1 /* 2 * Copyright (c) 2015, 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_VM_GC_G1_G1IHOPCONTROL_HPP 26 #define SHARE_VM_GC_G1_G1IHOPCONTROL_HPP 27 28 #include "memory/allocation.hpp" 29 #include "utilities/numberSeq.hpp" 30 31 class G1Predictions; 32 33 // Base class for algorithms that calculate the heap occupancy at which 34 // concurrent marking should start. This heap usage threshold should be relative 35 // to old gen size. 36 class G1IHOPControl : public CHeapObj<mtGC> { 37 protected: 38 // The initial IHOP value relative to the target occupancy. 39 double _initial_ihop_percent; 40 // The target maximum occupancy of the heap. 41 size_t _target_occupancy; 42 43 // Most recent complete mutator allocation period in seconds. 44 double _last_allocation_time_s; 45 // Amount of bytes allocated during _last_allocation_time_s. 46 size_t _last_allocated_bytes; 47 48 // Initialize an instance with the initial IHOP value in percent and the target 49 // occupancy. The target occupancy is the number of bytes when marking should 50 // be finished and reclaim started. 51 G1IHOPControl(double initial_ihop_percent, size_t target_occupancy); 52 53 // Most recent time from the end of the initial mark to the start of the first 54 // mixed gc. 55 virtual double last_marking_length_s() const = 0; 56 public: 57 virtual ~G1IHOPControl() { } 58 59 // Get the current non-young occupancy at which concurrent marking should start. 60 virtual size_t get_conc_mark_start_threshold() = 0; 61 62 // Update information about time during which allocations in the Java heap occurred, 63 // how large these allocations were in bytes, and an additional buffer. 64 // The allocations should contain any amount of space made unusable for further 65 // allocation, e.g. any waste caused by TLAB allocation, space at the end of 66 // humongous objects that can not be used for allocation, etc. 67 // Together with the target occupancy, this additional buffer should contain the 68 // difference between old gen size and total heap size at the start of reclamation, 69 // and space required for that reclamation. 70 virtual void update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size); 71 // Update the time spent in the mutator beginning from the end of initial mark to 72 // the first mixed gc. 73 virtual void update_marking_length(double marking_length_s) = 0; 74 75 virtual void print(); 76 }; 77 78 // The returned concurrent mark starting occupancy threshold is a fixed value 79 // relative to the maximum heap size. 80 class G1StaticIHOPControl : public G1IHOPControl { 81 // Most recent mutator time between the end of initial mark to the start of the 82 // first mixed gc. 83 double _last_marking_length_s; 84 protected: 85 double last_marking_length_s() const { return _last_marking_length_s; } 86 public: 87 G1StaticIHOPControl(double ihop_percent, size_t target_occupancy); 88 89 size_t get_conc_mark_start_threshold() { return (size_t) (_initial_ihop_percent * _target_occupancy / 100.0); } 90 91 virtual void update_marking_length(double marking_length_s) { 92 assert(marking_length_s > 0.0, "Marking length must be larger than zero but is %.3f", marking_length_s); 93 _last_marking_length_s = marking_length_s; 94 } 95 96 #ifndef PRODUCT 97 static void test(); 98 #endif 99 }; 100 101 // This algorithm tries to return a concurrent mark starting occupancy value that 102 // makes sure that during marking the given target occupancy is never exceeded, 103 // based on predictions of current allocation rate and time periods between 104 // initial mark and the first mixed gc. 105 class G1AdaptiveIHOPControl : public G1IHOPControl { 106 size_t _heap_reserve_percent; // Percentage of maximum heap capacity we should avoid to touch 107 size_t _heap_waste_percent; // Percentage of free heap that should be considered as waste. 108 109 const G1Predictions * _predictor; 110 111 TruncatedSeq _marking_times_s; 112 TruncatedSeq _allocation_rate_s; 113 114 size_t _last_allocation_bytes; // Most recent mutator allocation since last GC. 115 // The most recent unrestrained size of the young gen. This is used as an additional 116 // factor in the calculation of the threshold, as the threshold is based on 117 // non-young gen occupancy at the end of GC. For the IHOP threshold, we need to 118 // consider the young gen size during that time too. 119 // Since we cannot know what young gen sizes are used in the future, we will just 120 // use the current one. We expect that this one will be one with a fairly large size, 121 // as there is no marking or mixed gc that could impact its size too much. 122 size_t _last_unrestrained_young_size; 123 124 bool have_enough_data_for_prediction() const; 125 126 // The "actual" target threshold the algorithm wants to keep during and at the 127 // end of marking. This is typically lower than the requested threshold, as the 128 // algorithm needs to consider restrictions by the environment. 129 size_t actual_target_threshold() const; 130 protected: 131 virtual double last_marking_length_s() const { return _marking_times_s.last(); } 132 public: 133 G1AdaptiveIHOPControl(double ihop_percent, 134 size_t initial_target_occupancy, 135 G1Predictions const* predictor, 136 size_t heap_reserve_percent, // The percentage of total heap capacity that should not be tapped into. 137 size_t heap_waste_percent); // The percentage of the free space in the heap that we think is not usable for allocation. 138 139 virtual size_t get_conc_mark_start_threshold(); 140 141 virtual void update_allocation_info(double allocation_time_s, size_t allocated_bytes, size_t additional_buffer_size); 142 virtual void update_marking_length(double marking_length_s); 143 144 virtual void print(); 145 #ifndef PRODUCT 146 static void test(); 147 #endif 148 }; 149 150 #endif // SHARE_VM_GC_G1_G1IHOPCONTROL_HPP