1 /* 2 * Copyright (c) 2018, 2025, Oracle and/or its affiliates. All rights reserved. 3 * Copyright (c) 2017, Red Hat, Inc. and/or its affiliates. 4 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 5 * 6 * This code is free software; you can redistribute it and/or modify it 7 * under the terms of the GNU General Public License version 2 only, as 8 * published by the Free Software Foundation. 9 * 10 * This code is distributed in the hope that it will be useful, but WITHOUT 11 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 12 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 13 * version 2 for more details (a copy is included in the LICENSE file that 14 * accompanied this code). 15 * 16 * You should have received a copy of the GNU General Public License version 17 * 2 along with this work; if not, write to the Free Software Foundation, 18 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 19 * 20 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 21 * or visit www.oracle.com if you need additional information or have any 22 * questions. 23 * 24 */ 25 26 #include "cds/cdsConfig.hpp" 27 #include "gc/g1/g1Arguments.hpp" 28 #include "gc/g1/g1CardSet.hpp" 29 #include "gc/g1/g1CardSetContainers.inline.hpp" 30 #include "gc/g1/g1CollectedHeap.inline.hpp" 31 #include "gc/g1/g1HeapRegion.hpp" 32 #include "gc/g1/g1HeapRegionBounds.inline.hpp" 33 #include "gc/g1/g1HeapRegionRemSet.hpp" 34 #include "gc/g1/g1HeapVerifier.hpp" 35 #include "gc/shared/cardTable.hpp" 36 #include "gc/shared/gcArguments.hpp" 37 #include "gc/shared/workerPolicy.hpp" 38 #include "runtime/globals.hpp" 39 #include "runtime/globals_extension.hpp" 40 #include "runtime/java.hpp" 41 42 static size_t calculate_heap_alignment(size_t space_alignment) { 43 size_t card_table_alignment = CardTable::ct_max_alignment_constraint(); 44 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size(); 45 return MAX3(card_table_alignment, space_alignment, page_size); 46 } 47 48 void G1Arguments::initialize_alignments() { 49 // Initialize card size before initializing alignments 50 CardTable::initialize_card_size(); 51 52 // Set up the region size and associated fields. 53 // 54 // There is a circular dependency here. We base the region size on the heap 55 // size, but the heap size should be aligned with the region size. To get 56 // around this we use the unaligned values for the heap. 57 G1HeapRegion::setup_heap_region_size(MaxHeapSize); 58 59 SpaceAlignment = G1HeapRegion::GrainBytes; 60 HeapAlignment = calculate_heap_alignment(SpaceAlignment); 61 62 // We need to initialize card set configuration as soon as heap region size is 63 // known as it depends on it and is used really early. 64 initialize_card_set_configuration(); 65 // Needs remembered set initialization as the ergonomics are based 66 // on it. 67 if (FLAG_IS_DEFAULT(G1EagerReclaimRemSetThreshold)) { 68 FLAG_SET_ERGO(G1EagerReclaimRemSetThreshold, G1RemSetArrayOfCardsEntries); 69 } 70 } 71 72 size_t G1Arguments::conservative_max_heap_alignment() { 73 if (FLAG_IS_DEFAULT(G1HeapRegionSize)) { 74 return G1HeapRegion::max_ergonomics_size(); 75 } 76 return G1HeapRegion::max_region_size(); 77 } 78 79 void G1Arguments::initialize_verification_types() { 80 if (strlen(VerifyGCType) > 0) { 81 const char delimiter[] = " ,\n"; 82 size_t length = strlen(VerifyGCType); 83 char* type_list = NEW_C_HEAP_ARRAY(char, length + 1, mtInternal); 84 strncpy(type_list, VerifyGCType, length + 1); 85 char* save_ptr; 86 87 char* token = strtok_r(type_list, delimiter, &save_ptr); 88 while (token != nullptr) { 89 parse_verification_type(token); 90 token = strtok_r(nullptr, delimiter, &save_ptr); 91 } 92 FREE_C_HEAP_ARRAY(char, type_list); 93 } 94 } 95 96 void G1Arguments::parse_verification_type(const char* type) { 97 if (strcmp(type, "young-normal") == 0) { 98 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyYoungNormal); 99 } else if (strcmp(type, "concurrent-start") == 0) { 100 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyConcurrentStart); 101 } else if (strcmp(type, "mixed") == 0) { 102 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyMixed); 103 } else if (strcmp(type, "young-evac-fail") == 0) { 104 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyYoungEvacFail); 105 } else if (strcmp(type, "remark") == 0) { 106 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyRemark); 107 } else if (strcmp(type, "cleanup") == 0) { 108 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyCleanup); 109 } else if (strcmp(type, "full") == 0) { 110 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyFull); 111 } else { 112 log_warning(gc, verify)("VerifyGCType: '%s' is unknown. Available types are: " 113 "young-normal, young-evac-fail, concurrent-start, mixed, remark, cleanup and full", type); 114 } 115 } 116 117 // Returns the maximum number of workers to be used in a concurrent 118 // phase based on the number of GC workers being used in a STW 119 // phase. 120 static uint scale_concurrent_worker_threads(uint num_gc_workers) { 121 return MAX2((num_gc_workers + 2) / 4, 1U); 122 } 123 124 void G1Arguments::initialize_mark_stack_size() { 125 if (FLAG_IS_DEFAULT(MarkStackSize)) { 126 size_t mark_stack_size = MIN2(MarkStackSizeMax, 127 MAX2(MarkStackSize, (size_t)ConcGCThreads * TASKQUEUE_SIZE)); 128 FLAG_SET_ERGO(MarkStackSize, mark_stack_size); 129 } 130 } 131 132 void G1Arguments::initialize_card_set_configuration() { 133 assert(G1HeapRegion::LogOfHRGrainBytes != 0, "not initialized"); 134 // Array of Cards card set container globals. 135 const uint LOG_M = 20; 136 assert(log2i_exact(G1HeapRegionBounds::min_size()) == LOG_M, "inv"); 137 assert(G1HeapRegion::LogOfHRGrainBytes >= LOG_M, "from the above"); 138 uint region_size_log_mb = G1HeapRegion::LogOfHRGrainBytes - LOG_M; 139 140 if (FLAG_IS_DEFAULT(G1RemSetArrayOfCardsEntries)) { 141 uint max_cards_in_inline_ptr = G1CardSetConfiguration::max_cards_in_inline_ptr(G1HeapRegion::LogCardsPerRegion); 142 FLAG_SET_ERGO(G1RemSetArrayOfCardsEntries, MAX2(max_cards_in_inline_ptr * 2, 143 G1RemSetArrayOfCardsEntriesBase << region_size_log_mb)); 144 } 145 146 // Howl card set container globals. 147 if (FLAG_IS_DEFAULT(G1RemSetHowlNumBuckets)) { 148 FLAG_SET_ERGO(G1RemSetHowlNumBuckets, G1CardSetHowl::num_buckets(G1HeapRegion::CardsPerRegion, 149 G1RemSetArrayOfCardsEntries, 150 G1RemSetHowlMaxNumBuckets)); 151 } 152 153 if (FLAG_IS_DEFAULT(G1RemSetHowlMaxNumBuckets)) { 154 FLAG_SET_ERGO(G1RemSetHowlMaxNumBuckets, MAX2(G1RemSetHowlMaxNumBuckets, G1RemSetHowlNumBuckets)); 155 } else if (G1RemSetHowlMaxNumBuckets < G1RemSetHowlNumBuckets) { 156 FormatBuffer<> buf("Maximum Howl card set container bucket size %u smaller than requested bucket size %u", 157 G1RemSetHowlMaxNumBuckets, G1RemSetHowlNumBuckets); 158 vm_exit_during_initialization(buf); 159 } 160 } 161 162 void G1Arguments::initialize() { 163 GCArguments::initialize(); 164 assert(UseG1GC, "Error"); 165 FLAG_SET_DEFAULT(ParallelGCThreads, WorkerPolicy::parallel_worker_threads()); 166 if (ParallelGCThreads == 0) { 167 assert(!FLAG_IS_DEFAULT(ParallelGCThreads), "The default value for ParallelGCThreads should not be 0."); 168 vm_exit_during_initialization("The flag -XX:+UseG1GC can not be combined with -XX:ParallelGCThreads=0", nullptr); 169 } 170 171 // When dumping the CDS heap we want to reduce fragmentation by 172 // triggering a full collection. To get as low fragmentation as 173 // possible we only use one worker thread. 174 if (CDSConfig::is_dumping_heap()) { 175 FLAG_SET_ERGO(ParallelGCThreads, 1); 176 } 177 178 if (!G1UseConcRefinement) { 179 if (!FLAG_IS_DEFAULT(G1ConcRefinementThreads)) { 180 log_warning(gc, ergo)("Ignoring -XX:G1ConcRefinementThreads " 181 "because of -XX:-G1UseConcRefinement"); 182 } 183 FLAG_SET_DEFAULT(G1ConcRefinementThreads, 0); 184 } else if (FLAG_IS_DEFAULT(G1ConcRefinementThreads)) { 185 FLAG_SET_ERGO(G1ConcRefinementThreads, ParallelGCThreads); 186 } 187 188 if (FLAG_IS_DEFAULT(ConcGCThreads) || ConcGCThreads == 0) { 189 // Calculate the number of concurrent worker threads by scaling 190 // the number of parallel GC threads. 191 uint marking_thread_num = scale_concurrent_worker_threads(ParallelGCThreads); 192 FLAG_SET_ERGO(ConcGCThreads, marking_thread_num); 193 } 194 195 if (FLAG_IS_DEFAULT(GCTimeRatio) || GCTimeRatio == 0) { 196 // In G1, we want the default GC overhead goal to be higher than 197 // it is for PS, or the heap might be expanded too aggressively. 198 // We set it here to ~8%. 199 FLAG_SET_DEFAULT(GCTimeRatio, 12); 200 } 201 202 // Below, we might need to calculate the pause time interval based on 203 // the pause target. When we do so we are going to give G1 maximum 204 // flexibility and allow it to do pauses when it needs to. So, we'll 205 // arrange that the pause interval to be pause time target + 1 to 206 // ensure that a) the pause time target is maximized with respect to 207 // the pause interval and b) we maintain the invariant that pause 208 // time target < pause interval. If the user does not want this 209 // maximum flexibility, they will have to set the pause interval 210 // explicitly. 211 212 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) { 213 // The default pause time target in G1 is 200ms 214 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200); 215 } 216 217 // Then, if the interval parameter was not set, set it according to 218 // the pause time target (this will also deal with the case when the 219 // pause time target is the default value). 220 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) { 221 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1); 222 } 223 224 if (FLAG_IS_DEFAULT(ParallelRefProcEnabled) && ParallelGCThreads > 1) { 225 FLAG_SET_DEFAULT(ParallelRefProcEnabled, true); 226 } 227 228 #ifdef COMPILER2 229 // Enable loop strip mining to offer better pause time guarantees 230 if (FLAG_IS_DEFAULT(UseCountedLoopSafepoints)) { 231 FLAG_SET_DEFAULT(UseCountedLoopSafepoints, true); 232 if (FLAG_IS_DEFAULT(LoopStripMiningIter)) { 233 FLAG_SET_DEFAULT(LoopStripMiningIter, 1000); 234 } 235 } 236 #endif 237 238 initialize_mark_stack_size(); 239 initialize_verification_types(); 240 241 // Verify that the maximum parallelism isn't too high to eventually overflow 242 // the refcount in G1CardSetContainer. 243 uint max_parallel_refinement_threads = G1ConcRefinementThreads + G1DirtyCardQueueSet::num_par_ids(); 244 uint const divisor = 3; // Safe divisor; we increment by 2 for each claim, but there is a small initial value. 245 if (max_parallel_refinement_threads > UINT_MAX / divisor) { 246 vm_exit_during_initialization("Too large parallelism for remembered sets."); 247 } 248 } 249 250 CollectedHeap* G1Arguments::create_heap() { 251 return new G1CollectedHeap(); 252 } 253 254 size_t G1Arguments::heap_reserved_size_bytes() { 255 return MaxHeapSize; 256 }