1 /*
2 * Copyright (c) 2002, 2010, 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 "incls/_precompiled.incl"
26 #include "incls/_psAdaptiveSizePolicy.cpp.incl"
27
28 #include <math.h>
29
30 PSAdaptiveSizePolicy::PSAdaptiveSizePolicy(size_t init_eden_size,
31 size_t init_promo_size,
32 size_t init_survivor_size,
33 size_t intra_generation_alignment,
34 double gc_pause_goal_sec,
35 double gc_minor_pause_goal_sec,
36 uint gc_cost_ratio) :
37 AdaptiveSizePolicy(init_eden_size,
38 init_promo_size,
39 init_survivor_size,
40 gc_pause_goal_sec,
41 gc_cost_ratio),
42 _collection_cost_margin_fraction(AdaptiveSizePolicyCollectionCostMargin/
43 100.0),
44 _intra_generation_alignment(intra_generation_alignment),
45 _live_at_last_full_gc(init_promo_size),
46 _gc_minor_pause_goal_sec(gc_minor_pause_goal_sec),
47 _latest_major_mutator_interval_seconds(0),
48 _young_gen_change_for_major_pause_count(0)
49 {
50 // Sizing policy statistics
51 _avg_major_pause =
52 new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding);
53 _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
54 _avg_major_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
55
56 _avg_base_footprint = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
57 _major_pause_old_estimator =
58 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
59 _major_pause_young_estimator =
60 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
61 _major_collection_estimator =
62 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
63
64 _young_gen_size_increment_supplement = YoungGenerationSizeSupplement;
65 _old_gen_size_increment_supplement = TenuredGenerationSizeSupplement;
66
67 // Start the timers
68 _major_timer.start();
69
70 _old_gen_policy_is_ready = false;
71 }
72
73 void PSAdaptiveSizePolicy::major_collection_begin() {
74 // Update the interval time
75 _major_timer.stop();
76 // Save most recent collection time
77 _latest_major_mutator_interval_seconds = _major_timer.seconds();
78 _major_timer.reset();
79 _major_timer.start();
80 }
81
82 void PSAdaptiveSizePolicy::update_minor_pause_old_estimator(
83 double minor_pause_in_ms) {
84 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
85 _minor_pause_old_estimator->update(promo_size_in_mbytes,
86 minor_pause_in_ms);
87 }
88
89 void PSAdaptiveSizePolicy::major_collection_end(size_t amount_live,
90 GCCause::Cause gc_cause) {
91 // Update the pause time.
92 _major_timer.stop();
93
94 if (gc_cause != GCCause::_java_lang_system_gc ||
95 UseAdaptiveSizePolicyWithSystemGC) {
96 double major_pause_in_seconds = _major_timer.seconds();
97 double major_pause_in_ms = major_pause_in_seconds * MILLIUNITS;
98
99 // Sample for performance counter
100 _avg_major_pause->sample(major_pause_in_seconds);
101
102 // Cost of collection (unit-less)
103 double collection_cost = 0.0;
104 if ((_latest_major_mutator_interval_seconds > 0.0) &&
105 (major_pause_in_seconds > 0.0)) {
106 double interval_in_seconds =
107 _latest_major_mutator_interval_seconds + major_pause_in_seconds;
108 collection_cost =
109 major_pause_in_seconds / interval_in_seconds;
110 avg_major_gc_cost()->sample(collection_cost);
111
112 // Sample for performance counter
113 _avg_major_interval->sample(interval_in_seconds);
114 }
115
116 // Calculate variables used to estimate pause time vs. gen sizes
117 double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
118 double promo_size_in_mbytes = ((double)_promo_size)/((double)M);
119 _major_pause_old_estimator->update(promo_size_in_mbytes,
120 major_pause_in_ms);
121 _major_pause_young_estimator->update(eden_size_in_mbytes,
122 major_pause_in_ms);
123
124 if (PrintAdaptiveSizePolicy && Verbose) {
125 gclog_or_tty->print("psAdaptiveSizePolicy::major_collection_end: "
126 "major gc cost: %f average: %f", collection_cost,
127 avg_major_gc_cost()->average());
128 gclog_or_tty->print_cr(" major pause: %f major period %f",
129 major_pause_in_ms,
130 _latest_major_mutator_interval_seconds * MILLIUNITS);
131 }
132
133 // Calculate variable used to estimate collection cost vs. gen sizes
134 assert(collection_cost >= 0.0, "Expected to be non-negative");
135 _major_collection_estimator->update(promo_size_in_mbytes,
136 collection_cost);
137 }
138
139 // Update the amount live at the end of a full GC
140 _live_at_last_full_gc = amount_live;
141
142 // The policy does not have enough data until at least some major collections
143 // have been done.
144 if (_avg_major_pause->count() >= AdaptiveSizePolicyReadyThreshold) {
145 _old_gen_policy_is_ready = true;
146 }
147
148 // Interval times use this timer to measure the interval that
149 // the mutator runs. Reset after the GC pause has been measured.
150 _major_timer.reset();
151 _major_timer.start();
152 }
153
154 // If the remaining free space in the old generation is less that
155 // that expected to be needed by the next collection, do a full
156 // collection now.
157 bool PSAdaptiveSizePolicy::should_full_GC(size_t old_free_in_bytes) {
158
159 // A similar test is done in the scavenge's should_attempt_scavenge(). If
160 // this is changed, decide if that test should also be changed.
161 bool result = padded_average_promoted_in_bytes() > (float) old_free_in_bytes;
162 if (PrintGCDetails && Verbose) {
163 if (result) {
164 gclog_or_tty->print(" full after scavenge: ");
165 } else {
166 gclog_or_tty->print(" no full after scavenge: ");
167 }
168 gclog_or_tty->print_cr(" average_promoted " SIZE_FORMAT
169 " padded_average_promoted " SIZE_FORMAT
170 " free in old gen " SIZE_FORMAT,
171 (size_t) average_promoted_in_bytes(),
172 (size_t) padded_average_promoted_in_bytes(),
173 old_free_in_bytes);
174 }
175 return result;
176 }
177
178 void PSAdaptiveSizePolicy::clear_generation_free_space_flags() {
179
180 AdaptiveSizePolicy::clear_generation_free_space_flags();
181
182 set_change_old_gen_for_min_pauses(0);
183
184 set_change_young_gen_for_maj_pauses(0);
185 }
186
187 // If this is not a full GC, only test and modify the young generation.
188
189 void PSAdaptiveSizePolicy::compute_generation_free_space(
190 size_t young_live,
191 size_t eden_live,
192 size_t old_live,
193 size_t perm_live,
194 size_t cur_eden,
195 size_t max_old_gen_size,
196 size_t max_eden_size,
197 bool is_full_gc,
198 GCCause::Cause gc_cause,
199 CollectorPolicy* collector_policy) {
200
201 // Update statistics
202 // Time statistics are updated as we go, update footprint stats here
203 _avg_base_footprint->sample(BaseFootPrintEstimate + perm_live);
204 avg_young_live()->sample(young_live);
205 avg_eden_live()->sample(eden_live);
206 if (is_full_gc) {
207 // old_live is only accurate after a full gc
208 avg_old_live()->sample(old_live);
209 }
210
211 // This code used to return if the policy was not ready , i.e.,
212 // policy_is_ready() returning false. The intent was that
213 // decisions below needed major collection times and so could
214 // not be made before two major collections. A consequence was
215 // adjustments to the young generation were not done until after
216 // two major collections even if the minor collections times
217 // exceeded the requested goals. Now let the young generation
218 // adjust for the minor collection times. Major collection times
219 // will be zero for the first collection and will naturally be
220 // ignored. Tenured generation adjustments are only made at the
221 // full collections so until the second major collection has
222 // been reached, no tenured generation adjustments will be made.
223
224 // Until we know better, desired promotion size uses the last calculation
225 size_t desired_promo_size = _promo_size;
226
227 // Start eden at the current value. The desired value that is stored
228 // in _eden_size is not bounded by constraints of the heap and can
229 // run away.
230 //
231 // As expected setting desired_eden_size to the current
232 // value of desired_eden_size as a starting point
233 // caused desired_eden_size to grow way too large and caused
234 // an overflow down stream. It may have improved performance in
235 // some case but is dangerous.
236 size_t desired_eden_size = cur_eden;
237
238 #ifdef ASSERT
239 size_t original_promo_size = desired_promo_size;
240 size_t original_eden_size = desired_eden_size;
241 #endif
242
243 // Cache some values. There's a bit of work getting these, so
244 // we might save a little time.
245 const double major_cost = major_gc_cost();
246 const double minor_cost = minor_gc_cost();
247
248 // Used for diagnostics
249 clear_generation_free_space_flags();
250
251 // Limits on our growth
252 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());
253
254 // This method sets the desired eden size. That plus the
255 // desired survivor space sizes sets the desired young generation
256 // size. This methods does not know what the desired survivor
257 // size is but expects that other policy will attempt to make
258 // the survivor sizes compatible with the live data in the
259 // young generation. This limit is an estimate of the space left
260 // in the young generation after the survivor spaces have been
261 // subtracted out.
262 size_t eden_limit = max_eden_size;
263
264 // But don't force a promo size below the current promo size. Otherwise,
265 // the promo size will shrink for no good reason.
266 promo_limit = MAX2(promo_limit, _promo_size);
267
268 const double gc_cost_limit = GCTimeLimit/100.0;
269
270 // Which way should we go?
271 // if pause requirement is not met
272 // adjust size of any generation with average paus exceeding
273 // the pause limit. Adjust one pause at a time (the larger)
274 // and only make adjustments for the major pause at full collections.
275 // else if throughput requirement not met
276 // adjust the size of the generation with larger gc time. Only
277 // adjust one generation at a time.
278 // else
279 // adjust down the total heap size. Adjust down the larger of the
280 // generations.
281
282 // Add some checks for a threshhold for a change. For example,
283 // a change less than the necessary alignment is probably not worth
284 // attempting.
285
286
287 if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) ||
288 (_avg_major_pause->padded_average() > gc_pause_goal_sec())) {
289 //
290 // Check pauses
291 //
292 // Make changes only to affect one of the pauses (the larger)
293 // at a time.
294 adjust_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
295
296 } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) {
297 // Adjust only for the minor pause time goal
298 adjust_for_minor_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size);
299
300 } else if(adjusted_mutator_cost() < _throughput_goal) {
301 // This branch used to require that (mutator_cost() > 0.0 in 1.4.2.
302 // This sometimes resulted in skipping to the minimize footprint
303 // code. Change this to try and reduce GC time if mutator time is
304 // negative for whatever reason. Or for future consideration,
305 // bail out of the code if mutator time is negative.
306 //
307 // Throughput
308 //
309 assert(major_cost >= 0.0, "major cost is < 0.0");
310 assert(minor_cost >= 0.0, "minor cost is < 0.0");
311 // Try to reduce the GC times.
312 adjust_for_throughput(is_full_gc, &desired_promo_size, &desired_eden_size);
313
314 } else {
315
316 // Be conservative about reducing the footprint.
317 // Do a minimum number of major collections first.
318 // Have reasonable averages for major and minor collections costs.
319 if (UseAdaptiveSizePolicyFootprintGoal &&
320 young_gen_policy_is_ready() &&
321 avg_major_gc_cost()->average() >= 0.0 &&
322 avg_minor_gc_cost()->average() >= 0.0) {
323 size_t desired_sum = desired_eden_size + desired_promo_size;
324 desired_eden_size = adjust_eden_for_footprint(desired_eden_size,
325 desired_sum);
326 if (is_full_gc) {
327 set_decide_at_full_gc(decide_at_full_gc_true);
328 desired_promo_size = adjust_promo_for_footprint(desired_promo_size,
329 desired_sum);
330 }
331 }
332 }
333
334 // Note we make the same tests as in the code block below; the code
335 // seems a little easier to read with the printing in another block.
336 if (PrintAdaptiveSizePolicy) {
337 if (desired_promo_size > promo_limit) {
338 // "free_in_old_gen" was the original value for used for promo_limit
339 size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());
340 gclog_or_tty->print_cr(
341 "PSAdaptiveSizePolicy::compute_generation_free_space limits:"
342 " desired_promo_size: " SIZE_FORMAT
343 " promo_limit: " SIZE_FORMAT
344 " free_in_old_gen: " SIZE_FORMAT
345 " max_old_gen_size: " SIZE_FORMAT
346 " avg_old_live: " SIZE_FORMAT,
347 desired_promo_size, promo_limit, free_in_old_gen,
348 max_old_gen_size, (size_t) avg_old_live()->average());
349 }
350 if (desired_eden_size > eden_limit) {
351 gclog_or_tty->print_cr(
352 "AdaptiveSizePolicy::compute_generation_free_space limits:"
353 " desired_eden_size: " SIZE_FORMAT
354 " old_eden_size: " SIZE_FORMAT
355 " eden_limit: " SIZE_FORMAT
356 " cur_eden: " SIZE_FORMAT
357 " max_eden_size: " SIZE_FORMAT
358 " avg_young_live: " SIZE_FORMAT,
359 desired_eden_size, _eden_size, eden_limit, cur_eden,
360 max_eden_size, (size_t)avg_young_live()->average());
361 }
362 if (gc_cost() > gc_cost_limit) {
363 gclog_or_tty->print_cr(
364 "AdaptiveSizePolicy::compute_generation_free_space: gc time limit"
365 " gc_cost: %f "
366 " GCTimeLimit: %d",
367 gc_cost(), GCTimeLimit);
368 }
369 }
370
371 // Align everything and make a final limit check
372 const size_t alignment = _intra_generation_alignment;
373 desired_eden_size = align_size_up(desired_eden_size, alignment);
374 desired_eden_size = MAX2(desired_eden_size, alignment);
375 desired_promo_size = align_size_up(desired_promo_size, alignment);
376 desired_promo_size = MAX2(desired_promo_size, alignment);
377
378 eden_limit = align_size_down(eden_limit, alignment);
379 promo_limit = align_size_down(promo_limit, alignment);
380
381 // Is too much time being spent in GC?
382 // Is the heap trying to grow beyond it's limits?
383
384 const size_t free_in_old_gen =
385 (size_t)(max_old_gen_size - avg_old_live()->average());
386 if (desired_promo_size > free_in_old_gen && desired_eden_size > eden_limit) {
387 check_gc_overhead_limit(young_live,
388 eden_live,
389 max_old_gen_size,
390 max_eden_size,
391 is_full_gc,
392 gc_cause,
393 collector_policy);
394 }
395
396
397 // And one last limit check, now that we've aligned things.
398 if (desired_eden_size > eden_limit) {
399 // If the policy says to get a larger eden but
400 // is hitting the limit, don't decrease eden.
401 // This can lead to a general drifting down of the
402 // eden size. Let the tenuring calculation push more
403 // into the old gen.
404 desired_eden_size = MAX2(eden_limit, cur_eden);
405 }
406 desired_promo_size = MIN2(desired_promo_size, promo_limit);
407
408
409 if (PrintAdaptiveSizePolicy) {
410 // Timing stats
411 gclog_or_tty->print(
412 "PSAdaptiveSizePolicy::compute_generation_free_space: costs"
413 " minor_time: %f"
414 " major_cost: %f"
415 " mutator_cost: %f"
416 " throughput_goal: %f",
417 minor_gc_cost(), major_gc_cost(), mutator_cost(),
418 _throughput_goal);
419
420 // We give more details if Verbose is set
421 if (Verbose) {
422 gclog_or_tty->print( " minor_pause: %f"
423 " major_pause: %f"
424 " minor_interval: %f"
425 " major_interval: %f"
426 " pause_goal: %f",
427 _avg_minor_pause->padded_average(),
428 _avg_major_pause->padded_average(),
429 _avg_minor_interval->average(),
430 _avg_major_interval->average(),
431 gc_pause_goal_sec());
432 }
433
434 // Footprint stats
435 gclog_or_tty->print( " live_space: " SIZE_FORMAT
436 " free_space: " SIZE_FORMAT,
437 live_space(), free_space());
438 // More detail
439 if (Verbose) {
440 gclog_or_tty->print( " base_footprint: " SIZE_FORMAT
441 " avg_young_live: " SIZE_FORMAT
442 " avg_old_live: " SIZE_FORMAT,
443 (size_t)_avg_base_footprint->average(),
444 (size_t)avg_young_live()->average(),
445 (size_t)avg_old_live()->average());
446 }
447
448 // And finally, our old and new sizes.
449 gclog_or_tty->print(" old_promo_size: " SIZE_FORMAT
450 " old_eden_size: " SIZE_FORMAT
451 " desired_promo_size: " SIZE_FORMAT
452 " desired_eden_size: " SIZE_FORMAT,
453 _promo_size, _eden_size,
454 desired_promo_size, desired_eden_size);
455 gclog_or_tty->cr();
456 }
457
458 decay_supplemental_growth(is_full_gc);
459
460 set_promo_size(desired_promo_size);
461 set_eden_size(desired_eden_size);
462 };
463
464 void PSAdaptiveSizePolicy::decay_supplemental_growth(bool is_full_gc) {
465 // Decay the supplemental increment? Decay the supplement growth
466 // factor even if it is not used. It is only meant to give a boost
467 // to the initial growth and if it is not used, then it was not
468 // needed.
469 if (is_full_gc) {
470 // Don't wait for the threshold value for the major collections. If
471 // here, the supplemental growth term was used and should decay.
472 if ((_avg_major_pause->count() % TenuredGenerationSizeSupplementDecay)
473 == 0) {
474 _old_gen_size_increment_supplement =
475 _old_gen_size_increment_supplement >> 1;
476 }
477 } else {
478 if ((_avg_minor_pause->count() >= AdaptiveSizePolicyReadyThreshold) &&
479 (_avg_minor_pause->count() % YoungGenerationSizeSupplementDecay) == 0) {
480 _young_gen_size_increment_supplement =
481 _young_gen_size_increment_supplement >> 1;
482 }
483 }
484 }
485
486 void PSAdaptiveSizePolicy::adjust_for_minor_pause_time(bool is_full_gc,
487 size_t* desired_promo_size_ptr, size_t* desired_eden_size_ptr) {
488
489 // Adjust the young generation size to reduce pause time of
490 // of collections.
491 //
492 // The AdaptiveSizePolicyInitializingSteps test is not used
493 // here. It has not seemed to be needed but perhaps should
494 // be added for consistency.
495 if (minor_pause_young_estimator()->decrement_will_decrease()) {
496 // reduce eden size
497 set_change_young_gen_for_min_pauses(
498 decrease_young_gen_for_min_pauses_true);
499 *desired_eden_size_ptr = *desired_eden_size_ptr -
500 eden_decrement_aligned_down(*desired_eden_size_ptr);
501 } else {
502 // EXPERIMENTAL ADJUSTMENT
503 // Only record that the estimator indicated such an action.
504 // *desired_eden_size_ptr = *desired_eden_size_ptr + eden_heap_delta;
505 set_change_young_gen_for_min_pauses(
506 increase_young_gen_for_min_pauses_true);
507 }
508 if (PSAdjustTenuredGenForMinorPause) {
509 // If the desired eden size is as small as it will get,
510 // try to adjust the old gen size.
511 if (*desired_eden_size_ptr <= _intra_generation_alignment) {
512 // Vary the old gen size to reduce the young gen pause. This
513 // may not be a good idea. This is just a test.
514 if (minor_pause_old_estimator()->decrement_will_decrease()) {
515 set_change_old_gen_for_min_pauses(
516 decrease_old_gen_for_min_pauses_true);
517 *desired_promo_size_ptr =
518 _promo_size - promo_decrement_aligned_down(*desired_promo_size_ptr);
519 } else {
520 set_change_old_gen_for_min_pauses(
521 increase_old_gen_for_min_pauses_true);
522 size_t promo_heap_delta =
523 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
524 if ((*desired_promo_size_ptr + promo_heap_delta) >
525 *desired_promo_size_ptr) {
526 *desired_promo_size_ptr =
527 _promo_size + promo_heap_delta;
528 }
529 }
530 }
531 }
532 }
533
534 void PSAdaptiveSizePolicy::adjust_for_pause_time(bool is_full_gc,
535 size_t* desired_promo_size_ptr,
536 size_t* desired_eden_size_ptr) {
537
538 size_t promo_heap_delta = 0;
539 size_t eden_heap_delta = 0;
540 // Add some checks for a threshhold for a change. For example,
541 // a change less than the required alignment is probably not worth
542 // attempting.
543 if (is_full_gc) {
544 set_decide_at_full_gc(decide_at_full_gc_true);
545 }
546
547 if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) {
548 adjust_for_minor_pause_time(is_full_gc,
549 desired_promo_size_ptr,
550 desired_eden_size_ptr);
551 // major pause adjustments
552 } else if (is_full_gc) {
553 // Adjust for the major pause time only at full gc's because the
554 // affects of a change can only be seen at full gc's.
555
556 // Reduce old generation size to reduce pause?
557 if (major_pause_old_estimator()->decrement_will_decrease()) {
558 // reduce old generation size
559 set_change_old_gen_for_maj_pauses(decrease_old_gen_for_maj_pauses_true);
560 promo_heap_delta = promo_decrement_aligned_down(*desired_promo_size_ptr);
561 *desired_promo_size_ptr = _promo_size - promo_heap_delta;
562 } else {
563 // EXPERIMENTAL ADJUSTMENT
564 // Only record that the estimator indicated such an action.
565 // *desired_promo_size_ptr = _promo_size +
566 // promo_increment_aligned_up(*desired_promo_size_ptr);
567 set_change_old_gen_for_maj_pauses(increase_old_gen_for_maj_pauses_true);
568 }
569 if (PSAdjustYoungGenForMajorPause) {
570 // If the promo size is at the minimum (i.e., the old gen
571 // size will not actually decrease), consider changing the
572 // young gen size.
573 if (*desired_promo_size_ptr < _intra_generation_alignment) {
574 // If increasing the young generation will decrease the old gen
575 // pause, do it.
576 // During startup there is noise in the statistics for deciding
577 // on whether to increase or decrease the young gen size. For
578 // some number of iterations, just try to increase the young
579 // gen size if the major pause is too long to try and establish
580 // good statistics for later decisions.
581 if (major_pause_young_estimator()->increment_will_decrease() ||
582 (_young_gen_change_for_major_pause_count
583 <= AdaptiveSizePolicyInitializingSteps)) {
584 set_change_young_gen_for_maj_pauses(
585 increase_young_gen_for_maj_pauses_true);
586 eden_heap_delta = eden_increment_aligned_up(*desired_eden_size_ptr);
587 *desired_eden_size_ptr = _eden_size + eden_heap_delta;
588 _young_gen_change_for_major_pause_count++;
589 } else {
590 // Record that decreasing the young gen size would decrease
591 // the major pause
592 set_change_young_gen_for_maj_pauses(
593 decrease_young_gen_for_maj_pauses_true);
594 eden_heap_delta = eden_decrement_aligned_down(*desired_eden_size_ptr);
595 *desired_eden_size_ptr = _eden_size - eden_heap_delta;
596 }
597 }
598 }
599 }
600
601 if (PrintAdaptiveSizePolicy && Verbose) {
602 gclog_or_tty->print_cr(
603 "AdaptiveSizePolicy::compute_generation_free_space "
604 "adjusting gen sizes for major pause (avg %f goal %f). "
605 "desired_promo_size " SIZE_FORMAT "desired_eden_size "
606 SIZE_FORMAT
607 " promo delta " SIZE_FORMAT " eden delta " SIZE_FORMAT,
608 _avg_major_pause->average(), gc_pause_goal_sec(),
609 *desired_promo_size_ptr, *desired_eden_size_ptr,
610 promo_heap_delta, eden_heap_delta);
611 }
612 }
613
614 void PSAdaptiveSizePolicy::adjust_for_throughput(bool is_full_gc,
615 size_t* desired_promo_size_ptr,
616 size_t* desired_eden_size_ptr) {
617
618 // Add some checks for a threshhold for a change. For example,
619 // a change less than the required alignment is probably not worth
620 // attempting.
621 if (is_full_gc) {
622 set_decide_at_full_gc(decide_at_full_gc_true);
623 }
624
625 if ((gc_cost() + mutator_cost()) == 0.0) {
626 return;
627 }
628
629 if (PrintAdaptiveSizePolicy && Verbose) {
630 gclog_or_tty->print("\nPSAdaptiveSizePolicy::adjust_for_throughput("
631 "is_full: %d, promo: " SIZE_FORMAT ", cur_eden: " SIZE_FORMAT "): ",
632 is_full_gc, *desired_promo_size_ptr, *desired_eden_size_ptr);
633 gclog_or_tty->print_cr("mutator_cost %f major_gc_cost %f "
634 "minor_gc_cost %f", mutator_cost(), major_gc_cost(), minor_gc_cost());
635 }
636
637 // Tenured generation
638 if (is_full_gc) {
639
640 // Calculate the change to use for the tenured gen.
641 size_t scaled_promo_heap_delta = 0;
642 // Can the increment to the generation be scaled?
643 if (gc_cost() >= 0.0 && major_gc_cost() >= 0.0) {
644 size_t promo_heap_delta =
645 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
646 double scale_by_ratio = major_gc_cost() / gc_cost();
647 scaled_promo_heap_delta =
648 (size_t) (scale_by_ratio * (double) promo_heap_delta);
649 if (PrintAdaptiveSizePolicy && Verbose) {
650 gclog_or_tty->print_cr(
651 "Scaled tenured increment: " SIZE_FORMAT " by %f down to "
652 SIZE_FORMAT,
653 promo_heap_delta, scale_by_ratio, scaled_promo_heap_delta);
654 }
655 } else if (major_gc_cost() >= 0.0) {
656 // Scaling is not going to work. If the major gc time is the
657 // larger, give it a full increment.
658 if (major_gc_cost() >= minor_gc_cost()) {
659 scaled_promo_heap_delta =
660 promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr);
661 }
662 } else {
663 // Don't expect to get here but it's ok if it does
664 // in the product build since the delta will be 0
665 // and nothing will change.
666 assert(false, "Unexpected value for gc costs");
667 }
668
669 switch (AdaptiveSizeThroughPutPolicy) {
670 case 1:
671 // Early in the run the statistics might not be good. Until
672 // a specific number of collections have been, use the heuristic
673 // that a larger generation size means lower collection costs.
674 if (major_collection_estimator()->increment_will_decrease() ||
675 (_old_gen_change_for_major_throughput
676 <= AdaptiveSizePolicyInitializingSteps)) {
677 // Increase tenured generation size to reduce major collection cost
678 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
679 *desired_promo_size_ptr) {
680 *desired_promo_size_ptr = _promo_size + scaled_promo_heap_delta;
681 }
682 set_change_old_gen_for_throughput(
683 increase_old_gen_for_throughput_true);
684 _old_gen_change_for_major_throughput++;
685 } else {
686 // EXPERIMENTAL ADJUSTMENT
687 // Record that decreasing the old gen size would decrease
688 // the major collection cost but don't do it.
689 // *desired_promo_size_ptr = _promo_size -
690 // promo_decrement_aligned_down(*desired_promo_size_ptr);
691 set_change_old_gen_for_throughput(
692 decrease_old_gen_for_throughput_true);
693 }
694
695 break;
696 default:
697 // Simplest strategy
698 if ((*desired_promo_size_ptr + scaled_promo_heap_delta) >
699 *desired_promo_size_ptr) {
700 *desired_promo_size_ptr = *desired_promo_size_ptr +
701 scaled_promo_heap_delta;
702 }
703 set_change_old_gen_for_throughput(
704 increase_old_gen_for_throughput_true);
705 _old_gen_change_for_major_throughput++;
706 }
707
708 if (PrintAdaptiveSizePolicy && Verbose) {
709 gclog_or_tty->print_cr(
710 "adjusting tenured gen for throughput (avg %f goal %f). "
711 "desired_promo_size " SIZE_FORMAT " promo_delta " SIZE_FORMAT ,
712 mutator_cost(), _throughput_goal,
713 *desired_promo_size_ptr, scaled_promo_heap_delta);
714 }
715 }
716
717 // Young generation
718 size_t scaled_eden_heap_delta = 0;
719 // Can the increment to the generation be scaled?
720 if (gc_cost() >= 0.0 && minor_gc_cost() >= 0.0) {
721 size_t eden_heap_delta =
722 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
723 double scale_by_ratio = minor_gc_cost() / gc_cost();
724 assert(scale_by_ratio <= 1.0 && scale_by_ratio >= 0.0, "Scaling is wrong");
725 scaled_eden_heap_delta =
726 (size_t) (scale_by_ratio * (double) eden_heap_delta);
727 if (PrintAdaptiveSizePolicy && Verbose) {
728 gclog_or_tty->print_cr(
729 "Scaled eden increment: " SIZE_FORMAT " by %f down to "
730 SIZE_FORMAT,
731 eden_heap_delta, scale_by_ratio, scaled_eden_heap_delta);
732 }
733 } else if (minor_gc_cost() >= 0.0) {
734 // Scaling is not going to work. If the minor gc time is the
735 // larger, give it a full increment.
736 if (minor_gc_cost() > major_gc_cost()) {
737 scaled_eden_heap_delta =
738 eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr);
739 }
740 } else {
741 // Don't expect to get here but it's ok if it does
742 // in the product build since the delta will be 0
743 // and nothing will change.
744 assert(false, "Unexpected value for gc costs");
745 }
746
747 // Use a heuristic for some number of collections to give
748 // the averages time to settle down.
749 switch (AdaptiveSizeThroughPutPolicy) {
750 case 1:
751 if (minor_collection_estimator()->increment_will_decrease() ||
752 (_young_gen_change_for_minor_throughput
753 <= AdaptiveSizePolicyInitializingSteps)) {
754 // Expand young generation size to reduce frequency of
755 // of collections.
756 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
757 *desired_eden_size_ptr) {
758 *desired_eden_size_ptr =
759 *desired_eden_size_ptr + scaled_eden_heap_delta;
760 }
761 set_change_young_gen_for_throughput(
762 increase_young_gen_for_througput_true);
763 _young_gen_change_for_minor_throughput++;
764 } else {
765 // EXPERIMENTAL ADJUSTMENT
766 // Record that decreasing the young gen size would decrease
767 // the minor collection cost but don't do it.
768 // *desired_eden_size_ptr = _eden_size -
769 // eden_decrement_aligned_down(*desired_eden_size_ptr);
770 set_change_young_gen_for_throughput(
771 decrease_young_gen_for_througput_true);
772 }
773 break;
774 default:
775 if ((*desired_eden_size_ptr + scaled_eden_heap_delta) >
776 *desired_eden_size_ptr) {
777 *desired_eden_size_ptr =
778 *desired_eden_size_ptr + scaled_eden_heap_delta;
779 }
780 set_change_young_gen_for_throughput(
781 increase_young_gen_for_througput_true);
782 _young_gen_change_for_minor_throughput++;
783 }
784
785 if (PrintAdaptiveSizePolicy && Verbose) {
786 gclog_or_tty->print_cr(
787 "adjusting eden for throughput (avg %f goal %f). desired_eden_size "
788 SIZE_FORMAT " eden delta " SIZE_FORMAT "\n",
789 mutator_cost(), _throughput_goal,
790 *desired_eden_size_ptr, scaled_eden_heap_delta);
791 }
792 }
793
794 size_t PSAdaptiveSizePolicy::adjust_promo_for_footprint(
795 size_t desired_promo_size, size_t desired_sum) {
796 assert(desired_promo_size <= desired_sum, "Inconsistent parameters");
797 set_decrease_for_footprint(decrease_old_gen_for_footprint_true);
798
799 size_t change = promo_decrement(desired_promo_size);
800 change = scale_down(change, desired_promo_size, desired_sum);
801
802 size_t reduced_size = desired_promo_size - change;
803
804 if (PrintAdaptiveSizePolicy && Verbose) {
805 gclog_or_tty->print_cr(
806 "AdaptiveSizePolicy::compute_generation_free_space "
807 "adjusting tenured gen for footprint. "
808 "starting promo size " SIZE_FORMAT
809 " reduced promo size " SIZE_FORMAT,
810 " promo delta " SIZE_FORMAT,
811 desired_promo_size, reduced_size, change );
812 }
813
814 assert(reduced_size <= desired_promo_size, "Inconsistent result");
815 return reduced_size;
816 }
817
818 size_t PSAdaptiveSizePolicy::adjust_eden_for_footprint(
819 size_t desired_eden_size, size_t desired_sum) {
820 assert(desired_eden_size <= desired_sum, "Inconsistent parameters");
821 set_decrease_for_footprint(decrease_young_gen_for_footprint_true);
822
823 size_t change = eden_decrement(desired_eden_size);
824 change = scale_down(change, desired_eden_size, desired_sum);
825
826 size_t reduced_size = desired_eden_size - change;
827
828 if (PrintAdaptiveSizePolicy && Verbose) {
829 gclog_or_tty->print_cr(
830 "AdaptiveSizePolicy::compute_generation_free_space "
831 "adjusting eden for footprint. "
832 " starting eden size " SIZE_FORMAT
833 " reduced eden size " SIZE_FORMAT
834 " eden delta " SIZE_FORMAT,
835 desired_eden_size, reduced_size, change);
836 }
837
838 assert(reduced_size <= desired_eden_size, "Inconsistent result");
839 return reduced_size;
840 }
841
842 // Scale down "change" by the factor
843 // part / total
844 // Don't align the results.
845
846 size_t PSAdaptiveSizePolicy::scale_down(size_t change,
847 double part,
848 double total) {
849 assert(part <= total, "Inconsistent input");
850 size_t reduced_change = change;
851 if (total > 0) {
852 double fraction = part / total;
853 reduced_change = (size_t) (fraction * (double) change);
854 }
855 assert(reduced_change <= change, "Inconsistent result");
856 return reduced_change;
857 }
858
859 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden,
860 uint percent_change) {
861 size_t eden_heap_delta;
862 eden_heap_delta = cur_eden / 100 * percent_change;
863 return eden_heap_delta;
864 }
865
866 size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden) {
867 return eden_increment(cur_eden, YoungGenerationSizeIncrement);
868 }
869
870 size_t PSAdaptiveSizePolicy::eden_increment_aligned_up(size_t cur_eden) {
871 size_t result = eden_increment(cur_eden, YoungGenerationSizeIncrement);
872 return align_size_up(result, _intra_generation_alignment);
873 }
874
875 size_t PSAdaptiveSizePolicy::eden_increment_aligned_down(size_t cur_eden) {
876 size_t result = eden_increment(cur_eden);
877 return align_size_down(result, _intra_generation_alignment);
878 }
879
880 size_t PSAdaptiveSizePolicy::eden_increment_with_supplement_aligned_up(
881 size_t cur_eden) {
882 size_t result = eden_increment(cur_eden,
883 YoungGenerationSizeIncrement + _young_gen_size_increment_supplement);
884 return align_size_up(result, _intra_generation_alignment);
885 }
886
887 size_t PSAdaptiveSizePolicy::eden_decrement_aligned_down(size_t cur_eden) {
888 size_t eden_heap_delta = eden_decrement(cur_eden);
889 return align_size_down(eden_heap_delta, _intra_generation_alignment);
890 }
891
892 size_t PSAdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
893 size_t eden_heap_delta = eden_increment(cur_eden) /
894 AdaptiveSizeDecrementScaleFactor;
895 return eden_heap_delta;
896 }
897
898 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo,
899 uint percent_change) {
900 size_t promo_heap_delta;
901 promo_heap_delta = cur_promo / 100 * percent_change;
902 return promo_heap_delta;
903 }
904
905 size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo) {
906 return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
907 }
908
909 size_t PSAdaptiveSizePolicy::promo_increment_aligned_up(size_t cur_promo) {
910 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
911 return align_size_up(result, _intra_generation_alignment);
912 }
913
914 size_t PSAdaptiveSizePolicy::promo_increment_aligned_down(size_t cur_promo) {
915 size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement);
916 return align_size_down(result, _intra_generation_alignment);
917 }
918
919 size_t PSAdaptiveSizePolicy::promo_increment_with_supplement_aligned_up(
920 size_t cur_promo) {
921 size_t result = promo_increment(cur_promo,
922 TenuredGenerationSizeIncrement + _old_gen_size_increment_supplement);
923 return align_size_up(result, _intra_generation_alignment);
924 }
925
926 size_t PSAdaptiveSizePolicy::promo_decrement_aligned_down(size_t cur_promo) {
927 size_t promo_heap_delta = promo_decrement(cur_promo);
928 return align_size_down(promo_heap_delta, _intra_generation_alignment);
929 }
930
931 size_t PSAdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
932 size_t promo_heap_delta = promo_increment(cur_promo);
933 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
934 return promo_heap_delta;
935 }
936
937 int PSAdaptiveSizePolicy::compute_survivor_space_size_and_threshold(
938 bool is_survivor_overflow,
939 int tenuring_threshold,
940 size_t survivor_limit) {
941 assert(survivor_limit >= _intra_generation_alignment,
942 "survivor_limit too small");
943 assert((size_t)align_size_down(survivor_limit, _intra_generation_alignment)
944 == survivor_limit, "survivor_limit not aligned");
945
946 // This method is called even if the tenuring threshold and survivor
947 // spaces are not adjusted so that the averages are sampled above.
948 if (!UsePSAdaptiveSurvivorSizePolicy ||
949 !young_gen_policy_is_ready()) {
950 return tenuring_threshold;
951 }
952
953 // We'll decide whether to increase or decrease the tenuring
954 // threshold based partly on the newly computed survivor size
955 // (if we hit the maximum limit allowed, we'll always choose to
956 // decrement the threshold).
957 bool incr_tenuring_threshold = false;
958 bool decr_tenuring_threshold = false;
959
960 set_decrement_tenuring_threshold_for_gc_cost(false);
961 set_increment_tenuring_threshold_for_gc_cost(false);
962 set_decrement_tenuring_threshold_for_survivor_limit(false);
963
964 if (!is_survivor_overflow) {
965 // Keep running averages on how much survived
966
967 // We use the tenuring threshold to equalize the cost of major
968 // and minor collections.
969 // ThresholdTolerance is used to indicate how sensitive the
970 // tenuring threshold is to differences in cost betweent the
971 // collection types.
972
973 // Get the times of interest. This involves a little work, so
974 // we cache the values here.
975 const double major_cost = major_gc_cost();
976 const double minor_cost = minor_gc_cost();
977
978 if (minor_cost > major_cost * _threshold_tolerance_percent) {
979 // Minor times are getting too long; lower the threshold so
980 // less survives and more is promoted.
981 decr_tenuring_threshold = true;
982 set_decrement_tenuring_threshold_for_gc_cost(true);
983 } else if (major_cost > minor_cost * _threshold_tolerance_percent) {
984 // Major times are too long, so we want less promotion.
985 incr_tenuring_threshold = true;
986 set_increment_tenuring_threshold_for_gc_cost(true);
987 }
988
989 } else {
990 // Survivor space overflow occurred, so promoted and survived are
991 // not accurate. We'll make our best guess by combining survived
992 // and promoted and count them as survivors.
993 //
994 // We'll lower the tenuring threshold to see if we can correct
995 // things. Also, set the survivor size conservatively. We're
996 // trying to avoid many overflows from occurring if defnew size
997 // is just too small.
998
999 decr_tenuring_threshold = true;
1000 }
1001
1002 // The padded average also maintains a deviation from the average;
1003 // we use this to see how good of an estimate we have of what survived.
1004 // We're trying to pad the survivor size as little as possible without
1005 // overflowing the survivor spaces.
1006 size_t target_size = align_size_up((size_t)_avg_survived->padded_average(),
1007 _intra_generation_alignment);
1008 target_size = MAX2(target_size, _intra_generation_alignment);
1009
1010 if (target_size > survivor_limit) {
1011 // Target size is bigger than we can handle. Let's also reduce
1012 // the tenuring threshold.
1013 target_size = survivor_limit;
1014 decr_tenuring_threshold = true;
1015 set_decrement_tenuring_threshold_for_survivor_limit(true);
1016 }
1017
1018 // Finally, increment or decrement the tenuring threshold, as decided above.
1019 // We test for decrementing first, as we might have hit the target size
1020 // limit.
1021 if (decr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1022 if (tenuring_threshold > 1) {
1023 tenuring_threshold--;
1024 }
1025 } else if (incr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) {
1026 if (tenuring_threshold < MaxTenuringThreshold) {
1027 tenuring_threshold++;
1028 }
1029 }
1030
1031 // We keep a running average of the amount promoted which is used
1032 // to decide when we should collect the old generation (when
1033 // the amount of old gen free space is less than what we expect to
1034 // promote).
1035
1036 if (PrintAdaptiveSizePolicy) {
1037 // A little more detail if Verbose is on
1038 if (Verbose) {
1039 gclog_or_tty->print( " avg_survived: %f"
1040 " avg_deviation: %f",
1041 _avg_survived->average(),
1042 _avg_survived->deviation());
1043 }
1044
1045 gclog_or_tty->print( " avg_survived_padded_avg: %f",
1046 _avg_survived->padded_average());
1047
1048 if (Verbose) {
1049 gclog_or_tty->print( " avg_promoted_avg: %f"
1050 " avg_promoted_dev: %f",
1051 avg_promoted()->average(),
1052 avg_promoted()->deviation());
1053 }
1054
1055 gclog_or_tty->print( " avg_promoted_padded_avg: %f"
1056 " avg_pretenured_padded_avg: %f"
1057 " tenuring_thresh: %d"
1058 " target_size: " SIZE_FORMAT,
1059 avg_promoted()->padded_average(),
1060 _avg_pretenured->padded_average(),
1061 tenuring_threshold, target_size);
1062 tty->cr();
1063 }
1064
1065 set_survivor_size(target_size);
1066
1067 return tenuring_threshold;
1068 }
1069
1070 void PSAdaptiveSizePolicy::update_averages(bool is_survivor_overflow,
1071 size_t survived,
1072 size_t promoted) {
1073 // Update averages
1074 if (!is_survivor_overflow) {
1075 // Keep running averages on how much survived
1076 _avg_survived->sample(survived);
1077 } else {
1078 size_t survived_guess = survived + promoted;
1079 _avg_survived->sample(survived_guess);
1080 }
1081 avg_promoted()->sample(promoted + _avg_pretenured->padded_average());
1082
1083 if (PrintAdaptiveSizePolicy) {
1084 gclog_or_tty->print(
1085 "AdaptiveSizePolicy::compute_survivor_space_size_and_thresh:"
1086 " survived: " SIZE_FORMAT
1087 " promoted: " SIZE_FORMAT
1088 " overflow: %s",
1089 survived, promoted, is_survivor_overflow ? "true" : "false");
1090 }
1091 }
1092
1093 bool PSAdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st)
1094 const {
1095
1096 if (!UseAdaptiveSizePolicy) return false;
1097
1098 return AdaptiveSizePolicy::print_adaptive_size_policy_on(
1099 st,
1100 PSScavenge::tenuring_threshold());
1101 }