1 /*
2 * Copyright (c) 2002, 2014, 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/parallelScavengeHeap.hpp"
27 #include "gc_implementation/parallelScavenge/psAdaptiveSizePolicy.hpp"
28 #include "gc_implementation/parallelScavenge/psGCAdaptivePolicyCounters.hpp"
29 #include "gc_implementation/parallelScavenge/psScavenge.hpp"
30 #include "gc_implementation/shared/gcPolicyCounters.hpp"
31 #include "gc_interface/gcCause.hpp"
32 #include "memory/collectorPolicy.hpp"
33 #include "runtime/timer.hpp"
34 #include "utilities/top.hpp"
35
36 #include <math.h>
37
38 PRAGMA_FORMAT_MUTE_WARNINGS_FOR_GCC
39
40 PSAdaptiveSizePolicy::PSAdaptiveSizePolicy(size_t init_eden_size,
41 size_t init_promo_size,
42 size_t init_survivor_size,
43 size_t space_alignment,
44 double gc_pause_goal_sec,
45 double gc_minor_pause_goal_sec,
46 uint gc_cost_ratio) :
47 AdaptiveSizePolicy(init_eden_size,
48 init_promo_size,
49 init_survivor_size,
50 gc_pause_goal_sec,
51 gc_cost_ratio),
52 _collection_cost_margin_fraction(AdaptiveSizePolicyCollectionCostMargin / 100.0),
53 _space_alignment(space_alignment),
54 _live_at_last_full_gc(init_promo_size),
55 _gc_minor_pause_goal_sec(gc_minor_pause_goal_sec),
56 _latest_major_mutator_interval_seconds(0),
57 _young_gen_change_for_major_pause_count(0)
58 {
59 // Sizing policy statistics
60 _avg_major_pause =
61 new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding);
62 _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
63 _avg_major_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
64
65 _avg_base_footprint = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
66 _major_pause_old_estimator =
67 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
68 _major_pause_young_estimator =
69 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
70 _major_collection_estimator =
71 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
72
73 _young_gen_size_increment_supplement = YoungGenerationSizeSupplement;
74 _old_gen_size_increment_supplement = TenuredGenerationSizeSupplement;
75
76 // Start the timers
77 _major_timer.start();
78
79 _old_gen_policy_is_ready = false;
80 }
81
82 size_t PSAdaptiveSizePolicy::calculate_free_based_on_live(size_t live, uintx ratio_as_percentage) {
83 // We want to calculate how much free memory there can be based on the
84 // amount of live data currently in the old gen. Using the formula:
85 // ratio * (free + live) = free
86 // Some equation solving later we get:
87 // free = (live * ratio) / (1 - ratio)
88
89 const double ratio = ratio_as_percentage / 100.0;
90 const double ratio_inverse = 1.0 - ratio;
91 const double tmp = live * ratio;
92 size_t free = (size_t)(tmp / ratio_inverse);
93
94 return free;
95 }
96
97 size_t PSAdaptiveSizePolicy::calculated_old_free_size_in_bytes() const {
98 size_t free_size = (size_t)(_promo_size + avg_promoted()->padded_average());
99 size_t live = ParallelScavengeHeap::heap()->old_gen()->used_in_bytes();
100
101 if (MinHeapFreeRatio != 0) {
102 size_t min_free = calculate_free_based_on_live(live, MinHeapFreeRatio);
103 free_size = MAX2(free_size, min_free);
104 }
105
106 if (MaxHeapFreeRatio != 100) {
107 size_t max_free = calculate_free_based_on_live(live, MaxHeapFreeRatio);
108 free_size = MIN2(max_free, free_size);
109 }
110
111 return free_size;
112 }
113
114 void PSAdaptiveSizePolicy::major_collection_begin() {
115 // Update the interval time
116 _major_timer.stop();
117 // Save most recent collection time
118 _latest_major_mutator_interval_seconds = _major_timer.seconds();
119 _major_timer.reset();
120 _major_timer.start();
121 }
122
123 void PSAdaptiveSizePolicy::update_minor_pause_old_estimator(
124 double minor_pause_in_ms) {
125 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
126 _minor_pause_old_estimator->update(promo_size_in_mbytes,
127 minor_pause_in_ms);
128 }
129
130 void PSAdaptiveSizePolicy::major_collection_end(size_t amount_live,
131 GCCause::Cause gc_cause) {
132 // Update the pause time.
133 _major_timer.stop();
134
135 if (!GCCause::is_user_requested_gc(gc_cause) ||
136 UseAdaptiveSizePolicyWithSystemGC) {
137 double major_pause_in_seconds = _major_timer.seconds();
138 double major_pause_in_ms = major_pause_in_seconds * MILLIUNITS;
139
140 // Sample for performance counter
141 _avg_major_pause->sample(major_pause_in_seconds);
142
143 // Cost of collection (unit-less)
144 double collection_cost = 0.0;
145 if ((_latest_major_mutator_interval_seconds > 0.0) &&
146 (major_pause_in_seconds > 0.0)) {
147 double interval_in_seconds =
148 _latest_major_mutator_interval_seconds + major_pause_in_seconds;
149 collection_cost =
150 major_pause_in_seconds / interval_in_seconds;
151 avg_major_gc_cost()->sample(collection_cost);
152
153 // Sample for performance counter
154 _avg_major_interval->sample(interval_in_seconds);
155 }
156
157 // Calculate variables used to estimate pause time vs. gen sizes
158 double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
159 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
160 _major_pause_old_estimator->update(promo_size_in_mbytes,
161 major_pause_in_ms);
162 _major_pause_young_estimator->update(eden_size_in_mbytes,
163 major_pause_in_ms);
164
165 if (PrintAdaptiveSizePolicy && Verbose) {
166 gclog_or_tty->print("psAdaptiveSizePolicy::major_collection_end: "
167 "major gc cost: %f average: %f", collection_cost,
168 avg_major_gc_cost()->average());
169 gclog_or_tty->print_cr(" major pause: %f major period %f",
170 major_pause_in_ms,
171 _latest_major_mutator_interval_seconds * MILLIUNITS);
172 }
173
174 // Calculate variable used to estimate collection cost vs. gen sizes
175 assert(collection_cost >= 0.0, "Expected to be non-negative");
176 _major_collection_estimator->update(promo_size_in_mbytes,
177 collection_cost);
178 }
179
180 // Update the amount live at the end of a full GC
181 _live_at_last_full_gc = amount_live;
182
183 // The policy does not have enough data until at least some major collections
184 // have been done.
185 if (_avg_major_pause->count() >= AdaptiveSizePolicyReadyThreshold) {
186 _old_gen_policy_is_ready = true;
187 }
188
189 // Interval times use this timer to measure the interval that
190 // the mutator runs. Reset after the GC pause has been measured.
191 _major_timer.reset();
192 _major_timer.start();
193 }
194
195 // If the remaining free space in the old generation is less that
196 // that expected to be needed by the next collection, do a full
197 // collection now.
198 bool PSAdaptiveSizePolicy::should_full_GC(size_t old_free_in_bytes) {
199
200 // A similar test is done in the scavenge's should_attempt_scavenge(). If
201 // this is changed, decide if that test should also be changed.
202 bool result = padded_average_promoted_in_bytes() > (float) old_free_in_bytes;
203 if (PrintGCDetails && Verbose) {
204 if (result) {
205 gclog_or_tty->print(" full after scavenge: ");
206 } else {
207 gclog_or_tty->print(" no full after scavenge: ");
208 }
209 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
210 " padded_average_promoted " SIZE_FORMAT
211 " free in old gen " SIZE_FORMAT,
212 (size_t) average_promoted_in_bytes(),
213 (size_t) padded_average_promoted_in_bytes(),
214 old_free_in_bytes);
215 }
216 return result;
217 }
218
219 void PSAdaptiveSizePolicy::clear_generation_free_space_flags() {
220
221 AdaptiveSizePolicy::clear_generation_free_space_flags();
222
223 set_change_old_gen_for_min_pauses(0);
224
225 set_change_young_gen_for_maj_pauses(0);
226 }
227
228 // If this is not a full GC, only test and modify the young generation.
229
230 void PSAdaptiveSizePolicy::compute_generations_free_space(
231 size_t young_live,
232 size_t eden_live,
233 size_t old_live,
234 size_t cur_eden,
235 size_t max_old_gen_size,
236 size_t max_eden_size,
237 bool is_full_gc) {
238 compute_eden_space_size(young_live,
239 eden_live,
240 cur_eden,
241 max_eden_size,
242 is_full_gc);
243
244 compute_old_gen_free_space(old_live,
245 cur_eden,
246 max_old_gen_size,
247 is_full_gc);
248 }
249
250 void PSAdaptiveSizePolicy::compute_eden_space_size(
251 size_t young_live,
252 size_t eden_live,
253 size_t cur_eden,
254 size_t max_eden_size,
255 bool is_full_gc) {
256
257 // Update statistics
258 // Time statistics are updated as we go, update footprint stats here
259 _avg_base_footprint->sample(BaseFootPrintEstimate);
260 avg_young_live()->sample(young_live);
261 avg_eden_live()->sample(eden_live);
262
263 // This code used to return if the policy was not ready , i.e.,
264 // policy_is_ready() returning false. The intent was that
265 // decisions below needed major collection times and so could
266 // not be made before two major collections. A consequence was
267 // adjustments to the young generation were not done until after
268 // two major collections even if the minor collections times
269 // exceeded the requested goals. Now let the young generation
270 // adjust for the minor collection times. Major collection times
271 // will be zero for the first collection and will naturally be
272 // ignored. Tenured generation adjustments are only made at the
273 // full collections so until the second major collection has
274 // been reached, no tenured generation adjustments will be made.
275
276 // Until we know better, desired promotion size uses the last calculation
277 size_t desired_promo_size = _promo_size;
278
279 // Start eden at the current value. The desired value that is stored
280 // in _eden_size is not bounded by constraints of the heap and can
281 // run away.
282 //
283 // As expected setting desired_eden_size to the current
284 // value of desired_eden_size as a starting point
285 // caused desired_eden_size to grow way too large and caused
286 // an overflow down stream. It may have improved performance in
287 // some case but is dangerous.
288 size_t desired_eden_size = cur_eden;
289
290 // Cache some values. There's a bit of work getting these, so
291 // we might save a little time.
292 const double major_cost = major_gc_cost();
293 const double minor_cost = minor_gc_cost();
294
295 // This method sets the desired eden size. That plus the
296 // desired survivor space sizes sets the desired young generation
297 // size. This methods does not know what the desired survivor
298 // size is but expects that other policy will attempt to make
299 // the survivor sizes compatible with the live data in the
300 // young generation. This limit is an estimate of the space left
301 // in the young generation after the survivor spaces have been
302 // subtracted out.
303 size_t eden_limit = max_eden_size;
304
305 const double gc_cost_limit = GCTimeLimit/100.0;
306
307 // Which way should we go?
308 // if pause requirement is not met
309 // adjust size of any generation with average paus exceeding
310 // the pause limit. Adjust one pause at a time (the larger)
311 // and only make adjustments for the major pause at full collections.
312 // else if throughput requirement not met
313 // adjust the size of the generation with larger gc time. Only
314 // adjust one generation at a time.
315 // else
316 // adjust down the total heap size. Adjust down the larger of the
317 // generations.
318
319 // Add some checks for a threshold for a change. For example,
320 // a change less than the necessary alignment is probably not worth
321 // attempting.
322
323
324 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
325 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
326 //
327 // Check pauses
328 //
329 // Make changes only to affect one of the pauses (the larger)
330 // at a time.
331 adjust_eden_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
332
333 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
334 // Adjust only for the minor pause time goal
335 adjust_eden_for_minor_pause_time(is_full_gc, &desired_eden_size);
336
337 } else if(adjusted_mutator_cost() < _throughput_goal) {
338 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
339 // This sometimes resulted in skipping to the minimize footprint
340 // code. Change this to try and reduce GC time if mutator time is
341 // negative for whatever reason. Or for future consideration,
342 // bail out of the code if mutator time is negative.
343 //
344 // Throughput
345 //
346 assert(major_cost >= 0.0, "major cost is < 0.0");
347 assert(minor_cost >= 0.0, "minor cost is < 0.0");
348 // Try to reduce the GC times.
349 adjust_eden_for_throughput(is_full_gc, &desired_eden_size);
350
351 } else {
352
353 // Be conservative about reducing the footprint.
354 // Do a minimum number of major collections first.
355 // Have reasonable averages for major and minor collections costs.
356 if (UseAdaptiveSizePolicyFootprintGoal &&
357 young_gen_policy_is_ready() &&
358 avg_major_gc_cost()->average() >= 0.0 &&
359 avg_minor_gc_cost()->average() >= 0.0) {
360 size_t desired_sum = desired_eden_size + desired_promo_size;
361 desired_eden_size = adjust_eden_for_footprint(desired_eden_size, desired_sum);
362 }
363 }
364
365 // Note we make the same tests as in the code block below; the code
366 // seems a little easier to read with the printing in another block.
367 if (PrintAdaptiveSizePolicy) {
368 if (desired_eden_size > eden_limit) {
369 gclog_or_tty->print_cr(
370 "PSAdaptiveSizePolicy::compute_eden_space_size limits:"
371 " desired_eden_size: " SIZE_FORMAT
372 " old_eden_size: " SIZE_FORMAT
373 " eden_limit: " SIZE_FORMAT
374 " cur_eden: " SIZE_FORMAT
375 " max_eden_size: " SIZE_FORMAT
376 " avg_young_live: " SIZE_FORMAT,
377 desired_eden_size, _eden_size, eden_limit, cur_eden,
378 max_eden_size, (size_t)avg_young_live()->average());
379 }
380 if (gc_cost() > gc_cost_limit) {
381 gclog_or_tty->print_cr(
382 "PSAdaptiveSizePolicy::compute_eden_space_size: gc time limit"
383 " gc_cost: %f "
384 " GCTimeLimit: %d",
385 gc_cost(), GCTimeLimit);
386 }
387 }
388
389 // Align everything and make a final limit check
390 desired_eden_size = align_size_up(desired_eden_size, _space_alignment);
391 desired_eden_size = MAX2(desired_eden_size, _space_alignment);
392
393 eden_limit = align_size_down(eden_limit, _space_alignment);
394
395 // And one last limit check, now that we've aligned things.
396 if (desired_eden_size > eden_limit) {
397 // If the policy says to get a larger eden but
398 // is hitting the limit, don't decrease eden.
399 // This can lead to a general drifting down of the
400 // eden size. Let the tenuring calculation push more
401 // into the old gen.
402 desired_eden_size = MAX2(eden_limit, cur_eden);
403 }
404
405 if (PrintAdaptiveSizePolicy) {
406 // Timing stats
407 gclog_or_tty->print(
408 "PSAdaptiveSizePolicy::compute_eden_space_size: costs"
409 " minor_time: %f"
410 " major_cost: %f"
411 " mutator_cost: %f"
412 " throughput_goal: %f",
413 minor_gc_cost(), major_gc_cost(), mutator_cost(),
414 _throughput_goal);
415
416 // We give more details if Verbose is set
417 if (Verbose) {
418 gclog_or_tty->print( " minor_pause: %f"
419 " major_pause: %f"
420 " minor_interval: %f"
421 " major_interval: %f"
422 " pause_goal: %f",
423 _avg_minor_pause->padded_average(),
424 _avg_major_pause->padded_average(),
425 _avg_minor_interval->average(),
426 _avg_major_interval->average(),
427 gc_pause_goal_sec());
428 }
429
430 // Footprint stats
431 gclog_or_tty->print( " live_space: " SIZE_FORMAT
432 " free_space: " SIZE_FORMAT,
433 live_space(), free_space());
434 // More detail
435 if (Verbose) {
436 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
437 " avg_young_live: " SIZE_FORMAT
438 " avg_old_live: " SIZE_FORMAT,
439 (size_t)_avg_base_footprint->average(),
440 (size_t)avg_young_live()->average(),
441 (size_t)avg_old_live()->average());
442 }
443
444 // And finally, our old and new sizes.
445 gclog_or_tty->print(" old_eden_size: " SIZE_FORMAT
446 " desired_eden_size: " SIZE_FORMAT,
447 _eden_size, desired_eden_size);
448 gclog_or_tty->cr();
449 }
450
451 set_eden_size(desired_eden_size);
452 }
453
454 void PSAdaptiveSizePolicy::compute_old_gen_free_space(
455 size_t old_live,
456 size_t cur_eden,
457 size_t max_old_gen_size,
458 bool is_full_gc) {
459
460 // Update statistics
461 // Time statistics are updated as we go, update footprint stats here
462 if (is_full_gc) {
463 // old_live is only accurate after a full gc
464 avg_old_live()->sample(old_live);
465 }
466
467 // This code used to return if the policy was not ready , i.e.,
468 // policy_is_ready() returning false. The intent was that
469 // decisions below needed major collection times and so could
470 // not be made before two major collections. A consequence was
471 // adjustments to the young generation were not done until after
472 // two major collections even if the minor collections times
473 // exceeded the requested goals. Now let the young generation
474 // adjust for the minor collection times. Major collection times
475 // will be zero for the first collection and will naturally be
476 // ignored. Tenured generation adjustments are only made at the
477 // full collections so until the second major collection has
478 // been reached, no tenured generation adjustments will be made.
479
480 // Until we know better, desired promotion size uses the last calculation
481 size_t desired_promo_size = _promo_size;
482
483 // Start eden at the current value. The desired value that is stored
484 // in _eden_size is not bounded by constraints of the heap and can
485 // run away.
486 //
487 // As expected setting desired_eden_size to the current
488 // value of desired_eden_size as a starting point
489 // caused desired_eden_size to grow way too large and caused
490 // an overflow down stream. It may have improved performance in
491 // some case but is dangerous.
492 size_t desired_eden_size = cur_eden;
493
494 // Cache some values. There's a bit of work getting these, so
495 // we might save a little time.
496 const double major_cost = major_gc_cost();
497 const double minor_cost = minor_gc_cost();
498
499 // Limits on our growth
500 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());
501
502 // But don't force a promo size below the current promo size. Otherwise,
503 // the promo size will shrink for no good reason.
504 promo_limit = MAX2(promo_limit, _promo_size);
505
506 const double gc_cost_limit = GCTimeLimit/100.0;
507
508 // Which way should we go?
509 // if pause requirement is not met
510 // adjust size of any generation with average paus exceeding
511 // the pause limit. Adjust one pause at a time (the larger)
512 // and only make adjustments for the major pause at full collections.
513 // else if throughput requirement not met
514 // adjust the size of the generation with larger gc time. Only
515 // adjust one generation at a time.
516 // else
517 // adjust down the total heap size. Adjust down the larger of the
518 // generations.
519
520 // Add some checks for a threshhold for a change. For example,
521 // a change less than the necessary alignment is probably not worth
522 // attempting.
523
524 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
525 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
526 //
527 // Check pauses
528 //
529 // Make changes only to affect one of the pauses (the larger)
530 // at a time.
531 if (is_full_gc) {
532 set_decide_at_full_gc(decide_at_full_gc_true);
533 adjust_promo_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
534 }
535 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
536 // Adjust only for the minor pause time goal
537 adjust_promo_for_minor_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
538 } else if(adjusted_mutator_cost() < _throughput_goal) {
539 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
540 // This sometimes resulted in skipping to the minimize footprint
541 // code. Change this to try and reduce GC time if mutator time is
542 // negative for whatever reason. Or for future consideration,
543 // bail out of the code if mutator time is negative.
544 //
545 // Throughput
546 //
547 assert(major_cost >= 0.0, "major cost is < 0.0");
548 assert(minor_cost >= 0.0, "minor cost is < 0.0");
549 // Try to reduce the GC times.
550 if (is_full_gc) {
551 set_decide_at_full_gc(decide_at_full_gc_true);
552 adjust_promo_for_throughput(is_full_gc, &desired_promo_size);
553 }
554 } else {
555
556 // Be conservative about reducing the footprint.
557 // Do a minimum number of major collections first.
558 // Have reasonable averages for major and minor collections costs.
559 if (UseAdaptiveSizePolicyFootprintGoal &&
560 young_gen_policy_is_ready() &&
561 avg_major_gc_cost()->average() >= 0.0 &&
562 avg_minor_gc_cost()->average() >= 0.0) {
563 if (is_full_gc) {
564 set_decide_at_full_gc(decide_at_full_gc_true);
565 size_t desired_sum = desired_eden_size + desired_promo_size;
566 desired_promo_size = adjust_promo_for_footprint(desired_promo_size, desired_sum);
567 }
568 }
569 }
570
571 // Note we make the same tests as in the code block below; the code
572 // seems a little easier to read with the printing in another block.
573 if (PrintAdaptiveSizePolicy) {
574 if (desired_promo_size > promo_limit) {
575 // "free_in_old_gen" was the original value for used for promo_limit
576 size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());
577 gclog_or_tty->print_cr(
578 "PSAdaptiveSizePolicy::compute_old_gen_free_space limits:"
579 " desired_promo_size: " SIZE_FORMAT
580 " promo_limit: " SIZE_FORMAT
581 " free_in_old_gen: " SIZE_FORMAT
582 " max_old_gen_size: " SIZE_FORMAT
583 " avg_old_live: " SIZE_FORMAT,
584 desired_promo_size, promo_limit, free_in_old_gen,
585 max_old_gen_size, (size_t) avg_old_live()->average());
586 }
587 if (gc_cost() > gc_cost_limit) {
588 gclog_or_tty->print_cr(
589 "PSAdaptiveSizePolicy::compute_old_gen_free_space: gc time limit"
590 " gc_cost: %f "
591 " GCTimeLimit: %d",
592 gc_cost(), GCTimeLimit);
593 }
594 }
595
596 // Align everything and make a final limit check
597 desired_promo_size = align_size_up(desired_promo_size, _space_alignment);
598 desired_promo_size = MAX2(desired_promo_size, _space_alignment);
599
600 promo_limit = align_size_down(promo_limit, _space_alignment);
601
602 // And one last limit check, now that we've aligned things.
603 desired_promo_size = MIN2(desired_promo_size, promo_limit);
604
605 if (PrintAdaptiveSizePolicy) {
606 // Timing stats
607 gclog_or_tty->print(
608 "PSAdaptiveSizePolicy::compute_old_gen_free_space: costs"
609 " minor_time: %f"
610 " major_cost: %f"
611 " mutator_cost: %f"
612 " throughput_goal: %f",
613 minor_gc_cost(), major_gc_cost(), mutator_cost(),
614 _throughput_goal);
615
616 // We give more details if Verbose is set
617 if (Verbose) {
618 gclog_or_tty->print( " minor_pause: %f"
619 " major_pause: %f"
620 " minor_interval: %f"
621 " major_interval: %f"
622 " pause_goal: %f",
623 _avg_minor_pause->padded_average(),
624 _avg_major_pause->padded_average(),
625 _avg_minor_interval->average(),
626 _avg_major_interval->average(),
627 gc_pause_goal_sec());
628 }
629
630 // Footprint stats
631 gclog_or_tty->print( " live_space: " SIZE_FORMAT
632 " free_space: " SIZE_FORMAT,
633 live_space(), free_space());
634 // More detail
635 if (Verbose) {
636 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
637 " avg_young_live: " SIZE_FORMAT
638 " avg_old_live: " SIZE_FORMAT,
639 (size_t)_avg_base_footprint->average(),
640 (size_t)avg_young_live()->average(),
641 (size_t)avg_old_live()->average());
642 }
643
644 // And finally, our old and new sizes.
645 gclog_or_tty->print(" old_promo_size: " SIZE_FORMAT
646 " desired_promo_size: " SIZE_FORMAT,
647 _promo_size, desired_promo_size);
648 gclog_or_tty->cr();
649 }
650
651 set_promo_size(desired_promo_size);
652 }
653
654 void PSAdaptiveSizePolicy::decay_supplemental_growth(bool is_full_gc) {
655 // Decay the supplemental increment? Decay the supplement growth
656 // factor even if it is not used. It is only meant to give a boost
657 // to the initial growth and if it is not used, then it was not
658 // needed.
659 if (is_full_gc) {
660 // Don't wait for the threshold value for the major collections. If
661 // here, the supplemental growth term was used and should decay.
662 if ((_avg_major_pause->count() % TenuredGenerationSizeSupplementDecay)
663 == 0) {
664 _old_gen_size_increment_supplement =
665 _old_gen_size_increment_supplement >> 1;
666 }
667 } else {
668 if ((_avg_minor_pause->count() >= AdaptiveSizePolicyReadyThreshold) &&
669 (_avg_minor_pause->count() % YoungGenerationSizeSupplementDecay) == 0) {
670 _young_gen_size_increment_supplement =
671 _young_gen_size_increment_supplement >> 1;
672 }
673 }
674 }
675
676 void PSAdaptiveSizePolicy::adjust_promo_for_minor_pause_time(bool is_full_gc,
677 size_t* desired_promo_size_ptr, size_t* desired_eden_size_ptr) {
678
679 if (PSAdjustTenuredGenForMinorPause) {
680 if (is_full_gc) {
681 set_decide_at_full_gc(decide_at_full_gc_true);
682 }
683 // If the desired eden size is as small as it will get,
684 // try to adjust the old gen size.
685 if (*desired_eden_size_ptr <= _space_alignment) {
686 // Vary the old gen size to reduce the young gen pause. This
687 // may not be a good idea. This is just a test.
688 if (minor_pause_old_estimator()->decrement_will_decrease()) {
689 set_change_old_gen_for_min_pauses(decrease_old_gen_for_min_pauses_true);
690 *desired_promo_size_ptr =
691 _promo_size - promo_decrement_aligned_down(*desired_promo_size_ptr);
692 } else {
693 set_change_old_gen_for_min_pauses(increase_old_gen_for_min_pauses_true);
694 size_t promo_heap_delta =
695 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
696 if ((*desired_promo_size_ptr + promo_heap_delta) >
697 *desired_promo_size_ptr) {
698 *desired_promo_size_ptr =
699 _promo_size + promo_heap_delta;
700 }
701 }
702 }
703 }
704 }
705
706 void PSAdaptiveSizePolicy::adjust_eden_for_minor_pause_time(bool is_full_gc,
707 size_t* desired_eden_size_ptr) {
708
709 // Adjust the young generation size to reduce pause time of
710 // of collections.
711 //
712 // The AdaptiveSizePolicyInitializingSteps test is not used
713 // here. It has not seemed to be needed but perhaps should
714 // be added for consistency.
715 if (minor_pause_young_estimator()->decrement_will_decrease()) {
716 // reduce eden size
717 set_change_young_gen_for_min_pauses(
718 decrease_young_gen_for_min_pauses_true);
719 *desired_eden_size_ptr = *desired_eden_size_ptr -
720 eden_decrement_aligned_down(*desired_eden_size_ptr);
721 } else {
722 // EXPERIMENTAL ADJUSTMENT
723 // Only record that the estimator indicated such an action.
724 // *desired_eden_size_ptr = *desired_eden_size_ptr + eden_heap_delta;
725 set_change_young_gen_for_min_pauses(
726 increase_young_gen_for_min_pauses_true);
727 }
728 }
729
730 void PSAdaptiveSizePolicy::adjust_promo_for_pause_time(bool is_full_gc,
731 size_t* desired_promo_size_ptr,
732 size_t* desired_eden_size_ptr) {
733
734 size_t promo_heap_delta = 0;
735 // Add some checks for a threshold for a change. For example,
736 // a change less than the required alignment is probably not worth
737 // attempting.
738
739 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
740 adjust_promo_for_minor_pause_time(is_full_gc, desired_promo_size_ptr, desired_eden_size_ptr);
741 // major pause adjustments
742 } else if (is_full_gc) {
743 // Adjust for the major pause time only at full gc's because the
744 // affects of a change can only be seen at full gc's.
745
746 // Reduce old generation size to reduce pause?
747 if (major_pause_old_estimator()->decrement_will_decrease()) {
748 // reduce old generation size
749 set_change_old_gen_for_maj_pauses(decrease_old_gen_for_maj_pauses_true);
750 promo_heap_delta = promo_decrement_aligned_down(*desired_promo_size_ptr);
751 *desired_promo_size_ptr = _promo_size - promo_heap_delta;
752 } else {
753 // EXPERIMENTAL ADJUSTMENT
754 // Only record that the estimator indicated such an action.
755 // *desired_promo_size_ptr = _promo_size +
756 // promo_increment_aligned_up(*desired_promo_size_ptr);
757 set_change_old_gen_for_maj_pauses(increase_old_gen_for_maj_pauses_true);
758 }
759 }
760
761 if (PrintAdaptiveSizePolicy && Verbose) {
762 gclog_or_tty->print_cr(
763 "PSAdaptiveSizePolicy::adjust_promo_for_pause_time "
764 "adjusting gen sizes for major pause (avg %f goal %f). "
765 "desired_promo_size " SIZE_FORMAT " promo delta " SIZE_FORMAT,
766 _avg_major_pause->average(), gc_pause_goal_sec(),
767 *desired_promo_size_ptr, promo_heap_delta);
768 }
769 }
770
771 void PSAdaptiveSizePolicy::adjust_eden_for_pause_time(bool is_full_gc,
772 size_t* desired_promo_size_ptr,
773 size_t* desired_eden_size_ptr) {
774
775 size_t eden_heap_delta = 0;
776 // Add some checks for a threshold for a change. For example,
777 // a change less than the required alignment is probably not worth
778 // attempting.
779 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
780 adjust_eden_for_minor_pause_time(is_full_gc,
781 desired_eden_size_ptr);
782 // major pause adjustments
783 } else if (is_full_gc) {
784 // Adjust for the major pause time only at full gc's because the
785 // affects of a change can only be seen at full gc's.
786 if (PSAdjustYoungGenForMajorPause) {
787 // If the promo size is at the minimum (i.e., the old gen
788 // size will not actually decrease), consider changing the
789 // young gen size.
790 if (*desired_promo_size_ptr < _space_alignment) {
791 // If increasing the young generation will decrease the old gen
792 // pause, do it.
793 // During startup there is noise in the statistics for deciding
794 // on whether to increase or decrease the young gen size. For
795 // some number of iterations, just try to increase the young
796 // gen size if the major pause is too long to try and establish
797 // good statistics for later decisions.
798 if (major_pause_young_estimator()->increment_will_decrease() ||
799 (_young_gen_change_for_major_pause_count
800 <= AdaptiveSizePolicyInitializingSteps)) {
801 set_change_young_gen_for_maj_pauses(
802 increase_young_gen_for_maj_pauses_true);
803 eden_heap_delta = eden_increment_aligned_up(*desired_eden_size_ptr);
804 *desired_eden_size_ptr = _eden_size + eden_heap_delta;
805 _young_gen_change_for_major_pause_count++;
806 } else {
807 // Record that decreasing the young gen size would decrease
808 // the major pause
809 set_change_young_gen_for_maj_pauses(
810 decrease_young_gen_for_maj_pauses_true);
811 eden_heap_delta = eden_decrement_aligned_down(*desired_eden_size_ptr);
812 *desired_eden_size_ptr = _eden_size - eden_heap_delta;
813 }
814 }
815 }
816 }
817
818 if (PrintAdaptiveSizePolicy && Verbose) {
819 gclog_or_tty->print_cr(
820 "PSAdaptiveSizePolicy::adjust_eden_for_pause_time "
821 "adjusting gen sizes for major pause (avg %f goal %f). "
822 "desired_eden_size " SIZE_FORMAT " eden delta " SIZE_FORMAT,
823 _avg_major_pause->average(), gc_pause_goal_sec(),
824 *desired_eden_size_ptr, eden_heap_delta);
825 }
826 }
827
828 void PSAdaptiveSizePolicy::adjust_promo_for_throughput(bool is_full_gc,
829 size_t* desired_promo_size_ptr) {
830
831 // Add some checks for a threshold for a change. For example,
832 // a change less than the required alignment is probably not worth
833 // attempting.
834
835 if ((gc_cost() + mutator_cost()) == 0.0) {
836 return;
837 }
838
839 if (PrintAdaptiveSizePolicy && Verbose) {
840 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_promo_for_throughput("
841 "is_full: %d, promo: " SIZE_FORMAT "): ",
842 is_full_gc, *desired_promo_size_ptr);
843 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
844 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
845 }
846
847 // Tenured generation
848 if (is_full_gc) {
849 // Calculate the change to use for the tenured gen.
850 size_t scaled_promo_heap_delta = 0;
851 // Can the increment to the generation be scaled?
852 if (gc_cost() >= 0.0 && major_gc_cost() >= 0.0) {
853 size_t promo_heap_delta =
854 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
855 double scale_by_ratio = major_gc_cost() / gc_cost();
856 scaled_promo_heap_delta =
857 (size_t) (scale_by_ratio * (double) promo_heap_delta);
858 if (PrintAdaptiveSizePolicy && Verbose) {
859 gclog_or_tty->print_cr(
860 "Scaled tenured increment: " SIZE_FORMAT " by %f down to "
861 SIZE_FORMAT,
862 promo_heap_delta, scale_by_ratio, scaled_promo_heap_delta);
863 }
864 } else if (major_gc_cost() >= 0.0) {
865 // Scaling is not going to work. If the major gc time is the
866 // larger, give it a full increment.
867 if (major_gc_cost() >= minor_gc_cost()) {
868 scaled_promo_heap_delta =
869 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
870 }
871 } else {
872 // Don't expect to get here but it's ok if it does
873 // in the product build since the delta will be 0
874 // and nothing will change.
875 assert(false, "Unexpected value for gc costs");
876 }
877
878 switch (AdaptiveSizeThroughPutPolicy) {
879 case 1:
880 // Early in the run the statistics might not be good. Until
881 // a specific number of collections have been, use the heuristic
882 // that a larger generation size means lower collection costs.
883 if (major_collection_estimator()->increment_will_decrease() ||
884 (_old_gen_change_for_major_throughput
885 <= AdaptiveSizePolicyInitializingSteps)) {
886 // Increase tenured generation size to reduce major collection cost
887 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
888 *desired_promo_size_ptr) {
889 *desired_promo_size_ptr = _promo_size + scaled_promo_heap_delta;
890 }
891 set_change_old_gen_for_throughput(
892 increase_old_gen_for_throughput_true);
893 _old_gen_change_for_major_throughput++;
894 } else {
895 // EXPERIMENTAL ADJUSTMENT
896 // Record that decreasing the old gen size would decrease
897 // the major collection cost but don't do it.
898 // *desired_promo_size_ptr = _promo_size -
899 // promo_decrement_aligned_down(*desired_promo_size_ptr);
900 set_change_old_gen_for_throughput(
901 decrease_old_gen_for_throughput_true);
902 }
903
904 break;
905 default:
906 // Simplest strategy
907 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
908 *desired_promo_size_ptr) {
909 *desired_promo_size_ptr = *desired_promo_size_ptr +
910 scaled_promo_heap_delta;
911 }
912 set_change_old_gen_for_throughput(
913 increase_old_gen_for_throughput_true);
914 _old_gen_change_for_major_throughput++;
915 }
916
917 if (PrintAdaptiveSizePolicy && Verbose) {
918 gclog_or_tty->print_cr(
919 "adjusting tenured gen for throughput (avg %f goal %f). "
920 "desired_promo_size " SIZE_FORMAT " promo_delta " SIZE_FORMAT ,
921 mutator_cost(), _throughput_goal,
922 *desired_promo_size_ptr, scaled_promo_heap_delta);
923 }
924 }
925 }
926
927 void PSAdaptiveSizePolicy::adjust_eden_for_throughput(bool is_full_gc,
928 size_t* desired_eden_size_ptr) {
929
930 // Add some checks for a threshold for a change. For example,
931 // a change less than the required alignment is probably not worth
932 // attempting.
933
934 if ((gc_cost() + mutator_cost()) == 0.0) {
935 return;
936 }
937
938 if (PrintAdaptiveSizePolicy && Verbose) {
939 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_eden_for_throughput("
940 "is_full: %d, cur_eden: " SIZE_FORMAT "): ",
941 is_full_gc, *desired_eden_size_ptr);
942 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
943 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
944 }
945
946 // Young generation
947 size_t scaled_eden_heap_delta = 0;
948 // Can the increment to the generation be scaled?
949 if (gc_cost() >= 0.0 && minor_gc_cost() >= 0.0) {
950 size_t eden_heap_delta =
951 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
952 double scale_by_ratio = minor_gc_cost() / gc_cost();
953 assert(scale_by_ratio <= 1.0 && scale_by_ratio >= 0.0, "Scaling is wrong");
954 scaled_eden_heap_delta =
955 (size_t) (scale_by_ratio * (double) eden_heap_delta);
956 if (PrintAdaptiveSizePolicy && Verbose) {
957 gclog_or_tty->print_cr(
958 "Scaled eden increment: " SIZE_FORMAT " by %f down to "
959 SIZE_FORMAT,
960 eden_heap_delta, scale_by_ratio, scaled_eden_heap_delta);
961 }
962 } else if (minor_gc_cost() >= 0.0) {
963 // Scaling is not going to work. If the minor gc time is the
964 // larger, give it a full increment.
965 if (minor_gc_cost() > major_gc_cost()) {
966 scaled_eden_heap_delta =
967 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
968 }
969 } else {
970 // Don't expect to get here but it's ok if it does
971 // in the product build since the delta will be 0
972 // and nothing will change.
973 assert(false, "Unexpected value for gc costs");
974 }
975
976 // Use a heuristic for some number of collections to give
977 // the averages time to settle down.
978 switch (AdaptiveSizeThroughPutPolicy) {
979 case 1:
980 if (minor_collection_estimator()->increment_will_decrease() ||
981 (_young_gen_change_for_minor_throughput
982 <= AdaptiveSizePolicyInitializingSteps)) {
983 // Expand young generation size to reduce frequency of
984 // of collections.
985 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
986 *desired_eden_size_ptr) {
987 *desired_eden_size_ptr =
988 *desired_eden_size_ptr + scaled_eden_heap_delta;
989 }
990 set_change_young_gen_for_throughput(
991 increase_young_gen_for_througput_true);
992 _young_gen_change_for_minor_throughput++;
993 } else {
994 // EXPERIMENTAL ADJUSTMENT
995 // Record that decreasing the young gen size would decrease
996 // the minor collection cost but don't do it.
997 // *desired_eden_size_ptr = _eden_size -
998 // eden_decrement_aligned_down(*desired_eden_size_ptr);
999 set_change_young_gen_for_throughput(
1000 decrease_young_gen_for_througput_true);
1001 }
1002 break;
1003 default:
1004 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
1005 *desired_eden_size_ptr) {
1006 *desired_eden_size_ptr =
1007 *desired_eden_size_ptr + scaled_eden_heap_delta;
1008 }
1009 set_change_young_gen_for_throughput(
1010 increase_young_gen_for_througput_true);
1011 _young_gen_change_for_minor_throughput++;
1012 }
1013
1014 if (PrintAdaptiveSizePolicy && Verbose) {
1015 gclog_or_tty->print_cr(
1016 "adjusting eden for throughput (avg %f goal %f). desired_eden_size "
1017 SIZE_FORMAT " eden delta " SIZE_FORMAT "\n",
1018 mutator_cost(), _throughput_goal,
1019 *desired_eden_size_ptr, scaled_eden_heap_delta);
1020 }
1021 }
1022
1023 size_t PSAdaptiveSizePolicy::adjust_promo_for_footprint(
1024 size_t desired_promo_size, size_t desired_sum) {
1025 assert(desired_promo_size <= desired_sum, "Inconsistent parameters");
1026 set_decrease_for_footprint(decrease_old_gen_for_footprint_true);
1027
1028 size_t change = promo_decrement(desired_promo_size);
1029 change = scale_down(change, desired_promo_size, desired_sum);
1030
1031 size_t reduced_size = desired_promo_size - change;
1032
1033 if (PrintAdaptiveSizePolicy && Verbose) {
1034 gclog_or_tty->print_cr(
1035 "AdaptiveSizePolicy::adjust_promo_for_footprint "
1036 "adjusting tenured gen for footprint. "
1037 "starting promo size " SIZE_FORMAT
1038 " reduced promo size " SIZE_FORMAT
1039 " promo delta " SIZE_FORMAT,
1040 desired_promo_size, reduced_size, change );
1041 }
1042
1043 assert(reduced_size <= desired_promo_size, "Inconsistent result");
1044 return reduced_size;
1045 }
1046
1047 size_t PSAdaptiveSizePolicy::adjust_eden_for_footprint(
1048 size_t desired_eden_size, size_t desired_sum) {
1049 assert(desired_eden_size <= desired_sum, "Inconsistent parameters");
1050 set_decrease_for_footprint(decrease_young_gen_for_footprint_true);
1051
1052 size_t change = eden_decrement(desired_eden_size);
1053 change = scale_down(change, desired_eden_size, desired_sum);
1054
1055 size_t reduced_size = desired_eden_size - change;
1056
1057 if (PrintAdaptiveSizePolicy && Verbose) {
1058 gclog_or_tty->print_cr(
1059 "AdaptiveSizePolicy::adjust_eden_for_footprint "
1060 "adjusting eden for footprint. "
1061 " starting eden size " SIZE_FORMAT
1062 " reduced eden size " SIZE_FORMAT
1063 " eden delta " SIZE_FORMAT,
1064 desired_eden_size, reduced_size, change);
1065 }
1066
1067 assert(reduced_size <= desired_eden_size, "Inconsistent result");
1068 return reduced_size;
1069 }
1070
1071 // Scale down "change" by the factor
1072 // part / total
1073 // Don't align the results.
1074
1075 size_t PSAdaptiveSizePolicy::scale_down(size_t change,
1076 double part,
1077 double total) {
1078 assert(part <= total, "Inconsistent input");
1079 size_t reduced_change = change;
1080 if (total > 0) {
1081 double fraction = part / total;
1082 reduced_change = (size_t) (fraction * (double) change);
1083 }
1084 assert(reduced_change <= change, "Inconsistent result");
1085 return reduced_change;
1086 }
1087
1088 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden,
1089 uint percent_change) {
1090 size_t eden_heap_delta;
1091 eden_heap_delta = cur_eden / 100 * percent_change;
1092 return eden_heap_delta;
1093 }
1094
1095 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden) {
1096 return eden_increment(cur_eden, YoungGenerationSizeIncrement);
1097 }
1098
1099 size_t PSAdaptiveSizePolicy::eden_increment_aligned_up(size_t cur_eden) {
1100 size_t result = eden_increment(cur_eden, YoungGenerationSizeIncrement);
1101 return align_size_up(result, _space_alignment);
1102 }
1103
1104 size_t PSAdaptiveSizePolicy::eden_increment_aligned_down(size_t cur_eden) {
1105 size_t result = eden_increment(cur_eden);
1106 return align_size_down(result, _space_alignment);
1107 }
1108
1109 size_t PSAdaptiveSizePolicy::eden_increment_with_supplement_aligned_up(
1110 size_t cur_eden) {
1111 size_t result = eden_increment(cur_eden,
1112 YoungGenerationSizeIncrement + _young_gen_size_increment_supplement);
1113 return align_size_up(result, _space_alignment);
1114 }
1115
1116 size_t PSAdaptiveSizePolicy::eden_decrement_aligned_down(size_t cur_eden) {
1117 size_t eden_heap_delta = eden_decrement(cur_eden);
1118 return align_size_down(eden_heap_delta, _space_alignment);
1119 }
1120
1121 size_t PSAdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
1122 size_t eden_heap_delta = eden_increment(cur_eden) /
1123 AdaptiveSizeDecrementScaleFactor;
1124 return eden_heap_delta;
1125 }
1126
1127 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo,
1128 uint percent_change) {
1129 size_t promo_heap_delta;
1130 promo_heap_delta = cur_promo / 100 * percent_change;
1131 return promo_heap_delta;
1132 }
1133
1134 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo) {
1135 return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1136 }
1137
1138 size_t PSAdaptiveSizePolicy::promo_increment_aligned_up(size_t cur_promo) {
1139 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1140 return align_size_up(result, _space_alignment);
1141 }
1142
1143 size_t PSAdaptiveSizePolicy::promo_increment_aligned_down(size_t cur_promo) {
1144 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1145 return align_size_down(result, _space_alignment);
1146 }
1147
1148 size_t PSAdaptiveSizePolicy::promo_increment_with_supplement_aligned_up(
1149 size_t cur_promo) {
1150 size_t result = promo_increment(cur_promo,
1151 TenuredGenerationSizeIncrement + _old_gen_size_increment_supplement);
1152 return align_size_up(result, _space_alignment);
1153 }
1154
1155 size_t PSAdaptiveSizePolicy::promo_decrement_aligned_down(size_t cur_promo) {
1156 size_t promo_heap_delta = promo_decrement(cur_promo);
1157 return align_size_down(promo_heap_delta, _space_alignment);
1158 }
1159
1160 size_t PSAdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
1161 size_t promo_heap_delta = promo_increment(cur_promo);
1162 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
1163 return promo_heap_delta;
1164 }
1165
1166 uint PSAdaptiveSizePolicy::compute_survivor_space_size_and_threshold(
1167 bool is_survivor_overflow,
1168 uint tenuring_threshold,
1169 size_t survivor_limit) {
1170 assert(survivor_limit >= _space_alignment,
1171 "survivor_limit too small");
1172 assert((size_t)align_size_down(survivor_limit, _space_alignment)
1173 == survivor_limit, "survivor_limit not aligned");
1174
1175 // This method is called even if the tenuring threshold and survivor
1176 // spaces are not adjusted so that the averages are sampled above.
1177 if (!UsePSAdaptiveSurvivorSizePolicy ||
1178 !young_gen_policy_is_ready()) {
1179 return tenuring_threshold;
1180 }
1181
1182 // We'll decide whether to increase or decrease the tenuring
1183 // threshold based partly on the newly computed survivor size
1184 // (if we hit the maximum limit allowed, we'll always choose to
1185 // decrement the threshold).
1186 bool incr_tenuring_threshold = false;
1187 bool decr_tenuring_threshold = false;
1188
1189 set_decrement_tenuring_threshold_for_gc_cost(false);
1190 set_increment_tenuring_threshold_for_gc_cost(false);
1191 set_decrement_tenuring_threshold_for_survivor_limit(false);
1192
1193 if (!is_survivor_overflow) {
1194 // Keep running averages on how much survived
1195
1196 // We use the tenuring threshold to equalize the cost of major
1197 // and minor collections.
1198 // ThresholdTolerance is used to indicate how sensitive the
1199 // tenuring threshold is to differences in cost betweent the
1200 // collection types.
1201
1202 // Get the times of interest. This involves a little work, so
1203 // we cache the values here.
1204 const double major_cost = major_gc_cost();
1205 const double minor_cost = minor_gc_cost();
1206
1207 if (minor_cost > major_cost * _threshold_tolerance_percent) {
1208 // Minor times are getting too long; lower the threshold so
1209 // less survives and more is promoted.
1210 decr_tenuring_threshold = true;
1211 set_decrement_tenuring_threshold_for_gc_cost(true);
1212 } else if (major_cost > minor_cost * _threshold_tolerance_percent) {
1213 // Major times are too long, so we want less promotion.
1214 incr_tenuring_threshold = true;
1215 set_increment_tenuring_threshold_for_gc_cost(true);
1216 }
1217
1218 } else {
1219 // Survivor space overflow occurred, so promoted and survived are
1220 // not accurate. We'll make our best guess by combining survived
1221 // and promoted and count them as survivors.
1222 //
1223 // We'll lower the tenuring threshold to see if we can correct
1224 // things. Also, set the survivor size conservatively. We're
1225 // trying to avoid many overflows from occurring if defnew size
1226 // is just too small.
1227
1228 decr_tenuring_threshold = true;
1229 }
1230
1231 // The padded average also maintains a deviation from the average;
1232 // we use this to see how good of an estimate we have of what survived.
1233 // We're trying to pad the survivor size as little as possible without
1234 // overflowing the survivor spaces.
1235 size_t target_size = align_size_up((size_t)_avg_survived->padded_average(),
1236 _space_alignment);
1237 target_size = MAX2(target_size, _space_alignment);
1238
1239 if (target_size > survivor_limit) {
1240 // Target size is bigger than we can handle. Let's also reduce
1241 // the tenuring threshold.
1242 target_size = survivor_limit;
1243 decr_tenuring_threshold = true;
1244 set_decrement_tenuring_threshold_for_survivor_limit(true);
1245 }
1246
1247 // Finally, increment or decrement the tenuring threshold, as decided above.
1248 // We test for decrementing first, as we might have hit the target size
1249 // limit.
1250 if (decr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1251 if (tenuring_threshold > 1) {
1252 tenuring_threshold--;
1253 }
1254 } else if (incr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1255 if (tenuring_threshold < MaxTenuringThreshold) {
1256 tenuring_threshold++;
1257 }
1258 }
1259
1260 // We keep a running average of the amount promoted which is used
1261 // to decide when we should collect the old generation (when
1262 // the amount of old gen free space is less than what we expect to
1263 // promote).
1264
1265 if (PrintAdaptiveSizePolicy) {
1266 // A little more detail if Verbose is on
1267 if (Verbose) {
1268 gclog_or_tty->print( " avg_survived: %f"
1269 " avg_deviation: %f",
1270 _avg_survived->average(),
1271 _avg_survived->deviation());
1272 }
1273
1274 gclog_or_tty->print( " avg_survived_padded_avg: %f",
1275 _avg_survived->padded_average());
1276
1277 if (Verbose) {
1278 gclog_or_tty->print( " avg_promoted_avg: %f"
1279 " avg_promoted_dev: %f",
1280 avg_promoted()->average(),
1281 avg_promoted()->deviation());
1282 }
1283
1284 gclog_or_tty->print_cr( " avg_promoted_padded_avg: %f"
1285 " avg_pretenured_padded_avg: %f"
1286 " tenuring_thresh: %d"
1287 " target_size: " SIZE_FORMAT,
1288 avg_promoted()->padded_average(),
1289 _avg_pretenured->padded_average(),
1290 tenuring_threshold, target_size);
1291 }
1292
1293 set_survivor_size(target_size);
1294
1295 return tenuring_threshold;
1296 }
1297
1298 void PSAdaptiveSizePolicy::update_averages(bool is_survivor_overflow,
1299 size_t survived,
1300 size_t promoted) {
1301 // Update averages
1302 if (!is_survivor_overflow) {
1303 // Keep running averages on how much survived
1304 _avg_survived->sample(survived);
1305 } else {
1306 size_t survived_guess = survived + promoted;
1307 _avg_survived->sample(survived_guess);
1308 }
1309 avg_promoted()->sample(promoted + _avg_pretenured->padded_average());
1310
1311 if (PrintAdaptiveSizePolicy) {
1312 gclog_or_tty->print_cr(
1313 "AdaptiveSizePolicy::update_averages:"
1314 " survived: " SIZE_FORMAT
1315 " promoted: " SIZE_FORMAT
1316 " overflow: %s",
1317 survived, promoted, is_survivor_overflow ? "true" : "false");
1318 }
1319 }
1320
1321 bool PSAdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st)
1322 const {
1323
1324 if (!UseAdaptiveSizePolicy) return false;
1325
1326 return AdaptiveSizePolicy::print_adaptive_size_policy_on(
1327 st,
1328 PSScavenge::tenuring_threshold());
1329 }
1330
1331 #ifndef PRODUCT
1332
1333 void TestOldFreeSpaceCalculation_test() {
1334 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 20) == 25, "Calculation of free memory failed");
1335 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 50) == 100, "Calculation of free memory failed");
1336 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 60) == 150, "Calculation of free memory failed");
1337 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 75) == 300, "Calculation of free memory failed");
1338 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 20) == 100, "Calculation of free memory failed");
1339 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 50) == 400, "Calculation of free memory failed");
1340 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 60) == 600, "Calculation of free memory failed");
1341 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 75) == 1200, "Calculation of free memory failed");
1342 }
1343
1344 #endif /* !PRODUCT */