| /* |
| * Copyright (c) 2001, 2019, 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/g1/g1Analytics.hpp" |
| #include "gc/g1/g1Arguments.hpp" |
| #include "gc/g1/g1CollectedHeap.inline.hpp" |
| #include "gc/g1/g1CollectionSet.hpp" |
| #include "gc/g1/g1CollectionSetCandidates.hpp" |
| #include "gc/g1/g1ConcurrentMark.hpp" |
| #include "gc/g1/g1ConcurrentMarkThread.inline.hpp" |
| #include "gc/g1/g1ConcurrentRefine.hpp" |
| #include "gc/g1/g1CollectionSetChooser.hpp" |
| #include "gc/g1/g1HeterogeneousHeapPolicy.hpp" |
| #include "gc/g1/g1HotCardCache.hpp" |
| #include "gc/g1/g1IHOPControl.hpp" |
| #include "gc/g1/g1GCPhaseTimes.hpp" |
| #include "gc/g1/g1Policy.hpp" |
| #include "gc/g1/g1SurvivorRegions.hpp" |
| #include "gc/g1/g1YoungGenSizer.hpp" |
| #include "gc/g1/heapRegion.inline.hpp" |
| #include "gc/g1/heapRegionRemSet.hpp" |
| #include "gc/shared/gcPolicyCounters.hpp" |
| #include "logging/logStream.hpp" |
| #include "runtime/arguments.hpp" |
| #include "runtime/java.hpp" |
| #include "runtime/mutexLocker.hpp" |
| #include "utilities/debug.hpp" |
| #include "utilities/growableArray.hpp" |
| #include "utilities/pair.hpp" |
| |
| G1Policy::G1Policy(STWGCTimer* gc_timer) : |
| _predictor(G1ConfidencePercent / 100.0), |
| _analytics(new G1Analytics(&_predictor)), |
| _remset_tracker(), |
| _mmu_tracker(new G1MMUTrackerQueue(GCPauseIntervalMillis / 1000.0, MaxGCPauseMillis / 1000.0)), |
| _ihop_control(create_ihop_control(&_predictor)), |
| _policy_counters(new GCPolicyCounters("GarbageFirst", 1, 2)), |
| _full_collection_start_sec(0.0), |
| _collection_pause_end_millis(os::javaTimeNanos() / NANOSECS_PER_MILLISEC), |
| _young_list_target_length(0), |
| _young_list_fixed_length(0), |
| _young_list_max_length(0), |
| _short_lived_surv_rate_group(new SurvRateGroup()), |
| _survivor_surv_rate_group(new SurvRateGroup()), |
| _reserve_factor((double) G1ReservePercent / 100.0), |
| _reserve_regions(0), |
| _young_gen_sizer(G1YoungGenSizer::create_gen_sizer()), |
| _free_regions_at_end_of_collection(0), |
| _max_rs_lengths(0), |
| _rs_lengths_prediction(0), |
| _pending_cards(0), |
| _bytes_allocated_in_old_since_last_gc(0), |
| _initial_mark_to_mixed(), |
| _collection_set(NULL), |
| _bytes_copied_during_gc(0), |
| _g1h(NULL), |
| _phase_times(new G1GCPhaseTimes(gc_timer, ParallelGCThreads)), |
| _mark_remark_start_sec(0), |
| _mark_cleanup_start_sec(0), |
| _tenuring_threshold(MaxTenuringThreshold), |
| _max_survivor_regions(0), |
| _survivors_age_table(true) |
| { |
| } |
| |
| G1Policy::~G1Policy() { |
| delete _ihop_control; |
| delete _young_gen_sizer; |
| } |
| |
| G1Policy* G1Policy::create_policy(STWGCTimer* gc_timer_stw) { |
| if (G1Arguments::is_heterogeneous_heap()) { |
| return new G1HeterogeneousHeapPolicy(gc_timer_stw); |
| } else { |
| return new G1Policy(gc_timer_stw); |
| } |
| } |
| |
| G1CollectorState* G1Policy::collector_state() const { return _g1h->collector_state(); } |
| |
| void G1Policy::init(G1CollectedHeap* g1h, G1CollectionSet* collection_set) { |
| _g1h = g1h; |
| _collection_set = collection_set; |
| |
| assert(Heap_lock->owned_by_self(), "Locking discipline."); |
| |
| if (!use_adaptive_young_list_length()) { |
| _young_list_fixed_length = _young_gen_sizer->min_desired_young_length(); |
| } |
| _young_gen_sizer->adjust_max_new_size(_g1h->max_expandable_regions()); |
| |
| _free_regions_at_end_of_collection = _g1h->num_free_regions(); |
| |
| update_young_list_max_and_target_length(); |
| // We may immediately start allocating regions and placing them on the |
| // collection set list. Initialize the per-collection set info |
| _collection_set->start_incremental_building(); |
| } |
| |
| void G1Policy::note_gc_start() { |
| phase_times()->note_gc_start(); |
| } |
| |
| class G1YoungLengthPredictor { |
| const bool _during_cm; |
| const double _base_time_ms; |
| const double _base_free_regions; |
| const double _target_pause_time_ms; |
| const G1Policy* const _policy; |
| |
| public: |
| G1YoungLengthPredictor(bool during_cm, |
| double base_time_ms, |
| double base_free_regions, |
| double target_pause_time_ms, |
| const G1Policy* policy) : |
| _during_cm(during_cm), |
| _base_time_ms(base_time_ms), |
| _base_free_regions(base_free_regions), |
| _target_pause_time_ms(target_pause_time_ms), |
| _policy(policy) {} |
| |
| bool will_fit(uint young_length) const { |
| if (young_length >= _base_free_regions) { |
| // end condition 1: not enough space for the young regions |
| return false; |
| } |
| |
| const double accum_surv_rate = _policy->accum_yg_surv_rate_pred((int) young_length - 1); |
| const size_t bytes_to_copy = |
| (size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes); |
| const double copy_time_ms = |
| _policy->analytics()->predict_object_copy_time_ms(bytes_to_copy, _during_cm); |
| const double young_other_time_ms = _policy->analytics()->predict_young_other_time_ms(young_length); |
| const double pause_time_ms = _base_time_ms + copy_time_ms + young_other_time_ms; |
| if (pause_time_ms > _target_pause_time_ms) { |
| // end condition 2: prediction is over the target pause time |
| return false; |
| } |
| |
| const size_t free_bytes = (_base_free_regions - young_length) * HeapRegion::GrainBytes; |
| |
| // When copying, we will likely need more bytes free than is live in the region. |
| // Add some safety margin to factor in the confidence of our guess, and the |
| // natural expected waste. |
| // (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty |
| // of the calculation: the lower the confidence, the more headroom. |
| // (100 + TargetPLABWastePct) represents the increase in expected bytes during |
| // copying due to anticipated waste in the PLABs. |
| const double safety_factor = (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0; |
| const size_t expected_bytes_to_copy = (size_t)(safety_factor * bytes_to_copy); |
| |
| if (expected_bytes_to_copy > free_bytes) { |
| // end condition 3: out-of-space |
| return false; |
| } |
| |
| // success! |
| return true; |
| } |
| }; |
| |
| void G1Policy::record_new_heap_size(uint new_number_of_regions) { |
| // re-calculate the necessary reserve |
| double reserve_regions_d = (double) new_number_of_regions * _reserve_factor; |
| // We use ceiling so that if reserve_regions_d is > 0.0 (but |
| // smaller than 1.0) we'll get 1. |
| _reserve_regions = (uint) ceil(reserve_regions_d); |
| |
| _young_gen_sizer->heap_size_changed(new_number_of_regions); |
| |
| _ihop_control->update_target_occupancy(new_number_of_regions * HeapRegion::GrainBytes); |
| } |
| |
| uint G1Policy::calculate_young_list_desired_min_length(uint base_min_length) const { |
| uint desired_min_length = 0; |
| if (use_adaptive_young_list_length()) { |
| if (_analytics->num_alloc_rate_ms() > 3) { |
| double now_sec = os::elapsedTime(); |
| double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0; |
| double alloc_rate_ms = _analytics->predict_alloc_rate_ms(); |
| desired_min_length = (uint) ceil(alloc_rate_ms * when_ms); |
| } else { |
| // otherwise we don't have enough info to make the prediction |
| } |
| } |
| desired_min_length += base_min_length; |
| // make sure we don't go below any user-defined minimum bound |
| return MAX2(_young_gen_sizer->min_desired_young_length(), desired_min_length); |
| } |
| |
| uint G1Policy::calculate_young_list_desired_max_length() const { |
| // Here, we might want to also take into account any additional |
| // constraints (i.e., user-defined minimum bound). Currently, we |
| // effectively don't set this bound. |
| return _young_gen_sizer->max_desired_young_length(); |
| } |
| |
| uint G1Policy::update_young_list_max_and_target_length() { |
| return update_young_list_max_and_target_length(_analytics->predict_rs_lengths()); |
| } |
| |
| uint G1Policy::update_young_list_max_and_target_length(size_t rs_lengths) { |
| uint unbounded_target_length = update_young_list_target_length(rs_lengths); |
| update_max_gc_locker_expansion(); |
| return unbounded_target_length; |
| } |
| |
| uint G1Policy::update_young_list_target_length(size_t rs_lengths) { |
| YoungTargetLengths young_lengths = young_list_target_lengths(rs_lengths); |
| _young_list_target_length = young_lengths.first; |
| |
| return young_lengths.second; |
| } |
| |
| G1Policy::YoungTargetLengths G1Policy::young_list_target_lengths(size_t rs_lengths) const { |
| YoungTargetLengths result; |
| |
| // Calculate the absolute and desired min bounds first. |
| |
| // This is how many young regions we already have (currently: the survivors). |
| const uint base_min_length = _g1h->survivor_regions_count(); |
| uint desired_min_length = calculate_young_list_desired_min_length(base_min_length); |
| // This is the absolute minimum young length. Ensure that we |
| // will at least have one eden region available for allocation. |
| uint absolute_min_length = base_min_length + MAX2(_g1h->eden_regions_count(), (uint)1); |
| // If we shrank the young list target it should not shrink below the current size. |
| desired_min_length = MAX2(desired_min_length, absolute_min_length); |
| // Calculate the absolute and desired max bounds. |
| |
| uint desired_max_length = calculate_young_list_desired_max_length(); |
| |
| uint young_list_target_length = 0; |
| if (use_adaptive_young_list_length()) { |
| if (collector_state()->in_young_only_phase()) { |
| young_list_target_length = |
| calculate_young_list_target_length(rs_lengths, |
| base_min_length, |
| desired_min_length, |
| desired_max_length); |
| } else { |
| // Don't calculate anything and let the code below bound it to |
| // the desired_min_length, i.e., do the next GC as soon as |
| // possible to maximize how many old regions we can add to it. |
| } |
| } else { |
| // The user asked for a fixed young gen so we'll fix the young gen |
| // whether the next GC is young or mixed. |
| young_list_target_length = _young_list_fixed_length; |
| } |
| |
| result.second = young_list_target_length; |
| |
| // We will try our best not to "eat" into the reserve. |
| uint absolute_max_length = 0; |
| if (_free_regions_at_end_of_collection > _reserve_regions) { |
| absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions; |
| } |
| if (desired_max_length > absolute_max_length) { |
| desired_max_length = absolute_max_length; |
| } |
| |
| // Make sure we don't go over the desired max length, nor under the |
| // desired min length. In case they clash, desired_min_length wins |
| // which is why that test is second. |
| if (young_list_target_length > desired_max_length) { |
| young_list_target_length = desired_max_length; |
| } |
| if (young_list_target_length < desired_min_length) { |
| young_list_target_length = desired_min_length; |
| } |
| |
| assert(young_list_target_length > base_min_length, |
| "we should be able to allocate at least one eden region"); |
| assert(young_list_target_length >= absolute_min_length, "post-condition"); |
| |
| result.first = young_list_target_length; |
| return result; |
| } |
| |
| uint |
| G1Policy::calculate_young_list_target_length(size_t rs_lengths, |
| uint base_min_length, |
| uint desired_min_length, |
| uint desired_max_length) const { |
| assert(use_adaptive_young_list_length(), "pre-condition"); |
| assert(collector_state()->in_young_only_phase(), "only call this for young GCs"); |
| |
| // In case some edge-condition makes the desired max length too small... |
| if (desired_max_length <= desired_min_length) { |
| return desired_min_length; |
| } |
| |
| // We'll adjust min_young_length and max_young_length not to include |
| // the already allocated young regions (i.e., so they reflect the |
| // min and max eden regions we'll allocate). The base_min_length |
| // will be reflected in the predictions by the |
| // survivor_regions_evac_time prediction. |
| assert(desired_min_length > base_min_length, "invariant"); |
| uint min_young_length = desired_min_length - base_min_length; |
| assert(desired_max_length > base_min_length, "invariant"); |
| uint max_young_length = desired_max_length - base_min_length; |
| |
| const double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0; |
| const double survivor_regions_evac_time = predict_survivor_regions_evac_time(); |
| const size_t pending_cards = _analytics->predict_pending_cards(); |
| const size_t adj_rs_lengths = rs_lengths + _analytics->predict_rs_length_diff(); |
| const size_t scanned_cards = _analytics->predict_card_num(adj_rs_lengths, true /* for_young_gc */); |
| const double base_time_ms = |
| predict_base_elapsed_time_ms(pending_cards, scanned_cards) + |
| survivor_regions_evac_time; |
| const uint available_free_regions = _free_regions_at_end_of_collection; |
| const uint base_free_regions = |
| available_free_regions > _reserve_regions ? available_free_regions - _reserve_regions : 0; |
| |
| // Here, we will make sure that the shortest young length that |
| // makes sense fits within the target pause time. |
| |
| G1YoungLengthPredictor p(collector_state()->mark_or_rebuild_in_progress(), |
| base_time_ms, |
| base_free_regions, |
| target_pause_time_ms, |
| this); |
| if (p.will_fit(min_young_length)) { |
| // The shortest young length will fit into the target pause time; |
| // we'll now check whether the absolute maximum number of young |
| // regions will fit in the target pause time. If not, we'll do |
| // a binary search between min_young_length and max_young_length. |
| if (p.will_fit(max_young_length)) { |
| // The maximum young length will fit into the target pause time. |
| // We are done so set min young length to the maximum length (as |
| // the result is assumed to be returned in min_young_length). |
| min_young_length = max_young_length; |
| } else { |
| // The maximum possible number of young regions will not fit within |
| // the target pause time so we'll search for the optimal |
| // length. The loop invariants are: |
| // |
| // min_young_length < max_young_length |
| // min_young_length is known to fit into the target pause time |
| // max_young_length is known not to fit into the target pause time |
| // |
| // Going into the loop we know the above hold as we've just |
| // checked them. Every time around the loop we check whether |
| // the middle value between min_young_length and |
| // max_young_length fits into the target pause time. If it |
| // does, it becomes the new min. If it doesn't, it becomes |
| // the new max. This way we maintain the loop invariants. |
| |
| assert(min_young_length < max_young_length, "invariant"); |
| uint diff = (max_young_length - min_young_length) / 2; |
| while (diff > 0) { |
| uint young_length = min_young_length + diff; |
| if (p.will_fit(young_length)) { |
| min_young_length = young_length; |
| } else { |
| max_young_length = young_length; |
| } |
| assert(min_young_length < max_young_length, "invariant"); |
| diff = (max_young_length - min_young_length) / 2; |
| } |
| // The results is min_young_length which, according to the |
| // loop invariants, should fit within the target pause time. |
| |
| // These are the post-conditions of the binary search above: |
| assert(min_young_length < max_young_length, |
| "otherwise we should have discovered that max_young_length " |
| "fits into the pause target and not done the binary search"); |
| assert(p.will_fit(min_young_length), |
| "min_young_length, the result of the binary search, should " |
| "fit into the pause target"); |
| assert(!p.will_fit(min_young_length + 1), |
| "min_young_length, the result of the binary search, should be " |
| "optimal, so no larger length should fit into the pause target"); |
| } |
| } else { |
| // Even the minimum length doesn't fit into the pause time |
| // target, return it as the result nevertheless. |
| } |
| return base_min_length + min_young_length; |
| } |
| |
| double G1Policy::predict_survivor_regions_evac_time() const { |
| double survivor_regions_evac_time = 0.0; |
| const GrowableArray<HeapRegion*>* survivor_regions = _g1h->survivor()->regions(); |
| |
| for (GrowableArrayIterator<HeapRegion*> it = survivor_regions->begin(); |
| it != survivor_regions->end(); |
| ++it) { |
| survivor_regions_evac_time += predict_region_elapsed_time_ms(*it, collector_state()->in_young_only_phase()); |
| } |
| return survivor_regions_evac_time; |
| } |
| |
| void G1Policy::revise_young_list_target_length_if_necessary(size_t rs_lengths) { |
| guarantee(use_adaptive_young_list_length(), "should not call this otherwise" ); |
| |
| if (rs_lengths > _rs_lengths_prediction) { |
| // add 10% to avoid having to recalculate often |
| size_t rs_lengths_prediction = rs_lengths * 1100 / 1000; |
| update_rs_lengths_prediction(rs_lengths_prediction); |
| |
| update_young_list_max_and_target_length(rs_lengths_prediction); |
| } |
| } |
| |
| void G1Policy::update_rs_lengths_prediction() { |
| update_rs_lengths_prediction(_analytics->predict_rs_lengths()); |
| } |
| |
| void G1Policy::update_rs_lengths_prediction(size_t prediction) { |
| if (collector_state()->in_young_only_phase() && use_adaptive_young_list_length()) { |
| _rs_lengths_prediction = prediction; |
| } |
| } |
| |
| void G1Policy::record_full_collection_start() { |
| _full_collection_start_sec = os::elapsedTime(); |
| // Release the future to-space so that it is available for compaction into. |
| collector_state()->set_in_young_only_phase(false); |
| collector_state()->set_in_full_gc(true); |
| _collection_set->clear_candidates(); |
| } |
| |
| void G1Policy::record_full_collection_end() { |
| // Consider this like a collection pause for the purposes of allocation |
| // since last pause. |
| double end_sec = os::elapsedTime(); |
| double full_gc_time_sec = end_sec - _full_collection_start_sec; |
| double full_gc_time_ms = full_gc_time_sec * 1000.0; |
| |
| _analytics->update_recent_gc_times(end_sec, full_gc_time_ms); |
| |
| collector_state()->set_in_full_gc(false); |
| |
| // "Nuke" the heuristics that control the young/mixed GC |
| // transitions and make sure we start with young GCs after the Full GC. |
| collector_state()->set_in_young_only_phase(true); |
| collector_state()->set_in_young_gc_before_mixed(false); |
| collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0)); |
| collector_state()->set_in_initial_mark_gc(false); |
| collector_state()->set_mark_or_rebuild_in_progress(false); |
| collector_state()->set_clearing_next_bitmap(false); |
| |
| _short_lived_surv_rate_group->start_adding_regions(); |
| // also call this on any additional surv rate groups |
| |
| _free_regions_at_end_of_collection = _g1h->num_free_regions(); |
| // Reset survivors SurvRateGroup. |
| _survivor_surv_rate_group->reset(); |
| update_young_list_max_and_target_length(); |
| update_rs_lengths_prediction(); |
| |
| _bytes_allocated_in_old_since_last_gc = 0; |
| |
| record_pause(FullGC, _full_collection_start_sec, end_sec); |
| } |
| |
| void G1Policy::record_collection_pause_start(double start_time_sec) { |
| // We only need to do this here as the policy will only be applied |
| // to the GC we're about to start. so, no point is calculating this |
| // every time we calculate / recalculate the target young length. |
| update_survivors_policy(); |
| |
| assert(max_survivor_regions() + _g1h->num_used_regions() <= _g1h->max_regions(), |
| "Maximum survivor regions %u plus used regions %u exceeds max regions %u", |
| max_survivor_regions(), _g1h->num_used_regions(), _g1h->max_regions()); |
| |
| assert(_g1h->used() == _g1h->recalculate_used(), |
| "sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT, |
| _g1h->used(), _g1h->recalculate_used()); |
| |
| phase_times()->record_cur_collection_start_sec(start_time_sec); |
| _pending_cards = _g1h->pending_card_num(); |
| |
| _collection_set->reset_bytes_used_before(); |
| _bytes_copied_during_gc = 0; |
| |
| // do that for any other surv rate groups |
| _short_lived_surv_rate_group->stop_adding_regions(); |
| _survivors_age_table.clear(); |
| |
| assert(_g1h->collection_set()->verify_young_ages(), "region age verification failed"); |
| } |
| |
| void G1Policy::record_concurrent_mark_init_end(double mark_init_elapsed_time_ms) { |
| assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now"); |
| collector_state()->set_in_initial_mark_gc(false); |
| } |
| |
| void G1Policy::record_concurrent_mark_remark_start() { |
| _mark_remark_start_sec = os::elapsedTime(); |
| } |
| |
| void G1Policy::record_concurrent_mark_remark_end() { |
| double end_time_sec = os::elapsedTime(); |
| double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0; |
| _analytics->report_concurrent_mark_remark_times_ms(elapsed_time_ms); |
| _analytics->append_prev_collection_pause_end_ms(elapsed_time_ms); |
| |
| record_pause(Remark, _mark_remark_start_sec, end_time_sec); |
| } |
| |
| void G1Policy::record_concurrent_mark_cleanup_start() { |
| _mark_cleanup_start_sec = os::elapsedTime(); |
| } |
| |
| double G1Policy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const { |
| return phase_times()->average_time_ms(phase); |
| } |
| |
| double G1Policy::young_other_time_ms() const { |
| return phase_times()->young_cset_choice_time_ms() + |
| phase_times()->average_time_ms(G1GCPhaseTimes::YoungFreeCSet); |
| } |
| |
| double G1Policy::non_young_other_time_ms() const { |
| return phase_times()->non_young_cset_choice_time_ms() + |
| phase_times()->average_time_ms(G1GCPhaseTimes::NonYoungFreeCSet); |
| } |
| |
| double G1Policy::other_time_ms(double pause_time_ms) const { |
| return pause_time_ms - phase_times()->cur_collection_par_time_ms(); |
| } |
| |
| double G1Policy::constant_other_time_ms(double pause_time_ms) const { |
| return other_time_ms(pause_time_ms) - phase_times()->total_free_cset_time_ms(); |
| } |
| |
| bool G1Policy::about_to_start_mixed_phase() const { |
| return _g1h->concurrent_mark()->cm_thread()->during_cycle() || collector_state()->in_young_gc_before_mixed(); |
| } |
| |
| bool G1Policy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) { |
| if (about_to_start_mixed_phase()) { |
| return false; |
| } |
| |
| size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold(); |
| |
| size_t cur_used_bytes = _g1h->non_young_capacity_bytes(); |
| size_t alloc_byte_size = alloc_word_size * HeapWordSize; |
| size_t marking_request_bytes = cur_used_bytes + alloc_byte_size; |
| |
| bool result = false; |
| if (marking_request_bytes > marking_initiating_used_threshold) { |
| result = collector_state()->in_young_only_phase() && !collector_state()->in_young_gc_before_mixed(); |
| log_debug(gc, ergo, ihop)("%s occupancy: " SIZE_FORMAT "B allocation request: " SIZE_FORMAT "B threshold: " SIZE_FORMAT "B (%1.2f) source: %s", |
| result ? "Request concurrent cycle initiation (occupancy higher than threshold)" : "Do not request concurrent cycle initiation (still doing mixed collections)", |
| cur_used_bytes, alloc_byte_size, marking_initiating_used_threshold, (double) marking_initiating_used_threshold / _g1h->capacity() * 100, source); |
| } |
| |
| return result; |
| } |
| |
| // Anything below that is considered to be zero |
| #define MIN_TIMER_GRANULARITY 0.0000001 |
| |
| void G1Policy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned, size_t heap_used_bytes_before_gc) { |
| double end_time_sec = os::elapsedTime(); |
| |
| size_t cur_used_bytes = _g1h->used(); |
| assert(cur_used_bytes == _g1h->recalculate_used(), "It should!"); |
| bool this_pause_included_initial_mark = false; |
| bool this_pause_was_young_only = collector_state()->in_young_only_phase(); |
| |
| bool update_stats = !_g1h->evacuation_failed(); |
| |
| record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec); |
| |
| _collection_pause_end_millis = os::javaTimeNanos() / NANOSECS_PER_MILLISEC; |
| |
| this_pause_included_initial_mark = collector_state()->in_initial_mark_gc(); |
| if (this_pause_included_initial_mark) { |
| record_concurrent_mark_init_end(0.0); |
| } else { |
| maybe_start_marking(); |
| } |
| |
| double app_time_ms = (phase_times()->cur_collection_start_sec() * 1000.0 - _analytics->prev_collection_pause_end_ms()); |
| if (app_time_ms < MIN_TIMER_GRANULARITY) { |
| // This usually happens due to the timer not having the required |
| // granularity. Some Linuxes are the usual culprits. |
| // We'll just set it to something (arbitrarily) small. |
| app_time_ms = 1.0; |
| } |
| |
| if (update_stats) { |
| // We maintain the invariant that all objects allocated by mutator |
| // threads will be allocated out of eden regions. So, we can use |
| // the eden region number allocated since the previous GC to |
| // calculate the application's allocate rate. The only exception |
| // to that is humongous objects that are allocated separately. But |
| // given that humongous object allocations do not really affect |
| // either the pause's duration nor when the next pause will take |
| // place we can safely ignore them here. |
| uint regions_allocated = _collection_set->eden_region_length(); |
| double alloc_rate_ms = (double) regions_allocated / app_time_ms; |
| _analytics->report_alloc_rate_ms(alloc_rate_ms); |
| |
| double interval_ms = |
| (end_time_sec - _analytics->last_known_gc_end_time_sec()) * 1000.0; |
| _analytics->update_recent_gc_times(end_time_sec, pause_time_ms); |
| _analytics->compute_pause_time_ratio(interval_ms, pause_time_ms); |
| } |
| |
| if (collector_state()->in_young_gc_before_mixed()) { |
| assert(!this_pause_included_initial_mark, "The young GC before mixed is not allowed to be an initial mark GC"); |
| // This has been the young GC before we start doing mixed GCs. We already |
| // decided to start mixed GCs much earlier, so there is nothing to do except |
| // advancing the state. |
| collector_state()->set_in_young_only_phase(false); |
| collector_state()->set_in_young_gc_before_mixed(false); |
| } else if (!this_pause_was_young_only) { |
| // This is a mixed GC. Here we decide whether to continue doing more |
| // mixed GCs or not. |
| if (!next_gc_should_be_mixed("continue mixed GCs", |
| "do not continue mixed GCs")) { |
| collector_state()->set_in_young_only_phase(true); |
| |
| clear_collection_set_candidates(); |
| maybe_start_marking(); |
| } |
| } |
| |
| _short_lived_surv_rate_group->start_adding_regions(); |
| // Do that for any other surv rate groups |
| |
| double scan_hcc_time_ms = G1HotCardCache::default_use_cache() ? average_time_ms(G1GCPhaseTimes::ScanHCC) : 0.0; |
| |
| if (update_stats) { |
| double cost_per_card_ms = 0.0; |
| if (_pending_cards > 0) { |
| cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS)) / (double) _pending_cards; |
| _analytics->report_cost_per_card_ms(cost_per_card_ms); |
| } |
| _analytics->report_cost_scan_hcc(scan_hcc_time_ms); |
| |
| double cost_per_entry_ms = 0.0; |
| if (cards_scanned > 10) { |
| double avg_time_scan_rs = average_time_ms(G1GCPhaseTimes::ScanRS); |
| if (this_pause_was_young_only) { |
| avg_time_scan_rs += average_time_ms(G1GCPhaseTimes::OptScanRS); |
| } |
| cost_per_entry_ms = avg_time_scan_rs / cards_scanned; |
| _analytics->report_cost_per_entry_ms(cost_per_entry_ms, this_pause_was_young_only); |
| } |
| |
| if (_max_rs_lengths > 0) { |
| double cards_per_entry_ratio = |
| (double) cards_scanned / (double) _max_rs_lengths; |
| _analytics->report_cards_per_entry_ratio(cards_per_entry_ratio, this_pause_was_young_only); |
| } |
| |
| // This is defensive. For a while _max_rs_lengths could get |
| // smaller than _recorded_rs_lengths which was causing |
| // rs_length_diff to get very large and mess up the RSet length |
| // predictions. The reason was unsafe concurrent updates to the |
| // _inc_cset_recorded_rs_lengths field which the code below guards |
| // against (see CR 7118202). This bug has now been fixed (see CR |
| // 7119027). However, I'm still worried that |
| // _inc_cset_recorded_rs_lengths might still end up somewhat |
| // inaccurate. The concurrent refinement thread calculates an |
| // RSet's length concurrently with other CR threads updating it |
| // which might cause it to calculate the length incorrectly (if, |
| // say, it's in mid-coarsening). So I'll leave in the defensive |
| // conditional below just in case. |
| size_t rs_length_diff = 0; |
| size_t recorded_rs_lengths = _collection_set->recorded_rs_lengths(); |
| if (_max_rs_lengths > recorded_rs_lengths) { |
| rs_length_diff = _max_rs_lengths - recorded_rs_lengths; |
| } |
| _analytics->report_rs_length_diff((double) rs_length_diff); |
| |
| size_t freed_bytes = heap_used_bytes_before_gc - cur_used_bytes; |
| size_t copied_bytes = _collection_set->bytes_used_before() - freed_bytes; |
| double cost_per_byte_ms = 0.0; |
| |
| if (copied_bytes > 0) { |
| cost_per_byte_ms = (average_time_ms(G1GCPhaseTimes::ObjCopy) + average_time_ms(G1GCPhaseTimes::OptObjCopy)) / (double) copied_bytes; |
| _analytics->report_cost_per_byte_ms(cost_per_byte_ms, collector_state()->mark_or_rebuild_in_progress()); |
| } |
| |
| if (_collection_set->young_region_length() > 0) { |
| _analytics->report_young_other_cost_per_region_ms(young_other_time_ms() / |
| _collection_set->young_region_length()); |
| } |
| |
| if (_collection_set->old_region_length() > 0) { |
| _analytics->report_non_young_other_cost_per_region_ms(non_young_other_time_ms() / |
| _collection_set->old_region_length()); |
| } |
| |
| _analytics->report_constant_other_time_ms(constant_other_time_ms(pause_time_ms)); |
| |
| // Do not update RS lengths and the number of pending cards with information from mixed gc: |
| // these are is wildly different to during young only gc and mess up young gen sizing right |
| // after the mixed gc phase. |
| // During mixed gc we do not use them for young gen sizing. |
| if (this_pause_was_young_only) { |
| _analytics->report_pending_cards((double) _pending_cards); |
| _analytics->report_rs_lengths((double) _max_rs_lengths); |
| } |
| } |
| |
| assert(!(this_pause_included_initial_mark && collector_state()->mark_or_rebuild_in_progress()), |
| "If the last pause has been an initial mark, we should not have been in the marking window"); |
| if (this_pause_included_initial_mark) { |
| collector_state()->set_mark_or_rebuild_in_progress(true); |
| } |
| |
| _free_regions_at_end_of_collection = _g1h->num_free_regions(); |
| |
| update_rs_lengths_prediction(); |
| |
| // Do not update dynamic IHOP due to G1 periodic collection as it is highly likely |
| // that in this case we are not running in a "normal" operating mode. |
| if (_g1h->gc_cause() != GCCause::_g1_periodic_collection) { |
| // IHOP control wants to know the expected young gen length if it were not |
| // restrained by the heap reserve. Using the actual length would make the |
| // prediction too small and the limit the young gen every time we get to the |
| // predicted target occupancy. |
| size_t last_unrestrained_young_length = update_young_list_max_and_target_length(); |
| |
| update_ihop_prediction(app_time_ms / 1000.0, |
| _bytes_allocated_in_old_since_last_gc, |
| last_unrestrained_young_length * HeapRegion::GrainBytes, |
| this_pause_was_young_only); |
| _bytes_allocated_in_old_since_last_gc = 0; |
| |
| _ihop_control->send_trace_event(_g1h->gc_tracer_stw()); |
| } else { |
| // Any garbage collection triggered as periodic collection resets the time-to-mixed |
| // measurement. Periodic collection typically means that the application is "inactive", i.e. |
| // the marking threads may have received an uncharacterisic amount of cpu time |
| // for completing the marking, i.e. are faster than expected. |
| // This skews the predicted marking length towards smaller values which might cause |
| // the mark start being too late. |
| _initial_mark_to_mixed.reset(); |
| } |
| |
| // Note that _mmu_tracker->max_gc_time() returns the time in seconds. |
| double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0; |
| |
| if (update_rs_time_goal_ms < scan_hcc_time_ms) { |
| log_debug(gc, ergo, refine)("Adjust concurrent refinement thresholds (scanning the HCC expected to take longer than Update RS time goal)." |
| "Update RS time goal: %1.2fms Scan HCC time: %1.2fms", |
| update_rs_time_goal_ms, scan_hcc_time_ms); |
| |
| update_rs_time_goal_ms = 0; |
| } else { |
| update_rs_time_goal_ms -= scan_hcc_time_ms; |
| } |
| _g1h->concurrent_refine()->adjust(average_time_ms(G1GCPhaseTimes::UpdateRS), |
| phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS), |
| update_rs_time_goal_ms); |
| } |
| |
| G1IHOPControl* G1Policy::create_ihop_control(const G1Predictions* predictor){ |
| if (G1UseAdaptiveIHOP) { |
| return new G1AdaptiveIHOPControl(InitiatingHeapOccupancyPercent, |
| predictor, |
| G1ReservePercent, |
| G1HeapWastePercent); |
| } else { |
| return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent); |
| } |
| } |
| |
| void G1Policy::update_ihop_prediction(double mutator_time_s, |
| size_t mutator_alloc_bytes, |
| size_t young_gen_size, |
| bool this_gc_was_young_only) { |
| // Always try to update IHOP prediction. Even evacuation failures give information |
| // about e.g. whether to start IHOP earlier next time. |
| |
| // Avoid using really small application times that might create samples with |
| // very high or very low values. They may be caused by e.g. back-to-back gcs. |
| double const min_valid_time = 1e-6; |
| |
| bool report = false; |
| |
| double marking_to_mixed_time = -1.0; |
| if (!this_gc_was_young_only && _initial_mark_to_mixed.has_result()) { |
| marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time(); |
| assert(marking_to_mixed_time > 0.0, |
| "Initial mark to mixed time must be larger than zero but is %.3f", |
| marking_to_mixed_time); |
| if (marking_to_mixed_time > min_valid_time) { |
| _ihop_control->update_marking_length(marking_to_mixed_time); |
| report = true; |
| } |
| } |
| |
| // As an approximation for the young gc promotion rates during marking we use |
| // all of them. In many applications there are only a few if any young gcs during |
| // marking, which makes any prediction useless. This increases the accuracy of the |
| // prediction. |
| if (this_gc_was_young_only && mutator_time_s > min_valid_time) { |
| _ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size); |
| report = true; |
| } |
| |
| if (report) { |
| report_ihop_statistics(); |
| } |
| } |
| |
| void G1Policy::report_ihop_statistics() { |
| _ihop_control->print(); |
| } |
| |
| void G1Policy::print_phases() { |
| phase_times()->print(); |
| } |
| |
| double G1Policy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const { |
| TruncatedSeq* seq = surv_rate_group->get_seq(age); |
| guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age); |
| double pred = _predictor.get_new_prediction(seq); |
| if (pred > 1.0) { |
| pred = 1.0; |
| } |
| return pred; |
| } |
| |
| double G1Policy::accum_yg_surv_rate_pred(int age) const { |
| return _short_lived_surv_rate_group->accum_surv_rate_pred(age); |
| } |
| |
| double G1Policy::predict_base_elapsed_time_ms(size_t pending_cards, |
| size_t scanned_cards) const { |
| return |
| _analytics->predict_rs_update_time_ms(pending_cards) + |
| _analytics->predict_rs_scan_time_ms(scanned_cards, collector_state()->in_young_only_phase()) + |
| _analytics->predict_constant_other_time_ms(); |
| } |
| |
| double G1Policy::predict_base_elapsed_time_ms(size_t pending_cards) const { |
| size_t rs_length = _analytics->predict_rs_lengths() + _analytics->predict_rs_length_diff(); |
| size_t card_num = _analytics->predict_card_num(rs_length, collector_state()->in_young_only_phase()); |
| return predict_base_elapsed_time_ms(pending_cards, card_num); |
| } |
| |
| size_t G1Policy::predict_bytes_to_copy(HeapRegion* hr) const { |
| size_t bytes_to_copy; |
| if (!hr->is_young()) { |
| bytes_to_copy = hr->max_live_bytes(); |
| } else { |
| assert(hr->age_in_surv_rate_group() != -1, "invariant"); |
| int age = hr->age_in_surv_rate_group(); |
| double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group()); |
| bytes_to_copy = (size_t) (hr->used() * yg_surv_rate); |
| } |
| return bytes_to_copy; |
| } |
| |
| double G1Policy::predict_region_elapsed_time_ms(HeapRegion* hr, |
| bool for_young_gc) const { |
| size_t rs_length = hr->rem_set()->occupied(); |
| // Predicting the number of cards is based on which type of GC |
| // we're predicting for. |
| size_t card_num = _analytics->predict_card_num(rs_length, for_young_gc); |
| size_t bytes_to_copy = predict_bytes_to_copy(hr); |
| |
| double region_elapsed_time_ms = |
| _analytics->predict_rs_scan_time_ms(card_num, collector_state()->in_young_only_phase()) + |
| _analytics->predict_object_copy_time_ms(bytes_to_copy, collector_state()->mark_or_rebuild_in_progress()); |
| |
| // The prediction of the "other" time for this region is based |
| // upon the region type and NOT the GC type. |
| if (hr->is_young()) { |
| region_elapsed_time_ms += _analytics->predict_young_other_time_ms(1); |
| } else { |
| region_elapsed_time_ms += _analytics->predict_non_young_other_time_ms(1); |
| } |
| return region_elapsed_time_ms; |
| } |
| |
| bool G1Policy::should_allocate_mutator_region() const { |
| uint young_list_length = _g1h->young_regions_count(); |
| uint young_list_target_length = _young_list_target_length; |
| return young_list_length < young_list_target_length; |
| } |
| |
| bool G1Policy::can_expand_young_list() const { |
| uint young_list_length = _g1h->young_regions_count(); |
| uint young_list_max_length = _young_list_max_length; |
| return young_list_length < young_list_max_length; |
| } |
| |
| bool G1Policy::use_adaptive_young_list_length() const { |
| return _young_gen_sizer->use_adaptive_young_list_length(); |
| } |
| |
| size_t G1Policy::desired_survivor_size(uint max_regions) const { |
| size_t const survivor_capacity = HeapRegion::GrainWords * max_regions; |
| return (size_t)((((double)survivor_capacity) * TargetSurvivorRatio) / 100); |
| } |
| |
| void G1Policy::print_age_table() { |
| _survivors_age_table.print_age_table(_tenuring_threshold); |
| } |
| |
| void G1Policy::update_max_gc_locker_expansion() { |
| uint expansion_region_num = 0; |
| if (GCLockerEdenExpansionPercent > 0) { |
| double perc = (double) GCLockerEdenExpansionPercent / 100.0; |
| double expansion_region_num_d = perc * (double) _young_list_target_length; |
| // We use ceiling so that if expansion_region_num_d is > 0.0 (but |
| // less than 1.0) we'll get 1. |
| expansion_region_num = (uint) ceil(expansion_region_num_d); |
| } else { |
| assert(expansion_region_num == 0, "sanity"); |
| } |
| _young_list_max_length = _young_list_target_length + expansion_region_num; |
| assert(_young_list_target_length <= _young_list_max_length, "post-condition"); |
| } |
| |
| // Calculates survivor space parameters. |
| void G1Policy::update_survivors_policy() { |
| double max_survivor_regions_d = |
| (double) _young_list_target_length / (double) SurvivorRatio; |
| |
| // Calculate desired survivor size based on desired max survivor regions (unconstrained |
| // by remaining heap). Otherwise we may cause undesired promotions as we are |
| // already getting close to end of the heap, impacting performance even more. |
| uint const desired_max_survivor_regions = ceil(max_survivor_regions_d); |
| size_t const survivor_size = desired_survivor_size(desired_max_survivor_regions); |
| |
| _tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(survivor_size); |
| if (UsePerfData) { |
| _policy_counters->tenuring_threshold()->set_value(_tenuring_threshold); |
| _policy_counters->desired_survivor_size()->set_value(survivor_size * oopSize); |
| } |
| // The real maximum survivor size is bounded by the number of regions that can |
| // be allocated into. |
| _max_survivor_regions = MIN2(desired_max_survivor_regions, |
| _g1h->num_free_or_available_regions()); |
| } |
| |
| bool G1Policy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) { |
| // We actually check whether we are marking here and not if we are in a |
| // reclamation phase. This means that we will schedule a concurrent mark |
| // even while we are still in the process of reclaiming memory. |
| bool during_cycle = _g1h->concurrent_mark()->cm_thread()->during_cycle(); |
| if (!during_cycle) { |
| log_debug(gc, ergo)("Request concurrent cycle initiation (requested by GC cause). GC cause: %s", GCCause::to_string(gc_cause)); |
| collector_state()->set_initiate_conc_mark_if_possible(true); |
| return true; |
| } else { |
| log_debug(gc, ergo)("Do not request concurrent cycle initiation (concurrent cycle already in progress). GC cause: %s", GCCause::to_string(gc_cause)); |
| return false; |
| } |
| } |
| |
| void G1Policy::initiate_conc_mark() { |
| collector_state()->set_in_initial_mark_gc(true); |
| collector_state()->set_initiate_conc_mark_if_possible(false); |
| } |
| |
| void G1Policy::decide_on_conc_mark_initiation() { |
| // We are about to decide on whether this pause will be an |
| // initial-mark pause. |
| |
| // First, collector_state()->in_initial_mark_gc() should not be already set. We |
| // will set it here if we have to. However, it should be cleared by |
| // the end of the pause (it's only set for the duration of an |
| // initial-mark pause). |
| assert(!collector_state()->in_initial_mark_gc(), "pre-condition"); |
| |
| if (collector_state()->initiate_conc_mark_if_possible()) { |
| // We had noticed on a previous pause that the heap occupancy has |
| // gone over the initiating threshold and we should start a |
| // concurrent marking cycle. So we might initiate one. |
| |
| if (!about_to_start_mixed_phase() && collector_state()->in_young_only_phase()) { |
| // Initiate a new initial mark if there is no marking or reclamation going on. |
| initiate_conc_mark(); |
| log_debug(gc, ergo)("Initiate concurrent cycle (concurrent cycle initiation requested)"); |
| } else if (_g1h->is_user_requested_concurrent_full_gc(_g1h->gc_cause())) { |
| // Initiate a user requested initial mark. An initial mark must be young only |
| // GC, so the collector state must be updated to reflect this. |
| collector_state()->set_in_young_only_phase(true); |
| collector_state()->set_in_young_gc_before_mixed(false); |
| |
| // We might have ended up coming here about to start a mixed phase with a collection set |
| // active. The following remark might change the change the "evacuation efficiency" of |
| // the regions in this set, leading to failing asserts later. |
| // Since the concurrent cycle will recreate the collection set anyway, simply drop it here. |
| clear_collection_set_candidates(); |
| abort_time_to_mixed_tracking(); |
| initiate_conc_mark(); |
| log_debug(gc, ergo)("Initiate concurrent cycle (user requested concurrent cycle)"); |
| } else { |
| // The concurrent marking thread is still finishing up the |
| // previous cycle. If we start one right now the two cycles |
| // overlap. In particular, the concurrent marking thread might |
| // be in the process of clearing the next marking bitmap (which |
| // we will use for the next cycle if we start one). Starting a |
| // cycle now will be bad given that parts of the marking |
| // information might get cleared by the marking thread. And we |
| // cannot wait for the marking thread to finish the cycle as it |
| // periodically yields while clearing the next marking bitmap |
| // and, if it's in a yield point, it's waiting for us to |
| // finish. So, at this point we will not start a cycle and we'll |
| // let the concurrent marking thread complete the last one. |
| log_debug(gc, ergo)("Do not initiate concurrent cycle (concurrent cycle already in progress)"); |
| } |
| } |
| } |
| |
| void G1Policy::record_concurrent_mark_cleanup_end() { |
| G1CollectionSetCandidates* candidates = G1CollectionSetChooser::build(_g1h->workers(), _g1h->num_regions()); |
| _collection_set->set_candidates(candidates); |
| |
| bool mixed_gc_pending = next_gc_should_be_mixed("request mixed gcs", "request young-only gcs"); |
| if (!mixed_gc_pending) { |
| clear_collection_set_candidates(); |
| abort_time_to_mixed_tracking(); |
| } |
| collector_state()->set_in_young_gc_before_mixed(mixed_gc_pending); |
| collector_state()->set_mark_or_rebuild_in_progress(false); |
| |
| double end_sec = os::elapsedTime(); |
| double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0; |
| _analytics->report_concurrent_mark_cleanup_times_ms(elapsed_time_ms); |
| _analytics->append_prev_collection_pause_end_ms(elapsed_time_ms); |
| |
| record_pause(Cleanup, _mark_cleanup_start_sec, end_sec); |
| } |
| |
| double G1Policy::reclaimable_bytes_percent(size_t reclaimable_bytes) const { |
| return percent_of(reclaimable_bytes, _g1h->capacity()); |
| } |
| |
| class G1ClearCollectionSetCandidateRemSets : public HeapRegionClosure { |
| virtual bool do_heap_region(HeapRegion* r) { |
| r->rem_set()->clear_locked(true /* only_cardset */); |
| return false; |
| } |
| }; |
| |
| void G1Policy::clear_collection_set_candidates() { |
| // Clear remembered sets of remaining candidate regions and the actual candidate |
| // set. |
| G1ClearCollectionSetCandidateRemSets cl; |
| _collection_set->candidates()->iterate(&cl); |
| _collection_set->clear_candidates(); |
| } |
| |
| void G1Policy::maybe_start_marking() { |
| if (need_to_start_conc_mark("end of GC")) { |
| // Note: this might have already been set, if during the last |
| // pause we decided to start a cycle but at the beginning of |
| // this pause we decided to postpone it. That's OK. |
| collector_state()->set_initiate_conc_mark_if_possible(true); |
| } |
| } |
| |
| G1Policy::PauseKind G1Policy::young_gc_pause_kind() const { |
| assert(!collector_state()->in_full_gc(), "must be"); |
| if (collector_state()->in_initial_mark_gc()) { |
| assert(!collector_state()->in_young_gc_before_mixed(), "must be"); |
| return InitialMarkGC; |
| } else if (collector_state()->in_young_gc_before_mixed()) { |
| assert(!collector_state()->in_initial_mark_gc(), "must be"); |
| return LastYoungGC; |
| } else if (collector_state()->in_mixed_phase()) { |
| assert(!collector_state()->in_initial_mark_gc(), "must be"); |
| assert(!collector_state()->in_young_gc_before_mixed(), "must be"); |
| return MixedGC; |
| } else { |
| assert(!collector_state()->in_initial_mark_gc(), "must be"); |
| assert(!collector_state()->in_young_gc_before_mixed(), "must be"); |
| return YoungOnlyGC; |
| } |
| } |
| |
| void G1Policy::record_pause(PauseKind kind, double start, double end) { |
| // Manage the MMU tracker. For some reason it ignores Full GCs. |
| if (kind != FullGC) { |
| _mmu_tracker->add_pause(start, end); |
| } |
| // Manage the mutator time tracking from initial mark to first mixed gc. |
| switch (kind) { |
| case FullGC: |
| abort_time_to_mixed_tracking(); |
| break; |
| case Cleanup: |
| case Remark: |
| case YoungOnlyGC: |
| case LastYoungGC: |
| _initial_mark_to_mixed.add_pause(end - start); |
| break; |
| case InitialMarkGC: |
| if (_g1h->gc_cause() != GCCause::_g1_periodic_collection) { |
| _initial_mark_to_mixed.record_initial_mark_end(end); |
| } |
| break; |
| case MixedGC: |
| _initial_mark_to_mixed.record_mixed_gc_start(start); |
| break; |
| default: |
| ShouldNotReachHere(); |
| } |
| } |
| |
| void G1Policy::abort_time_to_mixed_tracking() { |
| _initial_mark_to_mixed.reset(); |
| } |
| |
| bool G1Policy::next_gc_should_be_mixed(const char* true_action_str, |
| const char* false_action_str) const { |
| G1CollectionSetCandidates* candidates = _collection_set->candidates(); |
| |
| if (candidates->is_empty()) { |
| log_debug(gc, ergo)("%s (candidate old regions not available)", false_action_str); |
| return false; |
| } |
| |
| // Is the amount of uncollected reclaimable space above G1HeapWastePercent? |
| size_t reclaimable_bytes = candidates->remaining_reclaimable_bytes(); |
| double reclaimable_percent = reclaimable_bytes_percent(reclaimable_bytes); |
| double threshold = (double) G1HeapWastePercent; |
| if (reclaimable_percent <= threshold) { |
| log_debug(gc, ergo)("%s (reclaimable percentage not over threshold). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT, |
| false_action_str, candidates->num_remaining(), reclaimable_bytes, reclaimable_percent, G1HeapWastePercent); |
| return false; |
| } |
| log_debug(gc, ergo)("%s (candidate old regions available). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT, |
| true_action_str, candidates->num_remaining(), reclaimable_bytes, reclaimable_percent, G1HeapWastePercent); |
| return true; |
| } |
| |
| uint G1Policy::calc_min_old_cset_length() const { |
| // The min old CSet region bound is based on the maximum desired |
| // number of mixed GCs after a cycle. I.e., even if some old regions |
| // look expensive, we should add them to the CSet anyway to make |
| // sure we go through the available old regions in no more than the |
| // maximum desired number of mixed GCs. |
| // |
| // The calculation is based on the number of marked regions we added |
| // to the CSet candidates in the first place, not how many remain, so |
| // that the result is the same during all mixed GCs that follow a cycle. |
| |
| const size_t region_num = _collection_set->candidates()->num_regions(); |
| const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1); |
| size_t result = region_num / gc_num; |
| // emulate ceiling |
| if (result * gc_num < region_num) { |
| result += 1; |
| } |
| return (uint) result; |
| } |
| |
| uint G1Policy::calc_max_old_cset_length() const { |
| // The max old CSet region bound is based on the threshold expressed |
| // as a percentage of the heap size. I.e., it should bound the |
| // number of old regions added to the CSet irrespective of how many |
| // of them are available. |
| |
| const G1CollectedHeap* g1h = G1CollectedHeap::heap(); |
| const size_t region_num = g1h->num_regions(); |
| const size_t perc = (size_t) G1OldCSetRegionThresholdPercent; |
| size_t result = region_num * perc / 100; |
| // emulate ceiling |
| if (100 * result < region_num * perc) { |
| result += 1; |
| } |
| return (uint) result; |
| } |
| |
| void G1Policy::calculate_old_collection_set_regions(G1CollectionSetCandidates* candidates, |
| double time_remaining_ms, |
| uint& num_initial_regions, |
| uint& num_optional_regions) { |
| assert(candidates != NULL, "Must be"); |
| |
| num_initial_regions = 0; |
| num_optional_regions = 0; |
| uint num_expensive_regions = 0; |
| |
| double predicted_old_time_ms = 0.0; |
| double predicted_initial_time_ms = 0.0; |
| double predicted_optional_time_ms = 0.0; |
| |
| double optional_threshold_ms = time_remaining_ms * optional_prediction_fraction(); |
| |
| const uint min_old_cset_length = calc_min_old_cset_length(); |
| const uint max_old_cset_length = MAX2(min_old_cset_length, calc_max_old_cset_length()); |
| const uint max_optional_regions = max_old_cset_length - min_old_cset_length; |
| bool check_time_remaining = use_adaptive_young_list_length(); |
| |
| uint candidate_idx = candidates->cur_idx(); |
| |
| log_debug(gc, ergo, cset)("Start adding old regions to collection set. Min %u regions, max %u regions, " |
| "time remaining %1.2fms, optional threshold %1.2fms", |
| min_old_cset_length, max_old_cset_length, time_remaining_ms, optional_threshold_ms); |
| |
| HeapRegion* hr = candidates->at(candidate_idx); |
| while (hr != NULL) { |
| if (num_initial_regions + num_optional_regions >= max_old_cset_length) { |
| // Added maximum number of old regions to the CSet. |
| log_debug(gc, ergo, cset)("Finish adding old regions to collection set (Maximum number of regions). " |
| "Initial %u regions, optional %u regions", |
| num_initial_regions, num_optional_regions); |
| break; |
| } |
| |
| // Stop adding regions if the remaining reclaimable space is |
| // not above G1HeapWastePercent. |
| size_t reclaimable_bytes = candidates->remaining_reclaimable_bytes(); |
| double reclaimable_percent = reclaimable_bytes_percent(reclaimable_bytes); |
| double threshold = (double) G1HeapWastePercent; |
| if (reclaimable_percent <= threshold) { |
| // We've added enough old regions that the amount of uncollected |
| // reclaimable space is at or below the waste threshold. Stop |
| // adding old regions to the CSet. |
| log_debug(gc, ergo, cset)("Finish adding old regions to collection set (Reclaimable percentage below threshold). " |
| "Reclaimable: " SIZE_FORMAT "%s (%1.2f%%) threshold: " UINTX_FORMAT "%%", |
| byte_size_in_proper_unit(reclaimable_bytes), proper_unit_for_byte_size(reclaimable_bytes), |
| reclaimable_percent, G1HeapWastePercent); |
| break; |
| } |
| |
| double predicted_time_ms = predict_region_elapsed_time_ms(hr, false); |
| time_remaining_ms = MAX2(time_remaining_ms - predicted_time_ms, 0.0); |
| // Add regions to old set until we reach the minimum amount |
| if (num_initial_regions < min_old_cset_length) { |
| predicted_old_time_ms += predicted_time_ms; |
| num_initial_regions++; |
| // Record the number of regions added with no time remaining |
| if (time_remaining_ms == 0.0) { |
| num_expensive_regions++; |
| } |
| } else if (!check_time_remaining) { |
| // In the non-auto-tuning case, we'll finish adding regions |
| // to the CSet if we reach the minimum. |
| log_debug(gc, ergo, cset)("Finish adding old regions to collection set (Region amount reached min)."); |
| break; |
| } else { |
| // Keep adding regions to old set until we reach the optional threshold |
| if (time_remaining_ms > optional_threshold_ms) { |
| predicted_old_time_ms += predicted_time_ms; |
| num_initial_regions++; |
| } else if (time_remaining_ms > 0) { |
| // Keep adding optional regions until time is up. |
| assert(num_optional_regions < max_optional_regions, "Should not be possible."); |
| predicted_optional_time_ms += predicted_time_ms; |
| num_optional_regions++; |
| } else { |
| log_debug(gc, ergo, cset)("Finish adding old regions to collection set (Predicted time too high)."); |
| break; |
| } |
| } |
| hr = candidates->at(++candidate_idx); |
| } |
| if (hr == NULL) { |
| log_debug(gc, ergo, cset)("Old candidate collection set empty."); |
| } |
| |
| if (num_expensive_regions > 0) { |
| log_debug(gc, ergo, cset)("Added %u initial old regions to collection set although the predicted time was too high.", |
| num_expensive_regions); |
| } |
| |
| log_debug(gc, ergo, cset)("Finish choosing collection set old regions. Initial: %u, optional: %u, " |
| "predicted old time: %1.2fms, predicted optional time: %1.2fms, time remaining: %1.2f", |
| num_initial_regions, num_optional_regions, |
| predicted_initial_time_ms, predicted_optional_time_ms, time_remaining_ms); |
| } |
| |
| void G1Policy::calculate_optional_collection_set_regions(G1CollectionSetCandidates* candidates, |
| uint const max_optional_regions, |
| double time_remaining_ms, |
| uint& num_optional_regions) { |
| assert(_g1h->collector_state()->in_mixed_phase(), "Should only be called in mixed phase"); |
| |
| num_optional_regions = 0; |
| double prediction_ms = 0; |
| uint candidate_idx = candidates->cur_idx(); |
| |
| HeapRegion* r = candidates->at(candidate_idx); |
| while (num_optional_regions < max_optional_regions) { |
| assert(r != NULL, "Region must exist"); |
| prediction_ms += predict_region_elapsed_time_ms(r, false); |
| |
| if (prediction_ms > time_remaining_ms) { |
| log_debug(gc, ergo, cset)("Prediction %.3fms for region %u does not fit remaining time: %.3fms.", |
| prediction_ms, r->hrm_index(), time_remaining_ms); |
| break; |
| } |
| // This region will be included in the next optional evacuation. |
| |
| time_remaining_ms -= prediction_ms; |
| num_optional_regions++; |
| r = candidates->at(++candidate_idx); |
| } |
| |
| log_debug(gc, ergo, cset)("Prepared %u regions out of %u for optional evacuation. Predicted time: %.3fms", |
| num_optional_regions, max_optional_regions, prediction_ms); |
| } |
| |
| void G1Policy::transfer_survivors_to_cset(const G1SurvivorRegions* survivors) { |
| |
| // Add survivor regions to SurvRateGroup. |
| note_start_adding_survivor_regions(); |
| finished_recalculating_age_indexes(true /* is_survivors */); |
| |
| HeapRegion* last = NULL; |
| for (GrowableArrayIterator<HeapRegion*> it = survivors->regions()->begin(); |
| it != survivors->regions()->end(); |
| ++it) { |
| HeapRegion* curr = *it; |
| set_region_survivor(curr); |
| |
| // The region is a non-empty survivor so let's add it to |
| // the incremental collection set for the next evacuation |
| // pause. |
| _collection_set->add_survivor_regions(curr); |
| |
| last = curr; |
| } |
| note_stop_adding_survivor_regions(); |
| |
| // Don't clear the survivor list handles until the start of |
| // the next evacuation pause - we need it in order to re-tag |
| // the survivor regions from this evacuation pause as 'young' |
| // at the start of the next. |
| |
| finished_recalculating_age_indexes(false /* is_survivors */); |
| } |