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 return G1HeapRegion::max_region_size(); 74 } 75 76 void G1Arguments::initialize_verification_types() { 77 if (strlen(VerifyGCType) > 0) { 78 const char delimiter[] = " ,\n"; 79 size_t length = strlen(VerifyGCType); 80 char* type_list = NEW_C_HEAP_ARRAY(char, length + 1, mtInternal); 81 strncpy(type_list, VerifyGCType, length + 1); 82 char* save_ptr; 83 84 char* token = strtok_r(type_list, delimiter, &save_ptr); 85 while (token != nullptr) { 86 parse_verification_type(token); 87 token = strtok_r(nullptr, delimiter, &save_ptr); 88 } 89 FREE_C_HEAP_ARRAY(char, type_list); 90 } 91 } 92 93 void G1Arguments::parse_verification_type(const char* type) { 94 if (strcmp(type, "young-normal") == 0) { 95 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyYoungNormal); 96 } else if (strcmp(type, "concurrent-start") == 0) { 97 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyConcurrentStart); 98 } else if (strcmp(type, "mixed") == 0) { 99 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyMixed); 100 } else if (strcmp(type, "young-evac-fail") == 0) { 101 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyYoungEvacFail); 102 } else if (strcmp(type, "remark") == 0) { 103 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyRemark); 104 } else if (strcmp(type, "cleanup") == 0) { 105 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyCleanup); 106 } else if (strcmp(type, "full") == 0) { 107 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyFull); 108 } else { 109 log_warning(gc, verify)("VerifyGCType: '%s' is unknown. Available types are: " 110 "young-normal, young-evac-fail, concurrent-start, mixed, remark, cleanup and full", type); 111 } 112 } 113 114 // Returns the maximum number of workers to be used in a concurrent 115 // phase based on the number of GC workers being used in a STW 116 // phase. 117 static uint scale_concurrent_worker_threads(uint num_gc_workers) { 118 return MAX2((num_gc_workers + 2) / 4, 1U); 119 } 120 121 void G1Arguments::initialize_mark_stack_size() { 122 if (FLAG_IS_DEFAULT(MarkStackSize)) { 123 size_t mark_stack_size = MIN2(MarkStackSizeMax, 124 MAX2(MarkStackSize, (size_t)ConcGCThreads * TASKQUEUE_SIZE)); 125 FLAG_SET_ERGO(MarkStackSize, mark_stack_size); 126 } 127 } 128 129 void G1Arguments::initialize_card_set_configuration() { 130 assert(G1HeapRegion::LogOfHRGrainBytes != 0, "not initialized"); 131 // Array of Cards card set container globals. 132 const uint LOG_M = 20; 133 assert(log2i_exact(G1HeapRegionBounds::min_size()) == LOG_M, "inv"); 134 assert(G1HeapRegion::LogOfHRGrainBytes >= LOG_M, "from the above"); 135 uint region_size_log_mb = G1HeapRegion::LogOfHRGrainBytes - LOG_M; 136 137 if (FLAG_IS_DEFAULT(G1RemSetArrayOfCardsEntries)) { 138 uint max_cards_in_inline_ptr = G1CardSetConfiguration::max_cards_in_inline_ptr(G1HeapRegion::LogCardsPerRegion); 139 FLAG_SET_ERGO(G1RemSetArrayOfCardsEntries, MAX2(max_cards_in_inline_ptr * 2, 140 G1RemSetArrayOfCardsEntriesBase << region_size_log_mb)); 141 } 142 143 // Howl card set container globals. 144 if (FLAG_IS_DEFAULT(G1RemSetHowlNumBuckets)) { 145 FLAG_SET_ERGO(G1RemSetHowlNumBuckets, G1CardSetHowl::num_buckets(G1HeapRegion::CardsPerRegion, 146 G1RemSetArrayOfCardsEntries, 147 G1RemSetHowlMaxNumBuckets)); 148 } 149 150 if (FLAG_IS_DEFAULT(G1RemSetHowlMaxNumBuckets)) { 151 FLAG_SET_ERGO(G1RemSetHowlMaxNumBuckets, MAX2(G1RemSetHowlMaxNumBuckets, G1RemSetHowlNumBuckets)); 152 } else if (G1RemSetHowlMaxNumBuckets < G1RemSetHowlNumBuckets) { 153 FormatBuffer<> buf("Maximum Howl card set container bucket size %u smaller than requested bucket size %u", 154 G1RemSetHowlMaxNumBuckets, G1RemSetHowlNumBuckets); 155 vm_exit_during_initialization(buf); 156 } 157 } 158 159 void G1Arguments::initialize() { 160 GCArguments::initialize(); 161 assert(UseG1GC, "Error"); 162 FLAG_SET_DEFAULT(ParallelGCThreads, WorkerPolicy::parallel_worker_threads()); 163 if (ParallelGCThreads == 0) { 164 assert(!FLAG_IS_DEFAULT(ParallelGCThreads), "The default value for ParallelGCThreads should not be 0."); 165 vm_exit_during_initialization("The flag -XX:+UseG1GC can not be combined with -XX:ParallelGCThreads=0", nullptr); 166 } 167 168 // When dumping the CDS heap we want to reduce fragmentation by 169 // triggering a full collection. To get as low fragmentation as 170 // possible we only use one worker thread. 171 if (CDSConfig::is_dumping_heap()) { 172 FLAG_SET_ERGO(ParallelGCThreads, 1); 173 } 174 175 if (!G1UseConcRefinement) { 176 if (!FLAG_IS_DEFAULT(G1ConcRefinementThreads)) { 177 log_warning(gc, ergo)("Ignoring -XX:G1ConcRefinementThreads " 178 "because of -XX:-G1UseConcRefinement"); 179 } 180 FLAG_SET_DEFAULT(G1ConcRefinementThreads, 0); 181 } else if (FLAG_IS_DEFAULT(G1ConcRefinementThreads)) { 182 FLAG_SET_ERGO(G1ConcRefinementThreads, ParallelGCThreads); 183 } 184 185 if (FLAG_IS_DEFAULT(ConcGCThreads) || ConcGCThreads == 0) { 186 // Calculate the number of concurrent worker threads by scaling 187 // the number of parallel GC threads. 188 uint marking_thread_num = scale_concurrent_worker_threads(ParallelGCThreads); 189 FLAG_SET_ERGO(ConcGCThreads, marking_thread_num); 190 } 191 192 if (FLAG_IS_DEFAULT(GCTimeRatio) || GCTimeRatio == 0) { 193 // In G1, we want the default GC overhead goal to be higher than 194 // it is for PS, or the heap might be expanded too aggressively. 195 // We set it here to ~8%. 196 FLAG_SET_DEFAULT(GCTimeRatio, 12); 197 } 198 199 // Below, we might need to calculate the pause time interval based on 200 // the pause target. When we do so we are going to give G1 maximum 201 // flexibility and allow it to do pauses when it needs to. So, we'll 202 // arrange that the pause interval to be pause time target + 1 to 203 // ensure that a) the pause time target is maximized with respect to 204 // the pause interval and b) we maintain the invariant that pause 205 // time target < pause interval. If the user does not want this 206 // maximum flexibility, they will have to set the pause interval 207 // explicitly. 208 209 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) { 210 // The default pause time target in G1 is 200ms 211 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200); 212 } 213 214 // Then, if the interval parameter was not set, set it according to 215 // the pause time target (this will also deal with the case when the 216 // pause time target is the default value). 217 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) { 218 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1); 219 } 220 221 if (FLAG_IS_DEFAULT(ParallelRefProcEnabled) && ParallelGCThreads > 1) { 222 FLAG_SET_DEFAULT(ParallelRefProcEnabled, true); 223 } 224 225 #ifdef COMPILER2 226 // Enable loop strip mining to offer better pause time guarantees 227 if (FLAG_IS_DEFAULT(UseCountedLoopSafepoints)) { 228 FLAG_SET_DEFAULT(UseCountedLoopSafepoints, true); 229 if (FLAG_IS_DEFAULT(LoopStripMiningIter)) { 230 FLAG_SET_DEFAULT(LoopStripMiningIter, 1000); 231 } 232 } 233 #endif 234 235 initialize_mark_stack_size(); 236 initialize_verification_types(); 237 238 // Verify that the maximum parallelism isn't too high to eventually overflow 239 // the refcount in G1CardSetContainer. 240 uint max_parallel_refinement_threads = G1ConcRefinementThreads + G1DirtyCardQueueSet::num_par_ids(); 241 uint const divisor = 3; // Safe divisor; we increment by 2 for each claim, but there is a small initial value. 242 if (max_parallel_refinement_threads > UINT_MAX / divisor) { 243 vm_exit_during_initialization("Too large parallelism for remembered sets."); 244 } 245 } 246 247 CollectedHeap* G1Arguments::create_heap() { 248 return new G1CollectedHeap(); 249 } 250 251 size_t G1Arguments::heap_reserved_size_bytes() { 252 return MaxHeapSize; 253 }