1 /* 2 * Copyright (c) 2015, 2019, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_GC_G1_G1IHOPCONTROL_HPP 26 #define SHARE_GC_G1_G1IHOPCONTROL_HPP 27 28 #include "memory/allocation.hpp" 29 #include "utilities/numberSeq.hpp" 30 31 class G1Predictions; 32 class G1NewTracer; 33 34 // Base class for algorithms that calculate the heap occupancy at which 35 // concurrent marking should start. This heap usage threshold should be relative 36 // to old gen size. 37 class G1IHOPControl : public CHeapObj<mtGC> { 38 protected: 39 // The initial IHOP value relative to the target occupancy. 40 double _initial_ihop_percent; 41 // The target maximum occupancy of the heap. The target occupancy is the number 42 // of bytes when marking should be finished and reclaim started. 43 size_t _target_occupancy; 44 45 // Most recent complete mutator allocation period in seconds. 46 double _last_allocation_time_s; 47 // Amount of bytes allocated during _last_allocation_time_s. 48 size_t _last_allocated_bytes; 49 50 // Initialize an instance with the initial IHOP value in percent. The target 51 // occupancy will be updated at the first heap expansion. 52 G1IHOPControl(double initial_ihop_percent); 53 54 // Most recent time from the end of the initial mark to the start of the first 55 // mixed gc. 56 virtual double last_marking_length_s() const = 0; 57 public: 58 virtual ~G1IHOPControl() { } 59 60 // Get the current non-young occupancy at which concurrent marking should start. 61 virtual size_t get_conc_mark_start_threshold() = 0; 62 63 // Adjust target occupancy. 64 virtual void update_target_occupancy(size_t new_target_occupancy); 65 // Update information about time during which allocations in the Java heap occurred, 66 // how large these allocations were in bytes, and an additional buffer. 67 // The allocations should contain any amount of space made unusable for further 68 // allocation, e.g. any waste caused by TLAB allocation, space at the end of 69 // humongous objects that can not be used for allocation, etc. 70 // Together with the target occupancy, this additional buffer should contain the 71 // difference between old gen size and total heap size at the start of reclamation, 72 // and space required for that reclamation. 73 virtual void update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size); 74 // Update the time spent in the mutator beginning from the end of initial mark to 75 // the first mixed gc. 76 virtual void update_marking_length(double marking_length_s) = 0; 77 78 virtual void print(); 79 virtual void send_trace_event(G1NewTracer* tracer); 80 81 virtual size_t predict_unstrained_buffer_size() const { return 0; } 82 }; 83 84 // The returned concurrent mark starting occupancy threshold is a fixed value 85 // relative to the maximum heap size. 86 class G1StaticIHOPControl : public G1IHOPControl { 87 // Most recent mutator time between the end of initial mark to the start of the 88 // first mixed gc. 89 double _last_marking_length_s; 90 protected: 91 double last_marking_length_s() const { return _last_marking_length_s; } 92 public: 93 G1StaticIHOPControl(double ihop_percent); 94 95 size_t get_conc_mark_start_threshold() { 96 guarantee(_target_occupancy > 0, "Target occupancy must have been initialized."); 97 return (size_t) (_initial_ihop_percent * _target_occupancy / 100.0); 98 } 99 100 virtual void update_marking_length(double marking_length_s) { 101 assert(marking_length_s > 0.0, "Marking length must be larger than zero but is %.3f", marking_length_s); 102 _last_marking_length_s = marking_length_s; 103 } 104 }; 105 106 // This algorithm tries to return a concurrent mark starting occupancy value that 107 // makes sure that during marking the given target occupancy is never exceeded, 108 // based on predictions of current allocation rate and time periods between 109 // initial mark and the first mixed gc. 110 class G1AdaptiveIHOPControl : public G1IHOPControl { 111 size_t _heap_reserve_percent; // Percentage of maximum heap capacity we should avoid to touch 112 size_t _heap_waste_percent; // Percentage of free heap that should be considered as waste. 113 114 const G1Predictions * _predictor; 115 116 TruncatedSeq _marking_times_s; 117 TruncatedSeq _allocation_rate_s; 118 119 // The most recent unrestrained size of the young gen. This is used as an additional 120 // factor in the calculation of the threshold, as the threshold is based on 121 // non-young gen occupancy at the end of GC. For the IHOP threshold, we need to 122 // consider the young gen size during that time too. 123 // Since we cannot know what young gen sizes are used in the future, we will just 124 // use the current one. We expect that this one will be one with a fairly large size, 125 // as there is no marking or mixed gc that could impact its size too much. 126 size_t _last_unrestrained_young_size; 127 128 // Get a new prediction bounded below by zero from the given sequence. 129 double predict(TruncatedSeq const* seq) const; 130 131 bool have_enough_data_for_prediction() const; 132 133 // The "actual" target threshold the algorithm wants to keep during and at the 134 // end of marking. This is typically lower than the requested threshold, as the 135 // algorithm needs to consider restrictions by the environment. 136 size_t actual_target_threshold() const; 137 protected: 138 virtual double last_marking_length_s() const { return _marking_times_s.last(); } 139 public: 140 G1AdaptiveIHOPControl(double ihop_percent, 141 G1Predictions const* predictor, 142 size_t heap_reserve_percent, // The percentage of total heap capacity that should not be tapped into. 143 size_t heap_waste_percent); // The percentage of the free space in the heap that we think is not usable for allocation. 144 145 virtual size_t get_conc_mark_start_threshold(); 146 147 virtual void update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size); 148 virtual void update_marking_length(double marking_length_s); 149 150 virtual void print(); 151 virtual void send_trace_event(G1NewTracer* tracer); 152 virtual size_t predict_unstrained_buffer_size() const; 153 }; 154 155 #endif // SHARE_GC_G1_G1IHOPCONTROL_HPP