Tue, 26 Nov 2013 14:35:38 +0100
8027675: Full collections with Serial slower in JDK 8 compared to 7u40
Summary: Reduced the number of calls to follow_class_loader and instead marked and pushed the klass holder directly. Also removed unneeded calls to adjust_klass.
Reviewed-by: coleenp, jmasa, mgerdin, tschatzl
1 /*
2 * Copyright (c) 2004, 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.
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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
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23 */
25 #include "precompiled.hpp"
26 #include "gc_implementation/shared/adaptiveSizePolicy.hpp"
27 #include "gc_interface/gcCause.hpp"
28 #include "memory/collectorPolicy.hpp"
29 #include "runtime/timer.hpp"
30 #include "utilities/ostream.hpp"
31 #include "utilities/workgroup.hpp"
32 elapsedTimer AdaptiveSizePolicy::_minor_timer;
33 elapsedTimer AdaptiveSizePolicy::_major_timer;
34 bool AdaptiveSizePolicy::_debug_perturbation = false;
36 // The throughput goal is implemented as
37 // _throughput_goal = 1 - ( 1 / (1 + gc_cost_ratio))
38 // gc_cost_ratio is the ratio
39 // application cost / gc cost
40 // For example a gc_cost_ratio of 4 translates into a
41 // throughput goal of .80
43 AdaptiveSizePolicy::AdaptiveSizePolicy(size_t init_eden_size,
44 size_t init_promo_size,
45 size_t init_survivor_size,
46 double gc_pause_goal_sec,
47 uint gc_cost_ratio) :
48 _eden_size(init_eden_size),
49 _promo_size(init_promo_size),
50 _survivor_size(init_survivor_size),
51 _gc_pause_goal_sec(gc_pause_goal_sec),
52 _throughput_goal(1.0 - double(1.0 / (1.0 + (double) gc_cost_ratio))),
53 _gc_overhead_limit_exceeded(false),
54 _print_gc_overhead_limit_would_be_exceeded(false),
55 _gc_overhead_limit_count(0),
56 _latest_minor_mutator_interval_seconds(0),
57 _threshold_tolerance_percent(1.0 + ThresholdTolerance/100.0),
58 _young_gen_change_for_minor_throughput(0),
59 _old_gen_change_for_major_throughput(0) {
60 assert(AdaptiveSizePolicyGCTimeLimitThreshold > 0,
61 "No opportunity to clear SoftReferences before GC overhead limit");
62 _avg_minor_pause =
63 new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding);
64 _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
65 _avg_minor_gc_cost = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
66 _avg_major_gc_cost = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
68 _avg_young_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
69 _avg_old_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
70 _avg_eden_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
72 _avg_survived = new AdaptivePaddedAverage(AdaptiveSizePolicyWeight,
73 SurvivorPadding);
74 _avg_pretenured = new AdaptivePaddedNoZeroDevAverage(
75 AdaptiveSizePolicyWeight,
76 SurvivorPadding);
78 _minor_pause_old_estimator =
79 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
80 _minor_pause_young_estimator =
81 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
82 _minor_collection_estimator =
83 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
84 _major_collection_estimator =
85 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
87 // Start the timers
88 _minor_timer.start();
90 _young_gen_policy_is_ready = false;
91 }
93 // If the number of GC threads was set on the command line,
94 // use it.
95 // Else
96 // Calculate the number of GC threads based on the number of Java threads.
97 // Calculate the number of GC threads based on the size of the heap.
98 // Use the larger.
100 int AdaptiveSizePolicy::calc_default_active_workers(uintx total_workers,
101 const uintx min_workers,
102 uintx active_workers,
103 uintx application_workers) {
104 // If the user has specifically set the number of
105 // GC threads, use them.
107 // If the user has turned off using a dynamic number of GC threads
108 // or the users has requested a specific number, set the active
109 // number of workers to all the workers.
111 uintx new_active_workers = total_workers;
112 uintx prev_active_workers = active_workers;
113 uintx active_workers_by_JT = 0;
114 uintx active_workers_by_heap_size = 0;
116 // Always use at least min_workers but use up to
117 // GCThreadsPerJavaThreads * application threads.
118 active_workers_by_JT =
119 MAX2((uintx) GCWorkersPerJavaThread * application_workers,
120 min_workers);
122 // Choose a number of GC threads based on the current size
123 // of the heap. This may be complicated because the size of
124 // the heap depends on factors such as the thoughput goal.
125 // Still a large heap should be collected by more GC threads.
126 active_workers_by_heap_size =
127 MAX2((size_t) 2U, Universe::heap()->capacity() / HeapSizePerGCThread);
129 uintx max_active_workers =
130 MAX2(active_workers_by_JT, active_workers_by_heap_size);
132 // Limit the number of workers to the the number created,
133 // (workers()).
134 new_active_workers = MIN2(max_active_workers,
135 (uintx) total_workers);
137 // Increase GC workers instantly but decrease them more
138 // slowly.
139 if (new_active_workers < prev_active_workers) {
140 new_active_workers =
141 MAX2(min_workers, (prev_active_workers + new_active_workers) / 2);
142 }
144 // Check once more that the number of workers is within the limits.
145 assert(min_workers <= total_workers, "Minimum workers not consistent with total workers");
146 assert(new_active_workers >= min_workers, "Minimum workers not observed");
147 assert(new_active_workers <= total_workers, "Total workers not observed");
149 if (ForceDynamicNumberOfGCThreads) {
150 // Assume this is debugging and jiggle the number of GC threads.
151 if (new_active_workers == prev_active_workers) {
152 if (new_active_workers < total_workers) {
153 new_active_workers++;
154 } else if (new_active_workers > min_workers) {
155 new_active_workers--;
156 }
157 }
158 if (new_active_workers == total_workers) {
159 if (_debug_perturbation) {
160 new_active_workers = min_workers;
161 }
162 _debug_perturbation = !_debug_perturbation;
163 }
164 assert((new_active_workers <= (uintx) ParallelGCThreads) &&
165 (new_active_workers >= min_workers),
166 "Jiggled active workers too much");
167 }
169 if (TraceDynamicGCThreads) {
170 gclog_or_tty->print_cr("GCTaskManager::calc_default_active_workers() : "
171 "active_workers(): %d new_acitve_workers: %d "
172 "prev_active_workers: %d\n"
173 " active_workers_by_JT: %d active_workers_by_heap_size: %d",
174 active_workers, new_active_workers, prev_active_workers,
175 active_workers_by_JT, active_workers_by_heap_size);
176 }
177 assert(new_active_workers > 0, "Always need at least 1");
178 return new_active_workers;
179 }
181 int AdaptiveSizePolicy::calc_active_workers(uintx total_workers,
182 uintx active_workers,
183 uintx application_workers) {
184 // If the user has specifically set the number of
185 // GC threads, use them.
187 // If the user has turned off using a dynamic number of GC threads
188 // or the users has requested a specific number, set the active
189 // number of workers to all the workers.
191 int new_active_workers;
192 if (!UseDynamicNumberOfGCThreads ||
193 (!FLAG_IS_DEFAULT(ParallelGCThreads) && !ForceDynamicNumberOfGCThreads)) {
194 new_active_workers = total_workers;
195 } else {
196 new_active_workers = calc_default_active_workers(total_workers,
197 2, /* Minimum number of workers */
198 active_workers,
199 application_workers);
200 }
201 assert(new_active_workers > 0, "Always need at least 1");
202 return new_active_workers;
203 }
205 int AdaptiveSizePolicy::calc_active_conc_workers(uintx total_workers,
206 uintx active_workers,
207 uintx application_workers) {
208 if (!UseDynamicNumberOfGCThreads ||
209 (!FLAG_IS_DEFAULT(ConcGCThreads) && !ForceDynamicNumberOfGCThreads)) {
210 return ConcGCThreads;
211 } else {
212 int no_of_gc_threads = calc_default_active_workers(
213 total_workers,
214 1, /* Minimum number of workers */
215 active_workers,
216 application_workers);
217 return no_of_gc_threads;
218 }
219 }
221 bool AdaptiveSizePolicy::tenuring_threshold_change() const {
222 return decrement_tenuring_threshold_for_gc_cost() ||
223 increment_tenuring_threshold_for_gc_cost() ||
224 decrement_tenuring_threshold_for_survivor_limit();
225 }
227 void AdaptiveSizePolicy::minor_collection_begin() {
228 // Update the interval time
229 _minor_timer.stop();
230 // Save most recent collection time
231 _latest_minor_mutator_interval_seconds = _minor_timer.seconds();
232 _minor_timer.reset();
233 _minor_timer.start();
234 }
236 void AdaptiveSizePolicy::update_minor_pause_young_estimator(
237 double minor_pause_in_ms) {
238 double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
239 _minor_pause_young_estimator->update(eden_size_in_mbytes,
240 minor_pause_in_ms);
241 }
243 void AdaptiveSizePolicy::minor_collection_end(GCCause::Cause gc_cause) {
244 // Update the pause time.
245 _minor_timer.stop();
247 if (gc_cause != GCCause::_java_lang_system_gc ||
248 UseAdaptiveSizePolicyWithSystemGC) {
249 double minor_pause_in_seconds = _minor_timer.seconds();
250 double minor_pause_in_ms = minor_pause_in_seconds * MILLIUNITS;
252 // Sample for performance counter
253 _avg_minor_pause->sample(minor_pause_in_seconds);
255 // Cost of collection (unit-less)
256 double collection_cost = 0.0;
257 if ((_latest_minor_mutator_interval_seconds > 0.0) &&
258 (minor_pause_in_seconds > 0.0)) {
259 double interval_in_seconds =
260 _latest_minor_mutator_interval_seconds + minor_pause_in_seconds;
261 collection_cost =
262 minor_pause_in_seconds / interval_in_seconds;
263 _avg_minor_gc_cost->sample(collection_cost);
264 // Sample for performance counter
265 _avg_minor_interval->sample(interval_in_seconds);
266 }
268 // The policy does not have enough data until at least some
269 // minor collections have been done.
270 _young_gen_policy_is_ready =
271 (_avg_minor_gc_cost->count() >= AdaptiveSizePolicyReadyThreshold);
273 // Calculate variables used to estimate pause time vs. gen sizes
274 double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
275 update_minor_pause_young_estimator(minor_pause_in_ms);
276 update_minor_pause_old_estimator(minor_pause_in_ms);
278 if (PrintAdaptiveSizePolicy && Verbose) {
279 gclog_or_tty->print("AdaptiveSizePolicy::minor_collection_end: "
280 "minor gc cost: %f average: %f", collection_cost,
281 _avg_minor_gc_cost->average());
282 gclog_or_tty->print_cr(" minor pause: %f minor period %f",
283 minor_pause_in_ms,
284 _latest_minor_mutator_interval_seconds * MILLIUNITS);
285 }
287 // Calculate variable used to estimate collection cost vs. gen sizes
288 assert(collection_cost >= 0.0, "Expected to be non-negative");
289 _minor_collection_estimator->update(eden_size_in_mbytes, collection_cost);
290 }
292 // Interval times use this timer to measure the mutator time.
293 // Reset the timer after the GC pause.
294 _minor_timer.reset();
295 _minor_timer.start();
296 }
298 size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden,
299 uint percent_change) {
300 size_t eden_heap_delta;
301 eden_heap_delta = cur_eden / 100 * percent_change;
302 return eden_heap_delta;
303 }
305 size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden) {
306 return eden_increment(cur_eden, YoungGenerationSizeIncrement);
307 }
309 size_t AdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
310 size_t eden_heap_delta = eden_increment(cur_eden) /
311 AdaptiveSizeDecrementScaleFactor;
312 return eden_heap_delta;
313 }
315 size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo,
316 uint percent_change) {
317 size_t promo_heap_delta;
318 promo_heap_delta = cur_promo / 100 * percent_change;
319 return promo_heap_delta;
320 }
322 size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo) {
323 return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
324 }
326 size_t AdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
327 size_t promo_heap_delta = promo_increment(cur_promo);
328 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
329 return promo_heap_delta;
330 }
332 double AdaptiveSizePolicy::time_since_major_gc() const {
333 _major_timer.stop();
334 double result = _major_timer.seconds();
335 _major_timer.start();
336 return result;
337 }
339 // Linear decay of major gc cost
340 double AdaptiveSizePolicy::decaying_major_gc_cost() const {
341 double major_interval = major_gc_interval_average_for_decay();
342 double major_gc_cost_average = major_gc_cost();
343 double decayed_major_gc_cost = major_gc_cost_average;
344 if(time_since_major_gc() > 0.0) {
345 decayed_major_gc_cost = major_gc_cost() *
346 (((double) AdaptiveSizeMajorGCDecayTimeScale) * major_interval)
347 / time_since_major_gc();
348 }
350 // The decayed cost should always be smaller than the
351 // average cost but the vagaries of finite arithmetic could
352 // produce a larger value in decayed_major_gc_cost so protect
353 // against that.
354 return MIN2(major_gc_cost_average, decayed_major_gc_cost);
355 }
357 // Use a value of the major gc cost that has been decayed
358 // by the factor
359 //
360 // average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale /
361 // time-since-last-major-gc
362 //
363 // if the average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale
364 // is less than time-since-last-major-gc.
365 //
366 // In cases where there are initial major gc's that
367 // are of a relatively high cost but no later major
368 // gc's, the total gc cost can remain high because
369 // the major gc cost remains unchanged (since there are no major
370 // gc's). In such a situation the value of the unchanging
371 // major gc cost can keep the mutator throughput below
372 // the goal when in fact the major gc cost is becoming diminishingly
373 // small. Use the decaying gc cost only to decide whether to
374 // adjust for throughput. Using it also to determine the adjustment
375 // to be made for throughput also seems reasonable but there is
376 // no test case to use to decide if it is the right thing to do
377 // don't do it yet.
379 double AdaptiveSizePolicy::decaying_gc_cost() const {
380 double decayed_major_gc_cost = major_gc_cost();
381 double avg_major_interval = major_gc_interval_average_for_decay();
382 if (UseAdaptiveSizeDecayMajorGCCost &&
383 (AdaptiveSizeMajorGCDecayTimeScale > 0) &&
384 (avg_major_interval > 0.00)) {
385 double time_since_last_major_gc = time_since_major_gc();
387 // Decay the major gc cost?
388 if (time_since_last_major_gc >
389 ((double) AdaptiveSizeMajorGCDecayTimeScale) * avg_major_interval) {
391 // Decay using the time-since-last-major-gc
392 decayed_major_gc_cost = decaying_major_gc_cost();
393 if (PrintGCDetails && Verbose) {
394 gclog_or_tty->print_cr("\ndecaying_gc_cost: major interval average:"
395 " %f time since last major gc: %f",
396 avg_major_interval, time_since_last_major_gc);
397 gclog_or_tty->print_cr(" major gc cost: %f decayed major gc cost: %f",
398 major_gc_cost(), decayed_major_gc_cost);
399 }
400 }
401 }
402 double result = MIN2(1.0, decayed_major_gc_cost + minor_gc_cost());
403 return result;
404 }
407 void AdaptiveSizePolicy::clear_generation_free_space_flags() {
408 set_change_young_gen_for_min_pauses(0);
409 set_change_old_gen_for_maj_pauses(0);
411 set_change_old_gen_for_throughput(0);
412 set_change_young_gen_for_throughput(0);
413 set_decrease_for_footprint(0);
414 set_decide_at_full_gc(0);
415 }
417 void AdaptiveSizePolicy::check_gc_overhead_limit(
418 size_t young_live,
419 size_t eden_live,
420 size_t max_old_gen_size,
421 size_t max_eden_size,
422 bool is_full_gc,
423 GCCause::Cause gc_cause,
424 CollectorPolicy* collector_policy) {
426 // Ignore explicit GC's. Exiting here does not set the flag and
427 // does not reset the count. Updating of the averages for system
428 // GC's is still controlled by UseAdaptiveSizePolicyWithSystemGC.
429 if (GCCause::is_user_requested_gc(gc_cause) ||
430 GCCause::is_serviceability_requested_gc(gc_cause)) {
431 return;
432 }
433 // eden_limit is the upper limit on the size of eden based on
434 // the maximum size of the young generation and the sizes
435 // of the survivor space.
436 // The question being asked is whether the gc costs are high
437 // and the space being recovered by a collection is low.
438 // free_in_young_gen is the free space in the young generation
439 // after a collection and promo_live is the free space in the old
440 // generation after a collection.
441 //
442 // Use the minimum of the current value of the live in the
443 // young gen or the average of the live in the young gen.
444 // If the current value drops quickly, that should be taken
445 // into account (i.e., don't trigger if the amount of free
446 // space has suddenly jumped up). If the current is much
447 // higher than the average, use the average since it represents
448 // the longer term behavor.
449 const size_t live_in_eden =
450 MIN2(eden_live, (size_t) avg_eden_live()->average());
451 const size_t free_in_eden = max_eden_size > live_in_eden ?
452 max_eden_size - live_in_eden : 0;
453 const size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());
454 const size_t total_free_limit = free_in_old_gen + free_in_eden;
455 const size_t total_mem = max_old_gen_size + max_eden_size;
456 const double mem_free_limit = total_mem * (GCHeapFreeLimit/100.0);
457 const double mem_free_old_limit = max_old_gen_size * (GCHeapFreeLimit/100.0);
458 const double mem_free_eden_limit = max_eden_size * (GCHeapFreeLimit/100.0);
459 const double gc_cost_limit = GCTimeLimit/100.0;
460 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());
461 // But don't force a promo size below the current promo size. Otherwise,
462 // the promo size will shrink for no good reason.
463 promo_limit = MAX2(promo_limit, _promo_size);
466 if (PrintAdaptiveSizePolicy && (Verbose ||
467 (free_in_old_gen < (size_t) mem_free_old_limit &&
468 free_in_eden < (size_t) mem_free_eden_limit))) {
469 gclog_or_tty->print_cr(
470 "PSAdaptiveSizePolicy::check_gc_overhead_limit:"
471 " promo_limit: " SIZE_FORMAT
472 " max_eden_size: " SIZE_FORMAT
473 " total_free_limit: " SIZE_FORMAT
474 " max_old_gen_size: " SIZE_FORMAT
475 " max_eden_size: " SIZE_FORMAT
476 " mem_free_limit: " SIZE_FORMAT,
477 promo_limit, max_eden_size, total_free_limit,
478 max_old_gen_size, max_eden_size,
479 (size_t) mem_free_limit);
480 }
482 bool print_gc_overhead_limit_would_be_exceeded = false;
483 if (is_full_gc) {
484 if (gc_cost() > gc_cost_limit &&
485 free_in_old_gen < (size_t) mem_free_old_limit &&
486 free_in_eden < (size_t) mem_free_eden_limit) {
487 // Collections, on average, are taking too much time, and
488 // gc_cost() > gc_cost_limit
489 // we have too little space available after a full gc.
490 // total_free_limit < mem_free_limit
491 // where
492 // total_free_limit is the free space available in
493 // both generations
494 // total_mem is the total space available for allocation
495 // in both generations (survivor spaces are not included
496 // just as they are not included in eden_limit).
497 // mem_free_limit is a fraction of total_mem judged to be an
498 // acceptable amount that is still unused.
499 // The heap can ask for the value of this variable when deciding
500 // whether to thrown an OutOfMemory error.
501 // Note that the gc time limit test only works for the collections
502 // of the young gen + tenured gen and not for collections of the
503 // permanent gen. That is because the calculation of the space
504 // freed by the collection is the free space in the young gen +
505 // tenured gen.
506 // At this point the GC overhead limit is being exceeded.
507 inc_gc_overhead_limit_count();
508 if (UseGCOverheadLimit) {
509 if (gc_overhead_limit_count() >=
510 AdaptiveSizePolicyGCTimeLimitThreshold){
511 // All conditions have been met for throwing an out-of-memory
512 set_gc_overhead_limit_exceeded(true);
513 // Avoid consecutive OOM due to the gc time limit by resetting
514 // the counter.
515 reset_gc_overhead_limit_count();
516 } else {
517 // The required consecutive collections which exceed the
518 // GC time limit may or may not have been reached. We
519 // are approaching that condition and so as not to
520 // throw an out-of-memory before all SoftRef's have been
521 // cleared, set _should_clear_all_soft_refs in CollectorPolicy.
522 // The clearing will be done on the next GC.
523 bool near_limit = gc_overhead_limit_near();
524 if (near_limit) {
525 collector_policy->set_should_clear_all_soft_refs(true);
526 if (PrintGCDetails && Verbose) {
527 gclog_or_tty->print_cr(" Nearing GC overhead limit, "
528 "will be clearing all SoftReference");
529 }
530 }
531 }
532 }
533 // Set this even when the overhead limit will not
534 // cause an out-of-memory. Diagnostic message indicating
535 // that the overhead limit is being exceeded is sometimes
536 // printed.
537 print_gc_overhead_limit_would_be_exceeded = true;
539 } else {
540 // Did not exceed overhead limits
541 reset_gc_overhead_limit_count();
542 }
543 }
545 if (UseGCOverheadLimit && PrintGCDetails && Verbose) {
546 if (gc_overhead_limit_exceeded()) {
547 gclog_or_tty->print_cr(" GC is exceeding overhead limit "
548 "of %d%%", GCTimeLimit);
549 reset_gc_overhead_limit_count();
550 } else if (print_gc_overhead_limit_would_be_exceeded) {
551 assert(gc_overhead_limit_count() > 0, "Should not be printing");
552 gclog_or_tty->print_cr(" GC would exceed overhead limit "
553 "of %d%% %d consecutive time(s)",
554 GCTimeLimit, gc_overhead_limit_count());
555 }
556 }
557 }
558 // Printing
560 bool AdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st) const {
562 // Should only be used with adaptive size policy turned on.
563 // Otherwise, there may be variables that are undefined.
564 if (!UseAdaptiveSizePolicy) return false;
566 // Print goal for which action is needed.
567 char* action = NULL;
568 bool change_for_pause = false;
569 if ((change_old_gen_for_maj_pauses() ==
570 decrease_old_gen_for_maj_pauses_true) ||
571 (change_young_gen_for_min_pauses() ==
572 decrease_young_gen_for_min_pauses_true)) {
573 action = (char*) " *** pause time goal ***";
574 change_for_pause = true;
575 } else if ((change_old_gen_for_throughput() ==
576 increase_old_gen_for_throughput_true) ||
577 (change_young_gen_for_throughput() ==
578 increase_young_gen_for_througput_true)) {
579 action = (char*) " *** throughput goal ***";
580 } else if (decrease_for_footprint()) {
581 action = (char*) " *** reduced footprint ***";
582 } else {
583 // No actions were taken. This can legitimately be the
584 // situation if not enough data has been gathered to make
585 // decisions.
586 return false;
587 }
589 // Pauses
590 // Currently the size of the old gen is only adjusted to
591 // change the major pause times.
592 char* young_gen_action = NULL;
593 char* tenured_gen_action = NULL;
595 char* shrink_msg = (char*) "(attempted to shrink)";
596 char* grow_msg = (char*) "(attempted to grow)";
597 char* no_change_msg = (char*) "(no change)";
598 if (change_young_gen_for_min_pauses() ==
599 decrease_young_gen_for_min_pauses_true) {
600 young_gen_action = shrink_msg;
601 } else if (change_for_pause) {
602 young_gen_action = no_change_msg;
603 }
605 if (change_old_gen_for_maj_pauses() == decrease_old_gen_for_maj_pauses_true) {
606 tenured_gen_action = shrink_msg;
607 } else if (change_for_pause) {
608 tenured_gen_action = no_change_msg;
609 }
611 // Throughput
612 if (change_old_gen_for_throughput() == increase_old_gen_for_throughput_true) {
613 assert(change_young_gen_for_throughput() ==
614 increase_young_gen_for_througput_true,
615 "Both generations should be growing");
616 young_gen_action = grow_msg;
617 tenured_gen_action = grow_msg;
618 } else if (change_young_gen_for_throughput() ==
619 increase_young_gen_for_througput_true) {
620 // Only the young generation may grow at start up (before
621 // enough full collections have been done to grow the old generation).
622 young_gen_action = grow_msg;
623 tenured_gen_action = no_change_msg;
624 }
626 // Minimum footprint
627 if (decrease_for_footprint() != 0) {
628 young_gen_action = shrink_msg;
629 tenured_gen_action = shrink_msg;
630 }
632 st->print_cr(" UseAdaptiveSizePolicy actions to meet %s", action);
633 st->print_cr(" GC overhead (%%)");
634 st->print_cr(" Young generation: %7.2f\t %s",
635 100.0 * avg_minor_gc_cost()->average(),
636 young_gen_action);
637 st->print_cr(" Tenured generation: %7.2f\t %s",
638 100.0 * avg_major_gc_cost()->average(),
639 tenured_gen_action);
640 return true;
641 }
643 bool AdaptiveSizePolicy::print_adaptive_size_policy_on(
644 outputStream* st,
645 uint tenuring_threshold_arg) const {
646 if (!AdaptiveSizePolicy::print_adaptive_size_policy_on(st)) {
647 return false;
648 }
650 // Tenuring threshold
651 bool tenuring_threshold_changed = true;
652 if (decrement_tenuring_threshold_for_survivor_limit()) {
653 st->print(" Tenuring threshold: (attempted to decrease to avoid"
654 " survivor space overflow) = ");
655 } else if (decrement_tenuring_threshold_for_gc_cost()) {
656 st->print(" Tenuring threshold: (attempted to decrease to balance"
657 " GC costs) = ");
658 } else if (increment_tenuring_threshold_for_gc_cost()) {
659 st->print(" Tenuring threshold: (attempted to increase to balance"
660 " GC costs) = ");
661 } else {
662 tenuring_threshold_changed = false;
663 assert(!tenuring_threshold_change(), "(no change was attempted)");
664 }
665 if (tenuring_threshold_changed) {
666 st->print_cr("%u", tenuring_threshold_arg);
667 }
668 return true;
669 }