1 /*
2 * Copyright (c) 2004, 2015, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc/shared/adaptiveSizePolicy.hpp"
27 #include "gc/shared/collectorPolicy.hpp"
28 #include "gc/shared/gcCause.hpp"
29 #include "gc/shared/workgroup.hpp"
30 #include "runtime/timer.hpp"
31 #include "utilities/ostream.hpp"
32 elapsedTimer AdaptiveSizePolicy::_minor_timer;
33 elapsedTimer AdaptiveSizePolicy::_major_timer;
34 bool AdaptiveSizePolicy::_debug_perturbation = false;
35
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
42
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);
67
68 _avg_young_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
69 _avg_old_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
70 _avg_eden_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
71
72 _avg_survived = new AdaptivePaddedAverage(AdaptiveSizePolicyWeight,
73 SurvivorPadding);
74 _avg_pretenured = new AdaptivePaddedNoZeroDevAverage(
75 AdaptiveSizePolicyWeight,
76 SurvivorPadding);
77
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);
86
87 // Start the timers
88 _minor_timer.start();
89
90 _young_gen_policy_is_ready = false;
91 }
92
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.
99
100 uint 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.
106
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.
110
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;
115
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);
121
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 throughput 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);
128
129 uintx max_active_workers =
130 MAX2(active_workers_by_JT, active_workers_by_heap_size);
131
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);
136
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 }
143
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");
148
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 <= ParallelGCThreads) &&
165 (new_active_workers >= min_workers),
166 "Jiggled active workers too much");
167 }
168
169 if (TraceDynamicGCThreads) {
170 gclog_or_tty->print_cr("GCTaskManager::calc_default_active_workers() : "
171 "active_workers(): " UINTX_FORMAT " new_active_workers: " UINTX_FORMAT " "
172 "prev_active_workers: " UINTX_FORMAT "\n"
173 " active_workers_by_JT: " UINTX_FORMAT " active_workers_by_heap_size: " UINTX_FORMAT,
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 }
180
181 uint 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.
186
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.
190
191 uint new_active_workers;
192 if (!UseDynamicNumberOfGCThreads ||
193 (!FLAG_IS_DEFAULT(ParallelGCThreads) && !ForceDynamicNumberOfGCThreads)) {
194 new_active_workers = total_workers;
195 } else {
196 uintx min_workers = (total_workers == 1) ? 1 : 2;
197 new_active_workers = calc_default_active_workers(total_workers,
198 min_workers,
199 active_workers,
200 application_workers);
201 }
202 assert(new_active_workers > 0, "Always need at least 1");
203 return new_active_workers;
204 }
205
206 uint AdaptiveSizePolicy::calc_active_conc_workers(uintx total_workers,
207 uintx active_workers,
208 uintx application_workers) {
209 if (!UseDynamicNumberOfGCThreads ||
210 (!FLAG_IS_DEFAULT(ConcGCThreads) && !ForceDynamicNumberOfGCThreads)) {
211 return ConcGCThreads;
212 } else {
213 uint no_of_gc_threads = calc_default_active_workers(total_workers,
214 1, /* Minimum number of workers */
215 active_workers,
216 application_workers);
217 return no_of_gc_threads;
218 }
219 }
220
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 }
226
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 }
235
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 }
242
243 void AdaptiveSizePolicy::minor_collection_end(GCCause::Cause gc_cause) {
244 // Update the pause time.
245 _minor_timer.stop();
246
247 if (!GCCause::is_user_requested_gc(gc_cause) ||
248 UseAdaptiveSizePolicyWithSystemGC) {
249 double minor_pause_in_seconds = _minor_timer.seconds();
250 double minor_pause_in_ms = minor_pause_in_seconds * MILLIUNITS;
251
252 // Sample for performance counter
253 _avg_minor_pause->sample(minor_pause_in_seconds);
254
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 }
267
268 // The policy does not have enough data until at least some
269 // young collections have been done.
270 _young_gen_policy_is_ready =
271 (_avg_minor_gc_cost->count() >= AdaptiveSizePolicyReadyThreshold);
272
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);
277
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 }
286
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 }
291
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 }
297
298 size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden, uint percent_change) {
299 size_t eden_heap_delta;
300 eden_heap_delta = cur_eden / 100 * percent_change;
301 return eden_heap_delta;
302 }
303
304 size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden) {
305 return eden_increment(cur_eden, YoungGenerationSizeIncrement);
306 }
307
308 size_t AdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
309 size_t eden_heap_delta = eden_increment(cur_eden) /
310 AdaptiveSizeDecrementScaleFactor;
311 return eden_heap_delta;
312 }
313
314 size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo, uint percent_change) {
315 size_t promo_heap_delta;
316 promo_heap_delta = cur_promo / 100 * percent_change;
317 return promo_heap_delta;
318 }
319
320 size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo) {
321 return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
322 }
323
324 size_t AdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
325 size_t promo_heap_delta = promo_increment(cur_promo);
326 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
327 return promo_heap_delta;
328 }
329
330 double AdaptiveSizePolicy::time_since_major_gc() const {
331 _major_timer.stop();
332 double result = _major_timer.seconds();
333 _major_timer.start();
334 return result;
335 }
336
337 // Linear decay of major gc cost
338 double AdaptiveSizePolicy::decaying_major_gc_cost() const {
339 double major_interval = major_gc_interval_average_for_decay();
340 double major_gc_cost_average = major_gc_cost();
341 double decayed_major_gc_cost = major_gc_cost_average;
342 if(time_since_major_gc() > 0.0) {
343 decayed_major_gc_cost = major_gc_cost() *
344 (((double) AdaptiveSizeMajorGCDecayTimeScale) * major_interval)
345 / time_since_major_gc();
346 }
347
348 // The decayed cost should always be smaller than the
349 // average cost but the vagaries of finite arithmetic could
350 // produce a larger value in decayed_major_gc_cost so protect
351 // against that.
352 return MIN2(major_gc_cost_average, decayed_major_gc_cost);
353 }
354
355 // Use a value of the major gc cost that has been decayed
356 // by the factor
357 //
358 // average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale /
359 // time-since-last-major-gc
360 //
361 // if the average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale
362 // is less than time-since-last-major-gc.
363 //
364 // In cases where there are initial major gc's that
365 // are of a relatively high cost but no later major
366 // gc's, the total gc cost can remain high because
367 // the major gc cost remains unchanged (since there are no major
368 // gc's). In such a situation the value of the unchanging
369 // major gc cost can keep the mutator throughput below
370 // the goal when in fact the major gc cost is becoming diminishingly
371 // small. Use the decaying gc cost only to decide whether to
372 // adjust for throughput. Using it also to determine the adjustment
373 // to be made for throughput also seems reasonable but there is
374 // no test case to use to decide if it is the right thing to do
375 // don't do it yet.
376
377 double AdaptiveSizePolicy::decaying_gc_cost() const {
378 double decayed_major_gc_cost = major_gc_cost();
379 double avg_major_interval = major_gc_interval_average_for_decay();
380 if (UseAdaptiveSizeDecayMajorGCCost &&
381 (AdaptiveSizeMajorGCDecayTimeScale > 0) &&
382 (avg_major_interval > 0.00)) {
383 double time_since_last_major_gc = time_since_major_gc();
384
385 // Decay the major gc cost?
386 if (time_since_last_major_gc >
387 ((double) AdaptiveSizeMajorGCDecayTimeScale) * avg_major_interval) {
388
389 // Decay using the time-since-last-major-gc
390 decayed_major_gc_cost = decaying_major_gc_cost();
391 if (PrintGCDetails && Verbose) {
392 gclog_or_tty->print_cr("\ndecaying_gc_cost: major interval average:"
393 " %f time since last major gc: %f",
394 avg_major_interval, time_since_last_major_gc);
395 gclog_or_tty->print_cr(" major gc cost: %f decayed major gc cost: %f",
396 major_gc_cost(), decayed_major_gc_cost);
397 }
398 }
399 }
400 double result = MIN2(1.0, decayed_major_gc_cost + minor_gc_cost());
401 return result;
402 }
403
404
405 void AdaptiveSizePolicy::clear_generation_free_space_flags() {
406 set_change_young_gen_for_min_pauses(0);
407 set_change_old_gen_for_maj_pauses(0);
408
409 set_change_old_gen_for_throughput(0);
410 set_change_young_gen_for_throughput(0);
411 set_decrease_for_footprint(0);
412 set_decide_at_full_gc(0);
413 }
414
415 void AdaptiveSizePolicy::check_gc_overhead_limit(
416 size_t young_live,
417 size_t eden_live,
418 size_t max_old_gen_size,
419 size_t max_eden_size,
420 bool is_full_gc,
421 GCCause::Cause gc_cause,
422 CollectorPolicy* collector_policy) {
423
424 // Ignore explicit GC's. Exiting here does not set the flag and
425 // does not reset the count. Updating of the averages for system
426 // GC's is still controlled by UseAdaptiveSizePolicyWithSystemGC.
427 if (GCCause::is_user_requested_gc(gc_cause) ||
428 GCCause::is_serviceability_requested_gc(gc_cause)) {
429 return;
430 }
431 // eden_limit is the upper limit on the size of eden based on
432 // the maximum size of the young generation and the sizes
433 // of the survivor space.
434 // The question being asked is whether the gc costs are high
435 // and the space being recovered by a collection is low.
436 // free_in_young_gen is the free space in the young generation
437 // after a collection and promo_live is the free space in the old
438 // generation after a collection.
439 //
440 // Use the minimum of the current value of the live in the
441 // young gen or the average of the live in the young gen.
442 // If the current value drops quickly, that should be taken
443 // into account (i.e., don't trigger if the amount of free
444 // space has suddenly jumped up). If the current is much
445 // higher than the average, use the average since it represents
446 // the longer term behavior.
447 const size_t live_in_eden =
448 MIN2(eden_live, (size_t) avg_eden_live()->average());
449 const size_t free_in_eden = max_eden_size > live_in_eden ?
450 max_eden_size - live_in_eden : 0;
451 const size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());
452 const size_t total_free_limit = free_in_old_gen + free_in_eden;
453 const size_t total_mem = max_old_gen_size + max_eden_size;
454 const double mem_free_limit = total_mem * (GCHeapFreeLimit/100.0);
455 const double mem_free_old_limit = max_old_gen_size * (GCHeapFreeLimit/100.0);
456 const double mem_free_eden_limit = max_eden_size * (GCHeapFreeLimit/100.0);
457 const double gc_cost_limit = GCTimeLimit/100.0;
458 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());
459 // But don't force a promo size below the current promo size. Otherwise,
460 // the promo size will shrink for no good reason.
461 promo_limit = MAX2(promo_limit, _promo_size);
462
463
464 if (PrintAdaptiveSizePolicy && (Verbose ||
465 (free_in_old_gen < (size_t) mem_free_old_limit &&
466 free_in_eden < (size_t) mem_free_eden_limit))) {
467 gclog_or_tty->print_cr(
468 "PSAdaptiveSizePolicy::check_gc_overhead_limit:"
469 " promo_limit: " SIZE_FORMAT
470 " max_eden_size: " SIZE_FORMAT
471 " total_free_limit: " SIZE_FORMAT
472 " max_old_gen_size: " SIZE_FORMAT
473 " max_eden_size: " SIZE_FORMAT
474 " mem_free_limit: " SIZE_FORMAT,
475 promo_limit, max_eden_size, total_free_limit,
476 max_old_gen_size, max_eden_size,
477 (size_t) mem_free_limit);
478 }
479
480 bool print_gc_overhead_limit_would_be_exceeded = false;
481 if (is_full_gc) {
482 if (gc_cost() > gc_cost_limit &&
483 free_in_old_gen < (size_t) mem_free_old_limit &&
484 free_in_eden < (size_t) mem_free_eden_limit) {
485 // Collections, on average, are taking too much time, and
486 // gc_cost() > gc_cost_limit
487 // we have too little space available after a full gc.
488 // total_free_limit < mem_free_limit
489 // where
490 // total_free_limit is the free space available in
491 // both generations
492 // total_mem is the total space available for allocation
493 // in both generations (survivor spaces are not included
494 // just as they are not included in eden_limit).
495 // mem_free_limit is a fraction of total_mem judged to be an
496 // acceptable amount that is still unused.
497 // The heap can ask for the value of this variable when deciding
498 // whether to thrown an OutOfMemory error.
499 // Note that the gc time limit test only works for the collections
500 // of the young gen + tenured gen and not for collections of the
501 // permanent gen. That is because the calculation of the space
502 // freed by the collection is the free space in the young gen +
503 // tenured gen.
504 // At this point the GC overhead limit is being exceeded.
505 inc_gc_overhead_limit_count();
506 if (UseGCOverheadLimit) {
507 if (gc_overhead_limit_count() >=
508 AdaptiveSizePolicyGCTimeLimitThreshold){
509 // All conditions have been met for throwing an out-of-memory
510 set_gc_overhead_limit_exceeded(true);
511 // Avoid consecutive OOM due to the gc time limit by resetting
512 // the counter.
513 reset_gc_overhead_limit_count();
514 } else {
515 // The required consecutive collections which exceed the
516 // GC time limit may or may not have been reached. We
517 // are approaching that condition and so as not to
518 // throw an out-of-memory before all SoftRef's have been
519 // cleared, set _should_clear_all_soft_refs in CollectorPolicy.
520 // The clearing will be done on the next GC.
521 bool near_limit = gc_overhead_limit_near();
522 if (near_limit) {
523 collector_policy->set_should_clear_all_soft_refs(true);
524 if (PrintGCDetails && Verbose) {
525 gclog_or_tty->print_cr(" Nearing GC overhead limit, "
526 "will be clearing all SoftReference");
527 }
528 }
529 }
530 }
531 // Set this even when the overhead limit will not
532 // cause an out-of-memory. Diagnostic message indicating
533 // that the overhead limit is being exceeded is sometimes
534 // printed.
535 print_gc_overhead_limit_would_be_exceeded = true;
536
537 } else {
538 // Did not exceed overhead limits
539 reset_gc_overhead_limit_count();
540 }
541 }
542
543 if (UseGCOverheadLimit && PrintGCDetails && Verbose) {
544 if (gc_overhead_limit_exceeded()) {
545 gclog_or_tty->print_cr(" GC is exceeding overhead limit "
546 "of " UINTX_FORMAT "%%", GCTimeLimit);
547 reset_gc_overhead_limit_count();
548 } else if (print_gc_overhead_limit_would_be_exceeded) {
549 assert(gc_overhead_limit_count() > 0, "Should not be printing");
550 gclog_or_tty->print_cr(" GC would exceed overhead limit "
551 "of " UINTX_FORMAT "%% %d consecutive time(s)",
552 GCTimeLimit, gc_overhead_limit_count());
553 }
554 }
555 }
556 // Printing
557
558 bool AdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st) const {
559
560 // Should only be used with adaptive size policy turned on.
561 // Otherwise, there may be variables that are undefined.
562 if (!UseAdaptiveSizePolicy) return false;
563
564 // Print goal for which action is needed.
565 char* action = NULL;
566 bool change_for_pause = false;
567 if ((change_old_gen_for_maj_pauses() ==
568 decrease_old_gen_for_maj_pauses_true) ||
569 (change_young_gen_for_min_pauses() ==
570 decrease_young_gen_for_min_pauses_true)) {
571 action = (char*) " *** pause time goal ***";
572 change_for_pause = true;
573 } else if ((change_old_gen_for_throughput() ==
574 increase_old_gen_for_throughput_true) ||
575 (change_young_gen_for_throughput() ==
576 increase_young_gen_for_througput_true)) {
577 action = (char*) " *** throughput goal ***";
578 } else if (decrease_for_footprint()) {
579 action = (char*) " *** reduced footprint ***";
580 } else {
581 // No actions were taken. This can legitimately be the
582 // situation if not enough data has been gathered to make
583 // decisions.
584 return false;
585 }
586
587 // Pauses
588 // Currently the size of the old gen is only adjusted to
589 // change the major pause times.
590 char* young_gen_action = NULL;
591 char* tenured_gen_action = NULL;
592
593 char* shrink_msg = (char*) "(attempted to shrink)";
594 char* grow_msg = (char*) "(attempted to grow)";
595 char* no_change_msg = (char*) "(no change)";
596 if (change_young_gen_for_min_pauses() ==
597 decrease_young_gen_for_min_pauses_true) {
598 young_gen_action = shrink_msg;
599 } else if (change_for_pause) {
600 young_gen_action = no_change_msg;
601 }
602
603 if (change_old_gen_for_maj_pauses() == decrease_old_gen_for_maj_pauses_true) {
604 tenured_gen_action = shrink_msg;
605 } else if (change_for_pause) {
606 tenured_gen_action = no_change_msg;
607 }
608
609 // Throughput
610 if (change_old_gen_for_throughput() == increase_old_gen_for_throughput_true) {
611 assert(change_young_gen_for_throughput() ==
612 increase_young_gen_for_througput_true,
613 "Both generations should be growing");
614 young_gen_action = grow_msg;
615 tenured_gen_action = grow_msg;
616 } else if (change_young_gen_for_throughput() ==
617 increase_young_gen_for_througput_true) {
618 // Only the young generation may grow at start up (before
619 // enough full collections have been done to grow the old generation).
620 young_gen_action = grow_msg;
621 tenured_gen_action = no_change_msg;
622 }
623
624 // Minimum footprint
625 if (decrease_for_footprint() != 0) {
626 young_gen_action = shrink_msg;
627 tenured_gen_action = shrink_msg;
628 }
629
630 st->print_cr(" UseAdaptiveSizePolicy actions to meet %s", action);
631 st->print_cr(" GC overhead (%%)");
632 st->print_cr(" Young generation: %7.2f\t %s",
633 100.0 * avg_minor_gc_cost()->average(),
634 young_gen_action);
635 st->print_cr(" Tenured generation: %7.2f\t %s",
636 100.0 * avg_major_gc_cost()->average(),
637 tenured_gen_action);
638 return true;
639 }
640
641 bool AdaptiveSizePolicy::print_adaptive_size_policy_on(
642 outputStream* st,
643 uint tenuring_threshold_arg) const {
644 if (!AdaptiveSizePolicy::print_adaptive_size_policy_on(st)) {
645 return false;
646 }
647
648 // Tenuring threshold
649 bool tenuring_threshold_changed = true;
650 if (decrement_tenuring_threshold_for_survivor_limit()) {
651 st->print(" Tenuring threshold: (attempted to decrease to avoid"
652 " survivor space overflow) = ");
653 } else if (decrement_tenuring_threshold_for_gc_cost()) {
654 st->print(" Tenuring threshold: (attempted to decrease to balance"
655 " GC costs) = ");
656 } else if (increment_tenuring_threshold_for_gc_cost()) {
657 st->print(" Tenuring threshold: (attempted to increase to balance"
658 " GC costs) = ");
659 } else {
660 tenuring_threshold_changed = false;
661 assert(!tenuring_threshold_change(), "(no change was attempted)");
662 }
663 if (tenuring_threshold_changed) {
664 st->print_cr("%u", tenuring_threshold_arg);
665 }
666 return true;
667 }