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/*
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* Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
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* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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*
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* This code is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 only, as
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* published by the Free Software Foundation.
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*
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* This code is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* version 2 for more details (a copy is included in the LICENSE file that
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* accompanied this code).
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*
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* You should have received a copy of the GNU General Public License version
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* 2 along with this work; if not, write to the Free Software Foundation,
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* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
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*
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* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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* or visit www.oracle.com if you need additional information or have any
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* questions.
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*
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*/
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#include "precompiled.hpp"
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#include "gc/g1/concurrentG1Refine.hpp"
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#include "gc/g1/concurrentMarkThread.inline.hpp"
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#include "gc/g1/g1Analytics.hpp"
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#include "gc/g1/g1CollectedHeap.inline.hpp"
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#include "gc/g1/g1CollectionSet.hpp"
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#include "gc/g1/g1ConcurrentMark.hpp"
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#include "gc/g1/g1DefaultPolicy.hpp"
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#include "gc/g1/g1IHOPControl.hpp"
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#include "gc/g1/g1GCPhaseTimes.hpp"
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#include "gc/g1/g1Policy.hpp"
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#include "gc/g1/g1YoungGenSizer.hpp"
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#include "gc/g1/heapRegion.inline.hpp"
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#include "gc/g1/heapRegionRemSet.hpp"
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#include "gc/shared/gcPolicyCounters.hpp"
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#include "runtime/arguments.hpp"
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#include "runtime/java.hpp"
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#include "runtime/mutexLocker.hpp"
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#include "utilities/debug.hpp"
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#include "utilities/pair.hpp"
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G1DefaultPolicy::G1DefaultPolicy() :
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_predictor(G1ConfidencePercent / 100.0),
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_analytics(new G1Analytics(&_predictor)),
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_mmu_tracker(new G1MMUTrackerQueue(GCPauseIntervalMillis / 1000.0, MaxGCPauseMillis / 1000.0)),
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_ihop_control(create_ihop_control(&_predictor)),
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_policy_counters(new GCPolicyCounters("GarbageFirst", 1, 3)),
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_young_list_fixed_length(0),
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_short_lived_surv_rate_group(new SurvRateGroup(&_predictor, "Short Lived", G1YoungSurvRateNumRegionsSummary)),
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_survivor_surv_rate_group(new SurvRateGroup(&_predictor, "Survivor", G1YoungSurvRateNumRegionsSummary)),
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_reserve_factor((double) G1ReservePercent / 100.0),
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_reserve_regions(0),
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_rs_lengths_prediction(0),
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_bytes_allocated_in_old_since_last_gc(0),
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_initial_mark_to_mixed(),
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_collection_set(NULL),
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_g1(NULL),
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_phase_times(new G1GCPhaseTimes(ParallelGCThreads)),
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_tenuring_threshold(MaxTenuringThreshold),
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_max_survivor_regions(0),
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_survivors_age_table(true) { }
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G1DefaultPolicy::~G1DefaultPolicy() {
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delete _ihop_control;
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}
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G1CollectorState* G1DefaultPolicy::collector_state() const { return _g1->collector_state(); }
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void G1DefaultPolicy::init(G1CollectedHeap* g1h, G1CollectionSet* collection_set) {
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_g1 = g1h;
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_collection_set = collection_set;
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assert(Heap_lock->owned_by_self(), "Locking discipline.");
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if (!adaptive_young_list_length()) {
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_young_list_fixed_length = _young_gen_sizer.min_desired_young_length();
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}
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_young_gen_sizer.adjust_max_new_size(_g1->max_regions());
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_free_regions_at_end_of_collection = _g1->num_free_regions();
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update_young_list_max_and_target_length();
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// We may immediately start allocating regions and placing them on the
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// collection set list. Initialize the per-collection set info
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_collection_set->start_incremental_building();
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}
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void G1DefaultPolicy::note_gc_start() {
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phase_times()->note_gc_start();
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}
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bool G1DefaultPolicy::predict_will_fit(uint young_length,
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double base_time_ms,
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uint base_free_regions,
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double target_pause_time_ms) const {
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if (young_length >= base_free_regions) {
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// end condition 1: not enough space for the young regions
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return false;
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}
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double accum_surv_rate = accum_yg_surv_rate_pred((int) young_length - 1);
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size_t bytes_to_copy =
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(size_t) (accum_surv_rate * (double) HeapRegion::GrainBytes);
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double copy_time_ms = _analytics->predict_object_copy_time_ms(bytes_to_copy,
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collector_state()->during_concurrent_mark());
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double young_other_time_ms = _analytics->predict_young_other_time_ms(young_length);
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double pause_time_ms = base_time_ms + copy_time_ms + young_other_time_ms;
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if (pause_time_ms > target_pause_time_ms) {
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// end condition 2: prediction is over the target pause time
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return false;
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}
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size_t free_bytes = (base_free_regions - young_length) * HeapRegion::GrainBytes;
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// When copying, we will likely need more bytes free than is live in the region.
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// Add some safety margin to factor in the confidence of our guess, and the
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// natural expected waste.
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// (100.0 / G1ConfidencePercent) is a scale factor that expresses the uncertainty
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// of the calculation: the lower the confidence, the more headroom.
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// (100 + TargetPLABWastePct) represents the increase in expected bytes during
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// copying due to anticipated waste in the PLABs.
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double safety_factor = (100.0 / G1ConfidencePercent) * (100 + TargetPLABWastePct) / 100.0;
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size_t expected_bytes_to_copy = (size_t)(safety_factor * bytes_to_copy);
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if (expected_bytes_to_copy > free_bytes) {
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// end condition 3: out-of-space
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return false;
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}
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// success!
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return true;
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}
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void G1DefaultPolicy::record_new_heap_size(uint new_number_of_regions) {
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// re-calculate the necessary reserve
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double reserve_regions_d = (double) new_number_of_regions * _reserve_factor;
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// We use ceiling so that if reserve_regions_d is > 0.0 (but
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// smaller than 1.0) we'll get 1.
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_reserve_regions = (uint) ceil(reserve_regions_d);
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_young_gen_sizer.heap_size_changed(new_number_of_regions);
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_ihop_control->update_target_occupancy(new_number_of_regions * HeapRegion::GrainBytes);
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}
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uint G1DefaultPolicy::calculate_young_list_desired_min_length(uint base_min_length) const {
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uint desired_min_length = 0;
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if (adaptive_young_list_length()) {
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if (_analytics->num_alloc_rate_ms() > 3) {
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double now_sec = os::elapsedTime();
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double when_ms = _mmu_tracker->when_max_gc_sec(now_sec) * 1000.0;
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double alloc_rate_ms = _analytics->predict_alloc_rate_ms();
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desired_min_length = (uint) ceil(alloc_rate_ms * when_ms);
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} else {
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// otherwise we don't have enough info to make the prediction
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}
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}
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desired_min_length += base_min_length;
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// make sure we don't go below any user-defined minimum bound
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return MAX2(_young_gen_sizer.min_desired_young_length(), desired_min_length);
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}
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uint G1DefaultPolicy::calculate_young_list_desired_max_length() const {
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// Here, we might want to also take into account any additional
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// constraints (i.e., user-defined minimum bound). Currently, we
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// effectively don't set this bound.
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return _young_gen_sizer.max_desired_young_length();
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}
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uint G1DefaultPolicy::update_young_list_max_and_target_length() {
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return update_young_list_max_and_target_length(_analytics->predict_rs_lengths());
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}
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uint G1DefaultPolicy::update_young_list_max_and_target_length(size_t rs_lengths) {
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uint unbounded_target_length = update_young_list_target_length(rs_lengths);
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update_max_gc_locker_expansion();
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return unbounded_target_length;
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}
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uint G1DefaultPolicy::update_young_list_target_length(size_t rs_lengths) {
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YoungTargetLengths young_lengths = young_list_target_lengths(rs_lengths);
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_young_list_target_length = young_lengths.first;
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return young_lengths.second;
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}
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G1DefaultPolicy::YoungTargetLengths G1DefaultPolicy::young_list_target_lengths(size_t rs_lengths) const {
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YoungTargetLengths result;
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// Calculate the absolute and desired min bounds first.
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// This is how many young regions we already have (currently: the survivors).
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const uint base_min_length = _g1->young_list()->survivor_length();
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uint desired_min_length = calculate_young_list_desired_min_length(base_min_length);
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// This is the absolute minimum young length. Ensure that we
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// will at least have one eden region available for allocation.
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uint absolute_min_length = base_min_length + MAX2(_g1->young_list()->eden_length(), (uint)1);
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// If we shrank the young list target it should not shrink below the current size.
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desired_min_length = MAX2(desired_min_length, absolute_min_length);
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// Calculate the absolute and desired max bounds.
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uint desired_max_length = calculate_young_list_desired_max_length();
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uint young_list_target_length = 0;
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if (adaptive_young_list_length()) {
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if (collector_state()->gcs_are_young()) {
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young_list_target_length =
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calculate_young_list_target_length(rs_lengths,
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base_min_length,
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desired_min_length,
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desired_max_length);
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} else {
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// Don't calculate anything and let the code below bound it to
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// the desired_min_length, i.e., do the next GC as soon as
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// possible to maximize how many old regions we can add to it.
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}
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} else {
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// The user asked for a fixed young gen so we'll fix the young gen
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// whether the next GC is young or mixed.
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young_list_target_length = _young_list_fixed_length;
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}
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result.second = young_list_target_length;
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// We will try our best not to "eat" into the reserve.
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uint absolute_max_length = 0;
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if (_free_regions_at_end_of_collection > _reserve_regions) {
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absolute_max_length = _free_regions_at_end_of_collection - _reserve_regions;
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}
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if (desired_max_length > absolute_max_length) {
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desired_max_length = absolute_max_length;
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}
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// Make sure we don't go over the desired max length, nor under the
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// desired min length. In case they clash, desired_min_length wins
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// which is why that test is second.
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if (young_list_target_length > desired_max_length) {
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young_list_target_length = desired_max_length;
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}
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if (young_list_target_length < desired_min_length) {
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young_list_target_length = desired_min_length;
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}
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assert(young_list_target_length > base_min_length,
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"we should be able to allocate at least one eden region");
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assert(young_list_target_length >= absolute_min_length, "post-condition");
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result.first = young_list_target_length;
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return result;
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}
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uint
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G1DefaultPolicy::calculate_young_list_target_length(size_t rs_lengths,
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uint base_min_length,
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uint desired_min_length,
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uint desired_max_length) const {
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assert(adaptive_young_list_length(), "pre-condition");
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assert(collector_state()->gcs_are_young(), "only call this for young GCs");
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// In case some edge-condition makes the desired max length too small...
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if (desired_max_length <= desired_min_length) {
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return desired_min_length;
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}
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// We'll adjust min_young_length and max_young_length not to include
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// the already allocated young regions (i.e., so they reflect the
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// min and max eden regions we'll allocate). The base_min_length
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// will be reflected in the predictions by the
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// survivor_regions_evac_time prediction.
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assert(desired_min_length > base_min_length, "invariant");
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uint min_young_length = desired_min_length - base_min_length;
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assert(desired_max_length > base_min_length, "invariant");
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uint max_young_length = desired_max_length - base_min_length;
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double target_pause_time_ms = _mmu_tracker->max_gc_time() * 1000.0;
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double survivor_regions_evac_time = predict_survivor_regions_evac_time();
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size_t pending_cards = _analytics->predict_pending_cards();
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size_t adj_rs_lengths = rs_lengths + _analytics->predict_rs_length_diff();
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size_t scanned_cards = _analytics->predict_card_num(adj_rs_lengths, /* gcs_are_young */ true);
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double base_time_ms =
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predict_base_elapsed_time_ms(pending_cards, scanned_cards) +
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survivor_regions_evac_time;
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uint available_free_regions = _free_regions_at_end_of_collection;
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uint base_free_regions = 0;
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if (available_free_regions > _reserve_regions) {
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base_free_regions = available_free_regions - _reserve_regions;
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}
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// Here, we will make sure that the shortest young length that
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// makes sense fits within the target pause time.
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if (predict_will_fit(min_young_length, base_time_ms,
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base_free_regions, target_pause_time_ms)) {
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// The shortest young length will fit into the target pause time;
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// we'll now check whether the absolute maximum number of young
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// regions will fit in the target pause time. If not, we'll do
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// a binary search between min_young_length and max_young_length.
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if (predict_will_fit(max_young_length, base_time_ms,
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base_free_regions, target_pause_time_ms)) {
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// The maximum young length will fit into the target pause time.
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// We are done so set min young length to the maximum length (as
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// the result is assumed to be returned in min_young_length).
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min_young_length = max_young_length;
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} else {
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// The maximum possible number of young regions will not fit within
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// the target pause time so we'll search for the optimal
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// length. The loop invariants are:
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//
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// min_young_length < max_young_length
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// min_young_length is known to fit into the target pause time
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// max_young_length is known not to fit into the target pause time
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//
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// Going into the loop we know the above hold as we've just
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// checked them. Every time around the loop we check whether
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// the middle value between min_young_length and
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// max_young_length fits into the target pause time. If it
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// does, it becomes the new min. If it doesn't, it becomes
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// the new max. This way we maintain the loop invariants.
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assert(min_young_length < max_young_length, "invariant");
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uint diff = (max_young_length - min_young_length) / 2;
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while (diff > 0) {
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uint young_length = min_young_length + diff;
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if (predict_will_fit(young_length, base_time_ms,
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base_free_regions, target_pause_time_ms)) {
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min_young_length = young_length;
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} else {
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max_young_length = young_length;
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}
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assert(min_young_length < max_young_length, "invariant");
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diff = (max_young_length - min_young_length) / 2;
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}
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// The results is min_young_length which, according to the
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// loop invariants, should fit within the target pause time.
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// These are the post-conditions of the binary search above:
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assert(min_young_length < max_young_length,
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"otherwise we should have discovered that max_young_length "
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"fits into the pause target and not done the binary search");
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assert(predict_will_fit(min_young_length, base_time_ms,
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base_free_regions, target_pause_time_ms),
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"min_young_length, the result of the binary search, should "
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"fit into the pause target");
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347 |
assert(!predict_will_fit(min_young_length + 1, base_time_ms,
|
|
348 |
base_free_regions, target_pause_time_ms),
|
|
349 |
"min_young_length, the result of the binary search, should be "
|
|
350 |
"optimal, so no larger length should fit into the pause target");
|
|
351 |
}
|
|
352 |
} else {
|
|
353 |
// Even the minimum length doesn't fit into the pause time
|
|
354 |
// target, return it as the result nevertheless.
|
|
355 |
}
|
|
356 |
return base_min_length + min_young_length;
|
|
357 |
}
|
|
358 |
|
|
359 |
double G1DefaultPolicy::predict_survivor_regions_evac_time() const {
|
|
360 |
double survivor_regions_evac_time = 0.0;
|
|
361 |
for (HeapRegion * r = _g1->young_list()->first_survivor_region();
|
|
362 |
r != NULL && r != _g1->young_list()->last_survivor_region()->get_next_young_region();
|
|
363 |
r = r->get_next_young_region()) {
|
|
364 |
survivor_regions_evac_time += predict_region_elapsed_time_ms(r, collector_state()->gcs_are_young());
|
|
365 |
}
|
|
366 |
return survivor_regions_evac_time;
|
|
367 |
}
|
|
368 |
|
|
369 |
void G1DefaultPolicy::revise_young_list_target_length_if_necessary(size_t rs_lengths) {
|
|
370 |
guarantee( adaptive_young_list_length(), "should not call this otherwise" );
|
|
371 |
|
|
372 |
if (rs_lengths > _rs_lengths_prediction) {
|
|
373 |
// add 10% to avoid having to recalculate often
|
|
374 |
size_t rs_lengths_prediction = rs_lengths * 1100 / 1000;
|
|
375 |
update_rs_lengths_prediction(rs_lengths_prediction);
|
|
376 |
|
|
377 |
update_young_list_max_and_target_length(rs_lengths_prediction);
|
|
378 |
}
|
|
379 |
}
|
|
380 |
|
|
381 |
void G1DefaultPolicy::update_rs_lengths_prediction() {
|
|
382 |
update_rs_lengths_prediction(_analytics->predict_rs_lengths());
|
|
383 |
}
|
|
384 |
|
|
385 |
void G1DefaultPolicy::update_rs_lengths_prediction(size_t prediction) {
|
|
386 |
if (collector_state()->gcs_are_young() && adaptive_young_list_length()) {
|
|
387 |
_rs_lengths_prediction = prediction;
|
|
388 |
}
|
|
389 |
}
|
|
390 |
|
|
391 |
#ifndef PRODUCT
|
|
392 |
bool G1DefaultPolicy::verify_young_ages() {
|
|
393 |
HeapRegion* head = _g1->young_list()->first_region();
|
|
394 |
return
|
|
395 |
verify_young_ages(head, _short_lived_surv_rate_group);
|
|
396 |
// also call verify_young_ages on any additional surv rate groups
|
|
397 |
}
|
|
398 |
|
|
399 |
bool G1DefaultPolicy::verify_young_ages(HeapRegion* head, SurvRateGroup *surv_rate_group) {
|
|
400 |
guarantee( surv_rate_group != NULL, "pre-condition" );
|
|
401 |
|
|
402 |
const char* name = surv_rate_group->name();
|
|
403 |
bool ret = true;
|
|
404 |
int prev_age = -1;
|
|
405 |
|
|
406 |
for (HeapRegion* curr = head;
|
|
407 |
curr != NULL;
|
|
408 |
curr = curr->get_next_young_region()) {
|
|
409 |
SurvRateGroup* group = curr->surv_rate_group();
|
|
410 |
if (group == NULL && !curr->is_survivor()) {
|
|
411 |
log_error(gc, verify)("## %s: encountered NULL surv_rate_group", name);
|
|
412 |
ret = false;
|
|
413 |
}
|
|
414 |
|
|
415 |
if (surv_rate_group == group) {
|
|
416 |
int age = curr->age_in_surv_rate_group();
|
|
417 |
|
|
418 |
if (age < 0) {
|
|
419 |
log_error(gc, verify)("## %s: encountered negative age", name);
|
|
420 |
ret = false;
|
|
421 |
}
|
|
422 |
|
|
423 |
if (age <= prev_age) {
|
|
424 |
log_error(gc, verify)("## %s: region ages are not strictly increasing (%d, %d)", name, age, prev_age);
|
|
425 |
ret = false;
|
|
426 |
}
|
|
427 |
prev_age = age;
|
|
428 |
}
|
|
429 |
}
|
|
430 |
|
|
431 |
return ret;
|
|
432 |
}
|
|
433 |
#endif // PRODUCT
|
|
434 |
|
|
435 |
void G1DefaultPolicy::record_full_collection_start() {
|
|
436 |
_full_collection_start_sec = os::elapsedTime();
|
|
437 |
// Release the future to-space so that it is available for compaction into.
|
|
438 |
collector_state()->set_full_collection(true);
|
|
439 |
}
|
|
440 |
|
|
441 |
void G1DefaultPolicy::record_full_collection_end() {
|
|
442 |
// Consider this like a collection pause for the purposes of allocation
|
|
443 |
// since last pause.
|
|
444 |
double end_sec = os::elapsedTime();
|
|
445 |
double full_gc_time_sec = end_sec - _full_collection_start_sec;
|
|
446 |
double full_gc_time_ms = full_gc_time_sec * 1000.0;
|
|
447 |
|
|
448 |
_analytics->update_recent_gc_times(end_sec, full_gc_time_ms);
|
|
449 |
|
|
450 |
collector_state()->set_full_collection(false);
|
|
451 |
|
|
452 |
// "Nuke" the heuristics that control the young/mixed GC
|
|
453 |
// transitions and make sure we start with young GCs after the Full GC.
|
|
454 |
collector_state()->set_gcs_are_young(true);
|
|
455 |
collector_state()->set_last_young_gc(false);
|
|
456 |
collector_state()->set_initiate_conc_mark_if_possible(need_to_start_conc_mark("end of Full GC", 0));
|
|
457 |
collector_state()->set_during_initial_mark_pause(false);
|
|
458 |
collector_state()->set_in_marking_window(false);
|
|
459 |
collector_state()->set_in_marking_window_im(false);
|
|
460 |
|
|
461 |
_short_lived_surv_rate_group->start_adding_regions();
|
|
462 |
// also call this on any additional surv rate groups
|
|
463 |
|
|
464 |
_free_regions_at_end_of_collection = _g1->num_free_regions();
|
|
465 |
// Reset survivors SurvRateGroup.
|
|
466 |
_survivor_surv_rate_group->reset();
|
|
467 |
update_young_list_max_and_target_length();
|
|
468 |
update_rs_lengths_prediction();
|
|
469 |
cset_chooser()->clear();
|
|
470 |
|
|
471 |
_bytes_allocated_in_old_since_last_gc = 0;
|
|
472 |
|
|
473 |
record_pause(FullGC, _full_collection_start_sec, end_sec);
|
|
474 |
}
|
|
475 |
|
|
476 |
void G1DefaultPolicy::record_collection_pause_start(double start_time_sec) {
|
|
477 |
// We only need to do this here as the policy will only be applied
|
|
478 |
// to the GC we're about to start. so, no point is calculating this
|
|
479 |
// every time we calculate / recalculate the target young length.
|
|
480 |
update_survivors_policy();
|
|
481 |
|
|
482 |
assert(_g1->used() == _g1->recalculate_used(),
|
|
483 |
"sanity, used: " SIZE_FORMAT " recalculate_used: " SIZE_FORMAT,
|
|
484 |
_g1->used(), _g1->recalculate_used());
|
|
485 |
|
|
486 |
phase_times()->record_cur_collection_start_sec(start_time_sec);
|
|
487 |
_pending_cards = _g1->pending_card_num();
|
|
488 |
|
|
489 |
_collection_set->reset_bytes_used_before();
|
|
490 |
_bytes_copied_during_gc = 0;
|
|
491 |
|
|
492 |
collector_state()->set_last_gc_was_young(false);
|
|
493 |
|
|
494 |
// do that for any other surv rate groups
|
|
495 |
_short_lived_surv_rate_group->stop_adding_regions();
|
|
496 |
_survivors_age_table.clear();
|
|
497 |
|
|
498 |
assert( verify_young_ages(), "region age verification" );
|
|
499 |
}
|
|
500 |
|
|
501 |
void G1DefaultPolicy::record_concurrent_mark_init_end(double mark_init_elapsed_time_ms) {
|
|
502 |
collector_state()->set_during_marking(true);
|
|
503 |
assert(!collector_state()->initiate_conc_mark_if_possible(), "we should have cleared it by now");
|
|
504 |
collector_state()->set_during_initial_mark_pause(false);
|
|
505 |
}
|
|
506 |
|
|
507 |
void G1DefaultPolicy::record_concurrent_mark_remark_start() {
|
|
508 |
_mark_remark_start_sec = os::elapsedTime();
|
|
509 |
collector_state()->set_during_marking(false);
|
|
510 |
}
|
|
511 |
|
|
512 |
void G1DefaultPolicy::record_concurrent_mark_remark_end() {
|
|
513 |
double end_time_sec = os::elapsedTime();
|
|
514 |
double elapsed_time_ms = (end_time_sec - _mark_remark_start_sec)*1000.0;
|
|
515 |
_analytics->report_concurrent_mark_remark_times_ms(elapsed_time_ms);
|
|
516 |
_analytics->append_prev_collection_pause_end_ms(elapsed_time_ms);
|
|
517 |
|
|
518 |
record_pause(Remark, _mark_remark_start_sec, end_time_sec);
|
|
519 |
}
|
|
520 |
|
|
521 |
void G1DefaultPolicy::record_concurrent_mark_cleanup_start() {
|
|
522 |
_mark_cleanup_start_sec = os::elapsedTime();
|
|
523 |
}
|
|
524 |
|
|
525 |
void G1DefaultPolicy::record_concurrent_mark_cleanup_completed() {
|
|
526 |
bool should_continue_with_reclaim = next_gc_should_be_mixed("request last young-only gc",
|
|
527 |
"skip last young-only gc");
|
|
528 |
collector_state()->set_last_young_gc(should_continue_with_reclaim);
|
|
529 |
// We skip the marking phase.
|
|
530 |
if (!should_continue_with_reclaim) {
|
|
531 |
abort_time_to_mixed_tracking();
|
|
532 |
}
|
|
533 |
collector_state()->set_in_marking_window(false);
|
|
534 |
}
|
|
535 |
|
|
536 |
double G1DefaultPolicy::average_time_ms(G1GCPhaseTimes::GCParPhases phase) const {
|
|
537 |
return phase_times()->average_time_ms(phase);
|
|
538 |
}
|
|
539 |
|
|
540 |
double G1DefaultPolicy::young_other_time_ms() const {
|
|
541 |
return phase_times()->young_cset_choice_time_ms() +
|
|
542 |
phase_times()->young_free_cset_time_ms();
|
|
543 |
}
|
|
544 |
|
|
545 |
double G1DefaultPolicy::non_young_other_time_ms() const {
|
|
546 |
return phase_times()->non_young_cset_choice_time_ms() +
|
|
547 |
phase_times()->non_young_free_cset_time_ms();
|
|
548 |
|
|
549 |
}
|
|
550 |
|
|
551 |
double G1DefaultPolicy::other_time_ms(double pause_time_ms) const {
|
|
552 |
return pause_time_ms -
|
|
553 |
average_time_ms(G1GCPhaseTimes::UpdateRS) -
|
|
554 |
average_time_ms(G1GCPhaseTimes::ScanRS) -
|
|
555 |
average_time_ms(G1GCPhaseTimes::ObjCopy) -
|
|
556 |
average_time_ms(G1GCPhaseTimes::Termination);
|
|
557 |
}
|
|
558 |
|
|
559 |
double G1DefaultPolicy::constant_other_time_ms(double pause_time_ms) const {
|
|
560 |
return other_time_ms(pause_time_ms) - young_other_time_ms() - non_young_other_time_ms();
|
|
561 |
}
|
|
562 |
|
|
563 |
CollectionSetChooser* G1DefaultPolicy::cset_chooser() const {
|
|
564 |
return _collection_set->cset_chooser();
|
|
565 |
}
|
|
566 |
|
|
567 |
bool G1DefaultPolicy::about_to_start_mixed_phase() const {
|
|
568 |
return _g1->concurrent_mark()->cmThread()->during_cycle() || collector_state()->last_young_gc();
|
|
569 |
}
|
|
570 |
|
|
571 |
bool G1DefaultPolicy::need_to_start_conc_mark(const char* source, size_t alloc_word_size) {
|
|
572 |
if (about_to_start_mixed_phase()) {
|
|
573 |
return false;
|
|
574 |
}
|
|
575 |
|
|
576 |
size_t marking_initiating_used_threshold = _ihop_control->get_conc_mark_start_threshold();
|
|
577 |
|
|
578 |
size_t cur_used_bytes = _g1->non_young_capacity_bytes();
|
|
579 |
size_t alloc_byte_size = alloc_word_size * HeapWordSize;
|
|
580 |
size_t marking_request_bytes = cur_used_bytes + alloc_byte_size;
|
|
581 |
|
|
582 |
bool result = false;
|
|
583 |
if (marking_request_bytes > marking_initiating_used_threshold) {
|
|
584 |
result = collector_state()->gcs_are_young() && !collector_state()->last_young_gc();
|
|
585 |
log_debug(gc, ergo, ihop)("%s occupancy: " SIZE_FORMAT "B allocation request: " SIZE_FORMAT "B threshold: " SIZE_FORMAT "B (%1.2f) source: %s",
|
|
586 |
result ? "Request concurrent cycle initiation (occupancy higher than threshold)" : "Do not request concurrent cycle initiation (still doing mixed collections)",
|
|
587 |
cur_used_bytes, alloc_byte_size, marking_initiating_used_threshold, (double) marking_initiating_used_threshold / _g1->capacity() * 100, source);
|
|
588 |
}
|
|
589 |
|
|
590 |
return result;
|
|
591 |
}
|
|
592 |
|
|
593 |
// Anything below that is considered to be zero
|
|
594 |
#define MIN_TIMER_GRANULARITY 0.0000001
|
|
595 |
|
|
596 |
void G1DefaultPolicy::record_collection_pause_end(double pause_time_ms, size_t cards_scanned, size_t heap_used_bytes_before_gc) {
|
|
597 |
double end_time_sec = os::elapsedTime();
|
|
598 |
|
|
599 |
size_t cur_used_bytes = _g1->used();
|
|
600 |
assert(cur_used_bytes == _g1->recalculate_used(), "It should!");
|
|
601 |
bool last_pause_included_initial_mark = false;
|
|
602 |
bool update_stats = !_g1->evacuation_failed();
|
|
603 |
|
|
604 |
NOT_PRODUCT(_short_lived_surv_rate_group->print());
|
|
605 |
|
|
606 |
record_pause(young_gc_pause_kind(), end_time_sec - pause_time_ms / 1000.0, end_time_sec);
|
|
607 |
|
|
608 |
last_pause_included_initial_mark = collector_state()->during_initial_mark_pause();
|
|
609 |
if (last_pause_included_initial_mark) {
|
|
610 |
record_concurrent_mark_init_end(0.0);
|
|
611 |
} else {
|
|
612 |
maybe_start_marking();
|
|
613 |
}
|
|
614 |
|
|
615 |
double app_time_ms = (phase_times()->cur_collection_start_sec() * 1000.0 - _analytics->prev_collection_pause_end_ms());
|
|
616 |
if (app_time_ms < MIN_TIMER_GRANULARITY) {
|
|
617 |
// This usually happens due to the timer not having the required
|
|
618 |
// granularity. Some Linuxes are the usual culprits.
|
|
619 |
// We'll just set it to something (arbitrarily) small.
|
|
620 |
app_time_ms = 1.0;
|
|
621 |
}
|
|
622 |
|
|
623 |
if (update_stats) {
|
|
624 |
// We maintain the invariant that all objects allocated by mutator
|
|
625 |
// threads will be allocated out of eden regions. So, we can use
|
|
626 |
// the eden region number allocated since the previous GC to
|
|
627 |
// calculate the application's allocate rate. The only exception
|
|
628 |
// to that is humongous objects that are allocated separately. But
|
|
629 |
// given that humongous object allocations do not really affect
|
|
630 |
// either the pause's duration nor when the next pause will take
|
|
631 |
// place we can safely ignore them here.
|
|
632 |
uint regions_allocated = _collection_set->eden_region_length();
|
|
633 |
double alloc_rate_ms = (double) regions_allocated / app_time_ms;
|
|
634 |
_analytics->report_alloc_rate_ms(alloc_rate_ms);
|
|
635 |
|
|
636 |
double interval_ms =
|
|
637 |
(end_time_sec - _analytics->last_known_gc_end_time_sec()) * 1000.0;
|
|
638 |
_analytics->update_recent_gc_times(end_time_sec, pause_time_ms);
|
|
639 |
_analytics->compute_pause_time_ratio(interval_ms, pause_time_ms);
|
|
640 |
}
|
|
641 |
|
|
642 |
bool new_in_marking_window = collector_state()->in_marking_window();
|
|
643 |
bool new_in_marking_window_im = false;
|
|
644 |
if (last_pause_included_initial_mark) {
|
|
645 |
new_in_marking_window = true;
|
|
646 |
new_in_marking_window_im = true;
|
|
647 |
}
|
|
648 |
|
|
649 |
if (collector_state()->last_young_gc()) {
|
|
650 |
// This is supposed to to be the "last young GC" before we start
|
|
651 |
// doing mixed GCs. Here we decide whether to start mixed GCs or not.
|
|
652 |
assert(!last_pause_included_initial_mark, "The last young GC is not allowed to be an initial mark GC");
|
|
653 |
|
|
654 |
if (next_gc_should_be_mixed("start mixed GCs",
|
|
655 |
"do not start mixed GCs")) {
|
|
656 |
collector_state()->set_gcs_are_young(false);
|
|
657 |
} else {
|
|
658 |
// We aborted the mixed GC phase early.
|
|
659 |
abort_time_to_mixed_tracking();
|
|
660 |
}
|
|
661 |
|
|
662 |
collector_state()->set_last_young_gc(false);
|
|
663 |
}
|
|
664 |
|
|
665 |
if (!collector_state()->last_gc_was_young()) {
|
|
666 |
// This is a mixed GC. Here we decide whether to continue doing
|
|
667 |
// mixed GCs or not.
|
|
668 |
if (!next_gc_should_be_mixed("continue mixed GCs",
|
|
669 |
"do not continue mixed GCs")) {
|
|
670 |
collector_state()->set_gcs_are_young(true);
|
|
671 |
|
|
672 |
maybe_start_marking();
|
|
673 |
}
|
|
674 |
}
|
|
675 |
|
|
676 |
_short_lived_surv_rate_group->start_adding_regions();
|
|
677 |
// Do that for any other surv rate groups
|
|
678 |
|
|
679 |
double scan_hcc_time_ms = ConcurrentG1Refine::hot_card_cache_enabled() ? average_time_ms(G1GCPhaseTimes::ScanHCC) : 0.0;
|
|
680 |
|
|
681 |
if (update_stats) {
|
|
682 |
double cost_per_card_ms = 0.0;
|
|
683 |
if (_pending_cards > 0) {
|
|
684 |
cost_per_card_ms = (average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms) / (double) _pending_cards;
|
|
685 |
_analytics->report_cost_per_card_ms(cost_per_card_ms);
|
|
686 |
}
|
|
687 |
_analytics->report_cost_scan_hcc(scan_hcc_time_ms);
|
|
688 |
|
|
689 |
double cost_per_entry_ms = 0.0;
|
|
690 |
if (cards_scanned > 10) {
|
|
691 |
cost_per_entry_ms = average_time_ms(G1GCPhaseTimes::ScanRS) / (double) cards_scanned;
|
|
692 |
_analytics->report_cost_per_entry_ms(cost_per_entry_ms, collector_state()->last_gc_was_young());
|
|
693 |
}
|
|
694 |
|
|
695 |
if (_max_rs_lengths > 0) {
|
|
696 |
double cards_per_entry_ratio =
|
|
697 |
(double) cards_scanned / (double) _max_rs_lengths;
|
|
698 |
_analytics->report_cards_per_entry_ratio(cards_per_entry_ratio, collector_state()->last_gc_was_young());
|
|
699 |
}
|
|
700 |
|
|
701 |
// This is defensive. For a while _max_rs_lengths could get
|
|
702 |
// smaller than _recorded_rs_lengths which was causing
|
|
703 |
// rs_length_diff to get very large and mess up the RSet length
|
|
704 |
// predictions. The reason was unsafe concurrent updates to the
|
|
705 |
// _inc_cset_recorded_rs_lengths field which the code below guards
|
|
706 |
// against (see CR 7118202). This bug has now been fixed (see CR
|
|
707 |
// 7119027). However, I'm still worried that
|
|
708 |
// _inc_cset_recorded_rs_lengths might still end up somewhat
|
|
709 |
// inaccurate. The concurrent refinement thread calculates an
|
|
710 |
// RSet's length concurrently with other CR threads updating it
|
|
711 |
// which might cause it to calculate the length incorrectly (if,
|
|
712 |
// say, it's in mid-coarsening). So I'll leave in the defensive
|
|
713 |
// conditional below just in case.
|
|
714 |
size_t rs_length_diff = 0;
|
|
715 |
size_t recorded_rs_lengths = _collection_set->recorded_rs_lengths();
|
|
716 |
if (_max_rs_lengths > recorded_rs_lengths) {
|
|
717 |
rs_length_diff = _max_rs_lengths - recorded_rs_lengths;
|
|
718 |
}
|
|
719 |
_analytics->report_rs_length_diff((double) rs_length_diff);
|
|
720 |
|
|
721 |
size_t freed_bytes = heap_used_bytes_before_gc - cur_used_bytes;
|
|
722 |
size_t copied_bytes = _collection_set->bytes_used_before() - freed_bytes;
|
|
723 |
double cost_per_byte_ms = 0.0;
|
|
724 |
|
|
725 |
if (copied_bytes > 0) {
|
|
726 |
cost_per_byte_ms = average_time_ms(G1GCPhaseTimes::ObjCopy) / (double) copied_bytes;
|
|
727 |
_analytics->report_cost_per_byte_ms(cost_per_byte_ms, collector_state()->in_marking_window());
|
|
728 |
}
|
|
729 |
|
|
730 |
if (_collection_set->young_region_length() > 0) {
|
|
731 |
_analytics->report_young_other_cost_per_region_ms(young_other_time_ms() /
|
|
732 |
_collection_set->young_region_length());
|
|
733 |
}
|
|
734 |
|
|
735 |
if (_collection_set->old_region_length() > 0) {
|
|
736 |
_analytics->report_non_young_other_cost_per_region_ms(non_young_other_time_ms() /
|
|
737 |
_collection_set->old_region_length());
|
|
738 |
}
|
|
739 |
|
|
740 |
_analytics->report_constant_other_time_ms(constant_other_time_ms(pause_time_ms));
|
|
741 |
|
|
742 |
_analytics->report_pending_cards((double) _pending_cards);
|
|
743 |
_analytics->report_rs_lengths((double) _max_rs_lengths);
|
|
744 |
}
|
|
745 |
|
|
746 |
collector_state()->set_in_marking_window(new_in_marking_window);
|
|
747 |
collector_state()->set_in_marking_window_im(new_in_marking_window_im);
|
|
748 |
_free_regions_at_end_of_collection = _g1->num_free_regions();
|
|
749 |
// IHOP control wants to know the expected young gen length if it were not
|
|
750 |
// restrained by the heap reserve. Using the actual length would make the
|
|
751 |
// prediction too small and the limit the young gen every time we get to the
|
|
752 |
// predicted target occupancy.
|
|
753 |
size_t last_unrestrained_young_length = update_young_list_max_and_target_length();
|
|
754 |
update_rs_lengths_prediction();
|
|
755 |
|
|
756 |
update_ihop_prediction(app_time_ms / 1000.0,
|
|
757 |
_bytes_allocated_in_old_since_last_gc,
|
|
758 |
last_unrestrained_young_length * HeapRegion::GrainBytes);
|
|
759 |
_bytes_allocated_in_old_since_last_gc = 0;
|
|
760 |
|
|
761 |
_ihop_control->send_trace_event(_g1->gc_tracer_stw());
|
|
762 |
|
|
763 |
// Note that _mmu_tracker->max_gc_time() returns the time in seconds.
|
|
764 |
double update_rs_time_goal_ms = _mmu_tracker->max_gc_time() * MILLIUNITS * G1RSetUpdatingPauseTimePercent / 100.0;
|
|
765 |
|
|
766 |
if (update_rs_time_goal_ms < scan_hcc_time_ms) {
|
|
767 |
log_debug(gc, ergo, refine)("Adjust concurrent refinement thresholds (scanning the HCC expected to take longer than Update RS time goal)."
|
|
768 |
"Update RS time goal: %1.2fms Scan HCC time: %1.2fms",
|
|
769 |
update_rs_time_goal_ms, scan_hcc_time_ms);
|
|
770 |
|
|
771 |
update_rs_time_goal_ms = 0;
|
|
772 |
} else {
|
|
773 |
update_rs_time_goal_ms -= scan_hcc_time_ms;
|
|
774 |
}
|
|
775 |
_g1->concurrent_g1_refine()->adjust(average_time_ms(G1GCPhaseTimes::UpdateRS) - scan_hcc_time_ms,
|
|
776 |
phase_times()->sum_thread_work_items(G1GCPhaseTimes::UpdateRS),
|
|
777 |
update_rs_time_goal_ms);
|
|
778 |
|
|
779 |
cset_chooser()->verify();
|
|
780 |
}
|
|
781 |
|
|
782 |
G1IHOPControl* G1DefaultPolicy::create_ihop_control(const G1Predictions* predictor){
|
|
783 |
if (G1UseAdaptiveIHOP) {
|
|
784 |
return new G1AdaptiveIHOPControl(InitiatingHeapOccupancyPercent,
|
|
785 |
predictor,
|
|
786 |
G1ReservePercent,
|
|
787 |
G1HeapWastePercent);
|
|
788 |
} else {
|
|
789 |
return new G1StaticIHOPControl(InitiatingHeapOccupancyPercent);
|
|
790 |
}
|
|
791 |
}
|
|
792 |
|
|
793 |
void G1DefaultPolicy::update_ihop_prediction(double mutator_time_s,
|
|
794 |
size_t mutator_alloc_bytes,
|
|
795 |
size_t young_gen_size) {
|
|
796 |
// Always try to update IHOP prediction. Even evacuation failures give information
|
|
797 |
// about e.g. whether to start IHOP earlier next time.
|
|
798 |
|
|
799 |
// Avoid using really small application times that might create samples with
|
|
800 |
// very high or very low values. They may be caused by e.g. back-to-back gcs.
|
|
801 |
double const min_valid_time = 1e-6;
|
|
802 |
|
|
803 |
bool report = false;
|
|
804 |
|
|
805 |
double marking_to_mixed_time = -1.0;
|
|
806 |
if (!collector_state()->last_gc_was_young() && _initial_mark_to_mixed.has_result()) {
|
|
807 |
marking_to_mixed_time = _initial_mark_to_mixed.last_marking_time();
|
|
808 |
assert(marking_to_mixed_time > 0.0,
|
|
809 |
"Initial mark to mixed time must be larger than zero but is %.3f",
|
|
810 |
marking_to_mixed_time);
|
|
811 |
if (marking_to_mixed_time > min_valid_time) {
|
|
812 |
_ihop_control->update_marking_length(marking_to_mixed_time);
|
|
813 |
report = true;
|
|
814 |
}
|
|
815 |
}
|
|
816 |
|
|
817 |
// As an approximation for the young gc promotion rates during marking we use
|
|
818 |
// all of them. In many applications there are only a few if any young gcs during
|
|
819 |
// marking, which makes any prediction useless. This increases the accuracy of the
|
|
820 |
// prediction.
|
|
821 |
if (collector_state()->last_gc_was_young() && mutator_time_s > min_valid_time) {
|
|
822 |
_ihop_control->update_allocation_info(mutator_time_s, mutator_alloc_bytes, young_gen_size);
|
|
823 |
report = true;
|
|
824 |
}
|
|
825 |
|
|
826 |
if (report) {
|
|
827 |
report_ihop_statistics();
|
|
828 |
}
|
|
829 |
}
|
|
830 |
|
|
831 |
void G1DefaultPolicy::report_ihop_statistics() {
|
|
832 |
_ihop_control->print();
|
|
833 |
}
|
|
834 |
|
|
835 |
void G1DefaultPolicy::print_phases() {
|
|
836 |
phase_times()->print();
|
|
837 |
}
|
|
838 |
|
|
839 |
double G1DefaultPolicy::predict_yg_surv_rate(int age, SurvRateGroup* surv_rate_group) const {
|
|
840 |
TruncatedSeq* seq = surv_rate_group->get_seq(age);
|
|
841 |
guarantee(seq->num() > 0, "There should be some young gen survivor samples available. Tried to access with age %d", age);
|
|
842 |
double pred = _predictor.get_new_prediction(seq);
|
|
843 |
if (pred > 1.0) {
|
|
844 |
pred = 1.0;
|
|
845 |
}
|
|
846 |
return pred;
|
|
847 |
}
|
|
848 |
|
|
849 |
double G1DefaultPolicy::predict_yg_surv_rate(int age) const {
|
|
850 |
return predict_yg_surv_rate(age, _short_lived_surv_rate_group);
|
|
851 |
}
|
|
852 |
|
|
853 |
double G1DefaultPolicy::accum_yg_surv_rate_pred(int age) const {
|
|
854 |
return _short_lived_surv_rate_group->accum_surv_rate_pred(age);
|
|
855 |
}
|
|
856 |
|
|
857 |
double G1DefaultPolicy::predict_base_elapsed_time_ms(size_t pending_cards,
|
|
858 |
size_t scanned_cards) const {
|
|
859 |
return
|
|
860 |
_analytics->predict_rs_update_time_ms(pending_cards) +
|
|
861 |
_analytics->predict_rs_scan_time_ms(scanned_cards, collector_state()->gcs_are_young()) +
|
|
862 |
_analytics->predict_constant_other_time_ms();
|
|
863 |
}
|
|
864 |
|
|
865 |
double G1DefaultPolicy::predict_base_elapsed_time_ms(size_t pending_cards) const {
|
|
866 |
size_t rs_length = _analytics->predict_rs_lengths() + _analytics->predict_rs_length_diff();
|
|
867 |
size_t card_num = _analytics->predict_card_num(rs_length, collector_state()->gcs_are_young());
|
|
868 |
return predict_base_elapsed_time_ms(pending_cards, card_num);
|
|
869 |
}
|
|
870 |
|
|
871 |
size_t G1DefaultPolicy::predict_bytes_to_copy(HeapRegion* hr) const {
|
|
872 |
size_t bytes_to_copy;
|
|
873 |
if (hr->is_marked())
|
|
874 |
bytes_to_copy = hr->max_live_bytes();
|
|
875 |
else {
|
|
876 |
assert(hr->is_young() && hr->age_in_surv_rate_group() != -1, "invariant");
|
|
877 |
int age = hr->age_in_surv_rate_group();
|
|
878 |
double yg_surv_rate = predict_yg_surv_rate(age, hr->surv_rate_group());
|
|
879 |
bytes_to_copy = (size_t) (hr->used() * yg_surv_rate);
|
|
880 |
}
|
|
881 |
return bytes_to_copy;
|
|
882 |
}
|
|
883 |
|
|
884 |
double G1DefaultPolicy::predict_region_elapsed_time_ms(HeapRegion* hr,
|
|
885 |
bool for_young_gc) const {
|
|
886 |
size_t rs_length = hr->rem_set()->occupied();
|
|
887 |
// Predicting the number of cards is based on which type of GC
|
|
888 |
// we're predicting for.
|
|
889 |
size_t card_num = _analytics->predict_card_num(rs_length, for_young_gc);
|
|
890 |
size_t bytes_to_copy = predict_bytes_to_copy(hr);
|
|
891 |
|
|
892 |
double region_elapsed_time_ms =
|
|
893 |
_analytics->predict_rs_scan_time_ms(card_num, collector_state()->gcs_are_young()) +
|
|
894 |
_analytics->predict_object_copy_time_ms(bytes_to_copy, collector_state()->during_concurrent_mark());
|
|
895 |
|
|
896 |
// The prediction of the "other" time for this region is based
|
|
897 |
// upon the region type and NOT the GC type.
|
|
898 |
if (hr->is_young()) {
|
|
899 |
region_elapsed_time_ms += _analytics->predict_young_other_time_ms(1);
|
|
900 |
} else {
|
|
901 |
region_elapsed_time_ms += _analytics->predict_non_young_other_time_ms(1);
|
|
902 |
}
|
|
903 |
return region_elapsed_time_ms;
|
|
904 |
}
|
|
905 |
|
|
906 |
|
|
907 |
void G1DefaultPolicy::print_yg_surv_rate_info() const {
|
|
908 |
#ifndef PRODUCT
|
|
909 |
_short_lived_surv_rate_group->print_surv_rate_summary();
|
|
910 |
// add this call for any other surv rate groups
|
|
911 |
#endif // PRODUCT
|
|
912 |
}
|
|
913 |
|
|
914 |
bool G1DefaultPolicy::is_young_list_full() const {
|
|
915 |
uint young_list_length = _g1->young_list()->length();
|
|
916 |
uint young_list_target_length = _young_list_target_length;
|
|
917 |
return young_list_length >= young_list_target_length;
|
|
918 |
}
|
|
919 |
|
|
920 |
bool G1DefaultPolicy::can_expand_young_list() const {
|
|
921 |
uint young_list_length = _g1->young_list()->length();
|
|
922 |
uint young_list_max_length = _young_list_max_length;
|
|
923 |
return young_list_length < young_list_max_length;
|
|
924 |
}
|
|
925 |
|
|
926 |
bool G1DefaultPolicy::adaptive_young_list_length() const {
|
|
927 |
return _young_gen_sizer.adaptive_young_list_length();
|
|
928 |
}
|
|
929 |
|
|
930 |
void G1DefaultPolicy::update_max_gc_locker_expansion() {
|
|
931 |
uint expansion_region_num = 0;
|
|
932 |
if (GCLockerEdenExpansionPercent > 0) {
|
|
933 |
double perc = (double) GCLockerEdenExpansionPercent / 100.0;
|
|
934 |
double expansion_region_num_d = perc * (double) _young_list_target_length;
|
|
935 |
// We use ceiling so that if expansion_region_num_d is > 0.0 (but
|
|
936 |
// less than 1.0) we'll get 1.
|
|
937 |
expansion_region_num = (uint) ceil(expansion_region_num_d);
|
|
938 |
} else {
|
|
939 |
assert(expansion_region_num == 0, "sanity");
|
|
940 |
}
|
|
941 |
_young_list_max_length = _young_list_target_length + expansion_region_num;
|
|
942 |
assert(_young_list_target_length <= _young_list_max_length, "post-condition");
|
|
943 |
}
|
|
944 |
|
|
945 |
// Calculates survivor space parameters.
|
|
946 |
void G1DefaultPolicy::update_survivors_policy() {
|
|
947 |
double max_survivor_regions_d =
|
|
948 |
(double) _young_list_target_length / (double) SurvivorRatio;
|
|
949 |
// We use ceiling so that if max_survivor_regions_d is > 0.0 (but
|
|
950 |
// smaller than 1.0) we'll get 1.
|
|
951 |
_max_survivor_regions = (uint) ceil(max_survivor_regions_d);
|
|
952 |
|
|
953 |
_tenuring_threshold = _survivors_age_table.compute_tenuring_threshold(
|
|
954 |
HeapRegion::GrainWords * _max_survivor_regions, _policy_counters);
|
|
955 |
}
|
|
956 |
|
|
957 |
bool G1DefaultPolicy::force_initial_mark_if_outside_cycle(GCCause::Cause gc_cause) {
|
|
958 |
// We actually check whether we are marking here and not if we are in a
|
|
959 |
// reclamation phase. This means that we will schedule a concurrent mark
|
|
960 |
// even while we are still in the process of reclaiming memory.
|
|
961 |
bool during_cycle = _g1->concurrent_mark()->cmThread()->during_cycle();
|
|
962 |
if (!during_cycle) {
|
|
963 |
log_debug(gc, ergo)("Request concurrent cycle initiation (requested by GC cause). GC cause: %s", GCCause::to_string(gc_cause));
|
|
964 |
collector_state()->set_initiate_conc_mark_if_possible(true);
|
|
965 |
return true;
|
|
966 |
} else {
|
|
967 |
log_debug(gc, ergo)("Do not request concurrent cycle initiation (concurrent cycle already in progress). GC cause: %s", GCCause::to_string(gc_cause));
|
|
968 |
return false;
|
|
969 |
}
|
|
970 |
}
|
|
971 |
|
|
972 |
void G1DefaultPolicy::initiate_conc_mark() {
|
|
973 |
collector_state()->set_during_initial_mark_pause(true);
|
|
974 |
collector_state()->set_initiate_conc_mark_if_possible(false);
|
|
975 |
}
|
|
976 |
|
|
977 |
void G1DefaultPolicy::decide_on_conc_mark_initiation() {
|
|
978 |
// We are about to decide on whether this pause will be an
|
|
979 |
// initial-mark pause.
|
|
980 |
|
|
981 |
// First, collector_state()->during_initial_mark_pause() should not be already set. We
|
|
982 |
// will set it here if we have to. However, it should be cleared by
|
|
983 |
// the end of the pause (it's only set for the duration of an
|
|
984 |
// initial-mark pause).
|
|
985 |
assert(!collector_state()->during_initial_mark_pause(), "pre-condition");
|
|
986 |
|
|
987 |
if (collector_state()->initiate_conc_mark_if_possible()) {
|
|
988 |
// We had noticed on a previous pause that the heap occupancy has
|
|
989 |
// gone over the initiating threshold and we should start a
|
|
990 |
// concurrent marking cycle. So we might initiate one.
|
|
991 |
|
|
992 |
if (!about_to_start_mixed_phase() && collector_state()->gcs_are_young()) {
|
|
993 |
// Initiate a new initial mark if there is no marking or reclamation going on.
|
|
994 |
initiate_conc_mark();
|
|
995 |
log_debug(gc, ergo)("Initiate concurrent cycle (concurrent cycle initiation requested)");
|
|
996 |
} else if (_g1->is_user_requested_concurrent_full_gc(_g1->gc_cause())) {
|
|
997 |
// Initiate a user requested initial mark. An initial mark must be young only
|
|
998 |
// GC, so the collector state must be updated to reflect this.
|
|
999 |
collector_state()->set_gcs_are_young(true);
|
|
1000 |
collector_state()->set_last_young_gc(false);
|
|
1001 |
|
|
1002 |
abort_time_to_mixed_tracking();
|
|
1003 |
initiate_conc_mark();
|
|
1004 |
log_debug(gc, ergo)("Initiate concurrent cycle (user requested concurrent cycle)");
|
|
1005 |
} else {
|
|
1006 |
// The concurrent marking thread is still finishing up the
|
|
1007 |
// previous cycle. If we start one right now the two cycles
|
|
1008 |
// overlap. In particular, the concurrent marking thread might
|
|
1009 |
// be in the process of clearing the next marking bitmap (which
|
|
1010 |
// we will use for the next cycle if we start one). Starting a
|
|
1011 |
// cycle now will be bad given that parts of the marking
|
|
1012 |
// information might get cleared by the marking thread. And we
|
|
1013 |
// cannot wait for the marking thread to finish the cycle as it
|
|
1014 |
// periodically yields while clearing the next marking bitmap
|
|
1015 |
// and, if it's in a yield point, it's waiting for us to
|
|
1016 |
// finish. So, at this point we will not start a cycle and we'll
|
|
1017 |
// let the concurrent marking thread complete the last one.
|
|
1018 |
log_debug(gc, ergo)("Do not initiate concurrent cycle (concurrent cycle already in progress)");
|
|
1019 |
}
|
|
1020 |
}
|
|
1021 |
}
|
|
1022 |
|
|
1023 |
void G1DefaultPolicy::record_concurrent_mark_cleanup_end() {
|
|
1024 |
cset_chooser()->rebuild(_g1->workers(), _g1->num_regions());
|
|
1025 |
|
|
1026 |
double end_sec = os::elapsedTime();
|
|
1027 |
double elapsed_time_ms = (end_sec - _mark_cleanup_start_sec) * 1000.0;
|
|
1028 |
_analytics->report_concurrent_mark_cleanup_times_ms(elapsed_time_ms);
|
|
1029 |
_analytics->append_prev_collection_pause_end_ms(elapsed_time_ms);
|
|
1030 |
|
|
1031 |
record_pause(Cleanup, _mark_cleanup_start_sec, end_sec);
|
|
1032 |
}
|
|
1033 |
|
|
1034 |
double G1DefaultPolicy::reclaimable_bytes_perc(size_t reclaimable_bytes) const {
|
|
1035 |
// Returns the given amount of reclaimable bytes (that represents
|
|
1036 |
// the amount of reclaimable space still to be collected) as a
|
|
1037 |
// percentage of the current heap capacity.
|
|
1038 |
size_t capacity_bytes = _g1->capacity();
|
|
1039 |
return (double) reclaimable_bytes * 100.0 / (double) capacity_bytes;
|
|
1040 |
}
|
|
1041 |
|
|
1042 |
void G1DefaultPolicy::maybe_start_marking() {
|
|
1043 |
if (need_to_start_conc_mark("end of GC")) {
|
|
1044 |
// Note: this might have already been set, if during the last
|
|
1045 |
// pause we decided to start a cycle but at the beginning of
|
|
1046 |
// this pause we decided to postpone it. That's OK.
|
|
1047 |
collector_state()->set_initiate_conc_mark_if_possible(true);
|
|
1048 |
}
|
|
1049 |
}
|
|
1050 |
|
|
1051 |
G1DefaultPolicy::PauseKind G1DefaultPolicy::young_gc_pause_kind() const {
|
|
1052 |
assert(!collector_state()->full_collection(), "must be");
|
|
1053 |
if (collector_state()->during_initial_mark_pause()) {
|
|
1054 |
assert(collector_state()->last_gc_was_young(), "must be");
|
|
1055 |
assert(!collector_state()->last_young_gc(), "must be");
|
|
1056 |
return InitialMarkGC;
|
|
1057 |
} else if (collector_state()->last_young_gc()) {
|
|
1058 |
assert(!collector_state()->during_initial_mark_pause(), "must be");
|
|
1059 |
assert(collector_state()->last_gc_was_young(), "must be");
|
|
1060 |
return LastYoungGC;
|
|
1061 |
} else if (!collector_state()->last_gc_was_young()) {
|
|
1062 |
assert(!collector_state()->during_initial_mark_pause(), "must be");
|
|
1063 |
assert(!collector_state()->last_young_gc(), "must be");
|
|
1064 |
return MixedGC;
|
|
1065 |
} else {
|
|
1066 |
assert(collector_state()->last_gc_was_young(), "must be");
|
|
1067 |
assert(!collector_state()->during_initial_mark_pause(), "must be");
|
|
1068 |
assert(!collector_state()->last_young_gc(), "must be");
|
|
1069 |
return YoungOnlyGC;
|
|
1070 |
}
|
|
1071 |
}
|
|
1072 |
|
|
1073 |
void G1DefaultPolicy::record_pause(PauseKind kind, double start, double end) {
|
|
1074 |
// Manage the MMU tracker. For some reason it ignores Full GCs.
|
|
1075 |
if (kind != FullGC) {
|
|
1076 |
_mmu_tracker->add_pause(start, end);
|
|
1077 |
}
|
|
1078 |
// Manage the mutator time tracking from initial mark to first mixed gc.
|
|
1079 |
switch (kind) {
|
|
1080 |
case FullGC:
|
|
1081 |
abort_time_to_mixed_tracking();
|
|
1082 |
break;
|
|
1083 |
case Cleanup:
|
|
1084 |
case Remark:
|
|
1085 |
case YoungOnlyGC:
|
|
1086 |
case LastYoungGC:
|
|
1087 |
_initial_mark_to_mixed.add_pause(end - start);
|
|
1088 |
break;
|
|
1089 |
case InitialMarkGC:
|
|
1090 |
_initial_mark_to_mixed.record_initial_mark_end(end);
|
|
1091 |
break;
|
|
1092 |
case MixedGC:
|
|
1093 |
_initial_mark_to_mixed.record_mixed_gc_start(start);
|
|
1094 |
break;
|
|
1095 |
default:
|
|
1096 |
ShouldNotReachHere();
|
|
1097 |
}
|
|
1098 |
}
|
|
1099 |
|
|
1100 |
void G1DefaultPolicy::abort_time_to_mixed_tracking() {
|
|
1101 |
_initial_mark_to_mixed.reset();
|
|
1102 |
}
|
|
1103 |
|
|
1104 |
bool G1DefaultPolicy::next_gc_should_be_mixed(const char* true_action_str,
|
|
1105 |
const char* false_action_str) const {
|
|
1106 |
if (cset_chooser()->is_empty()) {
|
|
1107 |
log_debug(gc, ergo)("%s (candidate old regions not available)", false_action_str);
|
|
1108 |
return false;
|
|
1109 |
}
|
|
1110 |
|
|
1111 |
// Is the amount of uncollected reclaimable space above G1HeapWastePercent?
|
|
1112 |
size_t reclaimable_bytes = cset_chooser()->remaining_reclaimable_bytes();
|
|
1113 |
double reclaimable_perc = reclaimable_bytes_perc(reclaimable_bytes);
|
|
1114 |
double threshold = (double) G1HeapWastePercent;
|
|
1115 |
if (reclaimable_perc <= threshold) {
|
|
1116 |
log_debug(gc, ergo)("%s (reclaimable percentage not over threshold). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,
|
|
1117 |
false_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
|
|
1118 |
return false;
|
|
1119 |
}
|
|
1120 |
log_debug(gc, ergo)("%s (candidate old regions available). candidate old regions: %u reclaimable: " SIZE_FORMAT " (%1.2f) threshold: " UINTX_FORMAT,
|
|
1121 |
true_action_str, cset_chooser()->remaining_regions(), reclaimable_bytes, reclaimable_perc, G1HeapWastePercent);
|
|
1122 |
return true;
|
|
1123 |
}
|
|
1124 |
|
|
1125 |
uint G1DefaultPolicy::calc_min_old_cset_length() const {
|
|
1126 |
// The min old CSet region bound is based on the maximum desired
|
|
1127 |
// number of mixed GCs after a cycle. I.e., even if some old regions
|
|
1128 |
// look expensive, we should add them to the CSet anyway to make
|
|
1129 |
// sure we go through the available old regions in no more than the
|
|
1130 |
// maximum desired number of mixed GCs.
|
|
1131 |
//
|
|
1132 |
// The calculation is based on the number of marked regions we added
|
|
1133 |
// to the CSet chooser in the first place, not how many remain, so
|
|
1134 |
// that the result is the same during all mixed GCs that follow a cycle.
|
|
1135 |
|
|
1136 |
const size_t region_num = (size_t) cset_chooser()->length();
|
|
1137 |
const size_t gc_num = (size_t) MAX2(G1MixedGCCountTarget, (uintx) 1);
|
|
1138 |
size_t result = region_num / gc_num;
|
|
1139 |
// emulate ceiling
|
|
1140 |
if (result * gc_num < region_num) {
|
|
1141 |
result += 1;
|
|
1142 |
}
|
|
1143 |
return (uint) result;
|
|
1144 |
}
|
|
1145 |
|
|
1146 |
uint G1DefaultPolicy::calc_max_old_cset_length() const {
|
|
1147 |
// The max old CSet region bound is based on the threshold expressed
|
|
1148 |
// as a percentage of the heap size. I.e., it should bound the
|
|
1149 |
// number of old regions added to the CSet irrespective of how many
|
|
1150 |
// of them are available.
|
|
1151 |
|
|
1152 |
const G1CollectedHeap* g1h = G1CollectedHeap::heap();
|
|
1153 |
const size_t region_num = g1h->num_regions();
|
|
1154 |
const size_t perc = (size_t) G1OldCSetRegionThresholdPercent;
|
|
1155 |
size_t result = region_num * perc / 100;
|
|
1156 |
// emulate ceiling
|
|
1157 |
if (100 * result < region_num * perc) {
|
|
1158 |
result += 1;
|
|
1159 |
}
|
|
1160 |
return (uint) result;
|
|
1161 |
}
|
|
1162 |
|
|
1163 |
void G1DefaultPolicy::finalize_collection_set(double target_pause_time_ms) {
|
|
1164 |
double time_remaining_ms = _collection_set->finalize_young_part(target_pause_time_ms);
|
|
1165 |
_collection_set->finalize_old_part(time_remaining_ms);
|
|
1166 |
}
|