1 /*
2 * Copyright (c) 2002, 2016, 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/gcUtil.inline.hpp"
33 #include "gc/shared/gcPolicyCounters.hpp"
34 #include "logging/log.hpp"
35 #include "runtime/timer.hpp"
36 #include "utilities/align.hpp"
37
38 #include <math.h>
39
PSAdaptiveSizePolicy(size_t init_eden_size,size_t init_promo_size,size_t init_survivor_size,size_t space_alignment,double gc_pause_goal_sec,double gc_minor_pause_goal_sec,uint gc_cost_ratio)40 PSAdaptiveSizePolicy::PSAdaptiveSizePolicy(size_t init_eden_size,
41 size_t init_promo_size,
42 size_t init_survivor_size,
43 size_t space_alignment,
44 double gc_pause_goal_sec,
45 double gc_minor_pause_goal_sec,
46 uint gc_cost_ratio) :
47 AdaptiveSizePolicy(init_eden_size,
48 init_promo_size,
49 init_survivor_size,
50 gc_pause_goal_sec,
51 gc_cost_ratio),
52 _collection_cost_margin_fraction(AdaptiveSizePolicyCollectionCostMargin / 100.0),
53 _latest_major_mutator_interval_seconds(0),
54 _space_alignment(space_alignment),
55 _gc_minor_pause_goal_sec(gc_minor_pause_goal_sec),
56 _live_at_last_full_gc(init_promo_size),
57 _young_gen_change_for_major_pause_count(0)
58 {
59 // Sizing policy statistics
60 _avg_major_pause =
61 new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding);
62 _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
63 _avg_major_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
64
65 _avg_base_footprint = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
66 _major_pause_old_estimator =
67 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
68 _major_pause_young_estimator =
69 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
70 _major_collection_estimator =
71 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
72
73 _young_gen_size_increment_supplement = YoungGenerationSizeSupplement;
74 _old_gen_size_increment_supplement = TenuredGenerationSizeSupplement;
75
76 // Start the timers
77 _major_timer.start();
78
79 _old_gen_policy_is_ready = false;
80 }
81
calculate_free_based_on_live(size_t live,uintx ratio_as_percentage)82 size_t PSAdaptiveSizePolicy::calculate_free_based_on_live(size_t live, uintx ratio_as_percentage) {
83 // We want to calculate how much free memory there can be based on the
84 // amount of live data currently in the old gen. Using the formula:
85 // ratio * (free + live) = free
86 // Some equation solving later we get:
87 // free = (live * ratio) / (1 - ratio)
88
89 const double ratio = ratio_as_percentage / 100.0;
90 const double ratio_inverse = 1.0 - ratio;
91 const double tmp = live * ratio;
92 size_t free = (size_t)(tmp / ratio_inverse);
93
94 return free;
95 }
96
calculated_old_free_size_in_bytes() const97 size_t PSAdaptiveSizePolicy::calculated_old_free_size_in_bytes() const {
98 size_t free_size = (size_t)(_promo_size + avg_promoted()->padded_average());
99 size_t live = ParallelScavengeHeap::heap()->old_gen()->used_in_bytes();
100
101 if (MinHeapFreeRatio != 0) {
102 size_t min_free = calculate_free_based_on_live(live, MinHeapFreeRatio);
103 free_size = MAX2(free_size, min_free);
104 }
105
106 if (MaxHeapFreeRatio != 100) {
107 size_t max_free = calculate_free_based_on_live(live, MaxHeapFreeRatio);
108 free_size = MIN2(max_free, free_size);
109 }
110
111 return free_size;
112 }
113
major_collection_begin()114 void PSAdaptiveSizePolicy::major_collection_begin() {
115 // Update the interval time
116 _major_timer.stop();
117 // Save most recent collection time
118 _latest_major_mutator_interval_seconds = _major_timer.seconds();
119 _major_timer.reset();
120 _major_timer.start();
121 }
122
update_minor_pause_old_estimator(double minor_pause_in_ms)123 void PSAdaptiveSizePolicy::update_minor_pause_old_estimator(
124 double minor_pause_in_ms) {
125 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
126 _minor_pause_old_estimator->update(promo_size_in_mbytes,
127 minor_pause_in_ms);
128 }
129
major_collection_end(size_t amount_live,GCCause::Cause gc_cause)130 void PSAdaptiveSizePolicy::major_collection_end(size_t amount_live,
131 GCCause::Cause gc_cause) {
132 // Update the pause time.
133 _major_timer.stop();
134
135 if (should_update_promo_stats(gc_cause)) {
136 double major_pause_in_seconds = _major_timer.seconds();
137 double major_pause_in_ms = major_pause_in_seconds * MILLIUNITS;
138
139 // Sample for performance counter
140 _avg_major_pause->sample(major_pause_in_seconds);
141
142 // Cost of collection (unit-less)
143 double collection_cost = 0.0;
144 if ((_latest_major_mutator_interval_seconds > 0.0) &&
145 (major_pause_in_seconds > 0.0)) {
146 double interval_in_seconds =
147 _latest_major_mutator_interval_seconds + major_pause_in_seconds;
148 collection_cost =
149 major_pause_in_seconds / interval_in_seconds;
150 avg_major_gc_cost()->sample(collection_cost);
151
152 // Sample for performance counter
153 _avg_major_interval->sample(interval_in_seconds);
154 }
155
156 // Calculate variables used to estimate pause time vs. gen sizes
157 double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
158 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
159 _major_pause_old_estimator->update(promo_size_in_mbytes,
160 major_pause_in_ms);
161 _major_pause_young_estimator->update(eden_size_in_mbytes,
162 major_pause_in_ms);
163
164 log_trace(gc, ergo)("psAdaptiveSizePolicy::major_collection_end: major gc cost: %f average: %f",
165 collection_cost,avg_major_gc_cost()->average());
166 log_trace(gc, ergo)(" major pause: %f major period %f",
167 major_pause_in_ms, _latest_major_mutator_interval_seconds * MILLIUNITS);
168
169 // Calculate variable used to estimate collection cost vs. gen sizes
170 assert(collection_cost >= 0.0, "Expected to be non-negative");
171 _major_collection_estimator->update(promo_size_in_mbytes,
172 collection_cost);
173 }
174
175 // Update the amount live at the end of a full GC
176 _live_at_last_full_gc = amount_live;
177
178 // The policy does not have enough data until at least some major collections
179 // have been done.
180 if (_avg_major_pause->count() >= AdaptiveSizePolicyReadyThreshold) {
181 _old_gen_policy_is_ready = true;
182 }
183
184 // Interval times use this timer to measure the interval that
185 // the mutator runs. Reset after the GC pause has been measured.
186 _major_timer.reset();
187 _major_timer.start();
188 }
189
190 // If the remaining free space in the old generation is less that
191 // that expected to be needed by the next collection, do a full
192 // collection now.
should_full_GC(size_t old_free_in_bytes)193 bool PSAdaptiveSizePolicy::should_full_GC(size_t old_free_in_bytes) {
194
195 // A similar test is done in the scavenge's should_attempt_scavenge(). If
196 // this is changed, decide if that test should also be changed.
197 bool result = padded_average_promoted_in_bytes() > (float) old_free_in_bytes;
198 log_trace(gc, ergo)("%s after scavenge average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT,
199 result ? "Full" : "No full",
200 (size_t) average_promoted_in_bytes(),
201 (size_t) padded_average_promoted_in_bytes(),
202 old_free_in_bytes);
203 return result;
204 }
205
clear_generation_free_space_flags()206 void PSAdaptiveSizePolicy::clear_generation_free_space_flags() {
207
208 AdaptiveSizePolicy::clear_generation_free_space_flags();
209
210 set_change_old_gen_for_min_pauses(0);
211
212 set_change_young_gen_for_maj_pauses(0);
213 }
214
215 // If this is not a full GC, only test and modify the young generation.
216
compute_generations_free_space(size_t young_live,size_t eden_live,size_t old_live,size_t cur_eden,size_t max_old_gen_size,size_t max_eden_size,bool is_full_gc)217 void PSAdaptiveSizePolicy::compute_generations_free_space(
218 size_t young_live,
219 size_t eden_live,
220 size_t old_live,
221 size_t cur_eden,
222 size_t max_old_gen_size,
223 size_t max_eden_size,
224 bool is_full_gc) {
225 compute_eden_space_size(young_live,
226 eden_live,
227 cur_eden,
228 max_eden_size,
229 is_full_gc);
230
231 compute_old_gen_free_space(old_live,
232 cur_eden,
233 max_old_gen_size,
234 is_full_gc);
235 }
236
compute_eden_space_size(size_t young_live,size_t eden_live,size_t cur_eden,size_t max_eden_size,bool is_full_gc)237 void PSAdaptiveSizePolicy::compute_eden_space_size(
238 size_t young_live,
239 size_t eden_live,
240 size_t cur_eden,
241 size_t max_eden_size,
242 bool is_full_gc) {
243
244 // Update statistics
245 // Time statistics are updated as we go, update footprint stats here
246 _avg_base_footprint->sample(BaseFootPrintEstimate);
247 avg_young_live()->sample(young_live);
248 avg_eden_live()->sample(eden_live);
249
250 // This code used to return if the policy was not ready , i.e.,
251 // policy_is_ready() returning false. The intent was that
252 // decisions below needed major collection times and so could
253 // not be made before two major collections. A consequence was
254 // adjustments to the young generation were not done until after
255 // two major collections even if the minor collections times
256 // exceeded the requested goals. Now let the young generation
257 // adjust for the minor collection times. Major collection times
258 // will be zero for the first collection and will naturally be
259 // ignored. Tenured generation adjustments are only made at the
260 // full collections so until the second major collection has
261 // been reached, no tenured generation adjustments will be made.
262
263 // Until we know better, desired promotion size uses the last calculation
264 size_t desired_promo_size = _promo_size;
265
266 // Start eden at the current value. The desired value that is stored
267 // in _eden_size is not bounded by constraints of the heap and can
268 // run away.
269 //
270 // As expected setting desired_eden_size to the current
271 // value of desired_eden_size as a starting point
272 // caused desired_eden_size to grow way too large and caused
273 // an overflow down stream. It may have improved performance in
274 // some case but is dangerous.
275 size_t desired_eden_size = cur_eden;
276
277 // Cache some values. There's a bit of work getting these, so
278 // we might save a little time.
279 const double major_cost = major_gc_cost();
280 const double minor_cost = minor_gc_cost();
281
282 // This method sets the desired eden size. That plus the
283 // desired survivor space sizes sets the desired young generation
284 // size. This methods does not know what the desired survivor
285 // size is but expects that other policy will attempt to make
286 // the survivor sizes compatible with the live data in the
287 // young generation. This limit is an estimate of the space left
288 // in the young generation after the survivor spaces have been
289 // subtracted out.
290 size_t eden_limit = max_eden_size;
291
292 const double gc_cost_limit = GCTimeLimit / 100.0;
293
294 // Which way should we go?
295 // if pause requirement is not met
296 // adjust size of any generation with average paus exceeding
297 // the pause limit. Adjust one pause at a time (the larger)
298 // and only make adjustments for the major pause at full collections.
299 // else if throughput requirement not met
300 // adjust the size of the generation with larger gc time. Only
301 // adjust one generation at a time.
302 // else
303 // adjust down the total heap size. Adjust down the larger of the
304 // generations.
305
306 // Add some checks for a threshold for a change. For example,
307 // a change less than the necessary alignment is probably not worth
308 // attempting.
309
310
311 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
312 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
313 //
314 // Check pauses
315 //
316 // Make changes only to affect one of the pauses (the larger)
317 // at a time.
318 adjust_eden_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
319
320 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
321 // Adjust only for the minor pause time goal
322 adjust_eden_for_minor_pause_time(is_full_gc, &desired_eden_size);
323
324 } else if(adjusted_mutator_cost() < _throughput_goal) {
325 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
326 // This sometimes resulted in skipping to the minimize footprint
327 // code. Change this to try and reduce GC time if mutator time is
328 // negative for whatever reason. Or for future consideration,
329 // bail out of the code if mutator time is negative.
330 //
331 // Throughput
332 //
333 assert(major_cost >= 0.0, "major cost is < 0.0");
334 assert(minor_cost >= 0.0, "minor cost is < 0.0");
335 // Try to reduce the GC times.
336 adjust_eden_for_throughput(is_full_gc, &desired_eden_size);
337
338 } else {
339
340 // Be conservative about reducing the footprint.
341 // Do a minimum number of major collections first.
342 // Have reasonable averages for major and minor collections costs.
343 if (UseAdaptiveSizePolicyFootprintGoal &&
344 young_gen_policy_is_ready() &&
345 avg_major_gc_cost()->average() >= 0.0 &&
346 avg_minor_gc_cost()->average() >= 0.0) {
347 size_t desired_sum = desired_eden_size + desired_promo_size;
348 desired_eden_size = adjust_eden_for_footprint(desired_eden_size, desired_sum);
349 }
350 }
351
352 // Note we make the same tests as in the code block below; the code
353 // seems a little easier to read with the printing in another block.
354 if (desired_eden_size > eden_limit) {
355 log_debug(gc, ergo)(
356 "PSAdaptiveSizePolicy::compute_eden_space_size limits:"
357 " desired_eden_size: " SIZE_FORMAT
358 " old_eden_size: " SIZE_FORMAT
359 " eden_limit: " SIZE_FORMAT
360 " cur_eden: " SIZE_FORMAT
361 " max_eden_size: " SIZE_FORMAT
362 " avg_young_live: " SIZE_FORMAT,
363 desired_eden_size, _eden_size, eden_limit, cur_eden,
364 max_eden_size, (size_t)avg_young_live()->average());
365 }
366 if (gc_cost() > gc_cost_limit) {
367 log_debug(gc, ergo)(
368 "PSAdaptiveSizePolicy::compute_eden_space_size: gc time limit"
369 " gc_cost: %f "
370 " GCTimeLimit: " UINTX_FORMAT,
371 gc_cost(), GCTimeLimit);
372 }
373
374 // Align everything and make a final limit check
375 desired_eden_size = align_up(desired_eden_size, _space_alignment);
376 desired_eden_size = MAX2(desired_eden_size, _space_alignment);
377
378 eden_limit = align_down(eden_limit, _space_alignment);
379
380 // And one last limit check, now that we've aligned things.
381 if (desired_eden_size > eden_limit) {
382 // If the policy says to get a larger eden but
383 // is hitting the limit, don't decrease eden.
384 // This can lead to a general drifting down of the
385 // eden size. Let the tenuring calculation push more
386 // into the old gen.
387 desired_eden_size = MAX2(eden_limit, cur_eden);
388 }
389
390 log_debug(gc, ergo)("PSAdaptiveSizePolicy::compute_eden_space_size: costs minor_time: %f major_cost: %f mutator_cost: %f throughput_goal: %f",
391 minor_gc_cost(), major_gc_cost(), mutator_cost(), _throughput_goal);
392
393 log_trace(gc, ergo)("Minor_pause: %f major_pause: %f minor_interval: %f major_interval: %fpause_goal: %f",
394 _avg_minor_pause->padded_average(),
395 _avg_major_pause->padded_average(),
396 _avg_minor_interval->average(),
397 _avg_major_interval->average(),
398 gc_pause_goal_sec());
399
400 log_debug(gc, ergo)("Live_space: " SIZE_FORMAT " free_space: " SIZE_FORMAT,
401 live_space(), free_space());
402
403 log_trace(gc, ergo)("Base_footprint: " SIZE_FORMAT " avg_young_live: " SIZE_FORMAT " avg_old_live: " SIZE_FORMAT,
404 (size_t)_avg_base_footprint->average(),
405 (size_t)avg_young_live()->average(),
406 (size_t)avg_old_live()->average());
407
408 log_debug(gc, ergo)("Old eden_size: " SIZE_FORMAT " desired_eden_size: " SIZE_FORMAT,
409 _eden_size, desired_eden_size);
410
411 set_eden_size(desired_eden_size);
412 }
413
compute_old_gen_free_space(size_t old_live,size_t cur_eden,size_t max_old_gen_size,bool is_full_gc)414 void PSAdaptiveSizePolicy::compute_old_gen_free_space(
415 size_t old_live,
416 size_t cur_eden,
417 size_t max_old_gen_size,
418 bool is_full_gc) {
419
420 // Update statistics
421 // Time statistics are updated as we go, update footprint stats here
422 if (is_full_gc) {
423 // old_live is only accurate after a full gc
424 avg_old_live()->sample(old_live);
425 }
426
427 // This code used to return if the policy was not ready , i.e.,
428 // policy_is_ready() returning false. The intent was that
429 // decisions below needed major collection times and so could
430 // not be made before two major collections. A consequence was
431 // adjustments to the young generation were not done until after
432 // two major collections even if the minor collections times
433 // exceeded the requested goals. Now let the young generation
434 // adjust for the minor collection times. Major collection times
435 // will be zero for the first collection and will naturally be
436 // ignored. Tenured generation adjustments are only made at the
437 // full collections so until the second major collection has
438 // been reached, no tenured generation adjustments will be made.
439
440 // Until we know better, desired promotion size uses the last calculation
441 size_t desired_promo_size = _promo_size;
442
443 // Start eden at the current value. The desired value that is stored
444 // in _eden_size is not bounded by constraints of the heap and can
445 // run away.
446 //
447 // As expected setting desired_eden_size to the current
448 // value of desired_eden_size as a starting point
449 // caused desired_eden_size to grow way too large and caused
450 // an overflow down stream. It may have improved performance in
451 // some case but is dangerous.
452 size_t desired_eden_size = cur_eden;
453
454 // Cache some values. There's a bit of work getting these, so
455 // we might save a little time.
456 const double major_cost = major_gc_cost();
457 const double minor_cost = minor_gc_cost();
458
459 // Limits on our growth
460 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());
461
462 // But don't force a promo size below the current promo size. Otherwise,
463 // the promo size will shrink for no good reason.
464 promo_limit = MAX2(promo_limit, _promo_size);
465
466 const double gc_cost_limit = GCTimeLimit/100.0;
467
468 // Which way should we go?
469 // if pause requirement is not met
470 // adjust size of any generation with average paus exceeding
471 // the pause limit. Adjust one pause at a time (the larger)
472 // and only make adjustments for the major pause at full collections.
473 // else if throughput requirement not met
474 // adjust the size of the generation with larger gc time. Only
475 // adjust one generation at a time.
476 // else
477 // adjust down the total heap size. Adjust down the larger of the
478 // generations.
479
480 // Add some checks for a threshold for a change. For example,
481 // a change less than the necessary alignment is probably not worth
482 // attempting.
483
484 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
485 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
486 //
487 // Check pauses
488 //
489 // Make changes only to affect one of the pauses (the larger)
490 // at a time.
491 if (is_full_gc) {
492 set_decide_at_full_gc(decide_at_full_gc_true);
493 adjust_promo_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
494 }
495 } else if (adjusted_mutator_cost() < _throughput_goal) {
496 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
497 // This sometimes resulted in skipping to the minimize footprint
498 // code. Change this to try and reduce GC time if mutator time is
499 // negative for whatever reason. Or for future consideration,
500 // bail out of the code if mutator time is negative.
501 //
502 // Throughput
503 //
504 assert(major_cost >= 0.0, "major cost is < 0.0");
505 assert(minor_cost >= 0.0, "minor cost is < 0.0");
506 // Try to reduce the GC times.
507 if (is_full_gc) {
508 set_decide_at_full_gc(decide_at_full_gc_true);
509 adjust_promo_for_throughput(is_full_gc, &desired_promo_size);
510 }
511 } else {
512
513 // Be conservative about reducing the footprint.
514 // Do a minimum number of major collections first.
515 // Have reasonable averages for major and minor collections costs.
516 if (UseAdaptiveSizePolicyFootprintGoal &&
517 young_gen_policy_is_ready() &&
518 avg_major_gc_cost()->average() >= 0.0 &&
519 avg_minor_gc_cost()->average() >= 0.0) {
520 if (is_full_gc) {
521 set_decide_at_full_gc(decide_at_full_gc_true);
522 size_t desired_sum = desired_eden_size + desired_promo_size;
523 desired_promo_size = adjust_promo_for_footprint(desired_promo_size, desired_sum);
524 }
525 }
526 }
527
528 // Note we make the same tests as in the code block below; the code
529 // seems a little easier to read with the printing in another block.
530 if (desired_promo_size > promo_limit) {
531 // "free_in_old_gen" was the original value for used for promo_limit
532 size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());
533 log_debug(gc, ergo)(
534 "PSAdaptiveSizePolicy::compute_old_gen_free_space limits:"
535 " desired_promo_size: " SIZE_FORMAT
536 " promo_limit: " SIZE_FORMAT
537 " free_in_old_gen: " SIZE_FORMAT
538 " max_old_gen_size: " SIZE_FORMAT
539 " avg_old_live: " SIZE_FORMAT,
540 desired_promo_size, promo_limit, free_in_old_gen,
541 max_old_gen_size, (size_t) avg_old_live()->average());
542 }
543 if (gc_cost() > gc_cost_limit) {
544 log_debug(gc, ergo)(
545 "PSAdaptiveSizePolicy::compute_old_gen_free_space: gc time limit"
546 " gc_cost: %f "
547 " GCTimeLimit: " UINTX_FORMAT,
548 gc_cost(), GCTimeLimit);
549 }
550
551 // Align everything and make a final limit check
552 desired_promo_size = align_up(desired_promo_size, _space_alignment);
553 desired_promo_size = MAX2(desired_promo_size, _space_alignment);
554
555 promo_limit = align_down(promo_limit, _space_alignment);
556
557 // And one last limit check, now that we've aligned things.
558 desired_promo_size = MIN2(desired_promo_size, promo_limit);
559
560 // Timing stats
561 log_debug(gc, ergo)("PSAdaptiveSizePolicy::compute_old_gen_free_space: costs minor_time: %f major_cost: %f mutator_cost: %f throughput_goal: %f",
562 minor_gc_cost(), major_gc_cost(), mutator_cost(), _throughput_goal);
563
564 log_trace(gc, ergo)("Minor_pause: %f major_pause: %f minor_interval: %f major_interval: %f pause_goal: %f",
565 _avg_minor_pause->padded_average(),
566 _avg_major_pause->padded_average(),
567 _avg_minor_interval->average(),
568 _avg_major_interval->average(),
569 gc_pause_goal_sec());
570
571 // Footprint stats
572 log_debug(gc, ergo)("Live_space: " SIZE_FORMAT " free_space: " SIZE_FORMAT,
573 live_space(), free_space());
574
575 log_trace(gc, ergo)("Base_footprint: " SIZE_FORMAT " avg_young_live: " SIZE_FORMAT " avg_old_live: " SIZE_FORMAT,
576 (size_t)_avg_base_footprint->average(),
577 (size_t)avg_young_live()->average(),
578 (size_t)avg_old_live()->average());
579
580 log_debug(gc, ergo)("Old promo_size: " SIZE_FORMAT " desired_promo_size: " SIZE_FORMAT,
581 _promo_size, desired_promo_size);
582
583 set_promo_size(desired_promo_size);
584 }
585
decay_supplemental_growth(bool is_full_gc)586 void PSAdaptiveSizePolicy::decay_supplemental_growth(bool is_full_gc) {
587 // Decay the supplemental increment? Decay the supplement growth
588 // factor even if it is not used. It is only meant to give a boost
589 // to the initial growth and if it is not used, then it was not
590 // needed.
591 if (is_full_gc) {
592 // Don't wait for the threshold value for the major collections. If
593 // here, the supplemental growth term was used and should decay.
594 if ((_avg_major_pause->count() % TenuredGenerationSizeSupplementDecay)
595 == 0) {
596 _old_gen_size_increment_supplement =
597 _old_gen_size_increment_supplement >> 1;
598 }
599 } else {
600 if ((_avg_minor_pause->count() >= AdaptiveSizePolicyReadyThreshold) &&
601 (_avg_minor_pause->count() % YoungGenerationSizeSupplementDecay) == 0) {
602 _young_gen_size_increment_supplement =
603 _young_gen_size_increment_supplement >> 1;
604 }
605 }
606 }
607
adjust_eden_for_minor_pause_time(bool is_full_gc,size_t * desired_eden_size_ptr)608 void PSAdaptiveSizePolicy::adjust_eden_for_minor_pause_time(bool is_full_gc,
609 size_t* desired_eden_size_ptr) {
610
611 // Adjust the young generation size to reduce pause time of
612 // of collections.
613 //
614 // The AdaptiveSizePolicyInitializingSteps test is not used
615 // here. It has not seemed to be needed but perhaps should
616 // be added for consistency.
617 if (minor_pause_young_estimator()->decrement_will_decrease()) {
618 // reduce eden size
619 set_change_young_gen_for_min_pauses(
620 decrease_young_gen_for_min_pauses_true);
621 *desired_eden_size_ptr = *desired_eden_size_ptr -
622 eden_decrement_aligned_down(*desired_eden_size_ptr);
623 } else {
624 // EXPERIMENTAL ADJUSTMENT
625 // Only record that the estimator indicated such an action.
626 // *desired_eden_size_ptr = *desired_eden_size_ptr + eden_heap_delta;
627 set_change_young_gen_for_min_pauses(
628 increase_young_gen_for_min_pauses_true);
629 }
630 }
631
adjust_promo_for_pause_time(bool is_full_gc,size_t * desired_promo_size_ptr,size_t * desired_eden_size_ptr)632 void PSAdaptiveSizePolicy::adjust_promo_for_pause_time(bool is_full_gc,
633 size_t* desired_promo_size_ptr,
634 size_t* desired_eden_size_ptr) {
635
636 size_t promo_heap_delta = 0;
637 // Add some checks for a threshold for a change. For example,
638 // a change less than the required alignment is probably not worth
639 // attempting.
640
641 if (_avg_minor_pause->padded_average() <= _avg_major_pause->padded_average() && is_full_gc) {
642 // Adjust for the major pause time only at full gc's because the
643 // affects of a change can only be seen at full gc's.
644
645 // Reduce old generation size to reduce pause?
646 if (major_pause_old_estimator()->decrement_will_decrease()) {
647 // reduce old generation size
648 set_change_old_gen_for_maj_pauses(decrease_old_gen_for_maj_pauses_true);
649 promo_heap_delta = promo_decrement_aligned_down(*desired_promo_size_ptr);
650 *desired_promo_size_ptr = _promo_size - promo_heap_delta;
651 } else {
652 // EXPERIMENTAL ADJUSTMENT
653 // Only record that the estimator indicated such an action.
654 // *desired_promo_size_ptr = _promo_size +
655 // promo_increment_aligned_up(*desired_promo_size_ptr);
656 set_change_old_gen_for_maj_pauses(increase_old_gen_for_maj_pauses_true);
657 }
658 }
659
660 log_trace(gc, ergo)(
661 "PSAdaptiveSizePolicy::adjust_promo_for_pause_time "
662 "adjusting gen sizes for major pause (avg %f goal %f). "
663 "desired_promo_size " SIZE_FORMAT " promo delta " SIZE_FORMAT,
664 _avg_major_pause->average(), gc_pause_goal_sec(),
665 *desired_promo_size_ptr, promo_heap_delta);
666 }
667
adjust_eden_for_pause_time(bool is_full_gc,size_t * desired_promo_size_ptr,size_t * desired_eden_size_ptr)668 void PSAdaptiveSizePolicy::adjust_eden_for_pause_time(bool is_full_gc,
669 size_t* desired_promo_size_ptr,
670 size_t* desired_eden_size_ptr) {
671
672 size_t eden_heap_delta = 0;
673 // Add some checks for a threshold for a change. For example,
674 // a change less than the required alignment is probably not worth
675 // attempting.
676 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
677 adjust_eden_for_minor_pause_time(is_full_gc, desired_eden_size_ptr);
678 }
679 log_trace(gc, ergo)(
680 "PSAdaptiveSizePolicy::adjust_eden_for_pause_time "
681 "adjusting gen sizes for major pause (avg %f goal %f). "
682 "desired_eden_size " SIZE_FORMAT " eden delta " SIZE_FORMAT,
683 _avg_major_pause->average(), gc_pause_goal_sec(),
684 *desired_eden_size_ptr, eden_heap_delta);
685 }
686
adjust_promo_for_throughput(bool is_full_gc,size_t * desired_promo_size_ptr)687 void PSAdaptiveSizePolicy::adjust_promo_for_throughput(bool is_full_gc,
688 size_t* desired_promo_size_ptr) {
689
690 // Add some checks for a threshold for a change. For example,
691 // a change less than the required alignment is probably not worth
692 // attempting.
693
694 if ((gc_cost() + mutator_cost()) == 0.0) {
695 return;
696 }
697
698 log_trace(gc, ergo)("PSAdaptiveSizePolicy::adjust_promo_for_throughput(is_full: %d, promo: " SIZE_FORMAT "): mutator_cost %f major_gc_cost %f minor_gc_cost %f",
699 is_full_gc, *desired_promo_size_ptr, mutator_cost(), major_gc_cost(), minor_gc_cost());
700
701 // Tenured generation
702 if (is_full_gc) {
703 // Calculate the change to use for the tenured gen.
704 size_t scaled_promo_heap_delta = 0;
705 // Can the increment to the generation be scaled?
706 if (gc_cost() >= 0.0 && major_gc_cost() >= 0.0) {
707 size_t promo_heap_delta =
708 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
709 double scale_by_ratio = major_gc_cost() / gc_cost();
710 scaled_promo_heap_delta =
711 (size_t) (scale_by_ratio * (double) promo_heap_delta);
712 log_trace(gc, ergo)("Scaled tenured increment: " SIZE_FORMAT " by %f down to " SIZE_FORMAT,
713 promo_heap_delta, scale_by_ratio, scaled_promo_heap_delta);
714 } else if (major_gc_cost() >= 0.0) {
715 // Scaling is not going to work. If the major gc time is the
716 // larger, give it a full increment.
717 if (major_gc_cost() >= minor_gc_cost()) {
718 scaled_promo_heap_delta =
719 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
720 }
721 } else {
722 // Don't expect to get here but it's ok if it does
723 // in the product build since the delta will be 0
724 // and nothing will change.
725 assert(false, "Unexpected value for gc costs");
726 }
727
728 switch (AdaptiveSizeThroughPutPolicy) {
729 case 1:
730 // Early in the run the statistics might not be good. Until
731 // a specific number of collections have been, use the heuristic
732 // that a larger generation size means lower collection costs.
733 if (major_collection_estimator()->increment_will_decrease() ||
734 (_old_gen_change_for_major_throughput
735 <= AdaptiveSizePolicyInitializingSteps)) {
736 // Increase tenured generation size to reduce major collection cost
737 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
738 *desired_promo_size_ptr) {
739 *desired_promo_size_ptr = _promo_size + scaled_promo_heap_delta;
740 }
741 set_change_old_gen_for_throughput(
742 increase_old_gen_for_throughput_true);
743 _old_gen_change_for_major_throughput++;
744 } else {
745 // EXPERIMENTAL ADJUSTMENT
746 // Record that decreasing the old gen size would decrease
747 // the major collection cost but don't do it.
748 // *desired_promo_size_ptr = _promo_size -
749 // promo_decrement_aligned_down(*desired_promo_size_ptr);
750 set_change_old_gen_for_throughput(
751 decrease_old_gen_for_throughput_true);
752 }
753
754 break;
755 default:
756 // Simplest strategy
757 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
758 *desired_promo_size_ptr) {
759 *desired_promo_size_ptr = *desired_promo_size_ptr +
760 scaled_promo_heap_delta;
761 }
762 set_change_old_gen_for_throughput(
763 increase_old_gen_for_throughput_true);
764 _old_gen_change_for_major_throughput++;
765 }
766
767 log_trace(gc, ergo)("Adjusting tenured gen for throughput (avg %f goal %f). desired_promo_size " SIZE_FORMAT " promo_delta " SIZE_FORMAT ,
768 mutator_cost(),
769 _throughput_goal,
770 *desired_promo_size_ptr, scaled_promo_heap_delta);
771 }
772 }
773
adjust_eden_for_throughput(bool is_full_gc,size_t * desired_eden_size_ptr)774 void PSAdaptiveSizePolicy::adjust_eden_for_throughput(bool is_full_gc,
775 size_t* desired_eden_size_ptr) {
776
777 // Add some checks for a threshold for a change. For example,
778 // a change less than the required alignment is probably not worth
779 // attempting.
780
781 if ((gc_cost() + mutator_cost()) == 0.0) {
782 return;
783 }
784
785 log_trace(gc, ergo)("PSAdaptiveSizePolicy::adjust_eden_for_throughput(is_full: %d, cur_eden: " SIZE_FORMAT "): mutator_cost %f major_gc_cost %f minor_gc_cost %f",
786 is_full_gc, *desired_eden_size_ptr, mutator_cost(), major_gc_cost(), minor_gc_cost());
787
788 // Young generation
789 size_t scaled_eden_heap_delta = 0;
790 // Can the increment to the generation be scaled?
791 if (gc_cost() >= 0.0 && minor_gc_cost() >= 0.0) {
792 size_t eden_heap_delta =
793 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
794 double scale_by_ratio = minor_gc_cost() / gc_cost();
795 assert(scale_by_ratio <= 1.0 && scale_by_ratio >= 0.0, "Scaling is wrong");
796 scaled_eden_heap_delta =
797 (size_t) (scale_by_ratio * (double) eden_heap_delta);
798 log_trace(gc, ergo)("Scaled eden increment: " SIZE_FORMAT " by %f down to " SIZE_FORMAT,
799 eden_heap_delta, scale_by_ratio, scaled_eden_heap_delta);
800 } else if (minor_gc_cost() >= 0.0) {
801 // Scaling is not going to work. If the minor gc time is the
802 // larger, give it a full increment.
803 if (minor_gc_cost() > major_gc_cost()) {
804 scaled_eden_heap_delta =
805 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
806 }
807 } else {
808 // Don't expect to get here but it's ok if it does
809 // in the product build since the delta will be 0
810 // and nothing will change.
811 assert(false, "Unexpected value for gc costs");
812 }
813
814 // Use a heuristic for some number of collections to give
815 // the averages time to settle down.
816 switch (AdaptiveSizeThroughPutPolicy) {
817 case 1:
818 if (minor_collection_estimator()->increment_will_decrease() ||
819 (_young_gen_change_for_minor_throughput
820 <= AdaptiveSizePolicyInitializingSteps)) {
821 // Expand young generation size to reduce frequency of
822 // of collections.
823 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
824 *desired_eden_size_ptr) {
825 *desired_eden_size_ptr =
826 *desired_eden_size_ptr + scaled_eden_heap_delta;
827 }
828 set_change_young_gen_for_throughput(
829 increase_young_gen_for_througput_true);
830 _young_gen_change_for_minor_throughput++;
831 } else {
832 // EXPERIMENTAL ADJUSTMENT
833 // Record that decreasing the young gen size would decrease
834 // the minor collection cost but don't do it.
835 // *desired_eden_size_ptr = _eden_size -
836 // eden_decrement_aligned_down(*desired_eden_size_ptr);
837 set_change_young_gen_for_throughput(
838 decrease_young_gen_for_througput_true);
839 }
840 break;
841 default:
842 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
843 *desired_eden_size_ptr) {
844 *desired_eden_size_ptr =
845 *desired_eden_size_ptr + scaled_eden_heap_delta;
846 }
847 set_change_young_gen_for_throughput(
848 increase_young_gen_for_througput_true);
849 _young_gen_change_for_minor_throughput++;
850 }
851
852 log_trace(gc, ergo)("Adjusting eden for throughput (avg %f goal %f). desired_eden_size " SIZE_FORMAT " eden delta " SIZE_FORMAT,
853 mutator_cost(), _throughput_goal, *desired_eden_size_ptr, scaled_eden_heap_delta);
854 }
855
adjust_promo_for_footprint(size_t desired_promo_size,size_t desired_sum)856 size_t PSAdaptiveSizePolicy::adjust_promo_for_footprint(
857 size_t desired_promo_size, size_t desired_sum) {
858 assert(desired_promo_size <= desired_sum, "Inconsistent parameters");
859 set_decrease_for_footprint(decrease_old_gen_for_footprint_true);
860
861 size_t change = promo_decrement(desired_promo_size);
862 change = scale_down(change, desired_promo_size, desired_sum);
863
864 size_t reduced_size = desired_promo_size - change;
865
866 log_trace(gc, ergo)(
867 "AdaptiveSizePolicy::adjust_promo_for_footprint "
868 "adjusting tenured gen for footprint. "
869 "starting promo size " SIZE_FORMAT
870 " reduced promo size " SIZE_FORMAT
871 " promo delta " SIZE_FORMAT,
872 desired_promo_size, reduced_size, change );
873
874 assert(reduced_size <= desired_promo_size, "Inconsistent result");
875 return reduced_size;
876 }
877
adjust_eden_for_footprint(size_t desired_eden_size,size_t desired_sum)878 size_t PSAdaptiveSizePolicy::adjust_eden_for_footprint(
879 size_t desired_eden_size, size_t desired_sum) {
880 assert(desired_eden_size <= desired_sum, "Inconsistent parameters");
881 set_decrease_for_footprint(decrease_young_gen_for_footprint_true);
882
883 size_t change = eden_decrement(desired_eden_size);
884 change = scale_down(change, desired_eden_size, desired_sum);
885
886 size_t reduced_size = desired_eden_size - change;
887
888 log_trace(gc, ergo)(
889 "AdaptiveSizePolicy::adjust_eden_for_footprint "
890 "adjusting eden for footprint. "
891 " starting eden size " SIZE_FORMAT
892 " reduced eden size " SIZE_FORMAT
893 " eden delta " SIZE_FORMAT,
894 desired_eden_size, reduced_size, change);
895
896 assert(reduced_size <= desired_eden_size, "Inconsistent result");
897 return reduced_size;
898 }
899
900 // Scale down "change" by the factor
901 // part / total
902 // Don't align the results.
903
scale_down(size_t change,double part,double total)904 size_t PSAdaptiveSizePolicy::scale_down(size_t change,
905 double part,
906 double total) {
907 assert(part <= total, "Inconsistent input");
908 size_t reduced_change = change;
909 if (total > 0) {
910 double fraction = part / total;
911 reduced_change = (size_t) (fraction * (double) change);
912 }
913 assert(reduced_change <= change, "Inconsistent result");
914 return reduced_change;
915 }
916
eden_increment(size_t cur_eden,uint percent_change)917 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden,
918 uint percent_change) {
919 size_t eden_heap_delta;
920 eden_heap_delta = cur_eden / 100 * percent_change;
921 return eden_heap_delta;
922 }
923
eden_increment(size_t cur_eden)924 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden) {
925 return eden_increment(cur_eden, YoungGenerationSizeIncrement);
926 }
927
eden_increment_aligned_up(size_t cur_eden)928 size_t PSAdaptiveSizePolicy::eden_increment_aligned_up(size_t cur_eden) {
929 size_t result = eden_increment(cur_eden, YoungGenerationSizeIncrement);
930 return align_up(result, _space_alignment);
931 }
932
eden_increment_aligned_down(size_t cur_eden)933 size_t PSAdaptiveSizePolicy::eden_increment_aligned_down(size_t cur_eden) {
934 size_t result = eden_increment(cur_eden);
935 return align_down(result, _space_alignment);
936 }
937
eden_increment_with_supplement_aligned_up(size_t cur_eden)938 size_t PSAdaptiveSizePolicy::eden_increment_with_supplement_aligned_up(
939 size_t cur_eden) {
940 size_t result = eden_increment(cur_eden,
941 YoungGenerationSizeIncrement + _young_gen_size_increment_supplement);
942 return align_up(result, _space_alignment);
943 }
944
eden_decrement_aligned_down(size_t cur_eden)945 size_t PSAdaptiveSizePolicy::eden_decrement_aligned_down(size_t cur_eden) {
946 size_t eden_heap_delta = eden_decrement(cur_eden);
947 return align_down(eden_heap_delta, _space_alignment);
948 }
949
eden_decrement(size_t cur_eden)950 size_t PSAdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
951 size_t eden_heap_delta = eden_increment(cur_eden) /
952 AdaptiveSizeDecrementScaleFactor;
953 return eden_heap_delta;
954 }
955
promo_increment(size_t cur_promo,uint percent_change)956 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo,
957 uint percent_change) {
958 size_t promo_heap_delta;
959 promo_heap_delta = cur_promo / 100 * percent_change;
960 return promo_heap_delta;
961 }
962
promo_increment(size_t cur_promo)963 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo) {
964 return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
965 }
966
promo_increment_aligned_up(size_t cur_promo)967 size_t PSAdaptiveSizePolicy::promo_increment_aligned_up(size_t cur_promo) {
968 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
969 return align_up(result, _space_alignment);
970 }
971
promo_increment_aligned_down(size_t cur_promo)972 size_t PSAdaptiveSizePolicy::promo_increment_aligned_down(size_t cur_promo) {
973 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
974 return align_down(result, _space_alignment);
975 }
976
promo_increment_with_supplement_aligned_up(size_t cur_promo)977 size_t PSAdaptiveSizePolicy::promo_increment_with_supplement_aligned_up(
978 size_t cur_promo) {
979 size_t result = promo_increment(cur_promo,
980 TenuredGenerationSizeIncrement + _old_gen_size_increment_supplement);
981 return align_up(result, _space_alignment);
982 }
983
promo_decrement_aligned_down(size_t cur_promo)984 size_t PSAdaptiveSizePolicy::promo_decrement_aligned_down(size_t cur_promo) {
985 size_t promo_heap_delta = promo_decrement(cur_promo);
986 return align_down(promo_heap_delta, _space_alignment);
987 }
988
promo_decrement(size_t cur_promo)989 size_t PSAdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
990 size_t promo_heap_delta = promo_increment(cur_promo);
991 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
992 return promo_heap_delta;
993 }
994
compute_survivor_space_size_and_threshold(bool is_survivor_overflow,uint tenuring_threshold,size_t survivor_limit)995 uint PSAdaptiveSizePolicy::compute_survivor_space_size_and_threshold(
996 bool is_survivor_overflow,
997 uint tenuring_threshold,
998 size_t survivor_limit) {
999 assert(survivor_limit >= _space_alignment,
1000 "survivor_limit too small");
1001 assert(is_aligned(survivor_limit, _space_alignment),
1002 "survivor_limit not aligned");
1003
1004 // This method is called even if the tenuring threshold and survivor
1005 // spaces are not adjusted so that the averages are sampled above.
1006 if (!UsePSAdaptiveSurvivorSizePolicy ||
1007 !young_gen_policy_is_ready()) {
1008 return tenuring_threshold;
1009 }
1010
1011 // We'll decide whether to increase or decrease the tenuring
1012 // threshold based partly on the newly computed survivor size
1013 // (if we hit the maximum limit allowed, we'll always choose to
1014 // decrement the threshold).
1015 bool incr_tenuring_threshold = false;
1016 bool decr_tenuring_threshold = false;
1017
1018 set_decrement_tenuring_threshold_for_gc_cost(false);
1019 set_increment_tenuring_threshold_for_gc_cost(false);
1020 set_decrement_tenuring_threshold_for_survivor_limit(false);
1021
1022 if (!is_survivor_overflow) {
1023 // Keep running averages on how much survived
1024
1025 // We use the tenuring threshold to equalize the cost of major
1026 // and minor collections.
1027 // ThresholdTolerance is used to indicate how sensitive the
1028 // tenuring threshold is to differences in cost between the
1029 // collection types.
1030
1031 // Get the times of interest. This involves a little work, so
1032 // we cache the values here.
1033 const double major_cost = major_gc_cost();
1034 const double minor_cost = minor_gc_cost();
1035
1036 if (minor_cost > major_cost * _threshold_tolerance_percent) {
1037 // Minor times are getting too long; lower the threshold so
1038 // less survives and more is promoted.
1039 decr_tenuring_threshold = true;
1040 set_decrement_tenuring_threshold_for_gc_cost(true);
1041 } else if (major_cost > minor_cost * _threshold_tolerance_percent) {
1042 // Major times are too long, so we want less promotion.
1043 incr_tenuring_threshold = true;
1044 set_increment_tenuring_threshold_for_gc_cost(true);
1045 }
1046
1047 } else {
1048 // Survivor space overflow occurred, so promoted and survived are
1049 // not accurate. We'll make our best guess by combining survived
1050 // and promoted and count them as survivors.
1051 //
1052 // We'll lower the tenuring threshold to see if we can correct
1053 // things. Also, set the survivor size conservatively. We're
1054 // trying to avoid many overflows from occurring if defnew size
1055 // is just too small.
1056
1057 decr_tenuring_threshold = true;
1058 }
1059
1060 // The padded average also maintains a deviation from the average;
1061 // we use this to see how good of an estimate we have of what survived.
1062 // We're trying to pad the survivor size as little as possible without
1063 // overflowing the survivor spaces.
1064 size_t target_size = align_up((size_t)_avg_survived->padded_average(),
1065 _space_alignment);
1066 target_size = MAX2(target_size, _space_alignment);
1067
1068 if (target_size > survivor_limit) {
1069 // Target size is bigger than we can handle. Let's also reduce
1070 // the tenuring threshold.
1071 target_size = survivor_limit;
1072 decr_tenuring_threshold = true;
1073 set_decrement_tenuring_threshold_for_survivor_limit(true);
1074 }
1075
1076 // Finally, increment or decrement the tenuring threshold, as decided above.
1077 // We test for decrementing first, as we might have hit the target size
1078 // limit.
1079 if (decr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1080 if (tenuring_threshold > 1) {
1081 tenuring_threshold--;
1082 }
1083 } else if (incr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1084 if (tenuring_threshold < MaxTenuringThreshold) {
1085 tenuring_threshold++;
1086 }
1087 }
1088
1089 // We keep a running average of the amount promoted which is used
1090 // to decide when we should collect the old generation (when
1091 // the amount of old gen free space is less than what we expect to
1092 // promote).
1093
1094 log_trace(gc, ergo)("avg_survived: %f avg_deviation: %f", _avg_survived->average(), _avg_survived->deviation());
1095 log_debug(gc, ergo)("avg_survived_padded_avg: %f", _avg_survived->padded_average());
1096
1097 log_trace(gc, ergo)("avg_promoted_avg: %f avg_promoted_dev: %f", avg_promoted()->average(), avg_promoted()->deviation());
1098 log_debug(gc, ergo)("avg_promoted_padded_avg: %f avg_pretenured_padded_avg: %f tenuring_thresh: %d target_size: " SIZE_FORMAT,
1099 avg_promoted()->padded_average(),
1100 _avg_pretenured->padded_average(),
1101 tenuring_threshold, target_size);
1102
1103 set_survivor_size(target_size);
1104
1105 return tenuring_threshold;
1106 }
1107
update_averages(bool is_survivor_overflow,size_t survived,size_t promoted)1108 void PSAdaptiveSizePolicy::update_averages(bool is_survivor_overflow,
1109 size_t survived,
1110 size_t promoted) {
1111 // Update averages
1112 if (!is_survivor_overflow) {
1113 // Keep running averages on how much survived
1114 _avg_survived->sample(survived);
1115 } else {
1116 size_t survived_guess = survived + promoted;
1117 _avg_survived->sample(survived_guess);
1118 }
1119 avg_promoted()->sample(promoted);
1120
1121 log_trace(gc, ergo)("AdaptiveSizePolicy::update_averages: survived: " SIZE_FORMAT " promoted: " SIZE_FORMAT " overflow: %s",
1122 survived, promoted, is_survivor_overflow ? "true" : "false");
1123 }
1124
print() const1125 bool PSAdaptiveSizePolicy::print() const {
1126
1127 if (!UseAdaptiveSizePolicy) {
1128 return false;
1129 }
1130
1131 if (AdaptiveSizePolicy::print()) {
1132 AdaptiveSizePolicy::print_tenuring_threshold(PSScavenge::tenuring_threshold());
1133 return true;
1134 }
1135
1136 return false;
1137 }
1138