1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/gc_implementation/shared/adaptiveSizePolicy.cpp Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,669 @@
1.4 +/*
1.5 + * Copyright (c) 2004, 2014, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#include "precompiled.hpp"
1.29 +#include "gc_implementation/shared/adaptiveSizePolicy.hpp"
1.30 +#include "gc_interface/gcCause.hpp"
1.31 +#include "memory/collectorPolicy.hpp"
1.32 +#include "runtime/timer.hpp"
1.33 +#include "utilities/ostream.hpp"
1.34 +#include "utilities/workgroup.hpp"
1.35 +elapsedTimer AdaptiveSizePolicy::_minor_timer;
1.36 +elapsedTimer AdaptiveSizePolicy::_major_timer;
1.37 +bool AdaptiveSizePolicy::_debug_perturbation = false;
1.38 +
1.39 +// The throughput goal is implemented as
1.40 +// _throughput_goal = 1 - ( 1 / (1 + gc_cost_ratio))
1.41 +// gc_cost_ratio is the ratio
1.42 +// application cost / gc cost
1.43 +// For example a gc_cost_ratio of 4 translates into a
1.44 +// throughput goal of .80
1.45 +
1.46 +AdaptiveSizePolicy::AdaptiveSizePolicy(size_t init_eden_size,
1.47 + size_t init_promo_size,
1.48 + size_t init_survivor_size,
1.49 + double gc_pause_goal_sec,
1.50 + uint gc_cost_ratio) :
1.51 + _eden_size(init_eden_size),
1.52 + _promo_size(init_promo_size),
1.53 + _survivor_size(init_survivor_size),
1.54 + _gc_pause_goal_sec(gc_pause_goal_sec),
1.55 + _throughput_goal(1.0 - double(1.0 / (1.0 + (double) gc_cost_ratio))),
1.56 + _gc_overhead_limit_exceeded(false),
1.57 + _print_gc_overhead_limit_would_be_exceeded(false),
1.58 + _gc_overhead_limit_count(0),
1.59 + _latest_minor_mutator_interval_seconds(0),
1.60 + _threshold_tolerance_percent(1.0 + ThresholdTolerance/100.0),
1.61 + _young_gen_change_for_minor_throughput(0),
1.62 + _old_gen_change_for_major_throughput(0) {
1.63 + assert(AdaptiveSizePolicyGCTimeLimitThreshold > 0,
1.64 + "No opportunity to clear SoftReferences before GC overhead limit");
1.65 + _avg_minor_pause =
1.66 + new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding);
1.67 + _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
1.68 + _avg_minor_gc_cost = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
1.69 + _avg_major_gc_cost = new AdaptiveWeightedAverage(AdaptiveTimeWeight);
1.70 +
1.71 + _avg_young_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
1.72 + _avg_old_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
1.73 + _avg_eden_live = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight);
1.74 +
1.75 + _avg_survived = new AdaptivePaddedAverage(AdaptiveSizePolicyWeight,
1.76 + SurvivorPadding);
1.77 + _avg_pretenured = new AdaptivePaddedNoZeroDevAverage(
1.78 + AdaptiveSizePolicyWeight,
1.79 + SurvivorPadding);
1.80 +
1.81 + _minor_pause_old_estimator =
1.82 + new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
1.83 + _minor_pause_young_estimator =
1.84 + new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
1.85 + _minor_collection_estimator =
1.86 + new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
1.87 + _major_collection_estimator =
1.88 + new LinearLeastSquareFit(AdaptiveSizePolicyWeight);
1.89 +
1.90 + // Start the timers
1.91 + _minor_timer.start();
1.92 +
1.93 + _young_gen_policy_is_ready = false;
1.94 +}
1.95 +
1.96 +// If the number of GC threads was set on the command line,
1.97 +// use it.
1.98 +// Else
1.99 +// Calculate the number of GC threads based on the number of Java threads.
1.100 +// Calculate the number of GC threads based on the size of the heap.
1.101 +// Use the larger.
1.102 +
1.103 +int AdaptiveSizePolicy::calc_default_active_workers(uintx total_workers,
1.104 + const uintx min_workers,
1.105 + uintx active_workers,
1.106 + uintx application_workers) {
1.107 + // If the user has specifically set the number of
1.108 + // GC threads, use them.
1.109 +
1.110 + // If the user has turned off using a dynamic number of GC threads
1.111 + // or the users has requested a specific number, set the active
1.112 + // number of workers to all the workers.
1.113 +
1.114 + uintx new_active_workers = total_workers;
1.115 + uintx prev_active_workers = active_workers;
1.116 + uintx active_workers_by_JT = 0;
1.117 + uintx active_workers_by_heap_size = 0;
1.118 +
1.119 + // Always use at least min_workers but use up to
1.120 + // GCThreadsPerJavaThreads * application threads.
1.121 + active_workers_by_JT =
1.122 + MAX2((uintx) GCWorkersPerJavaThread * application_workers,
1.123 + min_workers);
1.124 +
1.125 + // Choose a number of GC threads based on the current size
1.126 + // of the heap. This may be complicated because the size of
1.127 + // the heap depends on factors such as the thoughput goal.
1.128 + // Still a large heap should be collected by more GC threads.
1.129 + active_workers_by_heap_size =
1.130 + MAX2((size_t) 2U, Universe::heap()->capacity() / HeapSizePerGCThread);
1.131 +
1.132 + uintx max_active_workers =
1.133 + MAX2(active_workers_by_JT, active_workers_by_heap_size);
1.134 +
1.135 + // Limit the number of workers to the the number created,
1.136 + // (workers()).
1.137 + new_active_workers = MIN2(max_active_workers,
1.138 + (uintx) total_workers);
1.139 +
1.140 + // Increase GC workers instantly but decrease them more
1.141 + // slowly.
1.142 + if (new_active_workers < prev_active_workers) {
1.143 + new_active_workers =
1.144 + MAX2(min_workers, (prev_active_workers + new_active_workers) / 2);
1.145 + }
1.146 +
1.147 + // Check once more that the number of workers is within the limits.
1.148 + assert(min_workers <= total_workers, "Minimum workers not consistent with total workers");
1.149 + assert(new_active_workers >= min_workers, "Minimum workers not observed");
1.150 + assert(new_active_workers <= total_workers, "Total workers not observed");
1.151 +
1.152 + if (ForceDynamicNumberOfGCThreads) {
1.153 + // Assume this is debugging and jiggle the number of GC threads.
1.154 + if (new_active_workers == prev_active_workers) {
1.155 + if (new_active_workers < total_workers) {
1.156 + new_active_workers++;
1.157 + } else if (new_active_workers > min_workers) {
1.158 + new_active_workers--;
1.159 + }
1.160 + }
1.161 + if (new_active_workers == total_workers) {
1.162 + if (_debug_perturbation) {
1.163 + new_active_workers = min_workers;
1.164 + }
1.165 + _debug_perturbation = !_debug_perturbation;
1.166 + }
1.167 + assert((new_active_workers <= (uintx) ParallelGCThreads) &&
1.168 + (new_active_workers >= min_workers),
1.169 + "Jiggled active workers too much");
1.170 + }
1.171 +
1.172 + if (TraceDynamicGCThreads) {
1.173 + gclog_or_tty->print_cr("GCTaskManager::calc_default_active_workers() : "
1.174 + "active_workers(): %d new_acitve_workers: %d "
1.175 + "prev_active_workers: %d\n"
1.176 + " active_workers_by_JT: %d active_workers_by_heap_size: %d",
1.177 + (int) active_workers, (int) new_active_workers, (int) prev_active_workers,
1.178 + (int) active_workers_by_JT, (int) active_workers_by_heap_size);
1.179 + }
1.180 + assert(new_active_workers > 0, "Always need at least 1");
1.181 + return new_active_workers;
1.182 +}
1.183 +
1.184 +int AdaptiveSizePolicy::calc_active_workers(uintx total_workers,
1.185 + uintx active_workers,
1.186 + uintx application_workers) {
1.187 + // If the user has specifically set the number of
1.188 + // GC threads, use them.
1.189 +
1.190 + // If the user has turned off using a dynamic number of GC threads
1.191 + // or the users has requested a specific number, set the active
1.192 + // number of workers to all the workers.
1.193 +
1.194 + int new_active_workers;
1.195 + if (!UseDynamicNumberOfGCThreads ||
1.196 + (!FLAG_IS_DEFAULT(ParallelGCThreads) && !ForceDynamicNumberOfGCThreads)) {
1.197 + new_active_workers = total_workers;
1.198 + } else {
1.199 + new_active_workers = calc_default_active_workers(total_workers,
1.200 + 2, /* Minimum number of workers */
1.201 + active_workers,
1.202 + application_workers);
1.203 + }
1.204 + assert(new_active_workers > 0, "Always need at least 1");
1.205 + return new_active_workers;
1.206 +}
1.207 +
1.208 +int AdaptiveSizePolicy::calc_active_conc_workers(uintx total_workers,
1.209 + uintx active_workers,
1.210 + uintx application_workers) {
1.211 + if (!UseDynamicNumberOfGCThreads ||
1.212 + (!FLAG_IS_DEFAULT(ConcGCThreads) && !ForceDynamicNumberOfGCThreads)) {
1.213 + return ConcGCThreads;
1.214 + } else {
1.215 + int no_of_gc_threads = calc_default_active_workers(
1.216 + total_workers,
1.217 + 1, /* Minimum number of workers */
1.218 + active_workers,
1.219 + application_workers);
1.220 + return no_of_gc_threads;
1.221 + }
1.222 +}
1.223 +
1.224 +bool AdaptiveSizePolicy::tenuring_threshold_change() const {
1.225 + return decrement_tenuring_threshold_for_gc_cost() ||
1.226 + increment_tenuring_threshold_for_gc_cost() ||
1.227 + decrement_tenuring_threshold_for_survivor_limit();
1.228 +}
1.229 +
1.230 +void AdaptiveSizePolicy::minor_collection_begin() {
1.231 + // Update the interval time
1.232 + _minor_timer.stop();
1.233 + // Save most recent collection time
1.234 + _latest_minor_mutator_interval_seconds = _minor_timer.seconds();
1.235 + _minor_timer.reset();
1.236 + _minor_timer.start();
1.237 +}
1.238 +
1.239 +void AdaptiveSizePolicy::update_minor_pause_young_estimator(
1.240 + double minor_pause_in_ms) {
1.241 + double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
1.242 + _minor_pause_young_estimator->update(eden_size_in_mbytes,
1.243 + minor_pause_in_ms);
1.244 +}
1.245 +
1.246 +void AdaptiveSizePolicy::minor_collection_end(GCCause::Cause gc_cause) {
1.247 + // Update the pause time.
1.248 + _minor_timer.stop();
1.249 +
1.250 + if (gc_cause != GCCause::_java_lang_system_gc ||
1.251 + UseAdaptiveSizePolicyWithSystemGC) {
1.252 + double minor_pause_in_seconds = _minor_timer.seconds();
1.253 + double minor_pause_in_ms = minor_pause_in_seconds * MILLIUNITS;
1.254 +
1.255 + // Sample for performance counter
1.256 + _avg_minor_pause->sample(minor_pause_in_seconds);
1.257 +
1.258 + // Cost of collection (unit-less)
1.259 + double collection_cost = 0.0;
1.260 + if ((_latest_minor_mutator_interval_seconds > 0.0) &&
1.261 + (minor_pause_in_seconds > 0.0)) {
1.262 + double interval_in_seconds =
1.263 + _latest_minor_mutator_interval_seconds + minor_pause_in_seconds;
1.264 + collection_cost =
1.265 + minor_pause_in_seconds / interval_in_seconds;
1.266 + _avg_minor_gc_cost->sample(collection_cost);
1.267 + // Sample for performance counter
1.268 + _avg_minor_interval->sample(interval_in_seconds);
1.269 + }
1.270 +
1.271 + // The policy does not have enough data until at least some
1.272 + // minor collections have been done.
1.273 + _young_gen_policy_is_ready =
1.274 + (_avg_minor_gc_cost->count() >= AdaptiveSizePolicyReadyThreshold);
1.275 +
1.276 + // Calculate variables used to estimate pause time vs. gen sizes
1.277 + double eden_size_in_mbytes = ((double)_eden_size)/((double)M);
1.278 + update_minor_pause_young_estimator(minor_pause_in_ms);
1.279 + update_minor_pause_old_estimator(minor_pause_in_ms);
1.280 +
1.281 + if (PrintAdaptiveSizePolicy && Verbose) {
1.282 + gclog_or_tty->print("AdaptiveSizePolicy::minor_collection_end: "
1.283 + "minor gc cost: %f average: %f", collection_cost,
1.284 + _avg_minor_gc_cost->average());
1.285 + gclog_or_tty->print_cr(" minor pause: %f minor period %f",
1.286 + minor_pause_in_ms,
1.287 + _latest_minor_mutator_interval_seconds * MILLIUNITS);
1.288 + }
1.289 +
1.290 + // Calculate variable used to estimate collection cost vs. gen sizes
1.291 + assert(collection_cost >= 0.0, "Expected to be non-negative");
1.292 + _minor_collection_estimator->update(eden_size_in_mbytes, collection_cost);
1.293 + }
1.294 +
1.295 + // Interval times use this timer to measure the mutator time.
1.296 + // Reset the timer after the GC pause.
1.297 + _minor_timer.reset();
1.298 + _minor_timer.start();
1.299 +}
1.300 +
1.301 +size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden,
1.302 + uint percent_change) {
1.303 + size_t eden_heap_delta;
1.304 + eden_heap_delta = cur_eden / 100 * percent_change;
1.305 + return eden_heap_delta;
1.306 +}
1.307 +
1.308 +size_t AdaptiveSizePolicy::eden_increment(size_t cur_eden) {
1.309 + return eden_increment(cur_eden, YoungGenerationSizeIncrement);
1.310 +}
1.311 +
1.312 +size_t AdaptiveSizePolicy::eden_decrement(size_t cur_eden) {
1.313 + size_t eden_heap_delta = eden_increment(cur_eden) /
1.314 + AdaptiveSizeDecrementScaleFactor;
1.315 + return eden_heap_delta;
1.316 +}
1.317 +
1.318 +size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo,
1.319 + uint percent_change) {
1.320 + size_t promo_heap_delta;
1.321 + promo_heap_delta = cur_promo / 100 * percent_change;
1.322 + return promo_heap_delta;
1.323 +}
1.324 +
1.325 +size_t AdaptiveSizePolicy::promo_increment(size_t cur_promo) {
1.326 + return promo_increment(cur_promo, TenuredGenerationSizeIncrement);
1.327 +}
1.328 +
1.329 +size_t AdaptiveSizePolicy::promo_decrement(size_t cur_promo) {
1.330 + size_t promo_heap_delta = promo_increment(cur_promo);
1.331 + promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor;
1.332 + return promo_heap_delta;
1.333 +}
1.334 +
1.335 +double AdaptiveSizePolicy::time_since_major_gc() const {
1.336 + _major_timer.stop();
1.337 + double result = _major_timer.seconds();
1.338 + _major_timer.start();
1.339 + return result;
1.340 +}
1.341 +
1.342 +// Linear decay of major gc cost
1.343 +double AdaptiveSizePolicy::decaying_major_gc_cost() const {
1.344 + double major_interval = major_gc_interval_average_for_decay();
1.345 + double major_gc_cost_average = major_gc_cost();
1.346 + double decayed_major_gc_cost = major_gc_cost_average;
1.347 + if(time_since_major_gc() > 0.0) {
1.348 + decayed_major_gc_cost = major_gc_cost() *
1.349 + (((double) AdaptiveSizeMajorGCDecayTimeScale) * major_interval)
1.350 + / time_since_major_gc();
1.351 + }
1.352 +
1.353 + // The decayed cost should always be smaller than the
1.354 + // average cost but the vagaries of finite arithmetic could
1.355 + // produce a larger value in decayed_major_gc_cost so protect
1.356 + // against that.
1.357 + return MIN2(major_gc_cost_average, decayed_major_gc_cost);
1.358 +}
1.359 +
1.360 +// Use a value of the major gc cost that has been decayed
1.361 +// by the factor
1.362 +//
1.363 +// average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale /
1.364 +// time-since-last-major-gc
1.365 +//
1.366 +// if the average-interval-between-major-gc * AdaptiveSizeMajorGCDecayTimeScale
1.367 +// is less than time-since-last-major-gc.
1.368 +//
1.369 +// In cases where there are initial major gc's that
1.370 +// are of a relatively high cost but no later major
1.371 +// gc's, the total gc cost can remain high because
1.372 +// the major gc cost remains unchanged (since there are no major
1.373 +// gc's). In such a situation the value of the unchanging
1.374 +// major gc cost can keep the mutator throughput below
1.375 +// the goal when in fact the major gc cost is becoming diminishingly
1.376 +// small. Use the decaying gc cost only to decide whether to
1.377 +// adjust for throughput. Using it also to determine the adjustment
1.378 +// to be made for throughput also seems reasonable but there is
1.379 +// no test case to use to decide if it is the right thing to do
1.380 +// don't do it yet.
1.381 +
1.382 +double AdaptiveSizePolicy::decaying_gc_cost() const {
1.383 + double decayed_major_gc_cost = major_gc_cost();
1.384 + double avg_major_interval = major_gc_interval_average_for_decay();
1.385 + if (UseAdaptiveSizeDecayMajorGCCost &&
1.386 + (AdaptiveSizeMajorGCDecayTimeScale > 0) &&
1.387 + (avg_major_interval > 0.00)) {
1.388 + double time_since_last_major_gc = time_since_major_gc();
1.389 +
1.390 + // Decay the major gc cost?
1.391 + if (time_since_last_major_gc >
1.392 + ((double) AdaptiveSizeMajorGCDecayTimeScale) * avg_major_interval) {
1.393 +
1.394 + // Decay using the time-since-last-major-gc
1.395 + decayed_major_gc_cost = decaying_major_gc_cost();
1.396 + if (PrintGCDetails && Verbose) {
1.397 + gclog_or_tty->print_cr("\ndecaying_gc_cost: major interval average:"
1.398 + " %f time since last major gc: %f",
1.399 + avg_major_interval, time_since_last_major_gc);
1.400 + gclog_or_tty->print_cr(" major gc cost: %f decayed major gc cost: %f",
1.401 + major_gc_cost(), decayed_major_gc_cost);
1.402 + }
1.403 + }
1.404 + }
1.405 + double result = MIN2(1.0, decayed_major_gc_cost + minor_gc_cost());
1.406 + return result;
1.407 +}
1.408 +
1.409 +
1.410 +void AdaptiveSizePolicy::clear_generation_free_space_flags() {
1.411 + set_change_young_gen_for_min_pauses(0);
1.412 + set_change_old_gen_for_maj_pauses(0);
1.413 +
1.414 + set_change_old_gen_for_throughput(0);
1.415 + set_change_young_gen_for_throughput(0);
1.416 + set_decrease_for_footprint(0);
1.417 + set_decide_at_full_gc(0);
1.418 +}
1.419 +
1.420 +void AdaptiveSizePolicy::check_gc_overhead_limit(
1.421 + size_t young_live,
1.422 + size_t eden_live,
1.423 + size_t max_old_gen_size,
1.424 + size_t max_eden_size,
1.425 + bool is_full_gc,
1.426 + GCCause::Cause gc_cause,
1.427 + CollectorPolicy* collector_policy) {
1.428 +
1.429 + // Ignore explicit GC's. Exiting here does not set the flag and
1.430 + // does not reset the count. Updating of the averages for system
1.431 + // GC's is still controlled by UseAdaptiveSizePolicyWithSystemGC.
1.432 + if (GCCause::is_user_requested_gc(gc_cause) ||
1.433 + GCCause::is_serviceability_requested_gc(gc_cause)) {
1.434 + return;
1.435 + }
1.436 + // eden_limit is the upper limit on the size of eden based on
1.437 + // the maximum size of the young generation and the sizes
1.438 + // of the survivor space.
1.439 + // The question being asked is whether the gc costs are high
1.440 + // and the space being recovered by a collection is low.
1.441 + // free_in_young_gen is the free space in the young generation
1.442 + // after a collection and promo_live is the free space in the old
1.443 + // generation after a collection.
1.444 + //
1.445 + // Use the minimum of the current value of the live in the
1.446 + // young gen or the average of the live in the young gen.
1.447 + // If the current value drops quickly, that should be taken
1.448 + // into account (i.e., don't trigger if the amount of free
1.449 + // space has suddenly jumped up). If the current is much
1.450 + // higher than the average, use the average since it represents
1.451 + // the longer term behavor.
1.452 + const size_t live_in_eden =
1.453 + MIN2(eden_live, (size_t) avg_eden_live()->average());
1.454 + const size_t free_in_eden = max_eden_size > live_in_eden ?
1.455 + max_eden_size - live_in_eden : 0;
1.456 + const size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average());
1.457 + const size_t total_free_limit = free_in_old_gen + free_in_eden;
1.458 + const size_t total_mem = max_old_gen_size + max_eden_size;
1.459 + const double mem_free_limit = total_mem * (GCHeapFreeLimit/100.0);
1.460 + const double mem_free_old_limit = max_old_gen_size * (GCHeapFreeLimit/100.0);
1.461 + const double mem_free_eden_limit = max_eden_size * (GCHeapFreeLimit/100.0);
1.462 + const double gc_cost_limit = GCTimeLimit/100.0;
1.463 + size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average());
1.464 + // But don't force a promo size below the current promo size. Otherwise,
1.465 + // the promo size will shrink for no good reason.
1.466 + promo_limit = MAX2(promo_limit, _promo_size);
1.467 +
1.468 +
1.469 + if (PrintAdaptiveSizePolicy && (Verbose ||
1.470 + (free_in_old_gen < (size_t) mem_free_old_limit &&
1.471 + free_in_eden < (size_t) mem_free_eden_limit))) {
1.472 + gclog_or_tty->print_cr(
1.473 + "PSAdaptiveSizePolicy::check_gc_overhead_limit:"
1.474 + " promo_limit: " SIZE_FORMAT
1.475 + " max_eden_size: " SIZE_FORMAT
1.476 + " total_free_limit: " SIZE_FORMAT
1.477 + " max_old_gen_size: " SIZE_FORMAT
1.478 + " max_eden_size: " SIZE_FORMAT
1.479 + " mem_free_limit: " SIZE_FORMAT,
1.480 + promo_limit, max_eden_size, total_free_limit,
1.481 + max_old_gen_size, max_eden_size,
1.482 + (size_t) mem_free_limit);
1.483 + }
1.484 +
1.485 + bool print_gc_overhead_limit_would_be_exceeded = false;
1.486 + if (is_full_gc) {
1.487 + if (gc_cost() > gc_cost_limit &&
1.488 + free_in_old_gen < (size_t) mem_free_old_limit &&
1.489 + free_in_eden < (size_t) mem_free_eden_limit) {
1.490 + // Collections, on average, are taking too much time, and
1.491 + // gc_cost() > gc_cost_limit
1.492 + // we have too little space available after a full gc.
1.493 + // total_free_limit < mem_free_limit
1.494 + // where
1.495 + // total_free_limit is the free space available in
1.496 + // both generations
1.497 + // total_mem is the total space available for allocation
1.498 + // in both generations (survivor spaces are not included
1.499 + // just as they are not included in eden_limit).
1.500 + // mem_free_limit is a fraction of total_mem judged to be an
1.501 + // acceptable amount that is still unused.
1.502 + // The heap can ask for the value of this variable when deciding
1.503 + // whether to thrown an OutOfMemory error.
1.504 + // Note that the gc time limit test only works for the collections
1.505 + // of the young gen + tenured gen and not for collections of the
1.506 + // permanent gen. That is because the calculation of the space
1.507 + // freed by the collection is the free space in the young gen +
1.508 + // tenured gen.
1.509 + // At this point the GC overhead limit is being exceeded.
1.510 + inc_gc_overhead_limit_count();
1.511 + if (UseGCOverheadLimit) {
1.512 + if (gc_overhead_limit_count() >=
1.513 + AdaptiveSizePolicyGCTimeLimitThreshold){
1.514 + // All conditions have been met for throwing an out-of-memory
1.515 + set_gc_overhead_limit_exceeded(true);
1.516 + // Avoid consecutive OOM due to the gc time limit by resetting
1.517 + // the counter.
1.518 + reset_gc_overhead_limit_count();
1.519 + } else {
1.520 + // The required consecutive collections which exceed the
1.521 + // GC time limit may or may not have been reached. We
1.522 + // are approaching that condition and so as not to
1.523 + // throw an out-of-memory before all SoftRef's have been
1.524 + // cleared, set _should_clear_all_soft_refs in CollectorPolicy.
1.525 + // The clearing will be done on the next GC.
1.526 + bool near_limit = gc_overhead_limit_near();
1.527 + if (near_limit) {
1.528 + collector_policy->set_should_clear_all_soft_refs(true);
1.529 + if (PrintGCDetails && Verbose) {
1.530 + gclog_or_tty->print_cr(" Nearing GC overhead limit, "
1.531 + "will be clearing all SoftReference");
1.532 + }
1.533 + }
1.534 + }
1.535 + }
1.536 + // Set this even when the overhead limit will not
1.537 + // cause an out-of-memory. Diagnostic message indicating
1.538 + // that the overhead limit is being exceeded is sometimes
1.539 + // printed.
1.540 + print_gc_overhead_limit_would_be_exceeded = true;
1.541 +
1.542 + } else {
1.543 + // Did not exceed overhead limits
1.544 + reset_gc_overhead_limit_count();
1.545 + }
1.546 + }
1.547 +
1.548 + if (UseGCOverheadLimit && PrintGCDetails && Verbose) {
1.549 + if (gc_overhead_limit_exceeded()) {
1.550 + gclog_or_tty->print_cr(" GC is exceeding overhead limit "
1.551 + "of %d%%", (int) GCTimeLimit);
1.552 + reset_gc_overhead_limit_count();
1.553 + } else if (print_gc_overhead_limit_would_be_exceeded) {
1.554 + assert(gc_overhead_limit_count() > 0, "Should not be printing");
1.555 + gclog_or_tty->print_cr(" GC would exceed overhead limit "
1.556 + "of %d%% %d consecutive time(s)",
1.557 + (int) GCTimeLimit, gc_overhead_limit_count());
1.558 + }
1.559 + }
1.560 +}
1.561 +// Printing
1.562 +
1.563 +bool AdaptiveSizePolicy::print_adaptive_size_policy_on(outputStream* st) const {
1.564 +
1.565 + // Should only be used with adaptive size policy turned on.
1.566 + // Otherwise, there may be variables that are undefined.
1.567 + if (!UseAdaptiveSizePolicy) return false;
1.568 +
1.569 + // Print goal for which action is needed.
1.570 + char* action = NULL;
1.571 + bool change_for_pause = false;
1.572 + if ((change_old_gen_for_maj_pauses() ==
1.573 + decrease_old_gen_for_maj_pauses_true) ||
1.574 + (change_young_gen_for_min_pauses() ==
1.575 + decrease_young_gen_for_min_pauses_true)) {
1.576 + action = (char*) " *** pause time goal ***";
1.577 + change_for_pause = true;
1.578 + } else if ((change_old_gen_for_throughput() ==
1.579 + increase_old_gen_for_throughput_true) ||
1.580 + (change_young_gen_for_throughput() ==
1.581 + increase_young_gen_for_througput_true)) {
1.582 + action = (char*) " *** throughput goal ***";
1.583 + } else if (decrease_for_footprint()) {
1.584 + action = (char*) " *** reduced footprint ***";
1.585 + } else {
1.586 + // No actions were taken. This can legitimately be the
1.587 + // situation if not enough data has been gathered to make
1.588 + // decisions.
1.589 + return false;
1.590 + }
1.591 +
1.592 + // Pauses
1.593 + // Currently the size of the old gen is only adjusted to
1.594 + // change the major pause times.
1.595 + char* young_gen_action = NULL;
1.596 + char* tenured_gen_action = NULL;
1.597 +
1.598 + char* shrink_msg = (char*) "(attempted to shrink)";
1.599 + char* grow_msg = (char*) "(attempted to grow)";
1.600 + char* no_change_msg = (char*) "(no change)";
1.601 + if (change_young_gen_for_min_pauses() ==
1.602 + decrease_young_gen_for_min_pauses_true) {
1.603 + young_gen_action = shrink_msg;
1.604 + } else if (change_for_pause) {
1.605 + young_gen_action = no_change_msg;
1.606 + }
1.607 +
1.608 + if (change_old_gen_for_maj_pauses() == decrease_old_gen_for_maj_pauses_true) {
1.609 + tenured_gen_action = shrink_msg;
1.610 + } else if (change_for_pause) {
1.611 + tenured_gen_action = no_change_msg;
1.612 + }
1.613 +
1.614 + // Throughput
1.615 + if (change_old_gen_for_throughput() == increase_old_gen_for_throughput_true) {
1.616 + assert(change_young_gen_for_throughput() ==
1.617 + increase_young_gen_for_througput_true,
1.618 + "Both generations should be growing");
1.619 + young_gen_action = grow_msg;
1.620 + tenured_gen_action = grow_msg;
1.621 + } else if (change_young_gen_for_throughput() ==
1.622 + increase_young_gen_for_througput_true) {
1.623 + // Only the young generation may grow at start up (before
1.624 + // enough full collections have been done to grow the old generation).
1.625 + young_gen_action = grow_msg;
1.626 + tenured_gen_action = no_change_msg;
1.627 + }
1.628 +
1.629 + // Minimum footprint
1.630 + if (decrease_for_footprint() != 0) {
1.631 + young_gen_action = shrink_msg;
1.632 + tenured_gen_action = shrink_msg;
1.633 + }
1.634 +
1.635 + st->print_cr(" UseAdaptiveSizePolicy actions to meet %s", action);
1.636 + st->print_cr(" GC overhead (%%)");
1.637 + st->print_cr(" Young generation: %7.2f\t %s",
1.638 + 100.0 * avg_minor_gc_cost()->average(),
1.639 + young_gen_action);
1.640 + st->print_cr(" Tenured generation: %7.2f\t %s",
1.641 + 100.0 * avg_major_gc_cost()->average(),
1.642 + tenured_gen_action);
1.643 + return true;
1.644 +}
1.645 +
1.646 +bool AdaptiveSizePolicy::print_adaptive_size_policy_on(
1.647 + outputStream* st,
1.648 + uint tenuring_threshold_arg) const {
1.649 + if (!AdaptiveSizePolicy::print_adaptive_size_policy_on(st)) {
1.650 + return false;
1.651 + }
1.652 +
1.653 + // Tenuring threshold
1.654 + bool tenuring_threshold_changed = true;
1.655 + if (decrement_tenuring_threshold_for_survivor_limit()) {
1.656 + st->print(" Tenuring threshold: (attempted to decrease to avoid"
1.657 + " survivor space overflow) = ");
1.658 + } else if (decrement_tenuring_threshold_for_gc_cost()) {
1.659 + st->print(" Tenuring threshold: (attempted to decrease to balance"
1.660 + " GC costs) = ");
1.661 + } else if (increment_tenuring_threshold_for_gc_cost()) {
1.662 + st->print(" Tenuring threshold: (attempted to increase to balance"
1.663 + " GC costs) = ");
1.664 + } else {
1.665 + tenuring_threshold_changed = false;
1.666 + assert(!tenuring_threshold_change(), "(no change was attempted)");
1.667 + }
1.668 + if (tenuring_threshold_changed) {
1.669 + st->print_cr("%u", tenuring_threshold_arg);
1.670 + }
1.671 + return true;
1.672 +}
