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 static size_t num_young_spaces() {
41 // When using NUMA, we create one MutableNUMASpace for each NUMA node
42 const size_t num_eden_spaces = UseNUMA ? os::numa_get_groups_num() : 1;
43
44 // The young generation must have room for eden + two survivors
45 return num_eden_spaces + 2;
46 }
47
48 static size_t num_old_spaces() {
49 return 1;
50 }
51
52 void ParallelArguments::initialize_alignments() {
53 // Initialize card size before initializing alignments
54 CardTable::initialize_card_size();
55 const size_t card_table_alignment = CardTable::ct_max_alignment_constraint();
56 SpaceAlignment = ParallelScavengeHeap::default_space_alignment();
57
58 if (UseLargePages) {
59 const size_t total_spaces = num_young_spaces() + num_old_spaces();
60 const size_t page_size = os::page_size_for_region_unaligned(MaxHeapSize, total_spaces);
61 ParallelScavengeHeap::set_desired_page_size(page_size);
62
63 if (page_size == os::vm_page_size()) {
64 log_warning(gc, heap)("MaxHeapSize (%zu) must be large enough for %zu * page-size; Disabling UseLargePages for heap",
65 MaxHeapSize, total_spaces);
66 }
67
68 if (page_size > SpaceAlignment) {
69 SpaceAlignment = page_size;
70 }
71
72 HeapAlignment = lcm(page_size, card_table_alignment);
73
74 } else {
75 assert(is_aligned(SpaceAlignment, os::vm_page_size()), "");
76 ParallelScavengeHeap::set_desired_page_size(os::vm_page_size());
77 HeapAlignment = card_table_alignment;
78 }
79 }
80
81 void ParallelArguments::initialize() {
82 GCArguments::initialize();
83 assert(UseParallelGC, "Error");
84
85 // If no heap maximum was requested explicitly, use some reasonable fraction
86 // of the physical memory, up to a maximum of 1GB.
87 FLAG_SET_DEFAULT(ParallelGCThreads,
88 WorkerPolicy::parallel_worker_threads());
89 if (ParallelGCThreads == 0) {
90 jio_fprintf(defaultStream::error_stream(),
91 "The Parallel GC can not be combined with -XX:ParallelGCThreads=0\n");
92 vm_exit(1);
93 }
94
95 if (UseAdaptiveSizePolicy) {
96 // We don't want to limit adaptive heap sizing's freedom to adjust the heap
97 // unless the user actually sets these flags.
98 if (FLAG_IS_DEFAULT(MinHeapFreeRatio)) {
99 FLAG_SET_DEFAULT(MinHeapFreeRatio, 0);
100 }
101 if (FLAG_IS_DEFAULT(MaxHeapFreeRatio)) {
102 FLAG_SET_DEFAULT(MaxHeapFreeRatio, 100);
103 }
104 }
105
106 if (InitialSurvivorRatio < MinSurvivorRatio) {
107 if (FLAG_IS_CMDLINE(InitialSurvivorRatio)) {
108 if (FLAG_IS_CMDLINE(MinSurvivorRatio)) {
109 jio_fprintf(defaultStream::error_stream(),
110 "Inconsistent MinSurvivorRatio vs InitialSurvivorRatio: %zu vs %zu\n", MinSurvivorRatio, InitialSurvivorRatio);
111 }
112 FLAG_SET_DEFAULT(MinSurvivorRatio, InitialSurvivorRatio);
113 } else {
114 FLAG_SET_DEFAULT(InitialSurvivorRatio, MinSurvivorRatio);
115 }
116 }
117
118 // If InitialSurvivorRatio or MinSurvivorRatio were not specified, but the
119 // SurvivorRatio has been set, reset their default values to SurvivorRatio +
120 // 2. By doing this we make SurvivorRatio also work for Parallel Scavenger.
121 // See CR 6362902 for details.
122 if (!FLAG_IS_DEFAULT(SurvivorRatio)) {
123 if (FLAG_IS_DEFAULT(InitialSurvivorRatio)) {
124 FLAG_SET_DEFAULT(InitialSurvivorRatio, SurvivorRatio + 2);
125 }
126 if (FLAG_IS_DEFAULT(MinSurvivorRatio)) {
127 FLAG_SET_DEFAULT(MinSurvivorRatio, SurvivorRatio + 2);
128 }
129 }
130
131 FullGCForwarding::initialize_flags(heap_reserved_size_bytes());
132 }
133
134 size_t ParallelArguments::conservative_max_heap_alignment() {
135 // The card marking array and the offset arrays for old generations are
136 // committed in os pages as well. Make sure they are entirely full (to
137 // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1
138 // byte entry and the os page size is 4096, the maximum heap size should
139 // be 512*4096 = 2MB aligned.
140
141 size_t alignment = CardTable::ct_max_alignment_constraint();
142
143 if (UseLargePages) {
144 // In presence of large pages we have to make sure that our
145 // alignment is large page aware.
146 alignment = lcm(os::large_page_size(), alignment);
147 }
148
149 return alignment;
150 }
151
152 CollectedHeap* ParallelArguments::create_heap() {
153 return new ParallelScavengeHeap();
154 }
155
156 size_t ParallelArguments::young_gen_size_lower_bound() {
157 return num_young_spaces() * SpaceAlignment;
158 }
159
160 size_t ParallelArguments::old_gen_size_lower_bound() {
161 return num_old_spaces() * SpaceAlignment;
162 }
163
164 size_t ParallelArguments::heap_reserved_size_bytes() {
165 return MaxHeapSize;
166 }