1 /*
2 * Copyright (c) 2002, 2015, 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/parallel/parallelScavengeHeap.hpp"
27 #include "gc/parallel/psAdaptiveSizePolicy.hpp"
28 #include "gc/parallel/psGCAdaptivePolicyCounters.hpp"
29 #include "gc/parallel/psScavenge.hpp"
30 #include "gc/shared/collectorPolicy.hpp"
31 #include "gc/shared/gcCause.hpp"
32 #include "gc/shared/gcPolicyCounters.hpp"
33 #include "runtime/timer.hpp"
34 #include "utilities/top.hpp"
35
36 #include <math.h>
37
38 PSAdaptiveSizePolicy::PSAdaptiveSizePolicy(size_t init_eden_size,
39 size_t init_promo_size,
40 size_t init_survivor_size,
41 size_t space_alignment,
42 double gc_pause_goal_sec,
43 double gc_minor_pause_goal_sec,
44 uint gc_cost_ratio) :
45 AdaptiveSizePolicy(init_eden_size,
46 init_promo_size,
47 init_survivor_size,
48 gc_pause_goal_sec,
49 gc_cost_ratio),
50 _collection_cost_margin_fraction(AdaptiveSizePolicyCollectionCostMargin / 100.0),
51 _space_alignment(space_alignment),
52 _live_at_last_full_gc(init_promo_size),
53 _gc_minor_pause_goal_sec(gc_minor_pause_goal_sec),
54 _latest_major_mutator_interval_seconds(0),
55 _young_gen_change_for_major_pause_count(0)
56 {
57 // Sizing policy statistics
58 _avg_major_pause =
59 new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding);
60 _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
61 _avg_major_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
62
63 _avg_base_footprint = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
64 _major_pause_old_estimator =
65 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
66 _major_pause_young_estimator =
67 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
68 _major_collection_estimator =
69 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
70
71 _young_gen_size_increment_supplement = YoungGenerationSizeSupplement;
72 _old_gen_size_increment_supplement = TenuredGenerationSizeSupplement;
73
74 // Start the timers
75 _major_timer.start();
76
77 _old_gen_policy_is_ready = false;
78 }
79
80 size_t PSAdaptiveSizePolicy::calculate_free_based_on_live(size_t live, uintx ratio_as_percentage) {
81 // We want to calculate how much free memory there can be based on the
82 // amount of live data currently in the old gen. Using the formula:
83 // ratio * (free + live) = free
84 // Some equation solving later we get:
85 // free = (live * ratio) / (1 - ratio)
86
87 const double ratio = ratio_as_percentage / 100.0;
88 const double ratio_inverse = 1.0 - ratio;
89 const double tmp = live * ratio;
90 size_t free = (size_t)(tmp / ratio_inverse);
91
92 return free;
93 }
94
95 size_t PSAdaptiveSizePolicy::calculated_old_free_size_in_bytes() const {
96 size_t free_size = (size_t)(_promo_size + avg_promoted()->padded_average());
97 size_t live = ParallelScavengeHeap::heap()->old_gen()->used_in_bytes();
98
99 if (MinHeapFreeRatio != 0) {
100 size_t min_free = calculate_free_based_on_live(live, MinHeapFreeRatio);
101 free_size = MAX2(free_size, min_free);
102 }
103
104 if (MaxHeapFreeRatio != 100) {
105 size_t max_free = calculate_free_based_on_live(live, MaxHeapFreeRatio);
106 free_size = MIN2(max_free, free_size);
107 }
108
109 return free_size;
110 }
111
112 void PSAdaptiveSizePolicy::major_collection_begin() {
113 // Update the interval time
114 _major_timer.stop();
115 // Save most recent collection time
116 _latest_major_mutator_interval_seconds = _major_timer.seconds();
117 _major_timer.reset();
118 _major_timer.start();
119 }
120
121 void PSAdaptiveSizePolicy::update_minor_pause_old_estimator(
122 double minor_pause_in_ms) {
123 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
124 _minor_pause_old_estimator->update(promo_size_in_mbytes,
125 minor_pause_in_ms);
126 }
127
128 void PSAdaptiveSizePolicy::major_collection_end(size_t amount_live,
129 GCCause::Cause gc_cause) {
130 // Update the pause time.
131 _major_timer.stop();
132
133 if (should_update_promo_stats(gc_cause)) {
134 double major_pause_in_seconds = _major_timer.seconds();
135 double major_pause_in_ms = major_pause_in_seconds * MILLIUNITS;
136
137 // Sample for performance counter
138 _avg_major_pause->sample(major_pause_in_seconds);
139
140 // Cost of collection (unit-less)
141 double collection_cost = 0.0;
142 if ((_latest_major_mutator_interval_seconds > 0.0) &&
143 (major_pause_in_seconds > 0.0)) {
144 double interval_in_seconds =
145 _latest_major_mutator_interval_seconds + major_pause_in_seconds;
146 collection_cost =
147 major_pause_in_seconds / interval_in_seconds;
148 avg_major_gc_cost()->sample(collection_cost);
149
150 // Sample for performance counter
151 _avg_major_interval->sample(interval_in_seconds);
152 }
153
154 // Calculate variables used to estimate pause time vs. gen sizes
155 double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
156 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
157 _major_pause_old_estimator->update(promo_size_in_mbytes,
158 major_pause_in_ms);
159 _major_pause_young_estimator->update(eden_size_in_mbytes,
160 major_pause_in_ms);
161
162 if (PrintAdaptiveSizePolicy && Verbose) {
163 gclog_or_tty->print("psAdaptiveSizePolicy::major_collection_end: "
164 "major gc cost: %f average: %f", collection_cost,
165 avg_major_gc_cost()->average());
166 gclog_or_tty->print_cr(" major pause: %f major period %f",
167 major_pause_in_ms,
168 _latest_major_mutator_interval_seconds * MILLIUNITS);
169 }
170
171 // Calculate variable used to estimate collection cost vs. gen sizes
172 assert(collection_cost >= 0.0, "Expected to be non-negative");
173 _major_collection_estimator->update(promo_size_in_mbytes,
174 collection_cost);
175 }
176
177 // Update the amount live at the end of a full GC
178 _live_at_last_full_gc = amount_live;
179
180 // The policy does not have enough data until at least some major collections
181 // have been done.
182 if (_avg_major_pause->count() >= AdaptiveSizePolicyReadyThreshold) {
183 _old_gen_policy_is_ready = true;
184 }
185
186 // Interval times use this timer to measure the interval that
187 // the mutator runs. Reset after the GC pause has been measured.
188 _major_timer.reset();
189 _major_timer.start();
190 }
191
192 // If the remaining free space in the old generation is less that
193 // that expected to be needed by the next collection, do a full
194 // collection now.
195 bool PSAdaptiveSizePolicy::should_full_GC(size_t old_free_in_bytes) {
196
197 // A similar test is done in the scavenge's should_attempt_scavenge(). If
198 // this is changed, decide if that test should also be changed.
199 bool result = padded_average_promoted_in_bytes() > (float) old_free_in_bytes;
200 if (PrintGCDetails && Verbose) {
201 if (result) {
202 gclog_or_tty->print(" full after scavenge: ");
203 } else {
204 gclog_or_tty->print(" no full after scavenge: ");
205 }
206 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
207 " padded_average_promoted " SIZE_FORMAT
208 " free in old gen " SIZE_FORMAT,
209 (size_t) average_promoted_in_bytes(),
210 (size_t) padded_average_promoted_in_bytes(),
211 old_free_in_bytes);
212 }
213 return result;
214 }
215
216 void PSAdaptiveSizePolicy::clear_generation_free_space_flags() {
217
218 AdaptiveSizePolicy::clear_generation_free_space_flags();
219
220 set_change_old_gen_for_min_pauses(0);
221
222 set_change_young_gen_for_maj_pauses(0);
223 }
224
225 // If this is not a full GC, only test and modify the young generation.
226
227 void PSAdaptiveSizePolicy::compute_generations_free_space(
228 size_t young_live,
229 size_t eden_live,
230 size_t old_live,
231 size_t cur_eden,
232 size_t max_old_gen_size,
233 size_t max_eden_size,
234 bool is_full_gc) {
235 compute_eden_space_size(young_live,
236 eden_live,
237 cur_eden,
238 max_eden_size,
239 is_full_gc);
240
241 compute_old_gen_free_space(old_live,
242 cur_eden,
243 max_old_gen_size,
244 is_full_gc);
245 }
246
247 void PSAdaptiveSizePolicy::compute_eden_space_size(
248 size_t young_live,
249 size_t eden_live,
250 size_t cur_eden,
251 size_t max_eden_size,
252 bool is_full_gc) {
253
254 // Update statistics
255 // Time statistics are updated as we go, update footprint stats here
256 _avg_base_footprint->sample(BaseFootPrintEstimate);
257 avg_young_live()->sample(young_live);
258 avg_eden_live()->sample(eden_live);
259
260 // This code used to return if the policy was not ready , i.e.,
261 // policy_is_ready() returning false. The intent was that
262 // decisions below needed major collection times and so could
263 // not be made before two major collections. A consequence was
264 // adjustments to the young generation were not done until after
265 // two major collections even if the minor collections times
266 // exceeded the requested goals. Now let the young generation
267 // adjust for the minor collection times. Major collection times
268 // will be zero for the first collection and will naturally be
269 // ignored. Tenured generation adjustments are only made at the
270 // full collections so until the second major collection has
271 // been reached, no tenured generation adjustments will be made.
272
273 // Until we know better, desired promotion size uses the last calculation
274 size_t desired_promo_size = _promo_size;
275
276 // Start eden at the current value. The desired value that is stored
277 // in _eden_size is not bounded by constraints of the heap and can
278 // run away.
279 //
280 // As expected setting desired_eden_size to the current
281 // value of desired_eden_size as a starting point
282 // caused desired_eden_size to grow way too large and caused
283 // an overflow down stream. It may have improved performance in
284 // some case but is dangerous.
285 size_t desired_eden_size = cur_eden;
286
287 // Cache some values. There's a bit of work getting these, so
288 // we might save a little time.
289 const double major_cost = major_gc_cost();
290 const double minor_cost = minor_gc_cost();
291
292 // This method sets the desired eden size. That plus the
293 // desired survivor space sizes sets the desired young generation
294 // size. This methods does not know what the desired survivor
295 // size is but expects that other policy will attempt to make
296 // the survivor sizes compatible with the live data in the
297 // young generation. This limit is an estimate of the space left
298 // in the young generation after the survivor spaces have been
299 // subtracted out.
300 size_t eden_limit = max_eden_size;
301
302 const double gc_cost_limit = GCTimeLimit/100.0;
303
304 // Which way should we go?
305 // if pause requirement is not met
306 // adjust size of any generation with average paus exceeding
307 // the pause limit. Adjust one pause at a time (the larger)
308 // and only make adjustments for the major pause at full collections.
309 // else if throughput requirement not met
310 // adjust the size of the generation with larger gc time. Only
311 // adjust one generation at a time.
312 // else
313 // adjust down the total heap size. Adjust down the larger of the
314 // generations.
315
316 // Add some checks for a threshold for a change. For example,
317 // a change less than the necessary alignment is probably not worth
318 // attempting.
319
320
321 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
322 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
323 //
324 // Check pauses
325 //
326 // Make changes only to affect one of the pauses (the larger)
327 // at a time.
328 adjust_eden_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
329
330 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
331 // Adjust only for the minor pause time goal
332 adjust_eden_for_minor_pause_time(is_full_gc, &desired_eden_size);
333
334 } else if(adjusted_mutator_cost() < _throughput_goal) {
335 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
336 // This sometimes resulted in skipping to the minimize footprint
337 // code. Change this to try and reduce GC time if mutator time is
338 // negative for whatever reason. Or for future consideration,
339 // bail out of the code if mutator time is negative.
340 //
341 // Throughput
342 //
343 assert(major_cost >= 0.0, "major cost is < 0.0");
344 assert(minor_cost >= 0.0, "minor cost is < 0.0");
345 // Try to reduce the GC times.
346 adjust_eden_for_throughput(is_full_gc, &desired_eden_size);
347
348 } else {
349
350 // Be conservative about reducing the footprint.
351 // Do a minimum number of major collections first.
352 // Have reasonable averages for major and minor collections costs.
353 if (UseAdaptiveSizePolicyFootprintGoal &&
354 young_gen_policy_is_ready() &&
355 avg_major_gc_cost()->average() >= 0.0 &&
356 avg_minor_gc_cost()->average() >= 0.0) {
357 size_t desired_sum = desired_eden_size + desired_promo_size;
358 desired_eden_size = adjust_eden_for_footprint(desired_eden_size, desired_sum);
359 }
360 }
361
362 // Note we make the same tests as in the code block below; the code
363 // seems a little easier to read with the printing in another block.
364 if (PrintAdaptiveSizePolicy) {
365 if (desired_eden_size > eden_limit) {
366 gclog_or_tty->print_cr(
367 "PSAdaptiveSizePolicy::compute_eden_space_size limits:"
368 " desired_eden_size: " SIZE_FORMAT
369 " old_eden_size: " SIZE_FORMAT
370 " eden_limit: " SIZE_FORMAT
371 " cur_eden: " SIZE_FORMAT
372 " max_eden_size: " SIZE_FORMAT
373 " avg_young_live: " SIZE_FORMAT,
374 desired_eden_size, _eden_size, eden_limit, cur_eden,
375 max_eden_size, (size_t)avg_young_live()->average());
376 }
377 if (gc_cost() > gc_cost_limit) {
378 gclog_or_tty->print_cr(
379 "PSAdaptiveSizePolicy::compute_eden_space_size: gc time limit"
380 " gc_cost: %f "
381 " GCTimeLimit: " UINTX_FORMAT,
382 gc_cost(), GCTimeLimit);
383 }
384 }
385
386 // Align everything and make a final limit check
387 desired_eden_size = align_size_up(desired_eden_size, _space_alignment);
388 desired_eden_size = MAX2(desired_eden_size, _space_alignment);
389
390 eden_limit = align_size_down(eden_limit, _space_alignment);
391
392 // And one last limit check, now that we've aligned things.
393 if (desired_eden_size > eden_limit) {
394 // If the policy says to get a larger eden but
395 // is hitting the limit, don't decrease eden.
396 // This can lead to a general drifting down of the
397 // eden size. Let the tenuring calculation push more
398 // into the old gen.
399 desired_eden_size = MAX2(eden_limit, cur_eden);
400 }
401
402 if (PrintAdaptiveSizePolicy) {
403 // Timing stats
404 gclog_or_tty->print(
405 "PSAdaptiveSizePolicy::compute_eden_space_size: costs"
406 " minor_time: %f"
407 " major_cost: %f"
408 " mutator_cost: %f"
409 " throughput_goal: %f",
410 minor_gc_cost(), major_gc_cost(), mutator_cost(),
411 _throughput_goal);
412
413 // We give more details if Verbose is set
414 if (Verbose) {
415 gclog_or_tty->print( " minor_pause: %f"
416 " major_pause: %f"
417 " minor_interval: %f"
418 " major_interval: %f"
419 " pause_goal: %f",
420 _avg_minor_pause->padded_average(),
421 _avg_major_pause->padded_average(),
422 _avg_minor_interval->average(),
423 _avg_major_interval->average(),
424 gc_pause_goal_sec());
425 }
426
427 // Footprint stats
428 gclog_or_tty->print( " live_space: " SIZE_FORMAT
429 " free_space: " SIZE_FORMAT,
430 live_space(), free_space());
431 // More detail
432 if (Verbose) {
433 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
434 " avg_young_live: " SIZE_FORMAT
435 " avg_old_live: " SIZE_FORMAT,
436 (size_t)_avg_base_footprint->average(),
437 (size_t)avg_young_live()->average(),
438 (size_t)avg_old_live()->average());
439 }
440
441 // And finally, our old and new sizes.
442 gclog_or_tty->print(" old_eden_size: " SIZE_FORMAT
443 " desired_eden_size: " SIZE_FORMAT,
444 _eden_size, desired_eden_size);
445 gclog_or_tty->cr();
446 }
447
448 set_eden_size(desired_eden_size);
449 }
450
451 void PSAdaptiveSizePolicy::compute_old_gen_free_space(
452 size_t old_live,
453 size_t cur_eden,
454 size_t max_old_gen_size,
455 bool is_full_gc) {
456
457 // Update statistics
458 // Time statistics are updated as we go, update footprint stats here
459 if (is_full_gc) {
460 // old_live is only accurate after a full gc
461 avg_old_live()->sample(old_live);
462 }
463
464 // This code used to return if the policy was not ready , i.e.,
465 // policy_is_ready() returning false. The intent was that
466 // decisions below needed major collection times and so could
467 // not be made before two major collections. A consequence was
468 // adjustments to the young generation were not done until after
469 // two major collections even if the minor collections times
470 // exceeded the requested goals. Now let the young generation
471 // adjust for the minor collection times. Major collection times
472 // will be zero for the first collection and will naturally be
473 // ignored. Tenured generation adjustments are only made at the
474 // full collections so until the second major collection has
475 // been reached, no tenured generation adjustments will be made.
476
477 // Until we know better, desired promotion size uses the last calculation
478 size_t desired_promo_size = _promo_size;
479
480 // Start eden at the current value. The desired value that is stored
481 // in _eden_size is not bounded by constraints of the heap and can
482 // run away.
483 //
484 // As expected setting desired_eden_size to the current
485 // value of desired_eden_size as a starting point
486 // caused desired_eden_size to grow way too large and caused
487 // an overflow down stream. It may have improved performance in
488 // some case but is dangerous.
489 size_t desired_eden_size = cur_eden;
490
491 // Cache some values. There's a bit of work getting these, so
492 // we might save a little time.
493 const double major_cost = major_gc_cost();
494 const double minor_cost = minor_gc_cost();
495
496 // Limits on our growth
497 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());
498
499 // But don't force a promo size below the current promo size. Otherwise,
500 // the promo size will shrink for no good reason.
501 promo_limit = MAX2(promo_limit, _promo_size);
502
503 const double gc_cost_limit = GCTimeLimit/100.0;
504
505 // Which way should we go?
506 // if pause requirement is not met
507 // adjust size of any generation with average paus exceeding
508 // the pause limit. Adjust one pause at a time (the larger)
509 // and only make adjustments for the major pause at full collections.
510 // else if throughput requirement not met
511 // adjust the size of the generation with larger gc time. Only
512 // adjust one generation at a time.
513 // else
514 // adjust down the total heap size. Adjust down the larger of the
515 // generations.
516
517 // Add some checks for a threshold for a change. For example,
518 // a change less than the necessary alignment is probably not worth
519 // attempting.
520
521 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
522 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
523 //
524 // Check pauses
525 //
526 // Make changes only to affect one of the pauses (the larger)
527 // at a time.
528 if (is_full_gc) {
529 set_decide_at_full_gc(decide_at_full_gc_true);
530 adjust_promo_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
531 }
532 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
533 // Adjust only for the minor pause time goal
534 adjust_promo_for_minor_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
535 } else if(adjusted_mutator_cost() < _throughput_goal) {
536 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
537 // This sometimes resulted in skipping to the minimize footprint
538 // code. Change this to try and reduce GC time if mutator time is
539 // negative for whatever reason. Or for future consideration,
540 // bail out of the code if mutator time is negative.
541 //
542 // Throughput
543 //
544 assert(major_cost >= 0.0, "major cost is < 0.0");
545 assert(minor_cost >= 0.0, "minor cost is < 0.0");
546 // Try to reduce the GC times.
547 if (is_full_gc) {
548 set_decide_at_full_gc(decide_at_full_gc_true);
549 adjust_promo_for_throughput(is_full_gc, &desired_promo_size);
550 }
551 } else {
552
553 // Be conservative about reducing the footprint.
554 // Do a minimum number of major collections first.
555 // Have reasonable averages for major and minor collections costs.
556 if (UseAdaptiveSizePolicyFootprintGoal &&
557 young_gen_policy_is_ready() &&
558 avg_major_gc_cost()->average() >= 0.0 &&
559 avg_minor_gc_cost()->average() >= 0.0) {
560 if (is_full_gc) {
561 set_decide_at_full_gc(decide_at_full_gc_true);
562 size_t desired_sum = desired_eden_size + desired_promo_size;
563 desired_promo_size = adjust_promo_for_footprint(desired_promo_size, desired_sum);
564 }
565 }
566 }
567
568 // Note we make the same tests as in the code block below; the code
569 // seems a little easier to read with the printing in another block.
570 if (PrintAdaptiveSizePolicy) {
571 if (desired_promo_size > promo_limit) {
572 // "free_in_old_gen" was the original value for used for promo_limit
573 size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());
574 gclog_or_tty->print_cr(
575 "PSAdaptiveSizePolicy::compute_old_gen_free_space limits:"
576 " desired_promo_size: " SIZE_FORMAT
577 " promo_limit: " SIZE_FORMAT
578 " free_in_old_gen: " SIZE_FORMAT
579 " max_old_gen_size: " SIZE_FORMAT
580 " avg_old_live: " SIZE_FORMAT,
581 desired_promo_size, promo_limit, free_in_old_gen,
582 max_old_gen_size, (size_t) avg_old_live()->average());
583 }
584 if (gc_cost() > gc_cost_limit) {
585 gclog_or_tty->print_cr(
586 "PSAdaptiveSizePolicy::compute_old_gen_free_space: gc time limit"
587 " gc_cost: %f "
588 " GCTimeLimit: " UINTX_FORMAT,
589 gc_cost(), GCTimeLimit);
590 }
591 }
592
593 // Align everything and make a final limit check
594 desired_promo_size = align_size_up(desired_promo_size, _space_alignment);
595 desired_promo_size = MAX2(desired_promo_size, _space_alignment);
596
597 promo_limit = align_size_down(promo_limit, _space_alignment);
598
599 // And one last limit check, now that we've aligned things.
600 desired_promo_size = MIN2(desired_promo_size, promo_limit);
601
602 if (PrintAdaptiveSizePolicy) {
603 // Timing stats
604 gclog_or_tty->print(
605 "PSAdaptiveSizePolicy::compute_old_gen_free_space: costs"
606 " minor_time: %f"
607 " major_cost: %f"
608 " mutator_cost: %f"
609 " throughput_goal: %f",
610 minor_gc_cost(), major_gc_cost(), mutator_cost(),
611 _throughput_goal);
612
613 // We give more details if Verbose is set
614 if (Verbose) {
615 gclog_or_tty->print( " minor_pause: %f"
616 " major_pause: %f"
617 " minor_interval: %f"
618 " major_interval: %f"
619 " pause_goal: %f",
620 _avg_minor_pause->padded_average(),
621 _avg_major_pause->padded_average(),
622 _avg_minor_interval->average(),
623 _avg_major_interval->average(),
624 gc_pause_goal_sec());
625 }
626
627 // Footprint stats
628 gclog_or_tty->print( " live_space: " SIZE_FORMAT
629 " free_space: " SIZE_FORMAT,
630 live_space(), free_space());
631 // More detail
632 if (Verbose) {
633 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
634 " avg_young_live: " SIZE_FORMAT
635 " avg_old_live: " SIZE_FORMAT,
636 (size_t)_avg_base_footprint->average(),
637 (size_t)avg_young_live()->average(),
638 (size_t)avg_old_live()->average());
639 }
640
641 // And finally, our old and new sizes.
642 gclog_or_tty->print(" old_promo_size: " SIZE_FORMAT
643 " desired_promo_size: " SIZE_FORMAT,
644 _promo_size, desired_promo_size);
645 gclog_or_tty->cr();
646 }
647
648 set_promo_size(desired_promo_size);
649 }
650
651 void PSAdaptiveSizePolicy::decay_supplemental_growth(bool is_full_gc) {
652 // Decay the supplemental increment? Decay the supplement growth
653 // factor even if it is not used. It is only meant to give a boost
654 // to the initial growth and if it is not used, then it was not
655 // needed.
656 if (is_full_gc) {
657 // Don't wait for the threshold value for the major collections. If
658 // here, the supplemental growth term was used and should decay.
659 if ((_avg_major_pause->count() % TenuredGenerationSizeSupplementDecay)
660 == 0) {
661 _old_gen_size_increment_supplement =
662 _old_gen_size_increment_supplement >> 1;
663 }
664 } else {
665 if ((_avg_minor_pause->count() >= AdaptiveSizePolicyReadyThreshold) &&
666 (_avg_minor_pause->count() % YoungGenerationSizeSupplementDecay) == 0) {
667 _young_gen_size_increment_supplement =
668 _young_gen_size_increment_supplement >> 1;
669 }
670 }
671 }
672
673 void PSAdaptiveSizePolicy::adjust_promo_for_minor_pause_time(bool is_full_gc,
674 size_t* desired_promo_size_ptr, size_t* desired_eden_size_ptr) {
675
676 if (PSAdjustTenuredGenForMinorPause) {
677 if (is_full_gc) {
678 set_decide_at_full_gc(decide_at_full_gc_true);
679 }
680 // If the desired eden size is as small as it will get,
681 // try to adjust the old gen size.
682 if (*desired_eden_size_ptr <= _space_alignment) {
683 // Vary the old gen size to reduce the young gen pause. This
684 // may not be a good idea. This is just a test.
685 if (minor_pause_old_estimator()->decrement_will_decrease()) {
686 set_change_old_gen_for_min_pauses(decrease_old_gen_for_min_pauses_true);
687 *desired_promo_size_ptr =
688 _promo_size - promo_decrement_aligned_down(*desired_promo_size_ptr);
689 } else {
690 set_change_old_gen_for_min_pauses(increase_old_gen_for_min_pauses_true);
691 size_t promo_heap_delta =
692 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
693 if ((*desired_promo_size_ptr + promo_heap_delta) >
694 *desired_promo_size_ptr) {
695 *desired_promo_size_ptr =
696 _promo_size + promo_heap_delta;
697 }
698 }
699 }
700 }
701 }
702
703 void PSAdaptiveSizePolicy::adjust_eden_for_minor_pause_time(bool is_full_gc,
704 size_t* desired_eden_size_ptr) {
705
706 // Adjust the young generation size to reduce pause time of
707 // of collections.
708 //
709 // The AdaptiveSizePolicyInitializingSteps test is not used
710 // here. It has not seemed to be needed but perhaps should
711 // be added for consistency.
712 if (minor_pause_young_estimator()->decrement_will_decrease()) {
713 // reduce eden size
714 set_change_young_gen_for_min_pauses(
715 decrease_young_gen_for_min_pauses_true);
716 *desired_eden_size_ptr = *desired_eden_size_ptr -
717 eden_decrement_aligned_down(*desired_eden_size_ptr);
718 } else {
719 // EXPERIMENTAL ADJUSTMENT
720 // Only record that the estimator indicated such an action.
721 // *desired_eden_size_ptr = *desired_eden_size_ptr + eden_heap_delta;
722 set_change_young_gen_for_min_pauses(
723 increase_young_gen_for_min_pauses_true);
724 }
725 }
726
727 void PSAdaptiveSizePolicy::adjust_promo_for_pause_time(bool is_full_gc,
728 size_t* desired_promo_size_ptr,
729 size_t* desired_eden_size_ptr) {
730
731 size_t promo_heap_delta = 0;
732 // Add some checks for a threshold for a change. For example,
733 // a change less than the required alignment is probably not worth
734 // attempting.
735
736 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
737 adjust_promo_for_minor_pause_time(is_full_gc, desired_promo_size_ptr, desired_eden_size_ptr);
738 // major pause adjustments
739 } else if (is_full_gc) {
740 // Adjust for the major pause time only at full gc's because the
741 // affects of a change can only be seen at full gc's.
742
743 // Reduce old generation size to reduce pause?
744 if (major_pause_old_estimator()->decrement_will_decrease()) {
745 // reduce old generation size
746 set_change_old_gen_for_maj_pauses(decrease_old_gen_for_maj_pauses_true);
747 promo_heap_delta = promo_decrement_aligned_down(*desired_promo_size_ptr);
748 *desired_promo_size_ptr = _promo_size - promo_heap_delta;
749 } else {
750 // EXPERIMENTAL ADJUSTMENT
751 // Only record that the estimator indicated such an action.
752 // *desired_promo_size_ptr = _promo_size +
753 // promo_increment_aligned_up(*desired_promo_size_ptr);
754 set_change_old_gen_for_maj_pauses(increase_old_gen_for_maj_pauses_true);
755 }
756 }
757
758 if (PrintAdaptiveSizePolicy && Verbose) {
759 gclog_or_tty->print_cr(
760 "PSAdaptiveSizePolicy::adjust_promo_for_pause_time "
761 "adjusting gen sizes for major pause (avg %f goal %f). "
762 "desired_promo_size " SIZE_FORMAT " promo delta " SIZE_FORMAT,
763 _avg_major_pause->average(), gc_pause_goal_sec(),
764 *desired_promo_size_ptr, promo_heap_delta);
765 }
766 }
767
768 void PSAdaptiveSizePolicy::adjust_eden_for_pause_time(bool is_full_gc,
769 size_t* desired_promo_size_ptr,
770 size_t* desired_eden_size_ptr) {
771
772 size_t eden_heap_delta = 0;
773 // Add some checks for a threshold for a change. For example,
774 // a change less than the required alignment is probably not worth
775 // attempting.
776 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
777 adjust_eden_for_minor_pause_time(is_full_gc,
778 desired_eden_size_ptr);
779 // major pause adjustments
780 } else if (is_full_gc) {
781 // Adjust for the major pause time only at full gc's because the
782 // affects of a change can only be seen at full gc's.
783 if (PSAdjustYoungGenForMajorPause) {
784 // If the promo size is at the minimum (i.e., the old gen
785 // size will not actually decrease), consider changing the
786 // young gen size.
787 if (*desired_promo_size_ptr < _space_alignment) {
788 // If increasing the young generation will decrease the old gen
789 // pause, do it.
790 // During startup there is noise in the statistics for deciding
791 // on whether to increase or decrease the young gen size. For
792 // some number of iterations, just try to increase the young
793 // gen size if the major pause is too long to try and establish
794 // good statistics for later decisions.
795 if (major_pause_young_estimator()->increment_will_decrease() ||
796 (_young_gen_change_for_major_pause_count
797 <= AdaptiveSizePolicyInitializingSteps)) {
798 set_change_young_gen_for_maj_pauses(
799 increase_young_gen_for_maj_pauses_true);
800 eden_heap_delta = eden_increment_aligned_up(*desired_eden_size_ptr);
801 *desired_eden_size_ptr = _eden_size + eden_heap_delta;
802 _young_gen_change_for_major_pause_count++;
803 } else {
804 // Record that decreasing the young gen size would decrease
805 // the major pause
806 set_change_young_gen_for_maj_pauses(
807 decrease_young_gen_for_maj_pauses_true);
808 eden_heap_delta = eden_decrement_aligned_down(*desired_eden_size_ptr);
809 *desired_eden_size_ptr = _eden_size - eden_heap_delta;
810 }
811 }
812 }
813 }
814
815 if (PrintAdaptiveSizePolicy && Verbose) {
816 gclog_or_tty->print_cr(
817 "PSAdaptiveSizePolicy::adjust_eden_for_pause_time "
818 "adjusting gen sizes for major pause (avg %f goal %f). "
819 "desired_eden_size " SIZE_FORMAT " eden delta " SIZE_FORMAT,
820 _avg_major_pause->average(), gc_pause_goal_sec(),
821 *desired_eden_size_ptr, eden_heap_delta);
822 }
823 }
824
825 void PSAdaptiveSizePolicy::adjust_promo_for_throughput(bool is_full_gc,
826 size_t* desired_promo_size_ptr) {
827
828 // Add some checks for a threshold for a change. For example,
829 // a change less than the required alignment is probably not worth
830 // attempting.
831
832 if ((gc_cost() + mutator_cost()) == 0.0) {
833 return;
834 }
835
836 if (PrintAdaptiveSizePolicy && Verbose) {
837 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_promo_for_throughput("
838 "is_full: %d, promo: " SIZE_FORMAT "): ",
839 is_full_gc, *desired_promo_size_ptr);
840 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
841 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
842 }
843
844 // Tenured generation
845 if (is_full_gc) {
846 // Calculate the change to use for the tenured gen.
847 size_t scaled_promo_heap_delta = 0;
848 // Can the increment to the generation be scaled?
849 if (gc_cost() >= 0.0 && major_gc_cost() >= 0.0) {
850 size_t promo_heap_delta =
851 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
852 double scale_by_ratio = major_gc_cost() / gc_cost();
853 scaled_promo_heap_delta =
854 (size_t) (scale_by_ratio * (double) promo_heap_delta);
855 if (PrintAdaptiveSizePolicy && Verbose) {
856 gclog_or_tty->print_cr(
857 "Scaled tenured increment: " SIZE_FORMAT " by %f down to "
858 SIZE_FORMAT,
859 promo_heap_delta, scale_by_ratio, scaled_promo_heap_delta);
860 }
861 } else if (major_gc_cost() >= 0.0) {
862 // Scaling is not going to work. If the major gc time is the
863 // larger, give it a full increment.
864 if (major_gc_cost() >= minor_gc_cost()) {
865 scaled_promo_heap_delta =
866 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
867 }
868 } else {
869 // Don't expect to get here but it's ok if it does
870 // in the product build since the delta will be 0
871 // and nothing will change.
872 assert(false, "Unexpected value for gc costs");
873 }
874
875 switch (AdaptiveSizeThroughPutPolicy) {
876 case 1:
877 // Early in the run the statistics might not be good. Until
878 // a specific number of collections have been, use the heuristic
879 // that a larger generation size means lower collection costs.
880 if (major_collection_estimator()->increment_will_decrease() ||
881 (_old_gen_change_for_major_throughput
882 <= AdaptiveSizePolicyInitializingSteps)) {
883 // Increase tenured generation size to reduce major collection cost
884 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
885 *desired_promo_size_ptr) {
886 *desired_promo_size_ptr = _promo_size + scaled_promo_heap_delta;
887 }
888 set_change_old_gen_for_throughput(
889 increase_old_gen_for_throughput_true);
890 _old_gen_change_for_major_throughput++;
891 } else {
892 // EXPERIMENTAL ADJUSTMENT
893 // Record that decreasing the old gen size would decrease
894 // the major collection cost but don't do it.
895 // *desired_promo_size_ptr = _promo_size -
896 // promo_decrement_aligned_down(*desired_promo_size_ptr);
897 set_change_old_gen_for_throughput(
898 decrease_old_gen_for_throughput_true);
899 }
900
901 break;
902 default:
903 // Simplest strategy
904 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
905 *desired_promo_size_ptr) {
906 *desired_promo_size_ptr = *desired_promo_size_ptr +
907 scaled_promo_heap_delta;
908 }
909 set_change_old_gen_for_throughput(
910 increase_old_gen_for_throughput_true);
911 _old_gen_change_for_major_throughput++;
912 }
913
914 if (PrintAdaptiveSizePolicy && Verbose) {
915 gclog_or_tty->print_cr(
916 "adjusting tenured gen for throughput (avg %f goal %f). "
917 "desired_promo_size " SIZE_FORMAT " promo_delta " SIZE_FORMAT ,
918 mutator_cost(), _throughput_goal,
919 *desired_promo_size_ptr, scaled_promo_heap_delta);
920 }
921 }
922 }
923
924 void PSAdaptiveSizePolicy::adjust_eden_for_throughput(bool is_full_gc,
925 size_t* desired_eden_size_ptr) {
926
927 // Add some checks for a threshold for a change. For example,
928 // a change less than the required alignment is probably not worth
929 // attempting.
930
931 if ((gc_cost() + mutator_cost()) == 0.0) {
932 return;
933 }
934
935 if (PrintAdaptiveSizePolicy && Verbose) {
936 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_eden_for_throughput("
937 "is_full: %d, cur_eden: " SIZE_FORMAT "): ",
938 is_full_gc, *desired_eden_size_ptr);
939 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
940 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
941 }
942
943 // Young generation
944 size_t scaled_eden_heap_delta = 0;
945 // Can the increment to the generation be scaled?
946 if (gc_cost() >= 0.0 && minor_gc_cost() >= 0.0) {
947 size_t eden_heap_delta =
948 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
949 double scale_by_ratio = minor_gc_cost() / gc_cost();
950 assert(scale_by_ratio <= 1.0 && scale_by_ratio >= 0.0, "Scaling is wrong");
951 scaled_eden_heap_delta =
952 (size_t) (scale_by_ratio * (double) eden_heap_delta);
953 if (PrintAdaptiveSizePolicy && Verbose) {
954 gclog_or_tty->print_cr(
955 "Scaled eden increment: " SIZE_FORMAT " by %f down to "
956 SIZE_FORMAT,
957 eden_heap_delta, scale_by_ratio, scaled_eden_heap_delta);
958 }
959 } else if (minor_gc_cost() >= 0.0) {
960 // Scaling is not going to work. If the minor gc time is the
961 // larger, give it a full increment.
962 if (minor_gc_cost() > major_gc_cost()) {
963 scaled_eden_heap_delta =
964 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
965 }
966 } else {
967 // Don't expect to get here but it's ok if it does
968 // in the product build since the delta will be 0
969 // and nothing will change.
970 assert(false, "Unexpected value for gc costs");
971 }
972
973 // Use a heuristic for some number of collections to give
974 // the averages time to settle down.
975 switch (AdaptiveSizeThroughPutPolicy) {
976 case 1:
977 if (minor_collection_estimator()->increment_will_decrease() ||
978 (_young_gen_change_for_minor_throughput
979 <= AdaptiveSizePolicyInitializingSteps)) {
980 // Expand young generation size to reduce frequency of
981 // of collections.
982 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
983 *desired_eden_size_ptr) {
984 *desired_eden_size_ptr =
985 *desired_eden_size_ptr + scaled_eden_heap_delta;
986 }
987 set_change_young_gen_for_throughput(
988 increase_young_gen_for_througput_true);
989 _young_gen_change_for_minor_throughput++;
990 } else {
991 // EXPERIMENTAL ADJUSTMENT
992 // Record that decreasing the young gen size would decrease
993 // the minor collection cost but don't do it.
994 // *desired_eden_size_ptr = _eden_size -
995 // eden_decrement_aligned_down(*desired_eden_size_ptr);
996 set_change_young_gen_for_throughput(
997 decrease_young_gen_for_througput_true);
998 }
999 break;
1000 default:
1001 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
1002 *desired_eden_size_ptr) {
1003 *desired_eden_size_ptr =
1004 *desired_eden_size_ptr + scaled_eden_heap_delta;
1005 }
1006 set_change_young_gen_for_throughput(
1007 increase_young_gen_for_througput_true);
1008 _young_gen_change_for_minor_throughput++;
1009 }
1010
1011 if (PrintAdaptiveSizePolicy && Verbose) {
1012 gclog_or_tty->print_cr(
1013 "adjusting eden for throughput (avg %f goal %f). desired_eden_size "
1014 SIZE_FORMAT " eden delta " SIZE_FORMAT "\n",
1015 mutator_cost(), _throughput_goal,
1016 *desired_eden_size_ptr, scaled_eden_heap_delta);
1017 }
1018 }
1019
1020 size_t PSAdaptiveSizePolicy::adjust_promo_for_footprint(
1021 size_t desired_promo_size, size_t desired_sum) {
1022 assert(desired_promo_size <= desired_sum, "Inconsistent parameters");
1023 set_decrease_for_footprint(decrease_old_gen_for_footprint_true);
1024
1025 size_t change = promo_decrement(desired_promo_size);
1026 change = scale_down(change, desired_promo_size, desired_sum);
1027
1028 size_t reduced_size = desired_promo_size - change;
1029
1030 if (PrintAdaptiveSizePolicy && Verbose) {
1031 gclog_or_tty->print_cr(
1032 "AdaptiveSizePolicy::adjust_promo_for_footprint "
1033 "adjusting tenured gen for footprint. "
1034 "starting promo size " SIZE_FORMAT
1035 " reduced promo size " SIZE_FORMAT
1036 " promo delta " SIZE_FORMAT,
1037 desired_promo_size, reduced_size, change );
1038 }
1039
1040 assert(reduced_size <= desired_promo_size, "Inconsistent result");
1041 return reduced_size;
1042 }
1043
1044 size_t PSAdaptiveSizePolicy::adjust_eden_for_footprint(
1045 size_t desired_eden_size, size_t desired_sum) {
1046 assert(desired_eden_size <= desired_sum, "Inconsistent parameters");
1047 set_decrease_for_footprint(decrease_young_gen_for_footprint_true);
1048
1049 size_t change = eden_decrement(desired_eden_size);
1050 change = scale_down(change, desired_eden_size, desired_sum);
1051
1052 size_t reduced_size = desired_eden_size - change;
1053
1054 if (PrintAdaptiveSizePolicy && Verbose) {
1055 gclog_or_tty->print_cr(
1056 "AdaptiveSizePolicy::adjust_eden_for_footprint "
1057 "adjusting eden for footprint. "
1058 " starting eden size " SIZE_FORMAT
1059 " reduced eden size " SIZE_FORMAT
1060 " eden delta " SIZE_FORMAT,
1061 desired_eden_size, reduced_size, change);
1062 }
1063
1064 assert(reduced_size <= desired_eden_size, "Inconsistent result");
1065 return reduced_size;
1066 }
1067
1068 // Scale down "change" by the factor
1069 // part / total
1070 // Don't align the results.
1071
1072 size_t PSAdaptiveSizePolicy::scale_down(size_t change,
1073 double part,
1074 double total) {
1075 assert(part <= total, "Inconsistent input");
1076 size_t reduced_change = change;
1077 if (total > 0) {
1078 double fraction = part / total;
1079 reduced_change = (size_t) (fraction * (double) change);
1080 }
1081 assert(reduced_change <= change, "Inconsistent result");
1082 return reduced_change;
1083 }
1084
1085 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden,
1086 uint percent_change) {
1087 size_t eden_heap_delta;
1088 eden_heap_delta = cur_eden / 100 * percent_change;
1089 return eden_heap_delta;
1090 }
1091
1092 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden) {
1093 return eden_increment(cur_eden, YoungGenerationSizeIncrement);
1094 }
1095
1096 size_t PSAdaptiveSizePolicy::eden_increment_aligned_up(size_t cur_eden) {
1097 size_t result = eden_increment(cur_eden, YoungGenerationSizeIncrement);
1098 return align_size_up(result, _space_alignment);
1099 }
1100
1101 size_t PSAdaptiveSizePolicy::eden_increment_aligned_down(size_t cur_eden) {
1102 size_t result = eden_increment(cur_eden);
1103 return align_size_down(result, _space_alignment);
1104 }
1105
1106 size_t PSAdaptiveSizePolicy::eden_increment_with_supplement_aligned_up(
1107 size_t cur_eden) {
1108 size_t result = eden_increment(cur_eden,
1109 YoungGenerationSizeIncrement + _young_gen_size_increment_supplement);
1110 return align_size_up(result, _space_alignment);
1111 }
1112
1113 size_t PSAdaptiveSizePolicy::eden_decrement_aligned_down(size_t cur_eden) {
1114 size_t eden_heap_delta = eden_decrement(cur_eden);
1115 return align_size_down(eden_heap_delta, _space_alignment);
1116 }
1117
1118 size_t PSAdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
1119 size_t eden_heap_delta = eden_increment(cur_eden) /
1120 AdaptiveSizeDecrementScaleFactor;
1121 return eden_heap_delta;
1122 }
1123
1124 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo,
1125 uint percent_change) {
1126 size_t promo_heap_delta;
1127 promo_heap_delta = cur_promo / 100 * percent_change;
1128 return promo_heap_delta;
1129 }
1130
1131 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo) {
1132 return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1133 }
1134
1135 size_t PSAdaptiveSizePolicy::promo_increment_aligned_up(size_t cur_promo) {
1136 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1137 return align_size_up(result, _space_alignment);
1138 }
1139
1140 size_t PSAdaptiveSizePolicy::promo_increment_aligned_down(size_t cur_promo) {
1141 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1142 return align_size_down(result, _space_alignment);
1143 }
1144
1145 size_t PSAdaptiveSizePolicy::promo_increment_with_supplement_aligned_up(
1146 size_t cur_promo) {
1147 size_t result = promo_increment(cur_promo,
1148 TenuredGenerationSizeIncrement + _old_gen_size_increment_supplement);
1149 return align_size_up(result, _space_alignment);
1150 }
1151
1152 size_t PSAdaptiveSizePolicy::promo_decrement_aligned_down(size_t cur_promo) {
1153 size_t promo_heap_delta = promo_decrement(cur_promo);
1154 return align_size_down(promo_heap_delta, _space_alignment);
1155 }
1156
1157 size_t PSAdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
1158 size_t promo_heap_delta = promo_increment(cur_promo);
1159 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
1160 return promo_heap_delta;
1161 }
1162
1163 uint PSAdaptiveSizePolicy::compute_survivor_space_size_and_threshold(
1164 bool is_survivor_overflow,
1165 uint tenuring_threshold,
1166 size_t survivor_limit) {
1167 assert(survivor_limit >= _space_alignment,
1168 "survivor_limit too small");
1169 assert((size_t)align_size_down(survivor_limit, _space_alignment)
1170 == survivor_limit, "survivor_limit not aligned");
1171
1172 // This method is called even if the tenuring threshold and survivor
1173 // spaces are not adjusted so that the averages are sampled above.
1174 if (!UsePSAdaptiveSurvivorSizePolicy ||
1175 !young_gen_policy_is_ready()) {
1176 return tenuring_threshold;
1177 }
1178
1179 // We'll decide whether to increase or decrease the tenuring
1180 // threshold based partly on the newly computed survivor size
1181 // (if we hit the maximum limit allowed, we'll always choose to
1182 // decrement the threshold).
1183 bool incr_tenuring_threshold = false;
1184 bool decr_tenuring_threshold = false;
1185
1186 set_decrement_tenuring_threshold_for_gc_cost(false);
1187 set_increment_tenuring_threshold_for_gc_cost(false);
1188 set_decrement_tenuring_threshold_for_survivor_limit(false);
1189
1190 if (!is_survivor_overflow) {
1191 // Keep running averages on how much survived
1192
1193 // We use the tenuring threshold to equalize the cost of major
1194 // and minor collections.
1195 // ThresholdTolerance is used to indicate how sensitive the
1196 // tenuring threshold is to differences in cost between the
1197 // collection types.
1198
1199 // Get the times of interest. This involves a little work, so
1200 // we cache the values here.
1201 const double major_cost = major_gc_cost();
1202 const double minor_cost = minor_gc_cost();
1203
1204 if (minor_cost > major_cost * _threshold_tolerance_percent) {
1205 // Minor times are getting too long; lower the threshold so
1206 // less survives and more is promoted.
1207 decr_tenuring_threshold = true;
1208 set_decrement_tenuring_threshold_for_gc_cost(true);
1209 } else if (major_cost > minor_cost * _threshold_tolerance_percent) {
1210 // Major times are too long, so we want less promotion.
1211 incr_tenuring_threshold = true;
1212 set_increment_tenuring_threshold_for_gc_cost(true);
1213 }
1214
1215 } else {
1216 // Survivor space overflow occurred, so promoted and survived are
1217 // not accurate. We'll make our best guess by combining survived
1218 // and promoted and count them as survivors.
1219 //
1220 // We'll lower the tenuring threshold to see if we can correct
1221 // things. Also, set the survivor size conservatively. We're
1222 // trying to avoid many overflows from occurring if defnew size
1223 // is just too small.
1224
1225 decr_tenuring_threshold = true;
1226 }
1227
1228 // The padded average also maintains a deviation from the average;
1229 // we use this to see how good of an estimate we have of what survived.
1230 // We're trying to pad the survivor size as little as possible without
1231 // overflowing the survivor spaces.
1232 size_t target_size = align_size_up((size_t)_avg_survived->padded_average(),
1233 _space_alignment);
1234 target_size = MAX2(target_size, _space_alignment);
1235
1236 if (target_size > survivor_limit) {
1237 // Target size is bigger than we can handle. Let's also reduce
1238 // the tenuring threshold.
1239 target_size = survivor_limit;
1240 decr_tenuring_threshold = true;
1241 set_decrement_tenuring_threshold_for_survivor_limit(true);
1242 }
1243
1244 // Finally, increment or decrement the tenuring threshold, as decided above.
1245 // We test for decrementing first, as we might have hit the target size
1246 // limit.
1247 if (decr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1248 if (tenuring_threshold > 1) {
1249 tenuring_threshold--;
1250 }
1251 } else if (incr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1252 if (tenuring_threshold < MaxTenuringThreshold) {
1253 tenuring_threshold++;
1254 }
1255 }
1256
1257 // We keep a running average of the amount promoted which is used
1258 // to decide when we should collect the old generation (when
1259 // the amount of old gen free space is less than what we expect to
1260 // promote).
1261
1262 if (PrintAdaptiveSizePolicy) {
1263 // A little more detail if Verbose is on
1264 if (Verbose) {
1265 gclog_or_tty->print( " avg_survived: %f"
1266 " avg_deviation: %f",
1267 _avg_survived->average(),
1268 _avg_survived->deviation());
1269 }
1270
1271 gclog_or_tty->print( " avg_survived_padded_avg: %f",
1272 _avg_survived->padded_average());
1273
1274 if (Verbose) {
1275 gclog_or_tty->print( " avg_promoted_avg: %f"
1276 " avg_promoted_dev: %f",
1277 avg_promoted()->average(),
1278 avg_promoted()->deviation());
1279 }
1280
1281 gclog_or_tty->print_cr( " avg_promoted_padded_avg: %f"
1282 " avg_pretenured_padded_avg: %f"
1283 " tenuring_thresh: %d"
1284 " target_size: " SIZE_FORMAT,
1285 avg_promoted()->padded_average(),
1286 _avg_pretenured->padded_average(),
1287 tenuring_threshold, target_size);
1288 }
1289
1290 set_survivor_size(target_size);
1291
1292 return tenuring_threshold;
1293 }
1294
1295 void PSAdaptiveSizePolicy::update_averages(bool is_survivor_overflow,
1296 size_t survived,
1297 size_t promoted) {
1298 // Update averages
1299 if (!is_survivor_overflow) {
1300 // Keep running averages on how much survived
1301 _avg_survived->sample(survived);
1302 } else {
1303 size_t survived_guess = survived + promoted;
1304 _avg_survived->sample(survived_guess);
1305 }
1306 avg_promoted()->sample(promoted + _avg_pretenured->padded_average());
1307
1308 if (PrintAdaptiveSizePolicy) {
1309 gclog_or_tty->print_cr(
1310 "AdaptiveSizePolicy::update_averages:"
1311 " survived: " SIZE_FORMAT
1312 " promoted: " SIZE_FORMAT
1313 " overflow: %s",
1314 survived, promoted, is_survivor_overflow ? "true" : "false");
1315 }
1316 }
1317
1318 bool PSAdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st)
1319 const {
1320
1321 if (!UseAdaptiveSizePolicy) return false;
1322
1323 return AdaptiveSizePolicy::print_adaptive_size_policy_on(
1324 st,
1325 PSScavenge::tenuring_threshold());
1326 }
1327
1328 #ifndef PRODUCT
1329
1330 void TestOldFreeSpaceCalculation_test() {
1331 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 20) == 25, "Calculation of free memory failed");
1332 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 50) == 100, "Calculation of free memory failed");
1333 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 60) == 150, "Calculation of free memory failed");
1334 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 75) == 300, "Calculation of free memory failed");
1335 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 20) == 100, "Calculation of free memory failed");
1336 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 50) == 400, "Calculation of free memory failed");
1337 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 60) == 600, "Calculation of free memory failed");
1338 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 75) == 1200, "Calculation of free memory failed");
1339 }
1340
1341 #endif /* !PRODUCT */