1 /* 2 * Copyright (c) 2016, 2018, 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_G1COLLECTIONSET_HPP 26 #define SHARE_VM_GC_G1_G1COLLECTIONSET_HPP 27 28 #include "gc/g1/collectionSetChooser.hpp" 29 #include "utilities/debug.hpp" 30 #include "utilities/globalDefinitions.hpp" 31 32 class G1CollectedHeap; 33 class G1CollectorState; 34 class G1GCPhaseTimes; 35 class G1Policy; 36 class G1SurvivorRegions; 37 class HeapRegion; 38 39 class G1CollectionSet { 40 G1CollectedHeap* _g1h; 41 G1Policy* _policy; 42 43 CollectionSetChooser* _cset_chooser; 44 45 uint _eden_region_length; 46 uint _survivor_region_length; 47 uint _old_region_length; 48 49 // The actual collection set as a set of region indices. 50 // All entries in _collection_set_regions below _collection_set_cur_length are 51 // assumed to be valid entries. 52 // We assume that at any time there is at most only one writer and (one or more) 53 // concurrent readers. This means we are good with using storestore and loadload 54 // barriers on the writer and reader respectively only. 55 uint* _collection_set_regions; 56 volatile size_t _collection_set_cur_length; 57 size_t _collection_set_max_length; 58 59 // The number of bytes in the collection set before the pause. Set from 60 // the incrementally built collection set at the start of an evacuation 61 // pause, and incremented in finalize_old_part() when adding old regions 62 // (if any) to the collection set. 63 size_t _bytes_used_before; 64 65 size_t _recorded_rs_lengths; 66 67 // The associated information that is maintained while the incremental 68 // collection set is being built with young regions. Used to populate 69 // the recorded info for the evacuation pause. 70 71 enum CSetBuildType { 72 Active, // We are actively building the collection set 73 Inactive // We are not actively building the collection set 74 }; 75 76 CSetBuildType _inc_build_state; 77 78 // The number of bytes in the incrementally built collection set. 79 // Used to set _collection_set_bytes_used_before at the start of 80 // an evacuation pause. 81 size_t _inc_bytes_used_before; 82 83 // The RSet lengths recorded for regions in the CSet. It is updated 84 // by the thread that adds a new region to the CSet. We assume that 85 // only one thread can be allocating a new CSet region (currently, 86 // it does so after taking the Heap_lock) hence no need to 87 // synchronize updates to this field. 88 size_t _inc_recorded_rs_lengths; 89 90 // A concurrent refinement thread periodically samples the young 91 // region RSets and needs to update _inc_recorded_rs_lengths as 92 // the RSets grow. Instead of having to synchronize updates to that 93 // field we accumulate them in this field and add it to 94 // _inc_recorded_rs_lengths_diffs at the start of a GC. 95 ssize_t _inc_recorded_rs_lengths_diffs; 96 97 // The predicted elapsed time it will take to collect the regions in 98 // the CSet. This is updated by the thread that adds a new region to 99 // the CSet. See the comment for _inc_recorded_rs_lengths about 100 // MT-safety assumptions. 101 double _inc_predicted_elapsed_time_ms; 102 103 // See the comment for _inc_recorded_rs_lengths_diffs. 104 double _inc_predicted_elapsed_time_ms_diffs; 105 106 G1CollectorState* collector_state(); 107 G1GCPhaseTimes* phase_times(); 108 109 double predict_region_elapsed_time_ms(HeapRegion* hr); 110 111 void verify_young_cset_indices() const NOT_DEBUG_RETURN; 112 public: 113 G1CollectionSet(G1CollectedHeap* g1h, G1Policy* policy); 114 ~G1CollectionSet(); 115 116 // Initializes the collection set giving the maximum possible length of the collection set. 117 void initialize(uint max_region_length); 118 119 CollectionSetChooser* cset_chooser(); 120 121 void init_region_lengths(uint eden_cset_region_length, 122 uint survivor_cset_region_length); 123 124 void set_recorded_rs_lengths(size_t rs_lengths); 125 region_length() const126 uint region_length() const { return young_region_length() + 127 old_region_length(); } young_region_length() const128 uint young_region_length() const { return eden_region_length() + 129 survivor_region_length(); } 130 eden_region_length() const131 uint eden_region_length() const { return _eden_region_length; } survivor_region_length() const132 uint survivor_region_length() const { return _survivor_region_length; } old_region_length() const133 uint old_region_length() const { return _old_region_length; } 134 135 // Incremental collection set support 136 137 // Initialize incremental collection set info. 138 void start_incremental_building(); 139 140 // Perform any final calculations on the incremental collection set fields 141 // before we can use them. 142 void finalize_incremental_building(); 143 144 // Reset the contents of the collection set. 145 void clear(); 146 147 // Iterate over the collection set, applying the given HeapRegionClosure on all of them. 148 // If may_be_aborted is true, iteration may be aborted using the return value of the 149 // called closure method. 150 void iterate(HeapRegionClosure* cl) const; 151 152 // Iterate over the collection set, applying the given HeapRegionClosure on all of them, 153 // trying to optimally spread out starting position of total_workers workers given the 154 // caller's worker_id. 155 void iterate_from(HeapRegionClosure* cl, uint worker_id, uint total_workers) const; 156 157 // Stop adding regions to the incremental collection set. stop_incremental_building()158 void stop_incremental_building() { _inc_build_state = Inactive; } 159 recorded_rs_lengths()160 size_t recorded_rs_lengths() { return _recorded_rs_lengths; } 161 bytes_used_before() const162 size_t bytes_used_before() const { 163 return _bytes_used_before; 164 } 165 reset_bytes_used_before()166 void reset_bytes_used_before() { 167 _bytes_used_before = 0; 168 } 169 170 // Choose a new collection set. Marks the chosen regions as being 171 // "in_collection_set". 172 double finalize_young_part(double target_pause_time_ms, G1SurvivorRegions* survivors); 173 void finalize_old_part(double time_remaining_ms); 174 175 // Add old region "hr" to the collection set. 176 void add_old_region(HeapRegion* hr); 177 178 // Update information about hr in the aggregated information for 179 // the incrementally built collection set. 180 void update_young_region_prediction(HeapRegion* hr, size_t new_rs_length); 181 182 // Add eden region to the collection set. 183 void add_eden_region(HeapRegion* hr); 184 185 // Add survivor region to the collection set. 186 void add_survivor_regions(HeapRegion* hr); 187 188 #ifndef PRODUCT 189 bool verify_young_ages(); 190 191 void print(outputStream* st); 192 #endif // !PRODUCT 193 194 private: 195 // Update the incremental collection set information when adding a region. 196 void add_young_region_common(HeapRegion* hr); 197 }; 198 199 #endif // SHARE_VM_GC_G1_G1COLLECTIONSET_HPP 200 201