 }
934 } else {
935 // Don't expect to get here but it's ok if it does
936 // in the product build since the delta will be 0
937 // and nothing will change.
938 assert(false, "Unexpected value for gc costs");
939 }
940
941 // Use a heuristic for some number of collections to give
942 // the averages time to settle down.
943 switch (AdaptiveSizeThroughPutPolicy) {
944 case 1:
945 if (minor_collection_estimator()->increment_will_decrease() ||
946 (_young_gen_change_for_minor_throughput
947 <= AdaptiveSizePolicyInitializingSteps)) {
948 // Expand young generation size to reduce frequency of
949 // of collections.
950 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
951 *desired_eden_size_ptr) {
952 *desired_eden_size_ptr =
953 *desired_eden_size_ptr + scaled_eden_heap_delta;
954 }
955 set_change_young_gen_for_throughput(
956 increase_young_gen_for_througput_true);
957 _young_gen_change_for_minor_throughput++;
958 } else {
959 // EXPERIMENTAL ADJUSTMENT
960 // Record that decreasing the young gen size would decrease
961 // the minor collection cost but don't do it.
962 // *desired_eden_size_ptr = _eden_size -
963 // eden_decrement_aligned_down(*desired_eden_size_ptr);
964 set_change_young_gen_for_throughput(
965 decrease_young_gen_for_througput_true);
966 }
967 break;
968 default:
969 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
970 *desired_eden_size_ptr) {
971 *desired_eden_size_ptr =
972 *desired_eden_size_ptr + scaled_eden_heap_delta;
973 }
974 set_change_young_gen_for_throughput(
975 increase_young_gen_for_througput_true);
976 _young_gen_change_for_minor_throughput++;
977 }
978
979 if (PrintAdaptiveSizePolicy && Verbose) {
980 gclog_or_tty->print_cr(
981 "adjusting eden for throughput (avg %f goal %f). desired_eden_size "
982 SIZE_FORMAT " eden delta " SIZE_FORMAT "\n",
983 mutator_cost(), _throughput_goal,
984 *desired_eden_size_ptr, scaled_eden_heap_delta);
985 }
986 }
987
988 size_t PSAdaptiveSizePolicy::adjust_promo_for_footprint(
989 size_t desired_promo_size, size_t desired_sum) {
990 assert(desired_promo_size <= desired_sum, "Inconsistent parameters");
991 set_decrease_for_footprint(decrease_old_gen_for_footprint_true);
992
993 size_t change = promo_decrement(desired_promo_size);
994 change = scale_down(change, desired_promo_size, desired_sum);
995
996 size_t reduced_size = desired_promo_size - change;
997
998 if (PrintAdaptiveSizePolicy && Verbose) {
999 gclog_or_tty->print_cr(
1000 "AdaptiveSizePolicy::adjust_promo_for_footprint "
1001 "adjusting tenured gen for footprint. "
1002 "starting promo size " SIZE_FORMAT
1003 " reduced promo size " SIZE_FORMAT,
1004 " promo delta " SIZE_FORMAT,
1005 desired_promo_size, reduced_size, change );
1006 }
1007
1008 assert(reduced_size <= desired_promo_size, "Inconsistent result");
1009 return reduced_size;
1010 }
1011
1012 size_t PSAdaptiveSizePolicy::adjust_eden_for_footprint(
1013 size_t desired_eden_size, size_t desired_sum) {
1014 assert(desired_eden_size <= desired_sum, "Inconsistent parameters");
1015 set_decrease_for_footprint(decrease_young_gen_for_footprint_true);
1016
1017 size_t change = eden_decrement(desired_eden_size);
1018 change = scale_down(change, desired_eden_size, desired_sum);
1019
1020 size_t reduced_size = desired_eden_size - change;
1021
1022 if (PrintAdaptiveSizePolicy && Verbose) {
1023 gclog_or_tty->print_cr(
1024 "AdaptiveSizePolicy::adjust_eden_for_footprint "
1025 "adjusting eden for footprint. "
1026 " starting eden size " SIZE_FORMAT
1027 " reduced eden size " SIZE_FORMAT
1028 " eden delta " SIZE_FORMAT,
1029 desired_eden_size, reduced_size, change);
1030 }
1031
1032 assert(reduced_size <= desired_eden_size, "Inconsistent result");
1033 return reduced_size;
1034 }
1035
1036 // Scale down "change" by the factor
1037 // part / total
1038 // Don't align the results.
1039
1040 size_t PSAdaptiveSizePolicy::scale_down(size_t change,
1041 double part,
1042 double total) {
1043 assert(part <= total, "Inconsistent input");
1044 size_t reduced_change = change;
1045 if (total > 0) {
1046 double fraction = part / total;
1047 reduced_change = (size_t) (fraction * (double) change);
1048 }
1049 assert(reduced_change <= change, "Inconsistent result");
1050 return reduced_change;
1051 }
1052
1053 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden,
1054 uint percent_change) {
1055 size_t eden_heap_delta;
1056 eden_heap_delta = cur_eden / 100 * percent_change;
1057 return eden_heap_delta;
1058 }
1059
1060 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden) {
1061 return eden_increment(cur_eden, YoungGenerationSizeIncrement);
1062 }
1063
1064 size_t PSAdaptiveSizePolicy::eden_increment_aligned_up(size_t cur_eden) {
1065 size_t result = eden_increment(cur_eden, YoungGenerationSizeIncrement);
1066 return align_size_up(result, _space_alignment);
1067 }
1068
1069 size_t PSAdaptiveSizePolicy::eden_increment_aligned_down(size_t cur_eden) {
1070 size_t result = eden_increment(cur_eden);
1071 return align_size_down(result, _space_alignment);
1072 }
1073
1074 size_t PSAdaptiveSizePolicy::eden_increment_with_supplement_aligned_up(
1075 size_t cur_eden) {
1076 size_t result = eden_increment(cur_eden,
1077 YoungGenerationSizeIncrement + _young_gen_size_increment_supplement);
1078 return align_size_up(result, _space_alignment);
1079 }
1080
1081 size_t PSAdaptiveSizePolicy::eden_decrement_aligned_down(size_t cur_eden) {
1082 size_t eden_heap_delta = eden_decrement(cur_eden);
1083 return align_size_down(eden_heap_delta, _space_alignment);
1084 }
1085
1086 size_t PSAdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
1087 size_t eden_heap_delta = eden_increment(cur_eden) /
1088 AdaptiveSizeDecrementScaleFactor;
1089 return eden_heap_delta;
1090 }
1091
1092 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo,
1093 uint percent_change) {
1094 size_t promo_heap_delta;
1095 promo_heap_delta = cur_promo / 100 * percent_change;
1096 return promo_heap_delta;
1097 }
1098
1099 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo) {
1100 return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1101 }
1102
1103 size_t PSAdaptiveSizePolicy::promo_increment_aligned_up(size_t cur_promo) {
1104 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1105 return align_size_up(result, _space_alignment);
1106 }
1107
1108 size_t PSAdaptiveSizePolicy::promo_increment_aligned_down(size_t cur_promo) {
1109 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1110 return align_size_down(result, _space_alignment);
1111 }
1112
1113 size_t PSAdaptiveSizePolicy::promo_increment_with_supplement_aligned_up(
1114 size_t cur_promo) {
1115 size_t result = promo_increment(cur_promo,
1116 TenuredGenerationSizeIncrement + _old_gen_size_increment_supplement);
1117 return align_size_up(result, _space_alignment);
1118 }
1119
1120 size_t PSAdaptiveSizePolicy::promo_decrement_aligned_down(size_t cur_promo) {
1121 size_t promo_heap_delta = promo_decrement(cur_promo);
1122 return align_size_down(promo_heap_delta, _space_alignment);
1123 }
1124
1125 size_t PSAdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
1126 size_t promo_heap_delta = promo_increment(cur_promo);
1127 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
1128 return promo_heap_delta;
1129 }
1130
1131 uint PSAdaptiveSizePolicy::compute_survivor_space_size_and_threshold(
1132 bool is_survivor_overflow,
1133 uint tenuring_threshold,
1134 size_t survivor_limit) {
1135 assert(survivor_limit >= _space_alignment,
1136 "survivor_limit too small");
1137 assert((size_t)align_size_down(survivor_limit, _space_alignment)
1138 == survivor_limit, "survivor_limit not aligned");
1139
1140 // This method is called even if the tenuring threshold and survivor
1141 // spaces are not adjusted so that the averages are sampled above.
1142 if (!UsePSAdaptiveSurvivorSizePolicy ||
1143 !young_gen_policy_is_ready()) {
1144 return tenuring_threshold;
1145 }
1146
1147 // We'll decide whether to increase or decrease the tenuring
1148 // threshold based partly on the newly computed survivor size
1149 // (if we hit the maximum limit allowed, we'll always choose to
1150 // decrement the threshold).
1151 bool incr_tenuring_threshold = false;
1152 bool decr_tenuring_threshold = false;
1153
1154 set_decrement_tenuring_threshold_for_gc_cost(false);
1155 set_increment_tenuring_threshold_for_gc_cost(false);
1156 set_decrement_tenuring_threshold_for_survivor_limit(false);
1157
1158 if (!is_survivor_overflow) {
1159 // Keep running averages on how much survived
1160
1161 // We use the tenuring threshold to equalize the cost of major
1162 // and minor collections.
1163 // ThresholdTolerance is used to indicate how sensitive the
1164 // tenuring threshold is to differences in cost between the
1165 // collection types.
1166
1167 // Get the times of interest. This involves a little work, so
1168 // we cache the values here.
1169 const double major_cost = major_gc_cost();
1170 const double minor_cost = minor_gc_cost();
1171
1172 if (minor_cost > major_cost * _threshold_tolerance_percent) {
1173 // Minor times are getting too long; lower the threshold so
1174 // less survives and more is promoted.
1175 decr_tenuring_threshold = true;
1176 set_decrement_tenuring_threshold_for_gc_cost(true);
1177 } else if (major_cost > minor_cost * _threshold_tolerance_percent) {
1178 // Major times are too long, so we want less promotion.
1179 incr_tenuring_threshold = true;
1180 set_increment_tenuring_threshold_for_gc_cost(true);
1181 }
1182
1183 } else {
1184 // Survivor space overflow occurred, so promoted and survived are
1185 // not accurate. We'll make our best guess by combining survived
1186 // and promoted and count them as survivors.
1187 //
1188 // We'll lower the tenuring threshold to see if we can correct
1189 // things. Also, set the survivor size conservatively. We're
1190 // trying to avoid many overflows from occurring if defnew size
1191 // is just too small.
1192
1193 decr_tenuring_threshold = true;
1194 }
1195
1196 // The padded average also maintains a deviation from the average;
1197 // we use this to see how good of an estimate we have of what survived.
1198 // We're trying to pad the survivor size as little as possible without
1199 // overflowing the survivor spaces.
1200 size_t target_size = align_size_up((size_t)_avg_survived->padded_average(),
1201 _space_alignment);
1202 target_size = MAX2(target_size, _space_alignment);
1203
1204 if (target_size > survivor_limit) {
1205 // Target size is bigger than we can handle. Let's also reduce
1206 // the tenuring threshold.
1207 target_size = survivor_limit;
1208 decr_tenuring_threshold = true;
1209 set_decrement_tenuring_threshold_for_survivor_limit(true);
1210 }
1211
1212 // Finally, increment or decrement the tenuring threshold, as decided above.
1213 // We test for decrementing first, as we might have hit the target size
1214 // limit.
1215 if (decr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1216 if (tenuring_threshold > 1) {
1217 tenuring_threshold--;
1218 }
1219 } else if (incr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1220 if (tenuring_threshold < MaxTenuringThreshold) {
1221 tenuring_threshold++;
1222 }
1223 }
1224
1225 // We keep a running average of the amount promoted which is used
1226 // to decide when we should collect the old generation (when
1227 // the amount of old gen free space is less than what we expect to
1228 // promote).
1229
1230 if (PrintAdaptiveSizePolicy) {
1231 // A little more detail if Verbose is on
1232 if (Verbose) {
1233 gclog_or_tty->print( " avg_survived: %f"
1234 " avg_deviation: %f",
1235 _avg_survived->average(),
1236 _avg_survived->deviation());
1237 }
1238
1239 gclog_or_tty->print( " avg_survived_padded_avg: %f",
1240 _avg_survived->padded_average());
1241
1242 if (Verbose) {
1243 gclog_or_tty->print( " avg_promoted_avg: %f"
1244 " avg_promoted_dev: %f",
1245 avg_promoted()->average(),
1246 avg_promoted()->deviation());
1247 }
1248
1249 gclog_or_tty->print_cr( " avg_promoted_padded_avg: %f"
1250 " avg_pretenured_padded_avg: %f"
1251 " tenuring_thresh: %d"
1252 " target_size: " SIZE_FORMAT,
1253 avg_promoted()->padded_average(),
1254 _avg_pretenured->padded_average(),
1255 tenuring_threshold, target_size);
1256 }
1257
1258 set_survivor_size(target_size);
1259
1260 return tenuring_threshold;
1261 }
1262
1263 void PSAdaptiveSizePolicy::update_averages(bool is_survivor_overflow,
1264 size_t survived,
1265 size_t promoted) {
1266 // Update averages
1267 if (!is_survivor_overflow) {
1268 // Keep running averages on how much survived
1269 _avg_survived->sample(survived);
1270 } else {
1271 size_t survived_guess = survived + promoted;
1272 _avg_survived->sample(survived_guess);
1273 }
1274 avg_promoted()->sample(promoted + _avg_pretenured->padded_average());
1275
1276 if (PrintAdaptiveSizePolicy) {
1277 gclog_or_tty->print_cr(
1278 "AdaptiveSizePolicy::update_averages:"
1279 " survived: " SIZE_FORMAT
1280 " promoted: " SIZE_FORMAT
1281 " overflow: %s",
1282 survived, promoted, is_survivor_overflow ? "true" : "false");
1283 }
1284 }
1285
1286 bool PSAdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st)
1287 const {
1288
1289 if (!UseAdaptiveSizePolicy) return false;
1290
1291 return AdaptiveSizePolicy::print_adaptive_size_policy_on(
1292 st,
1293 PSScavenge::tenuring_threshold());
1294 }