1 /*
2 * Copyright (c) 2002, 2013, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc_implementation/parallelScavenge/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 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 (gc_cause != GCCause::_java_lang_system_gc ||
134 UseAdaptiveSizePolicyWithSystemGC) {
135 double major_pause_in_seconds = _major_timer.seconds();
136 double major_pause_in_ms = major_pause_in_seconds * MILLIUNITS;
137
138 // Sample for performance counter
139 _avg_major_pause->sample(major_pause_in_seconds);
140
141 // Cost of collection (unit-less)
142 double collection_cost = 0.0;
143 if ((_latest_major_mutator_interval_seconds > 0.0) &&
144 (major_pause_in_seconds > 0.0)) {
145 double interval_in_seconds =
146 _latest_major_mutator_interval_seconds + major_pause_in_seconds;
147 collection_cost =
148 major_pause_in_seconds / interval_in_seconds;
149 avg_major_gc_cost()->sample(collection_cost);
150
151 // Sample for performance counter
152 _avg_major_interval->sample(interval_in_seconds);
153 }
154
155 // Calculate variables used to estimate pause time vs. gen sizes
156 double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
157 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
158 _major_pause_old_estimator->update(promo_size_in_mbytes,
159 major_pause_in_ms);
160 _major_pause_young_estimator->update(eden_size_in_mbytes,
161 major_pause_in_ms);
162
163 if (PrintAdaptiveSizePolicy && Verbose) {
164 gclog_or_tty->print("psAdaptiveSizePolicy::major_collection_end: "
165 "major gc cost: %f average: %f", collection_cost,
166 avg_major_gc_cost()->average());
167 gclog_or_tty->print_cr(" major pause: %f major period %f",
168 major_pause_in_ms,
169 _latest_major_mutator_interval_seconds * MILLIUNITS);
170 }
171
172 // Calculate variable used to estimate collection cost vs. gen sizes
173 assert(collection_cost >= 0.0, "Expected to be non-negative");
174 _major_collection_estimator->update(promo_size_in_mbytes,
175 collection_cost);
176 }
177
178 // Update the amount live at the end of a full GC
179 _live_at_last_full_gc = amount_live;
180
181 // The policy does not have enough data until at least some major collections
182 // have been done.
183 if (_avg_major_pause->count() >= AdaptiveSizePolicyReadyThreshold) {
184 _old_gen_policy_is_ready = true;
185 }
186
187 // Interval times use this timer to measure the interval that
188 // the mutator runs. Reset after the GC pause has been measured.
189 _major_timer.reset();
190 _major_timer.start();
191 }
192
193 // If the remaining free space in the old generation is less that
194 // that expected to be needed by the next collection, do a full
195 // collection now.
196 bool PSAdaptiveSizePolicy::should_full_GC(size_t old_free_in_bytes) {
197
198 // A similar test is done in the scavenge's should_attempt_scavenge(). If
199 // this is changed, decide if that test should also be changed.
200 bool result = padded_average_promoted_in_bytes() > (float) old_free_in_bytes;
201 if (PrintGCDetails && Verbose) {
202 if (result) {
203 gclog_or_tty->print(" full after scavenge: ");
204 } else {
205 gclog_or_tty->print(" no full after scavenge: ");
206 }
207 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
208 " padded_average_promoted " SIZE_FORMAT
209 " free in old gen " SIZE_FORMAT,
210 (size_t) average_promoted_in_bytes(),
211 (size_t) padded_average_promoted_in_bytes(),
212 old_free_in_bytes);
213 }
214 return result;
215 }
216
217 void PSAdaptiveSizePolicy::clear_generation_free_space_flags() {
218
219 AdaptiveSizePolicy::clear_generation_free_space_flags();
220
221 set_change_old_gen_for_min_pauses(0);
222
223 set_change_young_gen_for_maj_pauses(0);
224 }
225
226 // If this is not a full GC, only test and modify the young generation.
227
228 void PSAdaptiveSizePolicy::compute_generations_free_space(
229 size_t young_live,
230 size_t eden_live,
231 size_t old_live,
232 size_t cur_eden,
233 size_t max_old_gen_size,
234 size_t max_eden_size,
235 bool is_full_gc) {
236 compute_eden_space_size(young_live,
237 eden_live,
238 cur_eden,
239 max_eden_size,
240 is_full_gc);
241
242 compute_old_gen_free_space(old_live,
243 cur_eden,
244 max_old_gen_size,
245 is_full_gc);
246 }
247
248 void PSAdaptiveSizePolicy::compute_eden_space_size(
249 size_t young_live,
250 size_t eden_live,
251 size_t cur_eden,
252 size_t max_eden_size,
253 bool is_full_gc) {
254
255 // Update statistics
256 // Time statistics are updated as we go, update footprint stats here
257 _avg_base_footprint->sample(BaseFootPrintEstimate);
258 avg_young_live()->sample(young_live);
259 avg_eden_live()->sample(eden_live);
260
261 // This code used to return if the policy was not ready , i.e.,
262 // policy_is_ready() returning false. The intent was that
263 // decisions below needed major collection times and so could
264 // not be made before two major collections. A consequence was
265 // adjustments to the young generation were not done until after
266 // two major collections even if the minor collections times
267 // exceeded the requested goals. Now let the young generation
268 // adjust for the minor collection times. Major collection times
269 // will be zero for the first collection and will naturally be
270 // ignored. Tenured generation adjustments are only made at the
271 // full collections so until the second major collection has
272 // been reached, no tenured generation adjustments will be made.
273
274 // Until we know better, desired promotion size uses the last calculation
275 size_t desired_promo_size = _promo_size;
276
277 // Start eden at the current value. The desired value that is stored
278 // in _eden_size is not bounded by constraints of the heap and can
279 // run away.
280 //
281 // As expected setting desired_eden_size to the current
282 // value of desired_eden_size as a starting point
283 // caused desired_eden_size to grow way too large and caused
284 // an overflow down stream. It may have improved performance in
285 // some case but is dangerous.
286 size_t desired_eden_size = cur_eden;
287
288 // Cache some values. There's a bit of work getting these, so
289 // we might save a little time.
290 const double major_cost = major_gc_cost();
291 const double minor_cost = minor_gc_cost();
292
293 // This method sets the desired eden size. That plus the
294 // desired survivor space sizes sets the desired young generation
295 // size. This methods does not know what the desired survivor
296 // size is but expects that other policy will attempt to make
297 // the survivor sizes compatible with the live data in the
298 // young generation. This limit is an estimate of the space left
299 // in the young generation after the survivor spaces have been
300 // subtracted out.
301 size_t eden_limit = max_eden_size;
302
303 const double gc_cost_limit = GCTimeLimit/100.0;
304
305 // Which way should we go?
306 // if pause requirement is not met
307 // adjust size of any generation with average paus exceeding
308 // the pause limit. Adjust one pause at a time (the larger)
309 // and only make adjustments for the major pause at full collections.
310 // else if throughput requirement not met
311 // adjust the size of the generation with larger gc time. Only
312 // adjust one generation at a time.
313 // else
314 // adjust down the total heap size. Adjust down the larger of the
315 // generations.
316
317 // Add some checks for a threshold for a change. For example,
318 // a change less than the necessary alignment is probably not worth
319 // attempting.
320
321
322 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
323 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
324 //
325 // Check pauses
326 //
327 // Make changes only to affect one of the pauses (the larger)
328 // at a time.
329 adjust_eden_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
330
331 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
332 // Adjust only for the minor pause time goal
333 adjust_eden_for_minor_pause_time(is_full_gc, &desired_eden_size);
334
335 } else if(adjusted_mutator_cost() < _throughput_goal) {
336 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
337 // This sometimes resulted in skipping to the minimize footprint
338 // code. Change this to try and reduce GC time if mutator time is
339 // negative for whatever reason. Or for future consideration,
340 // bail out of the code if mutator time is negative.
341 //
342 // Throughput
343 //
344 assert(major_cost >= 0.0, "major cost is < 0.0");
345 assert(minor_cost >= 0.0, "minor cost is < 0.0");
346 // Try to reduce the GC times.
347 adjust_eden_for_throughput(is_full_gc, &desired_eden_size);
348
349 } else {
350
351 // Be conservative about reducing the footprint.
352 // Do a minimum number of major collections first.
353 // Have reasonable averages for major and minor collections costs.
354 if (UseAdaptiveSizePolicyFootprintGoal &&
355 young_gen_policy_is_ready() &&
356 avg_major_gc_cost()->average() >= 0.0 &&
357 avg_minor_gc_cost()->average() >= 0.0) {
358 size_t desired_sum = desired_eden_size + desired_promo_size;
359 desired_eden_size = adjust_eden_for_footprint(desired_eden_size, desired_sum);
360 }
361 }
362
363 // Note we make the same tests as in the code block below; the code
364 // seems a little easier to read with the printing in another block.
365 if (PrintAdaptiveSizePolicy) {
366 if (desired_eden_size > eden_limit) {
367 gclog_or_tty->print_cr(
368 "PSAdaptiveSizePolicy::compute_eden_space_size limits:"
369 " desired_eden_size: " SIZE_FORMAT
370 " old_eden_size: " SIZE_FORMAT
371 " eden_limit: " SIZE_FORMAT
372 " cur_eden: " SIZE_FORMAT
373 " max_eden_size: " SIZE_FORMAT
374 " avg_young_live: " SIZE_FORMAT,
375 desired_eden_size, _eden_size, eden_limit, cur_eden,
376 max_eden_size, (size_t)avg_young_live()->average());
377 }
378 if (gc_cost() > gc_cost_limit) {
379 gclog_or_tty->print_cr(
380 "PSAdaptiveSizePolicy::compute_eden_space_size: gc time limit"
381 " gc_cost: %f "
382 " GCTimeLimit: %d",
383 gc_cost(), GCTimeLimit);
384 }
385 }
386
387 // Align everything and make a final limit check
388 desired_eden_size = align_size_up(desired_eden_size, _space_alignment);
389 desired_eden_size = MAX2(desired_eden_size, _space_alignment);
390
391 eden_limit = align_size_down(eden_limit, _space_alignment);
392
393 // And one last limit check, now that we've aligned things.
394 if (desired_eden_size > eden_limit) {
395 // If the policy says to get a larger eden but
396 // is hitting the limit, don't decrease eden.
397 // This can lead to a general drifting down of the
398 // eden size. Let the tenuring calculation push more
399 // into the old gen.
400 desired_eden_size = MAX2(eden_limit, cur_eden);
401 }
402
403 if (PrintAdaptiveSizePolicy) {
404 // Timing stats
405 gclog_or_tty->print(
406 "PSAdaptiveSizePolicy::compute_eden_space_size: costs"
407 " minor_time: %f"
408 " major_cost: %f"
409 " mutator_cost: %f"
410 " throughput_goal: %f",
411 minor_gc_cost(), major_gc_cost(), mutator_cost(),
412 _throughput_goal);
413
414 // We give more details if Verbose is set
415 if (Verbose) {
416 gclog_or_tty->print( " minor_pause: %f"
417 " major_pause: %f"
418 " minor_interval: %f"
419 " major_interval: %f"
420 " pause_goal: %f",
421 _avg_minor_pause->padded_average(),
422 _avg_major_pause->padded_average(),
423 _avg_minor_interval->average(),
424 _avg_major_interval->average(),
425 gc_pause_goal_sec());
426 }
427
428 // Footprint stats
429 gclog_or_tty->print( " live_space: " SIZE_FORMAT
430 " free_space: " SIZE_FORMAT,
431 live_space(), free_space());
432 // More detail
433 if (Verbose) {
434 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
435 " avg_young_live: " SIZE_FORMAT
436 " avg_old_live: " SIZE_FORMAT,
437 (size_t)_avg_base_footprint->average(),
438 (size_t)avg_young_live()->average(),
439 (size_t)avg_old_live()->average());
440 }
441
442 // And finally, our old and new sizes.
443 gclog_or_tty->print(" old_eden_size: " SIZE_FORMAT
444 " desired_eden_size: " SIZE_FORMAT,
445 _eden_size, desired_eden_size);
446 gclog_or_tty->cr();
447 }
448
449 set_eden_size(desired_eden_size);
450 }
451
452 void PSAdaptiveSizePolicy::compute_old_gen_free_space(
453 size_t old_live,
454 size_t cur_eden,
455 size_t max_old_gen_size,
456 bool is_full_gc) {
457
458 // Update statistics
459 // Time statistics are updated as we go, update footprint stats here
460 if (is_full_gc) {
461 // old_live is only accurate after a full gc
462 avg_old_live()->sample(old_live);
463 }
464
465 // This code used to return if the policy was not ready , i.e.,
466 // policy_is_ready() returning false. The intent was that
467 // decisions below needed major collection times and so could
468 // not be made before two major collections. A consequence was
469 // adjustments to the young generation were not done until after
470 // two major collections even if the minor collections times
471 // exceeded the requested goals. Now let the young generation
472 // adjust for the minor collection times. Major collection times
473 // will be zero for the first collection and will naturally be
474 // ignored. Tenured generation adjustments are only made at the
475 // full collections so until the second major collection has
476 // been reached, no tenured generation adjustments will be made.
477
478 // Until we know better, desired promotion size uses the last calculation
479 size_t desired_promo_size = _promo_size;
480
481 // Start eden at the current value. The desired value that is stored
482 // in _eden_size is not bounded by constraints of the heap and can
483 // run away.
484 //
485 // As expected setting desired_eden_size to the current
486 // value of desired_eden_size as a starting point
487 // caused desired_eden_size to grow way too large and caused
488 // an overflow down stream. It may have improved performance in
489 // some case but is dangerous.
490 size_t desired_eden_size = cur_eden;
491
492 // Cache some values. There's a bit of work getting these, so
493 // we might save a little time.
494 const double major_cost = major_gc_cost();
495 const double minor_cost = minor_gc_cost();
496
497 // Limits on our growth
498 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());
499
500 // But don't force a promo size below the current promo size. Otherwise,
501 // the promo size will shrink for no good reason.
502 promo_limit = MAX2(promo_limit, _promo_size);
503
504 const double gc_cost_limit = GCTimeLimit/100.0;
505
506 // Which way should we go?
507 // if pause requirement is not met
508 // adjust size of any generation with average paus exceeding
509 // the pause limit. Adjust one pause at a time (the larger)
510 // and only make adjustments for the major pause at full collections.
511 // else if throughput requirement not met
512 // adjust the size of the generation with larger gc time. Only
513 // adjust one generation at a time.
514 // else
515 // adjust down the total heap size. Adjust down the larger of the
516 // generations.
517
518 // Add some checks for a threshold for a change. For example,
519 // a change less than the necessary alignment is probably not worth
520 // attempting.
521
522 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
523 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
524 //
525 // Check pauses
526 //
527 // Make changes only to affect one of the pauses (the larger)
528 // at a time.
529 if (is_full_gc) {
530 set_decide_at_full_gc(decide_at_full_gc_true);
531 adjust_promo_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
532 }
533 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
534 // Adjust only for the minor pause time goal
535 adjust_promo_for_minor_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
536 } else if(adjusted_mutator_cost() < _throughput_goal) {
537 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
538 // This sometimes resulted in skipping to the minimize footprint
539 // code. Change this to try and reduce GC time if mutator time is
540 // negative for whatever reason. Or for future consideration,
541 // bail out of the code if mutator time is negative.
542 //
543 // Throughput
544 //
545 assert(major_cost >= 0.0, "major cost is < 0.0");
546 assert(minor_cost >= 0.0, "minor cost is < 0.0");
547 // Try to reduce the GC times.
548 if (is_full_gc) {
549 set_decide_at_full_gc(decide_at_full_gc_true);
550 adjust_promo_for_throughput(is_full_gc, &desired_promo_size);
551 }
552 } else {
553
554 // Be conservative about reducing the footprint.
555 // Do a minimum number of major collections first.
556 // Have reasonable averages for major and minor collections costs.
557 if (UseAdaptiveSizePolicyFootprintGoal &&
558 young_gen_policy_is_ready() &&
559 avg_major_gc_cost()->average() >= 0.0 &&
560 avg_minor_gc_cost()->average() >= 0.0) {
561 if (is_full_gc) {
562 set_decide_at_full_gc(decide_at_full_gc_true);
563 size_t desired_sum = desired_eden_size + desired_promo_size;
564 desired_promo_size = adjust_promo_for_footprint(desired_promo_size, desired_sum);
565 }
566 }
567 }
568
569 // Note we make the same tests as in the code block below; the code
570 // seems a little easier to read with the printing in another block.
571 if (PrintAdaptiveSizePolicy) {
572 if (desired_promo_size > promo_limit) {
573 // "free_in_old_gen" was the original value for used for promo_limit
574 size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());
575 gclog_or_tty->print_cr(
576 "PSAdaptiveSizePolicy::compute_old_gen_free_space limits:"
577 " desired_promo_size: " SIZE_FORMAT
578 " promo_limit: " SIZE_FORMAT
579 " free_in_old_gen: " SIZE_FORMAT
580 " max_old_gen_size: " SIZE_FORMAT
581 " avg_old_live: " SIZE_FORMAT,
582 desired_promo_size, promo_limit, free_in_old_gen,
583 max_old_gen_size, (size_t) avg_old_live()->average());
584 }
585 if (gc_cost() > gc_cost_limit) {
586 gclog_or_tty->print_cr(
587 "PSAdaptiveSizePolicy::compute_old_gen_free_space: gc time limit"
588 " gc_cost: %f "
589 " GCTimeLimit: %d",
590 gc_cost(), GCTimeLimit);
591 }
592 }
593
594 // Align everything and make a final limit check
595 desired_promo_size = align_size_up(desired_promo_size, _space_alignment);
596 desired_promo_size = MAX2(desired_promo_size, _space_alignment);
597
598 promo_limit = align_size_down(promo_limit, _space_alignment);
599
600 // And one last limit check, now that we've aligned things.
601 desired_promo_size = MIN2(desired_promo_size, promo_limit);
602
603 if (PrintAdaptiveSizePolicy) {
604 // Timing stats
605 gclog_or_tty->print(
606 "PSAdaptiveSizePolicy::compute_old_gen_free_space: costs"
607 " minor_time: %f"
608 " major_cost: %f"
609 " mutator_cost: %f"
610 " throughput_goal: %f",
611 minor_gc_cost(), major_gc_cost(), mutator_cost(),
612 _throughput_goal);
613
614 // We give more details if Verbose is set
615 if (Verbose) {
616 gclog_or_tty->print( " minor_pause: %f"
617 " major_pause: %f"
618 " minor_interval: %f"
619 " major_interval: %f"
620 " pause_goal: %f",
621 _avg_minor_pause->padded_average(),
622 _avg_major_pause->padded_average(),
623 _avg_minor_interval->average(),
624 _avg_major_interval->average(),
625 gc_pause_goal_sec());
626 }
627
628 // Footprint stats
629 gclog_or_tty->print( " live_space: " SIZE_FORMAT
630 " free_space: " SIZE_FORMAT,
631 live_space(), free_space());
632 // More detail
633 if (Verbose) {
634 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
635 " avg_young_live: " SIZE_FORMAT
636 " avg_old_live: " SIZE_FORMAT,
637 (size_t)_avg_base_footprint->average(),
638 (size_t)avg_young_live()->average(),
639 (size_t)avg_old_live()->average());
640 }
641
642 // And finally, our old and new sizes.
643 gclog_or_tty->print(" old_promo_size: " SIZE_FORMAT
644 " desired_promo_size: " SIZE_FORMAT,
645 _promo_size, desired_promo_size);
646 gclog_or_tty->cr();
647 }
648
649 set_promo_size(desired_promo_size);
650 }
651
652 void PSAdaptiveSizePolicy::decay_supplemental_growth(bool is_full_gc) {
653 // Decay the supplemental increment? Decay the supplement growth
654 // factor even if it is not used. It is only meant to give a boost
655 // to the initial growth and if it is not used, then it was not
656 // needed.
657 if (is_full_gc) {
658 // Don't wait for the threshold value for the major collections. If
659 // here, the supplemental growth term was used and should decay.
660 if ((_avg_major_pause->count() % TenuredGenerationSizeSupplementDecay)
661 == 0) {
662 _old_gen_size_increment_supplement =
663 _old_gen_size_increment_supplement >> 1;
664 }
665 } else {
666 if ((_avg_minor_pause->count() >= AdaptiveSizePolicyReadyThreshold) &&
667 (_avg_minor_pause->count() % YoungGenerationSizeSupplementDecay) == 0) {
668 _young_gen_size_increment_supplement =
669 _young_gen_size_increment_supplement >> 1;
670 }
671 }
672 }
673
674 void PSAdaptiveSizePolicy::adjust_promo_for_minor_pause_time(bool is_full_gc,
675 size_t* desired_promo_size_ptr, size_t* desired_eden_size_ptr) {
676
677 if (PSAdjustTenuredGenForMinorPause) {
678 if (is_full_gc) {
679 set_decide_at_full_gc(decide_at_full_gc_true);
680 }
681 // If the desired eden size is as small as it will get,
682 // try to adjust the old gen size.
683 if (*desired_eden_size_ptr <= _space_alignment) {
684 // Vary the old gen size to reduce the young gen pause. This
685 // may not be a good idea. This is just a test.
686 if (minor_pause_old_estimator()->decrement_will_decrease()) {
687 set_change_old_gen_for_min_pauses(decrease_old_gen_for_min_pauses_true);
688 *desired_promo_size_ptr =
689 _promo_size - promo_decrement_aligned_down(*desired_promo_size_ptr);
690 } else {
691 set_change_old_gen_for_min_pauses(increase_old_gen_for_min_pauses_true);
692 size_t promo_heap_delta =
693 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
694 if ((*desired_promo_size_ptr + promo_heap_delta) >
695 *desired_promo_size_ptr) {
696 *desired_promo_size_ptr =
697 _promo_size + promo_heap_delta;
698 }
699 }
700 }
701 }
702 }
703
704 void PSAdaptiveSizePolicy::adjust_eden_for_minor_pause_time(bool is_full_gc,
705 size_t* desired_eden_size_ptr) {
706
707 // Adjust the young generation size to reduce pause time of
708 // of collections.
709 //
710 // The AdaptiveSizePolicyInitializingSteps test is not used
711 // here. It has not seemed to be needed but perhaps should
712 // be added for consistency.
713 if (minor_pause_young_estimator()->decrement_will_decrease()) {
714 // reduce eden size
715 set_change_young_gen_for_min_pauses(
716 decrease_young_gen_for_min_pauses_true);
717 *desired_eden_size_ptr = *desired_eden_size_ptr -
718 eden_decrement_aligned_down(*desired_eden_size_ptr);
719 } else {
720 // EXPERIMENTAL ADJUSTMENT
721 // Only record that the estimator indicated such an action.
722 // *desired_eden_size_ptr = *desired_eden_size_ptr + eden_heap_delta;
723 set_change_young_gen_for_min_pauses(
724 increase_young_gen_for_min_pauses_true);
725 }
726 }
727
728 void PSAdaptiveSizePolicy::adjust_promo_for_pause_time(bool is_full_gc,
729 size_t* desired_promo_size_ptr,
730 size_t* desired_eden_size_ptr) {
731
732 size_t promo_heap_delta = 0;
733 // Add some checks for a threshold for a change. For example,
734 // a change less than the required alignment is probably not worth
735 // attempting.
736
737 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
738 adjust_promo_for_minor_pause_time(is_full_gc, desired_promo_size_ptr, desired_eden_size_ptr);
739 // major pause adjustments
740 } else if (is_full_gc) {
741 // Adjust for the major pause time only at full gc's because the
742 // affects of a change can only be seen at full gc's.
743
744 // Reduce old generation size to reduce pause?
745 if (major_pause_old_estimator()->decrement_will_decrease()) {
746 // reduce old generation size
747 set_change_old_gen_for_maj_pauses(decrease_old_gen_for_maj_pauses_true);
748 promo_heap_delta = promo_decrement_aligned_down(*desired_promo_size_ptr);
749 *desired_promo_size_ptr = _promo_size - promo_heap_delta;
750 } else {
751 // EXPERIMENTAL ADJUSTMENT
752 // Only record that the estimator indicated such an action.
753 // *desired_promo_size_ptr = _promo_size +
754 // promo_increment_aligned_up(*desired_promo_size_ptr);
755 set_change_old_gen_for_maj_pauses(increase_old_gen_for_maj_pauses_true);
756 }
757 }
758
759 if (PrintAdaptiveSizePolicy && Verbose) {
760 gclog_or_tty->print_cr(
761 "PSAdaptiveSizePolicy::adjust_promo_for_pause_time "
762 "adjusting gen sizes for major pause (avg %f goal %f). "
763 "desired_promo_size " SIZE_FORMAT " promo delta " SIZE_FORMAT,
764 _avg_major_pause->average(), gc_pause_goal_sec(),
765 *desired_promo_size_ptr, promo_heap_delta);
766 }
767 }
768
769 void PSAdaptiveSizePolicy::adjust_eden_for_pause_time(bool is_full_gc,
770 size_t* desired_promo_size_ptr,
771 size_t* desired_eden_size_ptr) {
772
773 size_t eden_heap_delta = 0;
774 // Add some checks for a threshold for a change. For example,
775 // a change less than the required alignment is probably not worth
776 // attempting.
777 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
778 adjust_eden_for_minor_pause_time(is_full_gc,
779 desired_eden_size_ptr);
780 // major pause adjustments
781 } else if (is_full_gc) {
782 // Adjust for the major pause time only at full gc's because the
783 // affects of a change can only be seen at full gc's.
784 if (PSAdjustYoungGenForMajorPause) {
785 // If the promo size is at the minimum (i.e., the old gen
786 // size will not actually decrease), consider changing the
787 // young gen size.
788 if (*desired_promo_size_ptr < _space_alignment) {
789 // If increasing the young generation will decrease the old gen
790 // pause, do it.
791 // During startup there is noise in the statistics for deciding
792 // on whether to increase or decrease the young gen size. For
793 // some number of iterations, just try to increase the young
794 // gen size if the major pause is too long to try and establish
795 // good statistics for later decisions.
796 if (major_pause_young_estimator()->increment_will_decrease() ||
797 (_young_gen_change_for_major_pause_count
798 <= AdaptiveSizePolicyInitializingSteps)) {
799 set_change_young_gen_for_maj_pauses(
800 increase_young_gen_for_maj_pauses_true);
801 eden_heap_delta = eden_increment_aligned_up(*desired_eden_size_ptr);
802 *desired_eden_size_ptr = _eden_size + eden_heap_delta;
803 _young_gen_change_for_major_pause_count++;
804 } else {
805 // Record that decreasing the young gen size would decrease
806 // the major pause
807 set_change_young_gen_for_maj_pauses(
808 decrease_young_gen_for_maj_pauses_true);
809 eden_heap_delta = eden_decrement_aligned_down(*desired_eden_size_ptr);
810 *desired_eden_size_ptr = _eden_size - eden_heap_delta;
811 }
812 }
813 }
814 }
815
816 if (PrintAdaptiveSizePolicy && Verbose) {
817 gclog_or_tty->print_cr(
818 "PSAdaptiveSizePolicy::adjust_eden_for_pause_time "
819 "adjusting gen sizes for major pause (avg %f goal %f). "
820 "desired_eden_size " SIZE_FORMAT " eden delta " SIZE_FORMAT,
821 _avg_major_pause->average(), gc_pause_goal_sec(),
822 *desired_eden_size_ptr, eden_heap_delta);
823 }
824 }
825
826 void PSAdaptiveSizePolicy::adjust_promo_for_throughput(bool is_full_gc,
827 size_t* desired_promo_size_ptr) {
828
829 // Add some checks for a threshold for a change. For example,
830 // a change less than the required alignment is probably not worth
831 // attempting.
832
833 if ((gc_cost() + mutator_cost()) == 0.0) {
834 return;
835 }
836
837 if (PrintAdaptiveSizePolicy && Verbose) {
838 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_promo_for_throughput("
839 "is_full: %d, promo: " SIZE_FORMAT "): ",
840 is_full_gc, *desired_promo_size_ptr);
841 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
842 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
843 }
844
845 // Tenured generation
846 if (is_full_gc) {
847 // Calculate the change to use for the tenured gen.
848 size_t scaled_promo_heap_delta = 0;
849 // Can the increment to the generation be scaled?
850 if (gc_cost() >= 0.0 && major_gc_cost() >= 0.0) {
851 size_t promo_heap_delta =
852 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
853 double scale_by_ratio = major_gc_cost() / gc_cost();
854 scaled_promo_heap_delta =
855 (size_t) (scale_by_ratio * (double) promo_heap_delta);
856 if (PrintAdaptiveSizePolicy && Verbose) {
857 gclog_or_tty->print_cr(
858 "Scaled tenured increment: " SIZE_FORMAT " by %f down to "
859 SIZE_FORMAT,
860 promo_heap_delta, scale_by_ratio, scaled_promo_heap_delta);
861 }
862 } else if (major_gc_cost() >= 0.0) {
863 // Scaling is not going to work. If the major gc time is the
864 // larger, give it a full increment.
865 if (major_gc_cost() >= minor_gc_cost()) {
866 scaled_promo_heap_delta =
867 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
868 }
869 } else {
870 // Don't expect to get here but it's ok if it does
871 // in the product build since the delta will be 0
872 // and nothing will change.
873 assert(false, "Unexpected value for gc costs");
874 }
875
876 switch (AdaptiveSizeThroughPutPolicy) {
877 case 1:
878 // Early in the run the statistics might not be good. Until
879 // a specific number of collections have been, use the heuristic
880 // that a larger generation size means lower collection costs.
881 if (major_collection_estimator()->increment_will_decrease() ||
882 (_old_gen_change_for_major_throughput
883 <= AdaptiveSizePolicyInitializingSteps)) {
884 // Increase tenured generation size to reduce major collection cost
885 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
886 *desired_promo_size_ptr) {
887 *desired_promo_size_ptr = _promo_size + scaled_promo_heap_delta;
888 }
889 set_change_old_gen_for_throughput(
890 increase_old_gen_for_throughput_true);
891 _old_gen_change_for_major_throughput++;
892 } else {
893 // EXPERIMENTAL ADJUSTMENT
894 // Record that decreasing the old gen size would decrease
895 // the major collection cost but don't do it.
896 // *desired_promo_size_ptr = _promo_size -
897 // promo_decrement_aligned_down(*desired_promo_size_ptr);
898 set_change_old_gen_for_throughput(
899 decrease_old_gen_for_throughput_true);
900 }
901
902 break;
903 default:
904 // Simplest strategy
905 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
906 *desired_promo_size_ptr) {
907 *desired_promo_size_ptr = *desired_promo_size_ptr +
908 scaled_promo_heap_delta;
909 }
910 set_change_old_gen_for_throughput(
911 increase_old_gen_for_throughput_true);
912 _old_gen_change_for_major_throughput++;
913 }
914
915 if (PrintAdaptiveSizePolicy && Verbose) {
916 gclog_or_tty->print_cr(
917 "adjusting tenured gen for throughput (avg %f goal %f). "
918 "desired_promo_size " SIZE_FORMAT " promo_delta " SIZE_FORMAT ,
919 mutator_cost(), _throughput_goal,
920 *desired_promo_size_ptr, scaled_promo_heap_delta);
921 }
922 }
923 }
924
925 void PSAdaptiveSizePolicy::adjust_eden_for_throughput(bool is_full_gc,
926 size_t* desired_eden_size_ptr) {
927
928 // Add some checks for a threshold for a change. For example,
929 // a change less than the required alignment is probably not worth
930 // attempting.
931
932 if ((gc_cost() + mutator_cost()) == 0.0) {
933 return;
934 }
935
936 if (PrintAdaptiveSizePolicy && Verbose) {
937 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_eden_for_throughput("
938 "is_full: %d, cur_eden: " SIZE_FORMAT "): ",
939 is_full_gc, *desired_eden_size_ptr);
940 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
941 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
942 }
943
944 // Young generation
945 size_t scaled_eden_heap_delta = 0;
946 // Can the increment to the generation be scaled?
947 if (gc_cost() >= 0.0 && minor_gc_cost() >= 0.0) {
948 size_t eden_heap_delta =
949 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
950 double scale_by_ratio = minor_gc_cost() / gc_cost();
951 assert(scale_by_ratio <= 1.0 && scale_by_ratio >= 0.0, "Scaling is wrong");
952 scaled_eden_heap_delta =
953 (size_t) (scale_by_ratio * (double) eden_heap_delta);
954 if (PrintAdaptiveSizePolicy && Verbose) {
955 gclog_or_tty->print_cr(
956 "Scaled eden increment: " SIZE_FORMAT " by %f down to "
957 SIZE_FORMAT,
958 eden_heap_delta, scale_by_ratio, scaled_eden_heap_delta);
959 }
960 } else if (minor_gc_cost() >= 0.0) {
961 // Scaling is not going to work. If the minor gc time is the
962 // larger, give it a full increment.
963 if (minor_gc_cost() > major_gc_cost()) {
964 scaled_eden_heap_delta =
965 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
966 }
967 } else {
968 // Don't expect to get here but it's ok if it does
969 // in the product build since the delta will be 0
970 // and nothing will change.
971 assert(false, "Unexpected value for gc costs");
972 }
973
974 // Use a heuristic for some number of collections to give
975 // the averages time to settle down.
976 switch (AdaptiveSizeThroughPutPolicy) {
977 case 1:
978 if (minor_collection_estimator()->increment_will_decrease() ||
979 (_young_gen_change_for_minor_throughput
980 <= AdaptiveSizePolicyInitializingSteps)) {
981 // Expand young generation size to reduce frequency of
982 // of collections.
983 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
984 *desired_eden_size_ptr) {
985 *desired_eden_size_ptr =
986 *desired_eden_size_ptr + scaled_eden_heap_delta;
987 }
988 set_change_young_gen_for_throughput(
989 increase_young_gen_for_througput_true);
990 _young_gen_change_for_minor_throughput++;
991 } else {
992 // EXPERIMENTAL ADJUSTMENT
993 // Record that decreasing the young gen size would decrease
994 // the minor collection cost but don't do it.
995 // *desired_eden_size_ptr = _eden_size -
996 // eden_decrement_aligned_down(*desired_eden_size_ptr);
997 set_change_young_gen_for_throughput(
998 decrease_young_gen_for_througput_true);
999 }
1000 break;
1001 default:
1002 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
1003 *desired_eden_size_ptr) {
1004 *desired_eden_size_ptr =
1005 *desired_eden_size_ptr + scaled_eden_heap_delta;
1006 }
1007 set_change_young_gen_for_throughput(
1008 increase_young_gen_for_througput_true);
1009 _young_gen_change_for_minor_throughput++;
1010 }
1011
1012 if (PrintAdaptiveSizePolicy && Verbose) {
1013 gclog_or_tty->print_cr(
1014 "adjusting eden for throughput (avg %f goal %f). desired_eden_size "
1015 SIZE_FORMAT " eden delta " SIZE_FORMAT "\n",
1016 mutator_cost(), _throughput_goal,
1017 *desired_eden_size_ptr, scaled_eden_heap_delta);
1018 }
1019 }
1020
1021 size_t PSAdaptiveSizePolicy::adjust_promo_for_footprint(
1022 size_t desired_promo_size, size_t desired_sum) {
1023 assert(desired_promo_size <= desired_sum, "Inconsistent parameters");
1024 set_decrease_for_footprint(decrease_old_gen_for_footprint_true);
1025
1026 size_t change = promo_decrement(desired_promo_size);
1027 change = scale_down(change, desired_promo_size, desired_sum);
1028
1029 size_t reduced_size = desired_promo_size - change;
1030
1031 if (PrintAdaptiveSizePolicy && Verbose) {
1032 gclog_or_tty->print_cr(
1033 "AdaptiveSizePolicy::adjust_promo_for_footprint "
1034 "adjusting tenured gen for footprint. "
1035 "starting promo size " SIZE_FORMAT
1036 " reduced promo size " SIZE_FORMAT,
1037 " promo delta " SIZE_FORMAT,
1038 desired_promo_size, reduced_size, change );
1039 }
1040
1041 assert(reduced_size <= desired_promo_size, "Inconsistent result");
1042 return reduced_size;
1043 }
1044
1045 size_t PSAdaptiveSizePolicy::adjust_eden_for_footprint(
1046 size_t desired_eden_size, size_t desired_sum) {
1047 assert(desired_eden_size <= desired_sum, "Inconsistent parameters");
1048 set_decrease_for_footprint(decrease_young_gen_for_footprint_true);
1049
1050 size_t change = eden_decrement(desired_eden_size);
1051 change = scale_down(change, desired_eden_size, desired_sum);
1052
1053 size_t reduced_size = desired_eden_size - change;
1054
1055 if (PrintAdaptiveSizePolicy && Verbose) {
1056 gclog_or_tty->print_cr(
1057 "AdaptiveSizePolicy::adjust_eden_for_footprint "
1058 "adjusting eden for footprint. "
1059 " starting eden size " SIZE_FORMAT
1060 " reduced eden size " SIZE_FORMAT
1061 " eden delta " SIZE_FORMAT,
1062 desired_eden_size, reduced_size, change);
1063 }
1064
1065 assert(reduced_size <= desired_eden_size, "Inconsistent result");
1066 return reduced_size;
1067 }
1068
1069 // Scale down "change" by the factor
1070 // part / total
1071 // Don't align the results.
1072
1073 size_t PSAdaptiveSizePolicy::scale_down(size_t change,
1074 double part,
1075 double total) {
1076 assert(part <= total, "Inconsistent input");
1077 size_t reduced_change = change;
1078 if (total > 0) {
1079 double fraction = part / total;
1080 reduced_change = (size_t) (fraction * (double) change);
1081 }
1082 assert(reduced_change <= change, "Inconsistent result");
1083 return reduced_change;
1084 }
1085
1086 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden,
1087 uint percent_change) {
1088 size_t eden_heap_delta;
1089 eden_heap_delta = cur_eden / 100 * percent_change;
1090 return eden_heap_delta;
1091 }
1092
1093 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden) {
1094 return eden_increment(cur_eden, YoungGenerationSizeIncrement);
1095 }
1096
1097 size_t PSAdaptiveSizePolicy::eden_increment_aligned_up(size_t cur_eden) {
1098 size_t result = eden_increment(cur_eden, YoungGenerationSizeIncrement);
1099 return align_size_up(result, _space_alignment);
1100 }
1101
1102 size_t PSAdaptiveSizePolicy::eden_increment_aligned_down(size_t cur_eden) {
1103 size_t result = eden_increment(cur_eden);
1104 return align_size_down(result, _space_alignment);
1105 }
1106
1107 size_t PSAdaptiveSizePolicy::eden_increment_with_supplement_aligned_up(
1108 size_t cur_eden) {
1109 size_t result = eden_increment(cur_eden,
1110 YoungGenerationSizeIncrement + _young_gen_size_increment_supplement);
1111 return align_size_up(result, _space_alignment);
1112 }
1113
1114 size_t PSAdaptiveSizePolicy::eden_decrement_aligned_down(size_t cur_eden) {
1115 size_t eden_heap_delta = eden_decrement(cur_eden);
1116 return align_size_down(eden_heap_delta, _space_alignment);
1117 }
1118
1119 size_t PSAdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
1120 size_t eden_heap_delta = eden_increment(cur_eden) /
1121 AdaptiveSizeDecrementScaleFactor;
1122 return eden_heap_delta;
1123 }
1124
1125 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo,
1126 uint percent_change) {
1127 size_t promo_heap_delta;
1128 promo_heap_delta = cur_promo / 100 * percent_change;
1129 return promo_heap_delta;
1130 }
1131
1132 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo) {
1133 return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1134 }
1135
1136 size_t PSAdaptiveSizePolicy::promo_increment_aligned_up(size_t cur_promo) {
1137 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1138 return align_size_up(result, _space_alignment);
1139 }
1140
1141 size_t PSAdaptiveSizePolicy::promo_increment_aligned_down(size_t cur_promo) {
1142 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1143 return align_size_down(result, _space_alignment);
1144 }
1145
1146 size_t PSAdaptiveSizePolicy::promo_increment_with_supplement_aligned_up(
1147 size_t cur_promo) {
1148 size_t result = promo_increment(cur_promo,
1149 TenuredGenerationSizeIncrement + _old_gen_size_increment_supplement);
1150 return align_size_up(result, _space_alignment);
1151 }
1152
1153 size_t PSAdaptiveSizePolicy::promo_decrement_aligned_down(size_t cur_promo) {
1154 size_t promo_heap_delta = promo_decrement(cur_promo);
1155 return align_size_down(promo_heap_delta, _space_alignment);
1156 }
1157
1158 size_t PSAdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
1159 size_t promo_heap_delta = promo_increment(cur_promo);
1160 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
1161 return promo_heap_delta;
1162 }
1163
1164 uint PSAdaptiveSizePolicy::compute_survivor_space_size_and_threshold(
1165 bool is_survivor_overflow,
1166 uint tenuring_threshold,
1167 size_t survivor_limit) {
1168 assert(survivor_limit >= _space_alignment,
1169 "survivor_limit too small");
1170 assert((size_t)align_size_down(survivor_limit, _space_alignment)
1171 == survivor_limit, "survivor_limit not aligned");
1172
1173 // This method is called even if the tenuring threshold and survivor
1174 // spaces are not adjusted so that the averages are sampled above.
1175 if (!UsePSAdaptiveSurvivorSizePolicy ||
1176 !young_gen_policy_is_ready()) {
1177 return tenuring_threshold;
1178 }
1179
1180 // We'll decide whether to increase or decrease the tenuring
1181 // threshold based partly on the newly computed survivor size
1182 // (if we hit the maximum limit allowed, we'll always choose to
1183 // decrement the threshold).
1184 bool incr_tenuring_threshold = false;
1185 bool decr_tenuring_threshold = false;
1186
1187 set_decrement_tenuring_threshold_for_gc_cost(false);
1188 set_increment_tenuring_threshold_for_gc_cost(false);
1189 set_decrement_tenuring_threshold_for_survivor_limit(false);
1190
1191 if (!is_survivor_overflow) {
1192 // Keep running averages on how much survived
1193
1194 // We use the tenuring threshold to equalize the cost of major
1195 // and minor collections.
1196 // ThresholdTolerance is used to indicate how sensitive the
1197 // tenuring threshold is to differences in cost between the
1198 // collection types.
1199
1200 // Get the times of interest. This involves a little work, so
1201 // we cache the values here.
1202 const double major_cost = major_gc_cost();
1203 const double minor_cost = minor_gc_cost();
1204
1205 if (minor_cost > major_cost * _threshold_tolerance_percent) {
1206 // Minor times are getting too long; lower the threshold so
1207 // less survives and more is promoted.
1208 decr_tenuring_threshold = true;
1209 set_decrement_tenuring_threshold_for_gc_cost(true);
1210 } else if (major_cost > minor_cost * _threshold_tolerance_percent) {
1211 // Major times are too long, so we want less promotion.
1212 incr_tenuring_threshold = true;
1213 set_increment_tenuring_threshold_for_gc_cost(true);
1214 }
1215
1216 } else {
1217 // Survivor space overflow occurred, so promoted and survived are
1218 // not accurate. We'll make our best guess by combining survived
1219 // and promoted and count them as survivors.
1220 //
1221 // We'll lower the tenuring threshold to see if we can correct
1222 // things. Also, set the survivor size conservatively. We're
1223 // trying to avoid many overflows from occurring if defnew size
1224 // is just too small.
1225
1226 decr_tenuring_threshold = true;
1227 }
1228
1229 // The padded average also maintains a deviation from the average;
1230 // we use this to see how good of an estimate we have of what survived.
1231 // We're trying to pad the survivor size as little as possible without
1232 // overflowing the survivor spaces.
1233 size_t target_size = align_size_up((size_t)_avg_survived->padded_average(),
1234 _space_alignment);
1235 target_size = MAX2(target_size, _space_alignment);
1236
1237 if (target_size > survivor_limit) {
1238 // Target size is bigger than we can handle. Let's also reduce
1239 // the tenuring threshold.
1240 target_size = survivor_limit;
1241 decr_tenuring_threshold = true;
1242 set_decrement_tenuring_threshold_for_survivor_limit(true);
1243 }
1244
1245 // Finally, increment or decrement the tenuring threshold, as decided above.
1246 // We test for decrementing first, as we might have hit the target size
1247 // limit.
1248 if (decr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1249 if (tenuring_threshold > 1) {
1250 tenuring_threshold--;
1251 }
1252 } else if (incr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1253 if (tenuring_threshold < MaxTenuringThreshold) {
1254 tenuring_threshold++;
1255 }
1256 }
1257
1258 // We keep a running average of the amount promoted which is used
1259 // to decide when we should collect the old generation (when
1260 // the amount of old gen free space is less than what we expect to
1261 // promote).
1262
1263 if (PrintAdaptiveSizePolicy) {
1264 // A little more detail if Verbose is on
1265 if (Verbose) {
1266 gclog_or_tty->print( " avg_survived: %f"
1267 " avg_deviation: %f",
1268 _avg_survived->average(),
1269 _avg_survived->deviation());
1270 }
1271
1272 gclog_or_tty->print( " avg_survived_padded_avg: %f",
1273 _avg_survived->padded_average());
1274
1275 if (Verbose) {
1276 gclog_or_tty->print( " avg_promoted_avg: %f"
1277 " avg_promoted_dev: %f",
1278 avg_promoted()->average(),
1279 avg_promoted()->deviation());
1280 }
1281
1282 gclog_or_tty->print_cr( " avg_promoted_padded_avg: %f"
1283 " avg_pretenured_padded_avg: %f"
1284 " tenuring_thresh: %d"
1285 " target_size: " SIZE_FORMAT,
1286 avg_promoted()->padded_average(),
1287 _avg_pretenured->padded_average(),
1288 tenuring_threshold, target_size);
1289 }
1290
1291 set_survivor_size(target_size);
1292
1293 return tenuring_threshold;
1294 }
1295
1296 void PSAdaptiveSizePolicy::update_averages(bool is_survivor_overflow,
1297 size_t survived,
1298 size_t promoted) {
1299 // Update averages
1300 if (!is_survivor_overflow) {
1301 // Keep running averages on how much survived
1302 _avg_survived->sample(survived);
1303 } else {
1304 size_t survived_guess = survived + promoted;
1305 _avg_survived->sample(survived_guess);
1306 }
1307 avg_promoted()->sample(promoted + _avg_pretenured->padded_average());
1308
1309 if (PrintAdaptiveSizePolicy) {
1310 gclog_or_tty->print_cr(
1311 "AdaptiveSizePolicy::update_averages:"
1312 " survived: " SIZE_FORMAT
1313 " promoted: " SIZE_FORMAT
1314 " overflow: %s",
1315 survived, promoted, is_survivor_overflow ? "true" : "false");
1316 }
1317 }
1318
1319 bool PSAdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st)
1320 const {
1321
1322 if (!UseAdaptiveSizePolicy) return false;
1323
1324 return AdaptiveSizePolicy::print_adaptive_size_policy_on(
1325 st,
1326 PSScavenge::tenuring_threshold());
1327 }
1328
1329 #ifndef PRODUCT
1330
1331 void TestOldFreeSpaceCalculation_test() {
1332 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 20) == 25, "Calculation of free memory failed");
1333 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 50) == 100, "Calculation of free memory failed");
1334 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 60) == 150, "Calculation of free memory failed");
1335 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 75) == 300, "Calculation of free memory failed");
1336 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 20) == 100, "Calculation of free memory failed");
1337 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 50) == 400, "Calculation of free memory failed");
1338 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 60) == 600, "Calculation of free memory failed");
1339 assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 75) == 1200, "Calculation of free memory failed");
1340 }
1341
1342 #endif /* !PRODUCT */