150 lines
6.6 KiB
C++
150 lines
6.6 KiB
C++
/*
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* Copyright (c) 2015, 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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#ifndef SHARE_VM_GC_G1_G1IHOPCONTROL_HPP
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#define SHARE_VM_GC_G1_G1IHOPCONTROL_HPP
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#include "memory/allocation.hpp"
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#include "utilities/numberSeq.hpp"
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class G1Predictions;
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class G1NewTracer;
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// Base class for algorithms that calculate the heap occupancy at which
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// concurrent marking should start. This heap usage threshold should be relative
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// to old gen size.
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class G1IHOPControl : public CHeapObj<mtGC> {
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protected:
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// The initial IHOP value relative to the target occupancy.
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double _initial_ihop_percent;
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// The target maximum occupancy of the heap. The target occupancy is the number
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// of bytes when marking should be finished and reclaim started.
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size_t _target_occupancy;
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// Most recent complete mutator allocation period in seconds.
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double _last_allocation_time_s;
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// Amount of bytes allocated during _last_allocation_time_s.
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size_t _last_allocated_bytes;
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// Initialize an instance with the initial IHOP value in percent. The target
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// occupancy will be updated at the first heap expansion.
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G1IHOPControl(double initial_ihop_percent);
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// Most recent time from the end of the initial mark to the start of the first
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// mixed gc.
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virtual double last_marking_length_s() const = 0;
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public:
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virtual ~G1IHOPControl() { }
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// Get the current non-young occupancy at which concurrent marking should start.
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virtual size_t get_conc_mark_start_threshold() = 0;
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// Adjust target occupancy.
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virtual void update_target_occupancy(size_t new_target_occupancy);
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// Update information about time during which allocations in the Java heap occurred,
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// how large these allocations were in bytes, and an additional buffer.
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// The allocations should contain any amount of space made unusable for further
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// allocation, e.g. any waste caused by TLAB allocation, space at the end of
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// humongous objects that can not be used for allocation, etc.
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// Together with the target occupancy, this additional buffer should contain the
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// difference between old gen size and total heap size at the start of reclamation,
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// and space required for that reclamation.
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virtual void update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size);
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// Update the time spent in the mutator beginning from the end of initial mark to
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// the first mixed gc.
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virtual void update_marking_length(double marking_length_s) = 0;
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virtual void print();
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virtual void send_trace_event(G1NewTracer* tracer);
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};
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// The returned concurrent mark starting occupancy threshold is a fixed value
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// relative to the maximum heap size.
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class G1StaticIHOPControl : public G1IHOPControl {
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// Most recent mutator time between the end of initial mark to the start of the
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// first mixed gc.
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double _last_marking_length_s;
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protected:
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double last_marking_length_s() const { return _last_marking_length_s; }
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public:
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G1StaticIHOPControl(double ihop_percent);
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size_t get_conc_mark_start_threshold() {
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guarantee(_target_occupancy > 0, "Target occupancy must have been initialized.");
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return (size_t) (_initial_ihop_percent * _target_occupancy / 100.0);
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}
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virtual void update_marking_length(double marking_length_s) {
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assert(marking_length_s > 0.0, "Marking length must be larger than zero but is %.3f", marking_length_s);
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_last_marking_length_s = marking_length_s;
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}
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};
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// This algorithm tries to return a concurrent mark starting occupancy value that
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// makes sure that during marking the given target occupancy is never exceeded,
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// based on predictions of current allocation rate and time periods between
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// initial mark and the first mixed gc.
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class G1AdaptiveIHOPControl : public G1IHOPControl {
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size_t _heap_reserve_percent; // Percentage of maximum heap capacity we should avoid to touch
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size_t _heap_waste_percent; // Percentage of free heap that should be considered as waste.
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const G1Predictions * _predictor;
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TruncatedSeq _marking_times_s;
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TruncatedSeq _allocation_rate_s;
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// The most recent unrestrained size of the young gen. This is used as an additional
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// factor in the calculation of the threshold, as the threshold is based on
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// non-young gen occupancy at the end of GC. For the IHOP threshold, we need to
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// consider the young gen size during that time too.
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// Since we cannot know what young gen sizes are used in the future, we will just
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// use the current one. We expect that this one will be one with a fairly large size,
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// as there is no marking or mixed gc that could impact its size too much.
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size_t _last_unrestrained_young_size;
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bool have_enough_data_for_prediction() const;
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// The "actual" target threshold the algorithm wants to keep during and at the
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// end of marking. This is typically lower than the requested threshold, as the
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// algorithm needs to consider restrictions by the environment.
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size_t actual_target_threshold() const;
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protected:
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virtual double last_marking_length_s() const { return _marking_times_s.last(); }
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public:
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G1AdaptiveIHOPControl(double ihop_percent,
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G1Predictions const* predictor,
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size_t heap_reserve_percent, // The percentage of total heap capacity that should not be tapped into.
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size_t heap_waste_percent); // The percentage of the free space in the heap that we think is not usable for allocation.
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virtual size_t get_conc_mark_start_threshold();
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virtual void update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size);
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virtual void update_marking_length(double marking_length_s);
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virtual void print();
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virtual void send_trace_event(G1NewTracer* tracer);
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};
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#endif // SHARE_VM_GC_G1_G1IHOPCONTROL_HPP
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