1 /*
2 * Copyright (c) 2004, 2016, Oracle and/or its affiliates. All rights reserved.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc/shared/adaptiveSizePolicy.hpp"
27 #include "gc/shared/collectorPolicy.hpp"
28 #include "gc/shared/gcCause.hpp"
29 #include "gc/shared/gcUtil.inline.hpp"
30 #include "gc/shared/workgroup.hpp"
31 #include "logging/log.hpp"
32 #include "runtime/timer.hpp"
33 #include "utilities/ostream.hpp"
34 elapsedTimer AdaptiveSizePolicy::_minor_timer;
35 elapsedTimer AdaptiveSizePolicy::_major_timer;
36 bool AdaptiveSizePolicy::_debug_perturbation = false;
37
38 // The throughput goal is implemented as
39 // _throughput_goal = 1 - ( 1 / (1 + gc_cost_ratio))
40 // gc_cost_ratio is the ratio
41 // application cost / gc cost
42 // For example a gc_cost_ratio of 4 translates into a
43 // throughput goal of .80
44
45 AdaptiveSizePolicy::AdaptiveSizePolicy(size_t init_eden_size,
46 size_t init_promo_size,
47 size_t init_survivor_size,
48 double gc_pause_goal_sec,
49 uint gc_cost_ratio) :
50 _eden_size(init_eden_size),
51 _promo_size(init_promo_size),
52 _survivor_size(init_survivor_size),
53 _gc_pause_goal_sec(gc_pause_goal_sec),
54 _throughput_goal(1.0 - double(1.0 / (1.0 + (double) gc_cost_ratio))),
55 _gc_overhead_limit_exceeded(false),
56 _print_gc_overhead_limit_would_be_exceeded(false),
57 _gc_overhead_limit_count(0),
58 _latest_minor_mutator_interval_seconds(0),
59 _threshold_tolerance_percent(1.0 + ThresholdTolerance/100.0),
60 _young_gen_change_for_minor_throughput(0),
61 _old_gen_change_for_major_throughput(0) {
62 assert(AdaptiveSizePolicyGCTimeLimitThreshold > 0,
63 "No opportunity to clear SoftReferences before GC overhead limit");
64 _avg_minor_pause =
65 new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding);
66 _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
67 _avg_minor_gc_cost = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
68 _avg_major_gc_cost = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
69
70 _avg_young_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
71 _avg_old_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
72 _avg_eden_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
73
74 _avg_survived = new AdaptivePaddedAverage(AdaptiveSizePolicyWeight,
75 SurvivorPadding);
76 _avg_pretenured = new AdaptivePaddedNoZeroDevAverage(
77 AdaptiveSizePolicyWeight,
78 SurvivorPadding);
79
80 _minor_pause_old_estimator =
81 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
82 _minor_pause_young_estimator =
83 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
84 _minor_collection_estimator =
85 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
86 _major_collection_estimator =
87 new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
88
89 // Start the timers
90 _minor_timer.start();
91
92 _young_gen_policy_is_ready = false;
93 }
94
95 // If the number of GC threads was set on the command line,
96 // use it.
97 // Else
98 // Calculate the number of GC threads based on the number of Java threads.
99 // Calculate the number of GC threads based on the size of the heap.
100 // Use the larger.
101
102 uint AdaptiveSizePolicy::calc_default_active_workers(uintx total_workers,
103 const uintx min_workers,
104 uintx active_workers,
105 uintx application_workers) {
106 // If the user has specifically set the number of
107 // GC threads, use them.
108
109 // If the user has turned off using a dynamic number of GC threads
110 // or the users has requested a specific number, set the active
111 // number of workers to all the workers.
112
113 uintx new_active_workers = total_workers;
114 uintx prev_active_workers = active_workers;
115 uintx active_workers_by_JT = 0;
116 uintx active_workers_by_heap_size = 0;
117
118 // Always use at least min_workers but use up to
119 // GCThreadsPerJavaThreads * application threads.
120 active_workers_by_JT =
121 MAX2((uintx) GCWorkersPerJavaThread * application_workers,
122 min_workers);
123
124 // Choose a number of GC threads based on the current size
125 // of the heap. This may be complicated because the size of
126 // the heap depends on factors such as the throughput goal.
127 // Still a large heap should be collected by more GC threads.
128 active_workers_by_heap_size =
129 MAX2((size_t) 2U, Universe::heap()->capacity() / HeapSizePerGCThread);
130
131 uintx max_active_workers =
132 MAX2(active_workers_by_JT, active_workers_by_heap_size);
133
134 new_active_workers = MIN2(max_active_workers, (uintx) total_workers);
135
136 // Increase GC workers instantly but decrease them more
137 // slowly.
138 if (new_active_workers < prev_active_workers) {
139 new_active_workers =
140 MAX2(min_workers, (prev_active_workers + new_active_workers) / 2);
141 }
142
143 // Check once more that the number of workers is within the limits.
144 assert(min_workers <= total_workers, "Minimum workers not consistent with total workers");
145 assert(new_active_workers >= min_workers, "Minimum workers not observed");
146 assert(new_active_workers <= total_workers, "Total workers not observed");
147
148 if (ForceDynamicNumberOfGCThreads) {
149 // Assume this is debugging and jiggle the number of GC threads.
150 if (new_active_workers == prev_active_workers) {
151 if (new_active_workers < total_workers) {
152 new_active_workers++;
153 } else if (new_active_workers > min_workers) {
154 new_active_workers--;
155 }
156 }
157 if (new_active_workers == total_workers) {
158 if (_debug_perturbation) {
159 new_active_workers = min_workers;
160 }
161 _debug_perturbation = !_debug_perturbation;
162 }
163 assert((new_active_workers <= ParallelGCThreads) &&
164 (new_active_workers >= min_workers),
165 "Jiggled active workers too much");
166 }
167
168 log_trace(gc, task)("GCTaskManager::calc_default_active_workers() : "
169 "active_workers(): " UINTX_FORMAT " new_active_workers: " UINTX_FORMAT " "
170 "prev_active_workers: " UINTX_FORMAT "\n"
171 " active_workers_by_JT: " UINTX_FORMAT " active_workers_by_heap_size: " UINTX_FORMAT,
172 active_workers, new_active_workers, prev_active_workers,
173 active_workers_by_JT, active_workers_by_heap_size);
174 assert(new_active_workers > 0, "Always need at least 1");
175 return new_active_workers;
176 }
177
178 uint AdaptiveSizePolicy::calc_active_workers(uintx total_workers,
179 uintx active_workers,
180 uintx application_workers) {
181 // If the user has specifically set the number of
182 // GC threads, use them.
183
184 // If the user has turned off using a dynamic number of GC threads
185 // or the users has requested a specific number, set the active
186 // number of workers to all the workers.
187
188 uint new_active_workers;
189 if (!UseDynamicNumberOfGCThreads ||
190 (!FLAG_IS_DEFAULT(ParallelGCThreads) && !ForceDynamicNumberOfGCThreads)) {
191 new_active_workers = total_workers;
192 } else {
193 uintx min_workers = (total_workers == 1) ? 1 : 2;
194 new_active_workers = calc_default_active_workers(total_workers,
195 min_workers,
196 active_workers,
197 application_workers);
198 }
199 assert(new_active_workers > 0, "Always need at least 1");
200 return new_active_workers;
201 }
202
203 uint AdaptiveSizePolicy::calc_active_conc_workers(uintx total_workers,
204 uintx active_workers,
205 uintx application_workers) {
206 if (!UseDynamicNumberOfGCThreads ||
207 (!FLAG_IS_DEFAULT(ConcGCThreads) && !ForceDynamicNumberOfGCThreads)) {
208 return ConcGCThreads;
209 } else {
210 uint no_of_gc_threads = calc_default_active_workers(total_workers,
211 1, /* Minimum number of workers */
212 active_workers,
213 application_workers);
214 return no_of_gc_threads;
215 }
216 }
217
218 bool AdaptiveSizePolicy::tenuring_threshold_change() const {
219 return decrement_tenuring_threshold_for_gc_cost() ||
220 increment_tenuring_threshold_for_gc_cost() ||
221 decrement_tenuring_threshold_for_survivor_limit();
222 }
223
224 void AdaptiveSizePolicy::minor_collection_begin() {
225 // Update the interval time
226 _minor_timer.stop();
227 // Save most recent collection time
228 _latest_minor_mutator_interval_seconds = _minor_timer.seconds();
229 _minor_timer.reset();
230 _minor_timer.start();
231 }
232
233 void AdaptiveSizePolicy::update_minor_pause_young_estimator(
234 double minor_pause_in_ms) {
235 double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
236 _minor_pause_young_estimator->update(eden_size_in_mbytes,
237 minor_pause_in_ms);
238 }
239
240 void AdaptiveSizePolicy::minor_collection_end(GCCause::Cause gc_cause) {
241 // Update the pause time.
242 _minor_timer.stop();
243
244 if (!GCCause::is_user_requested_gc(gc_cause) ||
245 UseAdaptiveSizePolicyWithSystemGC) {
246 double minor_pause_in_seconds = _minor_timer.seconds();
247 double minor_pause_in_ms = minor_pause_in_seconds * MILLIUNITS;
248
249 // Sample for performance counter
250 _avg_minor_pause->sample(minor_pause_in_seconds);
251
252 // Cost of collection (unit-less)
253 double collection_cost = 0.0;
254 if ((_latest_minor_mutator_interval_seconds > 0.0) &&
255 (minor_pause_in_seconds > 0.0)) {
256 double interval_in_seconds =
257 _latest_minor_mutator_interval_seconds + minor_pause_in_seconds;
258 collection_cost =
259 minor_pause_in_seconds / interval_in_seconds;
260 _avg_minor_gc_cost->sample(collection_cost);
261 // Sample for performance counter
262 _avg_minor_interval->sample(interval_in_seconds);
263 }
264
265 // The policy does not have enough data until at least some
266 // young collections have been done.
267 _young_gen_policy_is_ready =
268 (_avg_minor_gc_cost->count() >= AdaptiveSizePolicyReadyThreshold);
269
270 // Calculate variables used to estimate pause time vs. gen sizes
271 double eden_size_in_mbytes = ((double)_eden_size) / ((double)M);
272 update_minor_pause_young_estimator(minor_pause_in_ms);
273 update_minor_pause_old_estimator(minor_pause_in_ms);
274
275 log_trace(gc, ergo)("AdaptiveSizePolicy::minor_collection_end: minor gc cost: %f average: %f",
276 collection_cost, _avg_minor_gc_cost->average());
277 log_trace(gc, ergo)(" minor pause: %f minor period %f",
278 minor_pause_in_ms, _latest_minor_mutator_interval_seconds * MILLIUNITS);
279
280 // Calculate variable used to estimate collection cost vs. gen sizes
281 assert(collection_cost >= 0.0, "Expected to be non-negative");
282 _minor_collection_estimator->update(eden_size_in_mbytes, collection_cost);
283 }
284
285 // Interval times use this timer to measure the mutator time.
286 // Reset the timer after the GC pause.
287 _minor_timer.reset();
288 _minor_timer.start();
289 }
290
291 size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden, uint percent_change) {
292 size_t eden_heap_delta;
293 eden_heap_delta = cur_eden / 100 * percent_change;
294 return eden_heap_delta;
295 }
296
297 size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden) {
298 return eden_increment(cur_eden, YoungGenerationSizeIncrement);
299 }
300
301 size_t AdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
302 size_t eden_heap_delta = eden_increment(cur_eden) /
303 AdaptiveSizeDecrementScaleFactor;
304 return eden_heap_delta;
305 }
306
307 size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo, uint percent_change) {
308 size_t promo_heap_delta;
309 promo_heap_delta = cur_promo / 100 * percent_change;
310 return promo_heap_delta;
311 }
312
313 size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo) {
314 return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
315 }
316
317 size_t AdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
318 size_t promo_heap_delta = promo_increment(cur_promo);
319 promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
320 return promo_heap_delta;
321 }
322
323 double AdaptiveSizePolicy::time_since_major_gc() const {
324 _major_timer.stop();
325 double result = _major_timer.seconds();
326 _major_timer.start();
327 return result;
328 }
329
330 // Linear decay of major gc cost
331 double AdaptiveSizePolicy::decaying_major_gc_cost() const {
332 double major_interval = major_gc_interval_average_for_decay();
333 double major_gc_cost_average = major_gc_cost();
334 double decayed_major_gc_cost = major_gc_cost_average;
335 if(time_since_major_gc() > 0.0) {
336 decayed_major_gc_cost = major_gc_cost() *
337 (((double) AdaptiveSizeMajorGCDecayTimeScale) * major_interval)
338 / time_since_major_gc();
339 }
340
341 // The decayed cost should always be smaller than the
342 // average cost but the vagaries of finite arithmetic could
343 // produce a larger value in decayed_major_gc_cost so protect
344 // against that.
345 return MIN2(major_gc_cost_average, decayed_major_gc_cost);
346 }
347
348 // Use a value of the major gc cost that has been decayed
349 // by the factor
350 //
351 // average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale /
352 // time-since-last-major-gc
353 //
354 // if the average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale
355 // is less than time-since-last-major-gc.
356 //
357 // In cases where there are initial major gc's that
358 // are of a relatively high cost but no later major
359 // gc's, the total gc cost can remain high because
360 // the major gc cost remains unchanged (since there are no major
361 // gc's). In such a situation the value of the unchanging
362 // major gc cost can keep the mutator throughput below
363 // the goal when in fact the major gc cost is becoming diminishingly
364 // small. Use the decaying gc cost only to decide whether to
365 // adjust for throughput. Using it also to determine the adjustment
366 // to be made for throughput also seems reasonable but there is
367 // no test case to use to decide if it is the right thing to do
368 // don't do it yet.
369
370 double AdaptiveSizePolicy::decaying_gc_cost() const {
371 double decayed_major_gc_cost = major_gc_cost();
372 double avg_major_interval = major_gc_interval_average_for_decay();
373 if (UseAdaptiveSizeDecayMajorGCCost &&
374 (AdaptiveSizeMajorGCDecayTimeScale > 0) &&
375 (avg_major_interval > 0.00)) {
376 double time_since_last_major_gc = time_since_major_gc();
377
378 // Decay the major gc cost?
379 if (time_since_last_major_gc >
380 ((double) AdaptiveSizeMajorGCDecayTimeScale) * avg_major_interval) {
381
382 // Decay using the time-since-last-major-gc
383 decayed_major_gc_cost = decaying_major_gc_cost();
384 log_trace(gc, ergo)("decaying_gc_cost: major interval average: %f time since last major gc: %f",
385 avg_major_interval, time_since_last_major_gc);
386 log_trace(gc, ergo)(" major gc cost: %f decayed major gc cost: %f",
387 major_gc_cost(), decayed_major_gc_cost);
388 }
389 }
390 double result = MIN2(1.0, decayed_major_gc_cost + minor_gc_cost());
391 return result;
392 }
393
394
395 void AdaptiveSizePolicy::clear_generation_free_space_flags() {
396 set_change_young_gen_for_min_pauses(0);
397 set_change_old_gen_for_maj_pauses(0);
398
399 set_change_old_gen_for_throughput(0);
400 set_change_young_gen_for_throughput(0);
401 set_decrease_for_footprint(0);
402 set_decide_at_full_gc(0);
403 }
404
405 void AdaptiveSizePolicy::check_gc_overhead_limit(
406 size_t young_live,
407 size_t eden_live,
408 size_t max_old_gen_size,
409 size_t max_eden_size,
410 bool is_full_gc,
411 GCCause::Cause gc_cause,
412 CollectorPolicy* collector_policy) {
413
414 // Ignore explicit GC's. Exiting here does not set the flag and
415 // does not reset the count. Updating of the averages for system
416 // GC's is still controlled by UseAdaptiveSizePolicyWithSystemGC.
417 if (GCCause::is_user_requested_gc(gc_cause) ||
418 GCCause::is_serviceability_requested_gc(gc_cause)) {
419 return;
420 }
421 // eden_limit is the upper limit on the size of eden based on
422 // the maximum size of the young generation and the sizes
423 // of the survivor space.
424 // The question being asked is whether the gc costs are high
425 // and the space being recovered by a collection is low.
426 // free_in_young_gen is the free space in the young generation
427 // after a collection and promo_live is the free space in the old
428 // generation after a collection.
429 //
430 // Use the minimum of the current value of the live in the
431 // young gen or the average of the live in the young gen.
432 // If the current value drops quickly, that should be taken
433 // into account (i.e., don't trigger if the amount of free
434 // space has suddenly jumped up). If the current is much
435 // higher than the average, use the average since it represents
436 // the longer term behavior.
437 const size_t live_in_eden =
438 MIN2(eden_live, (size_t) avg_eden_live()->average());
439 const size_t free_in_eden = max_eden_size > live_in_eden ?
440 max_eden_size - live_in_eden : 0;
441 const size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());
442 const size_t total_free_limit = free_in_old_gen + free_in_eden;
443 const size_t total_mem = max_old_gen_size + max_eden_size;
444 const double mem_free_limit = total_mem * (GCHeapFreeLimit/100.0);
445 const double mem_free_old_limit = max_old_gen_size * (GCHeapFreeLimit/100.0);
446 const double mem_free_eden_limit = max_eden_size * (GCHeapFreeLimit/100.0);
447 const double gc_cost_limit = GCTimeLimit/100.0;
448 size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());
449 // But don't force a promo size below the current promo size. Otherwise,
450 // the promo size will shrink for no good reason.
451 promo_limit = MAX2(promo_limit, _promo_size);
452
453
454 log_trace(gc, ergo)(
455 "PSAdaptiveSizePolicy::check_gc_overhead_limit:"
456 " promo_limit: " SIZE_FORMAT
457 " max_eden_size: " SIZE_FORMAT
458 " total_free_limit: " SIZE_FORMAT
459 " max_old_gen_size: " SIZE_FORMAT
460 " max_eden_size: " SIZE_FORMAT
461 " mem_free_limit: " SIZE_FORMAT,
462 promo_limit, max_eden_size, total_free_limit,
463 max_old_gen_size, max_eden_size,
464 (size_t) mem_free_limit);
465
466 bool print_gc_overhead_limit_would_be_exceeded = false;
467 if (is_full_gc) {
468 if (gc_cost() > gc_cost_limit &&
469 free_in_old_gen < (size_t) mem_free_old_limit &&
470 free_in_eden < (size_t) mem_free_eden_limit) {
471 // Collections, on average, are taking too much time, and
472 // gc_cost() > gc_cost_limit
473 // we have too little space available after a full gc.
474 // total_free_limit < mem_free_limit
475 // where
476 // total_free_limit is the free space available in
477 // both generations
478 // total_mem is the total space available for allocation
479 // in both generations (survivor spaces are not included
480 // just as they are not included in eden_limit).
481 // mem_free_limit is a fraction of total_mem judged to be an
482 // acceptable amount that is still unused.
483 // The heap can ask for the value of this variable when deciding
484 // whether to thrown an OutOfMemory error.
485 // Note that the gc time limit test only works for the collections
486 // of the young gen + tenured gen and not for collections of the
487 // permanent gen. That is because the calculation of the space
488 // freed by the collection is the free space in the young gen +
489 // tenured gen.
490 // At this point the GC overhead limit is being exceeded.
491 inc_gc_overhead_limit_count();
492 if (UseGCOverheadLimit) {
493 if (gc_overhead_limit_count() >=
494 AdaptiveSizePolicyGCTimeLimitThreshold){
495 // All conditions have been met for throwing an out-of-memory
496 set_gc_overhead_limit_exceeded(true);
497 // Avoid consecutive OOM due to the gc time limit by resetting
498 // the counter.
499 reset_gc_overhead_limit_count();
500 } else {
501 // The required consecutive collections which exceed the
502 // GC time limit may or may not have been reached. We
503 // are approaching that condition and so as not to
504 // throw an out-of-memory before all SoftRef's have been
505 // cleared, set _should_clear_all_soft_refs in CollectorPolicy.
506 // The clearing will be done on the next GC.
507 bool near_limit = gc_overhead_limit_near();
508 if (near_limit) {
509 collector_policy->set_should_clear_all_soft_refs(true);
510 log_trace(gc, ergo)("Nearing GC overhead limit, will be clearing all SoftReference");
511 }
512 }
513 }
514 // Set this even when the overhead limit will not
515 // cause an out-of-memory. Diagnostic message indicating
516 // that the overhead limit is being exceeded is sometimes
517 // printed.
518 print_gc_overhead_limit_would_be_exceeded = true;
519
520 } else {
521 // Did not exceed overhead limits
522 reset_gc_overhead_limit_count();
523 }
524 }
525
526 if (UseGCOverheadLimit) {
527 if (gc_overhead_limit_exceeded()) {
528 log_trace(gc, ergo)("GC is exceeding overhead limit of " UINTX_FORMAT "%%", GCTimeLimit);
529 reset_gc_overhead_limit_count();
530 } else if (print_gc_overhead_limit_would_be_exceeded) {
531 assert(gc_overhead_limit_count() > 0, "Should not be printing");
532 log_trace(gc, ergo)("GC would exceed overhead limit of " UINTX_FORMAT "%% %d consecutive time(s)",
533 GCTimeLimit, gc_overhead_limit_count());
534 }
535 }
536 }
537 // Printing
538
539 bool AdaptiveSizePolicy::print() const {
540 assert(UseAdaptiveSizePolicy, "UseAdaptiveSizePolicy need to be enabled.");
541
542 if (!log_is_enabled(Debug, gc, ergo)) {
543 return false;
544 }
545
546 // Print goal for which action is needed.
547 char* action = NULL;
548 bool change_for_pause = false;
549 if ((change_old_gen_for_maj_pauses() ==
550 decrease_old_gen_for_maj_pauses_true) ||
551 (change_young_gen_for_min_pauses() ==
552 decrease_young_gen_for_min_pauses_true)) {
553 action = (char*) " *** pause time goal ***";
554 change_for_pause = true;
555 } else if ((change_old_gen_for_throughput() ==
556 increase_old_gen_for_throughput_true) ||
557 (change_young_gen_for_throughput() ==
558 increase_young_gen_for_througput_true)) {
559 action = (char*) " *** throughput goal ***";
560 } else if (decrease_for_footprint()) {
561 action = (char*) " *** reduced footprint ***";
562 } else {
563 // No actions were taken. This can legitimately be the
564 // situation if not enough data has been gathered to make
565 // decisions.
566 return false;
567 }
568
569 // Pauses
570 // Currently the size of the old gen is only adjusted to
571 // change the major pause times.
572 char* young_gen_action = NULL;
573 char* tenured_gen_action = NULL;
574
575 char* shrink_msg = (char*) "(attempted to shrink)";
576 char* grow_msg = (char*) "(attempted to grow)";
577 char* no_change_msg = (char*) "(no change)";
578 if (change_young_gen_for_min_pauses() ==
579 decrease_young_gen_for_min_pauses_true) {
580 young_gen_action = shrink_msg;
581 } else if (change_for_pause) {
582 young_gen_action = no_change_msg;
583 }
584
585 if (change_old_gen_for_maj_pauses() == decrease_old_gen_for_maj_pauses_true) {
586 tenured_gen_action = shrink_msg;
587 } else if (change_for_pause) {
588 tenured_gen_action = no_change_msg;
589 }
590
591 // Throughput
592 if (change_old_gen_for_throughput() == increase_old_gen_for_throughput_true) {
593 assert(change_young_gen_for_throughput() ==
594 increase_young_gen_for_througput_true,
595 "Both generations should be growing");
596 young_gen_action = grow_msg;
597 tenured_gen_action = grow_msg;
598 } else if (change_young_gen_for_throughput() ==
599 increase_young_gen_for_througput_true) {
600 // Only the young generation may grow at start up (before
601 // enough full collections have been done to grow the old generation).
602 young_gen_action = grow_msg;
603 tenured_gen_action = no_change_msg;
604 }
605
606 // Minimum footprint
607 if (decrease_for_footprint() != 0) {
608 young_gen_action = shrink_msg;
609 tenured_gen_action = shrink_msg;
610 }
611
612 log_debug(gc, ergo)("UseAdaptiveSizePolicy actions to meet %s", action);
613 log_debug(gc, ergo)(" GC overhead (%%)");
614 log_debug(gc, ergo)(" Young generation: %7.2f\t %s",
615 100.0 * avg_minor_gc_cost()->average(), young_gen_action);
616 log_debug(gc, ergo)(" Tenured generation: %7.2f\t %s",
617 100.0 * avg_major_gc_cost()->average(), tenured_gen_action);
618 return true;
619 }
620
621 void AdaptiveSizePolicy::print_tenuring_threshold( uint new_tenuring_threshold_arg) const {
622 // Tenuring threshold
623 if (decrement_tenuring_threshold_for_survivor_limit()) {
624 log_debug(gc, ergo)("Tenuring threshold: (attempted to decrease to avoid survivor space overflow) = %u", new_tenuring_threshold_arg);
625 } else if (decrement_tenuring_threshold_for_gc_cost()) {
626 log_debug(gc, ergo)("Tenuring threshold: (attempted to decrease to balance GC costs) = %u", new_tenuring_threshold_arg);
627 } else if (increment_tenuring_threshold_for_gc_cost()) {
628 log_debug(gc, ergo)("Tenuring threshold: (attempted to increase to balance GC costs) = %u", new_tenuring_threshold_arg);
629 } else {
630 assert(!tenuring_threshold_change(), "(no change was attempted)");
631 }
632 }