/* * Copyright (c) 2002, 2015, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "gc/parallel/parallelScavengeHeap.hpp" #include "gc/parallel/psAdaptiveSizePolicy.hpp" #include "gc/parallel/psGCAdaptivePolicyCounters.hpp" #include "gc/parallel/psScavenge.hpp" #include "gc/shared/collectorPolicy.hpp" #include "gc/shared/gcCause.hpp" #include "gc/shared/gcPolicyCounters.hpp" #include "logging/log.hpp" #include "runtime/timer.hpp" #include "utilities/top.hpp" #include PSAdaptiveSizePolicy::PSAdaptiveSizePolicy(size_t init_eden_size, size_t init_promo_size, size_t init_survivor_size, size_t space_alignment, double gc_pause_goal_sec, double gc_minor_pause_goal_sec, uint gc_cost_ratio) : AdaptiveSizePolicy(init_eden_size, init_promo_size, init_survivor_size, gc_pause_goal_sec, gc_cost_ratio), _collection_cost_margin_fraction(AdaptiveSizePolicyCollectionCostMargin / 100.0), _space_alignment(space_alignment), _live_at_last_full_gc(init_promo_size), _gc_minor_pause_goal_sec(gc_minor_pause_goal_sec), _latest_major_mutator_interval_seconds(0), _young_gen_change_for_major_pause_count(0) { // Sizing policy statistics _avg_major_pause = new AdaptivePaddedAverage(AdaptiveTimeWeight, PausePadding); _avg_minor_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight); _avg_major_interval = new AdaptiveWeightedAverage(AdaptiveTimeWeight); _avg_base_footprint = new AdaptiveWeightedAverage(AdaptiveSizePolicyWeight); _major_pause_old_estimator = new LinearLeastSquareFit(AdaptiveSizePolicyWeight); _major_pause_young_estimator = new LinearLeastSquareFit(AdaptiveSizePolicyWeight); _major_collection_estimator = new LinearLeastSquareFit(AdaptiveSizePolicyWeight); _young_gen_size_increment_supplement = YoungGenerationSizeSupplement; _old_gen_size_increment_supplement = TenuredGenerationSizeSupplement; // Start the timers _major_timer.start(); _old_gen_policy_is_ready = false; } size_t PSAdaptiveSizePolicy::calculate_free_based_on_live(size_t live, uintx ratio_as_percentage) { // We want to calculate how much free memory there can be based on the // amount of live data currently in the old gen. Using the formula: // ratio * (free + live) = free // Some equation solving later we get: // free = (live * ratio) / (1 - ratio) const double ratio = ratio_as_percentage / 100.0; const double ratio_inverse = 1.0 - ratio; const double tmp = live * ratio; size_t free = (size_t)(tmp / ratio_inverse); return free; } size_t PSAdaptiveSizePolicy::calculated_old_free_size_in_bytes() const { size_t free_size = (size_t)(_promo_size + avg_promoted()->padded_average()); size_t live = ParallelScavengeHeap::heap()->old_gen()->used_in_bytes(); if (MinHeapFreeRatio != 0) { size_t min_free = calculate_free_based_on_live(live, MinHeapFreeRatio); free_size = MAX2(free_size, min_free); } if (MaxHeapFreeRatio != 100) { size_t max_free = calculate_free_based_on_live(live, MaxHeapFreeRatio); free_size = MIN2(max_free, free_size); } return free_size; } void PSAdaptiveSizePolicy::major_collection_begin() { // Update the interval time _major_timer.stop(); // Save most recent collection time _latest_major_mutator_interval_seconds = _major_timer.seconds(); _major_timer.reset(); _major_timer.start(); } void PSAdaptiveSizePolicy::update_minor_pause_old_estimator( double minor_pause_in_ms) { double promo_size_in_mbytes = ((double)_promo_size)/((double)M); _minor_pause_old_estimator->update(promo_size_in_mbytes, minor_pause_in_ms); } void PSAdaptiveSizePolicy::major_collection_end(size_t amount_live, GCCause::Cause gc_cause) { // Update the pause time. _major_timer.stop(); if (should_update_promo_stats(gc_cause)) { double major_pause_in_seconds = _major_timer.seconds(); double major_pause_in_ms = major_pause_in_seconds * MILLIUNITS; // Sample for performance counter _avg_major_pause->sample(major_pause_in_seconds); // Cost of collection (unit-less) double collection_cost = 0.0; if ((_latest_major_mutator_interval_seconds > 0.0) && (major_pause_in_seconds > 0.0)) { double interval_in_seconds = _latest_major_mutator_interval_seconds + major_pause_in_seconds; collection_cost = major_pause_in_seconds / interval_in_seconds; avg_major_gc_cost()->sample(collection_cost); // Sample for performance counter _avg_major_interval->sample(interval_in_seconds); } // Calculate variables used to estimate pause time vs. gen sizes double eden_size_in_mbytes = ((double)_eden_size)/((double)M); double promo_size_in_mbytes = ((double)_promo_size)/((double)M); _major_pause_old_estimator->update(promo_size_in_mbytes, major_pause_in_ms); _major_pause_young_estimator->update(eden_size_in_mbytes, major_pause_in_ms); log_trace(gc, ergo)("psAdaptiveSizePolicy::major_collection_end: major gc cost: %f average: %f", collection_cost,avg_major_gc_cost()->average()); log_trace(gc, ergo)(" major pause: %f major period %f", major_pause_in_ms, _latest_major_mutator_interval_seconds * MILLIUNITS); // Calculate variable used to estimate collection cost vs. gen sizes assert(collection_cost >= 0.0, "Expected to be non-negative"); _major_collection_estimator->update(promo_size_in_mbytes, collection_cost); } // Update the amount live at the end of a full GC _live_at_last_full_gc = amount_live; // The policy does not have enough data until at least some major collections // have been done. if (_avg_major_pause->count() >= AdaptiveSizePolicyReadyThreshold) { _old_gen_policy_is_ready = true; } // Interval times use this timer to measure the interval that // the mutator runs. Reset after the GC pause has been measured. _major_timer.reset(); _major_timer.start(); } // If the remaining free space in the old generation is less that // that expected to be needed by the next collection, do a full // collection now. bool PSAdaptiveSizePolicy::should_full_GC(size_t old_free_in_bytes) { // A similar test is done in the scavenge's should_attempt_scavenge(). If // this is changed, decide if that test should also be changed. bool result = padded_average_promoted_in_bytes() > (float) old_free_in_bytes; log_trace(gc, ergo)("%s after scavenge average_promoted " SIZE_FORMAT " padded_average_promoted " SIZE_FORMAT " free in old gen " SIZE_FORMAT, result ? "Full" : "No full", (size_t) average_promoted_in_bytes(), (size_t) padded_average_promoted_in_bytes(), old_free_in_bytes); return result; } void PSAdaptiveSizePolicy::clear_generation_free_space_flags() { AdaptiveSizePolicy::clear_generation_free_space_flags(); set_change_old_gen_for_min_pauses(0); set_change_young_gen_for_maj_pauses(0); } // If this is not a full GC, only test and modify the young generation. void PSAdaptiveSizePolicy::compute_generations_free_space( size_t young_live, size_t eden_live, size_t old_live, size_t cur_eden, size_t max_old_gen_size, size_t max_eden_size, bool is_full_gc) { compute_eden_space_size(young_live, eden_live, cur_eden, max_eden_size, is_full_gc); compute_old_gen_free_space(old_live, cur_eden, max_old_gen_size, is_full_gc); } void PSAdaptiveSizePolicy::compute_eden_space_size( size_t young_live, size_t eden_live, size_t cur_eden, size_t max_eden_size, bool is_full_gc) { // Update statistics // Time statistics are updated as we go, update footprint stats here _avg_base_footprint->sample(BaseFootPrintEstimate); avg_young_live()->sample(young_live); avg_eden_live()->sample(eden_live); // This code used to return if the policy was not ready , i.e., // policy_is_ready() returning false. The intent was that // decisions below needed major collection times and so could // not be made before two major collections. A consequence was // adjustments to the young generation were not done until after // two major collections even if the minor collections times // exceeded the requested goals. Now let the young generation // adjust for the minor collection times. Major collection times // will be zero for the first collection and will naturally be // ignored. Tenured generation adjustments are only made at the // full collections so until the second major collection has // been reached, no tenured generation adjustments will be made. // Until we know better, desired promotion size uses the last calculation size_t desired_promo_size = _promo_size; // Start eden at the current value. The desired value that is stored // in _eden_size is not bounded by constraints of the heap and can // run away. // // As expected setting desired_eden_size to the current // value of desired_eden_size as a starting point // caused desired_eden_size to grow way too large and caused // an overflow down stream. It may have improved performance in // some case but is dangerous. size_t desired_eden_size = cur_eden; // Cache some values. There's a bit of work getting these, so // we might save a little time. const double major_cost = major_gc_cost(); const double minor_cost = minor_gc_cost(); // This method sets the desired eden size. That plus the // desired survivor space sizes sets the desired young generation // size. This methods does not know what the desired survivor // size is but expects that other policy will attempt to make // the survivor sizes compatible with the live data in the // young generation. This limit is an estimate of the space left // in the young generation after the survivor spaces have been // subtracted out. size_t eden_limit = max_eden_size; const double gc_cost_limit = GCTimeLimit / 100.0; // Which way should we go? // if pause requirement is not met // adjust size of any generation with average paus exceeding // the pause limit. Adjust one pause at a time (the larger) // and only make adjustments for the major pause at full collections. // else if throughput requirement not met // adjust the size of the generation with larger gc time. Only // adjust one generation at a time. // else // adjust down the total heap size. Adjust down the larger of the // generations. // Add some checks for a threshold for a change. For example, // a change less than the necessary alignment is probably not worth // attempting. if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) || (_avg_major_pause->padded_average() > gc_pause_goal_sec())) { // // Check pauses // // Make changes only to affect one of the pauses (the larger) // at a time. adjust_eden_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size); } else if (_avg_minor_pause->padded_average() > gc_minor_pause_goal_sec()) { // Adjust only for the minor pause time goal adjust_eden_for_minor_pause_time(is_full_gc, &desired_eden_size); } else if(adjusted_mutator_cost() < _throughput_goal) { // This branch used to require that (mutator_cost() > 0.0 in 1.4.2. // This sometimes resulted in skipping to the minimize footprint // code. Change this to try and reduce GC time if mutator time is // negative for whatever reason. Or for future consideration, // bail out of the code if mutator time is negative. // // Throughput // assert(major_cost >= 0.0, "major cost is < 0.0"); assert(minor_cost >= 0.0, "minor cost is < 0.0"); // Try to reduce the GC times. adjust_eden_for_throughput(is_full_gc, &desired_eden_size); } else { // Be conservative about reducing the footprint. // Do a minimum number of major collections first. // Have reasonable averages for major and minor collections costs. if (UseAdaptiveSizePolicyFootprintGoal && young_gen_policy_is_ready() && avg_major_gc_cost()->average() >= 0.0 && avg_minor_gc_cost()->average() >= 0.0) { size_t desired_sum = desired_eden_size + desired_promo_size; desired_eden_size = adjust_eden_for_footprint(desired_eden_size, desired_sum); } } // Note we make the same tests as in the code block below; the code // seems a little easier to read with the printing in another block. if (desired_eden_size > eden_limit) { log_debug(gc, ergo)( "PSAdaptiveSizePolicy::compute_eden_space_size limits:" " desired_eden_size: " SIZE_FORMAT " old_eden_size: " SIZE_FORMAT " eden_limit: " SIZE_FORMAT " cur_eden: " SIZE_FORMAT " max_eden_size: " SIZE_FORMAT " avg_young_live: " SIZE_FORMAT, desired_eden_size, _eden_size, eden_limit, cur_eden, max_eden_size, (size_t)avg_young_live()->average()); } if (gc_cost() > gc_cost_limit) { log_debug(gc, ergo)( "PSAdaptiveSizePolicy::compute_eden_space_size: gc time limit" " gc_cost: %f " " GCTimeLimit: " UINTX_FORMAT, gc_cost(), GCTimeLimit); } // Align everything and make a final limit check desired_eden_size = align_size_up(desired_eden_size, _space_alignment); desired_eden_size = MAX2(desired_eden_size, _space_alignment); eden_limit = align_size_down(eden_limit, _space_alignment); // And one last limit check, now that we've aligned things. if (desired_eden_size > eden_limit) { // If the policy says to get a larger eden but // is hitting the limit, don't decrease eden. // This can lead to a general drifting down of the // eden size. Let the tenuring calculation push more // into the old gen. desired_eden_size = MAX2(eden_limit, cur_eden); } log_debug(gc, ergo)("PSAdaptiveSizePolicy::compute_eden_space_size: costs minor_time: %f major_cost: %f mutator_cost: %f throughput_goal: %f", minor_gc_cost(), major_gc_cost(), mutator_cost(), _throughput_goal); log_trace(gc, ergo)("Minor_pause: %f major_pause: %f minor_interval: %f major_interval: %fpause_goal: %f", _avg_minor_pause->padded_average(), _avg_major_pause->padded_average(), _avg_minor_interval->average(), _avg_major_interval->average(), gc_pause_goal_sec()); log_debug(gc, ergo)("Live_space: " SIZE_FORMAT " free_space: " SIZE_FORMAT, live_space(), free_space()); log_trace(gc, ergo)("Base_footprint: " SIZE_FORMAT " avg_young_live: " SIZE_FORMAT " avg_old_live: " SIZE_FORMAT, (size_t)_avg_base_footprint->average(), (size_t)avg_young_live()->average(), (size_t)avg_old_live()->average()); log_debug(gc, ergo)("Old eden_size: " SIZE_FORMAT " desired_eden_size: " SIZE_FORMAT, _eden_size, desired_eden_size); set_eden_size(desired_eden_size); } void PSAdaptiveSizePolicy::compute_old_gen_free_space( size_t old_live, size_t cur_eden, size_t max_old_gen_size, bool is_full_gc) { // Update statistics // Time statistics are updated as we go, update footprint stats here if (is_full_gc) { // old_live is only accurate after a full gc avg_old_live()->sample(old_live); } // This code used to return if the policy was not ready , i.e., // policy_is_ready() returning false. The intent was that // decisions below needed major collection times and so could // not be made before two major collections. A consequence was // adjustments to the young generation were not done until after // two major collections even if the minor collections times // exceeded the requested goals. Now let the young generation // adjust for the minor collection times. Major collection times // will be zero for the first collection and will naturally be // ignored. Tenured generation adjustments are only made at the // full collections so until the second major collection has // been reached, no tenured generation adjustments will be made. // Until we know better, desired promotion size uses the last calculation size_t desired_promo_size = _promo_size; // Start eden at the current value. The desired value that is stored // in _eden_size is not bounded by constraints of the heap and can // run away. // // As expected setting desired_eden_size to the current // value of desired_eden_size as a starting point // caused desired_eden_size to grow way too large and caused // an overflow down stream. It may have improved performance in // some case but is dangerous. size_t desired_eden_size = cur_eden; // Cache some values. There's a bit of work getting these, so // we might save a little time. const double major_cost = major_gc_cost(); const double minor_cost = minor_gc_cost(); // Limits on our growth size_t promo_limit = (size_t)(max_old_gen_size - avg_old_live()->average()); // But don't force a promo size below the current promo size. Otherwise, // the promo size will shrink for no good reason. promo_limit = MAX2(promo_limit, _promo_size); const double gc_cost_limit = GCTimeLimit/100.0; // Which way should we go? // if pause requirement is not met // adjust size of any generation with average paus exceeding // the pause limit. Adjust one pause at a time (the larger) // and only make adjustments for the major pause at full collections. // else if throughput requirement not met // adjust the size of the generation with larger gc time. Only // adjust one generation at a time. // else // adjust down the total heap size. Adjust down the larger of the // generations. // Add some checks for a threshold for a change. For example, // a change less than the necessary alignment is probably not worth // attempting. if ((_avg_minor_pause->padded_average() > gc_pause_goal_sec()) || (_avg_major_pause->padded_average() > gc_pause_goal_sec())) { // // Check pauses // // Make changes only to affect one of the pauses (the larger) // at a time. if (is_full_gc) { set_decide_at_full_gc(decide_at_full_gc_true); adjust_promo_for_pause_time(is_full_gc, &desired_promo_size, &desired_eden_size); } } else if (adjusted_mutator_cost() < _throughput_goal) { // This branch used to require that (mutator_cost() > 0.0 in 1.4.2. // This sometimes resulted in skipping to the minimize footprint // code. Change this to try and reduce GC time if mutator time is // negative for whatever reason. Or for future consideration, // bail out of the code if mutator time is negative. // // Throughput // assert(major_cost >= 0.0, "major cost is < 0.0"); assert(minor_cost >= 0.0, "minor cost is < 0.0"); // Try to reduce the GC times. if (is_full_gc) { set_decide_at_full_gc(decide_at_full_gc_true); adjust_promo_for_throughput(is_full_gc, &desired_promo_size); } } else { // Be conservative about reducing the footprint. // Do a minimum number of major collections first. // Have reasonable averages for major and minor collections costs. if (UseAdaptiveSizePolicyFootprintGoal && young_gen_policy_is_ready() && avg_major_gc_cost()->average() >= 0.0 && avg_minor_gc_cost()->average() >= 0.0) { if (is_full_gc) { set_decide_at_full_gc(decide_at_full_gc_true); size_t desired_sum = desired_eden_size + desired_promo_size; desired_promo_size = adjust_promo_for_footprint(desired_promo_size, desired_sum); } } } // Note we make the same tests as in the code block below; the code // seems a little easier to read with the printing in another block. if (desired_promo_size > promo_limit) { // "free_in_old_gen" was the original value for used for promo_limit size_t free_in_old_gen = (size_t)(max_old_gen_size - avg_old_live()->average()); log_debug(gc, ergo)( "PSAdaptiveSizePolicy::compute_old_gen_free_space limits:" " desired_promo_size: " SIZE_FORMAT " promo_limit: " SIZE_FORMAT " free_in_old_gen: " SIZE_FORMAT " max_old_gen_size: " SIZE_FORMAT " avg_old_live: " SIZE_FORMAT, desired_promo_size, promo_limit, free_in_old_gen, max_old_gen_size, (size_t) avg_old_live()->average()); } if (gc_cost() > gc_cost_limit) { log_debug(gc, ergo)( "PSAdaptiveSizePolicy::compute_old_gen_free_space: gc time limit" " gc_cost: %f " " GCTimeLimit: " UINTX_FORMAT, gc_cost(), GCTimeLimit); } // Align everything and make a final limit check desired_promo_size = align_size_up(desired_promo_size, _space_alignment); desired_promo_size = MAX2(desired_promo_size, _space_alignment); promo_limit = align_size_down(promo_limit, _space_alignment); // And one last limit check, now that we've aligned things. desired_promo_size = MIN2(desired_promo_size, promo_limit); // Timing stats log_debug(gc, ergo)("PSAdaptiveSizePolicy::compute_old_gen_free_space: costs minor_time: %f major_cost: %f mutator_cost: %f throughput_goal: %f", minor_gc_cost(), major_gc_cost(), mutator_cost(), _throughput_goal); log_trace(gc, ergo)("Minor_pause: %f major_pause: %f minor_interval: %f major_interval: %f pause_goal: %f", _avg_minor_pause->padded_average(), _avg_major_pause->padded_average(), _avg_minor_interval->average(), _avg_major_interval->average(), gc_pause_goal_sec()); // Footprint stats log_debug(gc, ergo)("Live_space: " SIZE_FORMAT " free_space: " SIZE_FORMAT, live_space(), free_space()); log_trace(gc, ergo)("Base_footprint: " SIZE_FORMAT " avg_young_live: " SIZE_FORMAT " avg_old_live: " SIZE_FORMAT, (size_t)_avg_base_footprint->average(), (size_t)avg_young_live()->average(), (size_t)avg_old_live()->average()); log_debug(gc, ergo)("Old promo_size: " SIZE_FORMAT " desired_promo_size: " SIZE_FORMAT, _promo_size, desired_promo_size); set_promo_size(desired_promo_size); } void PSAdaptiveSizePolicy::decay_supplemental_growth(bool is_full_gc) { // Decay the supplemental increment? Decay the supplement growth // factor even if it is not used. It is only meant to give a boost // to the initial growth and if it is not used, then it was not // needed. if (is_full_gc) { // Don't wait for the threshold value for the major collections. If // here, the supplemental growth term was used and should decay. if ((_avg_major_pause->count() % TenuredGenerationSizeSupplementDecay) == 0) { _old_gen_size_increment_supplement = _old_gen_size_increment_supplement >> 1; } } else { if ((_avg_minor_pause->count() >= AdaptiveSizePolicyReadyThreshold) && (_avg_minor_pause->count() % YoungGenerationSizeSupplementDecay) == 0) { _young_gen_size_increment_supplement = _young_gen_size_increment_supplement >> 1; } } } void PSAdaptiveSizePolicy::adjust_eden_for_minor_pause_time(bool is_full_gc, size_t* desired_eden_size_ptr) { // Adjust the young generation size to reduce pause time of // of collections. // // The AdaptiveSizePolicyInitializingSteps test is not used // here. It has not seemed to be needed but perhaps should // be added for consistency. if (minor_pause_young_estimator()->decrement_will_decrease()) { // reduce eden size set_change_young_gen_for_min_pauses( decrease_young_gen_for_min_pauses_true); *desired_eden_size_ptr = *desired_eden_size_ptr - eden_decrement_aligned_down(*desired_eden_size_ptr); } else { // EXPERIMENTAL ADJUSTMENT // Only record that the estimator indicated such an action. // *desired_eden_size_ptr = *desired_eden_size_ptr + eden_heap_delta; set_change_young_gen_for_min_pauses( increase_young_gen_for_min_pauses_true); } } void PSAdaptiveSizePolicy::adjust_promo_for_pause_time(bool is_full_gc, size_t* desired_promo_size_ptr, size_t* desired_eden_size_ptr) { size_t promo_heap_delta = 0; // Add some checks for a threshold for a change. For example, // a change less than the required alignment is probably not worth // attempting. if (_avg_minor_pause->padded_average() <= _avg_major_pause->padded_average() && is_full_gc) { // Adjust for the major pause time only at full gc's because the // affects of a change can only be seen at full gc's. // Reduce old generation size to reduce pause? if (major_pause_old_estimator()->decrement_will_decrease()) { // reduce old generation size set_change_old_gen_for_maj_pauses(decrease_old_gen_for_maj_pauses_true); promo_heap_delta = promo_decrement_aligned_down(*desired_promo_size_ptr); *desired_promo_size_ptr = _promo_size - promo_heap_delta; } else { // EXPERIMENTAL ADJUSTMENT // Only record that the estimator indicated such an action. // *desired_promo_size_ptr = _promo_size + // promo_increment_aligned_up(*desired_promo_size_ptr); set_change_old_gen_for_maj_pauses(increase_old_gen_for_maj_pauses_true); } } log_trace(gc, ergo)( "PSAdaptiveSizePolicy::adjust_promo_for_pause_time " "adjusting gen sizes for major pause (avg %f goal %f). " "desired_promo_size " SIZE_FORMAT " promo delta " SIZE_FORMAT, _avg_major_pause->average(), gc_pause_goal_sec(), *desired_promo_size_ptr, promo_heap_delta); } void PSAdaptiveSizePolicy::adjust_eden_for_pause_time(bool is_full_gc, size_t* desired_promo_size_ptr, size_t* desired_eden_size_ptr) { size_t eden_heap_delta = 0; // Add some checks for a threshold for a change. For example, // a change less than the required alignment is probably not worth // attempting. if (_avg_minor_pause->padded_average() > _avg_major_pause->padded_average()) { adjust_eden_for_minor_pause_time(is_full_gc, desired_eden_size_ptr); } log_trace(gc, ergo)( "PSAdaptiveSizePolicy::adjust_eden_for_pause_time " "adjusting gen sizes for major pause (avg %f goal %f). " "desired_eden_size " SIZE_FORMAT " eden delta " SIZE_FORMAT, _avg_major_pause->average(), gc_pause_goal_sec(), *desired_eden_size_ptr, eden_heap_delta); } void PSAdaptiveSizePolicy::adjust_promo_for_throughput(bool is_full_gc, size_t* desired_promo_size_ptr) { // Add some checks for a threshold for a change. For example, // a change less than the required alignment is probably not worth // attempting. if ((gc_cost() + mutator_cost()) == 0.0) { return; } log_trace(gc, ergo)("PSAdaptiveSizePolicy::adjust_promo_for_throughput(is_full: %d, promo: " SIZE_FORMAT "): mutator_cost %f major_gc_cost %f minor_gc_cost %f", is_full_gc, *desired_promo_size_ptr, mutator_cost(), major_gc_cost(), minor_gc_cost()); // Tenured generation if (is_full_gc) { // Calculate the change to use for the tenured gen. size_t scaled_promo_heap_delta = 0; // Can the increment to the generation be scaled? if (gc_cost() >= 0.0 && major_gc_cost() >= 0.0) { size_t promo_heap_delta = promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr); double scale_by_ratio = major_gc_cost() / gc_cost(); scaled_promo_heap_delta = (size_t) (scale_by_ratio * (double) promo_heap_delta); log_trace(gc, ergo)("Scaled tenured increment: " SIZE_FORMAT " by %f down to " SIZE_FORMAT, promo_heap_delta, scale_by_ratio, scaled_promo_heap_delta); } else if (major_gc_cost() >= 0.0) { // Scaling is not going to work. If the major gc time is the // larger, give it a full increment. if (major_gc_cost() >= minor_gc_cost()) { scaled_promo_heap_delta = promo_increment_with_supplement_aligned_up(*desired_promo_size_ptr); } } else { // Don't expect to get here but it's ok if it does // in the product build since the delta will be 0 // and nothing will change. assert(false, "Unexpected value for gc costs"); } switch (AdaptiveSizeThroughPutPolicy) { case 1: // Early in the run the statistics might not be good. Until // a specific number of collections have been, use the heuristic // that a larger generation size means lower collection costs. if (major_collection_estimator()->increment_will_decrease() || (_old_gen_change_for_major_throughput <= AdaptiveSizePolicyInitializingSteps)) { // Increase tenured generation size to reduce major collection cost if ((*desired_promo_size_ptr + scaled_promo_heap_delta) > *desired_promo_size_ptr) { *desired_promo_size_ptr = _promo_size + scaled_promo_heap_delta; } set_change_old_gen_for_throughput( increase_old_gen_for_throughput_true); _old_gen_change_for_major_throughput++; } else { // EXPERIMENTAL ADJUSTMENT // Record that decreasing the old gen size would decrease // the major collection cost but don't do it. // *desired_promo_size_ptr = _promo_size - // promo_decrement_aligned_down(*desired_promo_size_ptr); set_change_old_gen_for_throughput( decrease_old_gen_for_throughput_true); } break; default: // Simplest strategy if ((*desired_promo_size_ptr + scaled_promo_heap_delta) > *desired_promo_size_ptr) { *desired_promo_size_ptr = *desired_promo_size_ptr + scaled_promo_heap_delta; } set_change_old_gen_for_throughput( increase_old_gen_for_throughput_true); _old_gen_change_for_major_throughput++; } log_trace(gc, ergo)("Adjusting tenured gen for throughput (avg %f goal %f). desired_promo_size " SIZE_FORMAT " promo_delta " SIZE_FORMAT , mutator_cost(), _throughput_goal, *desired_promo_size_ptr, scaled_promo_heap_delta); } } void PSAdaptiveSizePolicy::adjust_eden_for_throughput(bool is_full_gc, size_t* desired_eden_size_ptr) { // Add some checks for a threshold for a change. For example, // a change less than the required alignment is probably not worth // attempting. if ((gc_cost() + mutator_cost()) == 0.0) { return; } log_trace(gc, ergo)("PSAdaptiveSizePolicy::adjust_eden_for_throughput(is_full: %d, cur_eden: " SIZE_FORMAT "): mutator_cost %f major_gc_cost %f minor_gc_cost %f", is_full_gc, *desired_eden_size_ptr, mutator_cost(), major_gc_cost(), minor_gc_cost()); // Young generation size_t scaled_eden_heap_delta = 0; // Can the increment to the generation be scaled? if (gc_cost() >= 0.0 && minor_gc_cost() >= 0.0) { size_t eden_heap_delta = eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr); double scale_by_ratio = minor_gc_cost() / gc_cost(); assert(scale_by_ratio <= 1.0 && scale_by_ratio >= 0.0, "Scaling is wrong"); scaled_eden_heap_delta = (size_t) (scale_by_ratio * (double) eden_heap_delta); log_trace(gc, ergo)("Scaled eden increment: " SIZE_FORMAT " by %f down to " SIZE_FORMAT, eden_heap_delta, scale_by_ratio, scaled_eden_heap_delta); } else if (minor_gc_cost() >= 0.0) { // Scaling is not going to work. If the minor gc time is the // larger, give it a full increment. if (minor_gc_cost() > major_gc_cost()) { scaled_eden_heap_delta = eden_increment_with_supplement_aligned_up(*desired_eden_size_ptr); } } else { // Don't expect to get here but it's ok if it does // in the product build since the delta will be 0 // and nothing will change. assert(false, "Unexpected value for gc costs"); } // Use a heuristic for some number of collections to give // the averages time to settle down. switch (AdaptiveSizeThroughPutPolicy) { case 1: if (minor_collection_estimator()->increment_will_decrease() || (_young_gen_change_for_minor_throughput <= AdaptiveSizePolicyInitializingSteps)) { // Expand young generation size to reduce frequency of // of collections. if ((*desired_eden_size_ptr + scaled_eden_heap_delta) > *desired_eden_size_ptr) { *desired_eden_size_ptr = *desired_eden_size_ptr + scaled_eden_heap_delta; } set_change_young_gen_for_throughput( increase_young_gen_for_througput_true); _young_gen_change_for_minor_throughput++; } else { // EXPERIMENTAL ADJUSTMENT // Record that decreasing the young gen size would decrease // the minor collection cost but don't do it. // *desired_eden_size_ptr = _eden_size - // eden_decrement_aligned_down(*desired_eden_size_ptr); set_change_young_gen_for_throughput( decrease_young_gen_for_througput_true); } break; default: if ((*desired_eden_size_ptr + scaled_eden_heap_delta) > *desired_eden_size_ptr) { *desired_eden_size_ptr = *desired_eden_size_ptr + scaled_eden_heap_delta; } set_change_young_gen_for_throughput( increase_young_gen_for_througput_true); _young_gen_change_for_minor_throughput++; } log_trace(gc, ergo)("Adjusting eden for throughput (avg %f goal %f). desired_eden_size " SIZE_FORMAT " eden delta " SIZE_FORMAT, mutator_cost(), _throughput_goal, *desired_eden_size_ptr, scaled_eden_heap_delta); } size_t PSAdaptiveSizePolicy::adjust_promo_for_footprint( size_t desired_promo_size, size_t desired_sum) { assert(desired_promo_size <= desired_sum, "Inconsistent parameters"); set_decrease_for_footprint(decrease_old_gen_for_footprint_true); size_t change = promo_decrement(desired_promo_size); change = scale_down(change, desired_promo_size, desired_sum); size_t reduced_size = desired_promo_size - change; log_trace(gc, ergo)( "AdaptiveSizePolicy::adjust_promo_for_footprint " "adjusting tenured gen for footprint. " "starting promo size " SIZE_FORMAT " reduced promo size " SIZE_FORMAT " promo delta " SIZE_FORMAT, desired_promo_size, reduced_size, change ); assert(reduced_size <= desired_promo_size, "Inconsistent result"); return reduced_size; } size_t PSAdaptiveSizePolicy::adjust_eden_for_footprint( size_t desired_eden_size, size_t desired_sum) { assert(desired_eden_size <= desired_sum, "Inconsistent parameters"); set_decrease_for_footprint(decrease_young_gen_for_footprint_true); size_t change = eden_decrement(desired_eden_size); change = scale_down(change, desired_eden_size, desired_sum); size_t reduced_size = desired_eden_size - change; log_trace(gc, ergo)( "AdaptiveSizePolicy::adjust_eden_for_footprint " "adjusting eden for footprint. " " starting eden size " SIZE_FORMAT " reduced eden size " SIZE_FORMAT " eden delta " SIZE_FORMAT, desired_eden_size, reduced_size, change); assert(reduced_size <= desired_eden_size, "Inconsistent result"); return reduced_size; } // Scale down "change" by the factor // part / total // Don't align the results. size_t PSAdaptiveSizePolicy::scale_down(size_t change, double part, double total) { assert(part <= total, "Inconsistent input"); size_t reduced_change = change; if (total > 0) { double fraction = part / total; reduced_change = (size_t) (fraction * (double) change); } assert(reduced_change <= change, "Inconsistent result"); return reduced_change; } size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden, uint percent_change) { size_t eden_heap_delta; eden_heap_delta = cur_eden / 100 * percent_change; return eden_heap_delta; } size_t PSAdaptiveSizePolicy::eden_increment(size_t cur_eden) { return eden_increment(cur_eden, YoungGenerationSizeIncrement); } size_t PSAdaptiveSizePolicy::eden_increment_aligned_up(size_t cur_eden) { size_t result = eden_increment(cur_eden, YoungGenerationSizeIncrement); return align_size_up(result, _space_alignment); } size_t PSAdaptiveSizePolicy::eden_increment_aligned_down(size_t cur_eden) { size_t result = eden_increment(cur_eden); return align_size_down(result, _space_alignment); } size_t PSAdaptiveSizePolicy::eden_increment_with_supplement_aligned_up( size_t cur_eden) { size_t result = eden_increment(cur_eden, YoungGenerationSizeIncrement + _young_gen_size_increment_supplement); return align_size_up(result, _space_alignment); } size_t PSAdaptiveSizePolicy::eden_decrement_aligned_down(size_t cur_eden) { size_t eden_heap_delta = eden_decrement(cur_eden); return align_size_down(eden_heap_delta, _space_alignment); } size_t PSAdaptiveSizePolicy::eden_decrement(size_t cur_eden) { size_t eden_heap_delta = eden_increment(cur_eden) / AdaptiveSizeDecrementScaleFactor; return eden_heap_delta; } size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo, uint percent_change) { size_t promo_heap_delta; promo_heap_delta = cur_promo / 100 * percent_change; return promo_heap_delta; } size_t PSAdaptiveSizePolicy::promo_increment(size_t cur_promo) { return promo_increment(cur_promo, TenuredGenerationSizeIncrement); } size_t PSAdaptiveSizePolicy::promo_increment_aligned_up(size_t cur_promo) { size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement); return align_size_up(result, _space_alignment); } size_t PSAdaptiveSizePolicy::promo_increment_aligned_down(size_t cur_promo) { size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement); return align_size_down(result, _space_alignment); } size_t PSAdaptiveSizePolicy::promo_increment_with_supplement_aligned_up( size_t cur_promo) { size_t result = promo_increment(cur_promo, TenuredGenerationSizeIncrement + _old_gen_size_increment_supplement); return align_size_up(result, _space_alignment); } size_t PSAdaptiveSizePolicy::promo_decrement_aligned_down(size_t cur_promo) { size_t promo_heap_delta = promo_decrement(cur_promo); return align_size_down(promo_heap_delta, _space_alignment); } size_t PSAdaptiveSizePolicy::promo_decrement(size_t cur_promo) { size_t promo_heap_delta = promo_increment(cur_promo); promo_heap_delta = promo_heap_delta / AdaptiveSizeDecrementScaleFactor; return promo_heap_delta; } uint PSAdaptiveSizePolicy::compute_survivor_space_size_and_threshold( bool is_survivor_overflow, uint tenuring_threshold, size_t survivor_limit) { assert(survivor_limit >= _space_alignment, "survivor_limit too small"); assert((size_t)align_size_down(survivor_limit, _space_alignment) == survivor_limit, "survivor_limit not aligned"); // This method is called even if the tenuring threshold and survivor // spaces are not adjusted so that the averages are sampled above. if (!UsePSAdaptiveSurvivorSizePolicy || !young_gen_policy_is_ready()) { return tenuring_threshold; } // We'll decide whether to increase or decrease the tenuring // threshold based partly on the newly computed survivor size // (if we hit the maximum limit allowed, we'll always choose to // decrement the threshold). bool incr_tenuring_threshold = false; bool decr_tenuring_threshold = false; set_decrement_tenuring_threshold_for_gc_cost(false); set_increment_tenuring_threshold_for_gc_cost(false); set_decrement_tenuring_threshold_for_survivor_limit(false); if (!is_survivor_overflow) { // Keep running averages on how much survived // We use the tenuring threshold to equalize the cost of major // and minor collections. // ThresholdTolerance is used to indicate how sensitive the // tenuring threshold is to differences in cost between the // collection types. // Get the times of interest. This involves a little work, so // we cache the values here. const double major_cost = major_gc_cost(); const double minor_cost = minor_gc_cost(); if (minor_cost > major_cost * _threshold_tolerance_percent) { // Minor times are getting too long; lower the threshold so // less survives and more is promoted. decr_tenuring_threshold = true; set_decrement_tenuring_threshold_for_gc_cost(true); } else if (major_cost > minor_cost * _threshold_tolerance_percent) { // Major times are too long, so we want less promotion. incr_tenuring_threshold = true; set_increment_tenuring_threshold_for_gc_cost(true); } } else { // Survivor space overflow occurred, so promoted and survived are // not accurate. We'll make our best guess by combining survived // and promoted and count them as survivors. // // We'll lower the tenuring threshold to see if we can correct // things. Also, set the survivor size conservatively. We're // trying to avoid many overflows from occurring if defnew size // is just too small. decr_tenuring_threshold = true; } // The padded average also maintains a deviation from the average; // we use this to see how good of an estimate we have of what survived. // We're trying to pad the survivor size as little as possible without // overflowing the survivor spaces. size_t target_size = align_size_up((size_t)_avg_survived->padded_average(), _space_alignment); target_size = MAX2(target_size, _space_alignment); if (target_size > survivor_limit) { // Target size is bigger than we can handle. Let's also reduce // the tenuring threshold. target_size = survivor_limit; decr_tenuring_threshold = true; set_decrement_tenuring_threshold_for_survivor_limit(true); } // Finally, increment or decrement the tenuring threshold, as decided above. // We test for decrementing first, as we might have hit the target size // limit. if (decr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) { if (tenuring_threshold > 1) { tenuring_threshold--; } } else if (incr_tenuring_threshold && !(AlwaysTenure || NeverTenure)) { if (tenuring_threshold < MaxTenuringThreshold) { tenuring_threshold++; } } // We keep a running average of the amount promoted which is used // to decide when we should collect the old generation (when // the amount of old gen free space is less than what we expect to // promote). log_trace(gc, ergo)("avg_survived: %f avg_deviation: %f", _avg_survived->average(), _avg_survived->deviation()); log_debug(gc, ergo)("avg_survived_padded_avg: %f", _avg_survived->padded_average()); log_trace(gc, ergo)("avg_promoted_avg: %f avg_promoted_dev: %f", avg_promoted()->average(), avg_promoted()->deviation()); log_debug(gc, ergo)("avg_promoted_padded_avg: %f avg_pretenured_padded_avg: %f tenuring_thresh: %d target_size: " SIZE_FORMAT, avg_promoted()->padded_average(), _avg_pretenured->padded_average(), tenuring_threshold, target_size); set_survivor_size(target_size); return tenuring_threshold; } void PSAdaptiveSizePolicy::update_averages(bool is_survivor_overflow, size_t survived, size_t promoted) { // Update averages if (!is_survivor_overflow) { // Keep running averages on how much survived _avg_survived->sample(survived); } else { size_t survived_guess = survived + promoted; _avg_survived->sample(survived_guess); } avg_promoted()->sample(promoted); log_trace(gc, ergo)("AdaptiveSizePolicy::update_averages: survived: " SIZE_FORMAT " promoted: " SIZE_FORMAT " overflow: %s", survived, promoted, is_survivor_overflow ? "true" : "false"); } bool PSAdaptiveSizePolicy::print() const { if (!UseAdaptiveSizePolicy) { return false; } if (AdaptiveSizePolicy::print()) { AdaptiveSizePolicy::print_tenuring_threshold(PSScavenge::tenuring_threshold()); return true; } return false; } #ifndef PRODUCT void TestOldFreeSpaceCalculation_test() { assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 20) == 25, "Calculation of free memory failed"); assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 50) == 100, "Calculation of free memory failed"); assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 60) == 150, "Calculation of free memory failed"); assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(100, 75) == 300, "Calculation of free memory failed"); assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 20) == 100, "Calculation of free memory failed"); assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 50) == 400, "Calculation of free memory failed"); assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 60) == 600, "Calculation of free memory failed"); assert(PSAdaptiveSizePolicy::calculate_free_based_on_live(400, 75) == 1200, "Calculation of free memory failed"); } #endif /* !PRODUCT */