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 "gc/parallel/parallelArguments.hpp"
 27 #include "gc/parallel/parallelScavengeHeap.hpp"
 28 #include "gc/shared/adaptiveSizePolicy.hpp"
 29 #include "gc/shared/fullGCForwarding.hpp"
 30 #include "gc/shared/gcArguments.hpp"
 31 #include "gc/shared/genArguments.hpp"
 32 #include "gc/shared/workerPolicy.hpp"
 33 #include "logging/log.hpp"
 34 #include "runtime/globals.hpp"
 35 #include "runtime/globals_extension.hpp"
 36 #include "runtime/java.hpp"
 37 #include "utilities/defaultStream.hpp"
 38 #include "utilities/powerOfTwo.hpp"
 39 
 40 size_t ParallelArguments::conservative_max_heap_alignment() {
 41   return compute_heap_alignment();
 42 }
 43 
 44 void ParallelArguments::initialize() {
 45   GCArguments::initialize();
 46   assert(UseParallelGC, "Error");
 47 
 48   // If no heap maximum was requested explicitly, use some reasonable fraction
 49   // of the physical memory, up to a maximum of 1GB.
 50   FLAG_SET_DEFAULT(ParallelGCThreads,
 51                    WorkerPolicy::parallel_worker_threads());
 52   if (ParallelGCThreads == 0) {
 53     jio_fprintf(defaultStream::error_stream(),
 54         "The Parallel GC can not be combined with -XX:ParallelGCThreads=0\n");
 55     vm_exit(1);
 56   }
 57 
 58   if (UseAdaptiveSizePolicy) {
 59     // We don't want to limit adaptive heap sizing's freedom to adjust the heap
 60     // unless the user actually sets these flags.
 61     if (FLAG_IS_DEFAULT(MinHeapFreeRatio)) {
 62       FLAG_SET_DEFAULT(MinHeapFreeRatio, 0);
 63     }
 64     if (FLAG_IS_DEFAULT(MaxHeapFreeRatio)) {
 65       FLAG_SET_DEFAULT(MaxHeapFreeRatio, 100);
 66     }
 67   }
 68 
 69   // If InitialSurvivorRatio or MinSurvivorRatio were not specified, but the
 70   // SurvivorRatio has been set, reset their default values to SurvivorRatio +
 71   // 2.  By doing this we make SurvivorRatio also work for Parallel Scavenger.
 72   // See CR 6362902 for details.
 73   if (!FLAG_IS_DEFAULT(SurvivorRatio)) {
 74     if (FLAG_IS_DEFAULT(InitialSurvivorRatio)) {
 75        FLAG_SET_DEFAULT(InitialSurvivorRatio, SurvivorRatio + 2);
 76     }
 77     if (FLAG_IS_DEFAULT(MinSurvivorRatio)) {
 78       FLAG_SET_DEFAULT(MinSurvivorRatio, SurvivorRatio + 2);
 79     }
 80   }
 81 
 82   if (FLAG_IS_DEFAULT(ParallelRefProcEnabled) && ParallelGCThreads > 1) {
 83     FLAG_SET_DEFAULT(ParallelRefProcEnabled, true);
 84   }
 85 
 86   FullGCForwarding::initialize_flags(heap_reserved_size_bytes());
 87 }
 88 
 89 // The alignment used for boundary between young gen and old gen
 90 static size_t default_gen_alignment() {
 91   return 64 * K * HeapWordSize;
 92 }
 93 
 94 void ParallelArguments::initialize_alignments() {
 95   // Initialize card size before initializing alignments
 96   CardTable::initialize_card_size();
 97   SpaceAlignment = GenAlignment = default_gen_alignment();
 98   HeapAlignment = compute_heap_alignment();
 99 }
100 
101 void ParallelArguments::initialize_heap_flags_and_sizes_one_pass() {
102   // Do basic sizing work
103   GenArguments::initialize_heap_flags_and_sizes();
104 
105   // The survivor ratio's are calculated "raw", unlike the
106   // default gc, which adds 2 to the ratio value. We need to
107   // make sure the values are valid before using them.
108   if (MinSurvivorRatio < 3) {
109     FLAG_SET_ERGO(MinSurvivorRatio, 3);
110   }
111 
112   if (InitialSurvivorRatio < 3) {
113     FLAG_SET_ERGO(InitialSurvivorRatio, 3);
114   }
115 }
116 
117 void ParallelArguments::initialize_heap_flags_and_sizes() {
118   initialize_heap_flags_and_sizes_one_pass();
119 
120   const size_t min_pages = 4; // 1 for eden + 1 for each survivor + 1 for old
121   const size_t page_sz = os::page_size_for_region_aligned(MinHeapSize, min_pages);
122 
123   // Can a page size be something else than a power of two?
124   assert(is_power_of_2((intptr_t)page_sz), "must be a power of 2");
125   size_t new_alignment = align_up(page_sz, GenAlignment);
126   if (new_alignment != GenAlignment) {
127     GenAlignment = new_alignment;
128     SpaceAlignment = new_alignment;
129     // Redo everything from the start
130     initialize_heap_flags_and_sizes_one_pass();
131   }
132 }
133 
134 size_t ParallelArguments::heap_reserved_size_bytes() {
135   return MaxHeapSize;
136 }
137 
138 CollectedHeap* ParallelArguments::create_heap() {
139   return new ParallelScavengeHeap();
140 }