1 /*
2 * Copyright (c) 2018, 2020, 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 "precompiled.hpp"
27 #include "gc/shared/cardTableRS.hpp"
28 #include "gc/shared/gcArguments.hpp"
29 #include "logging/log.hpp"
30 #include "runtime/arguments.hpp"
31 #include "runtime/globals.hpp"
32 #include "runtime/globals_extension.hpp"
33 #include "utilities/defaultStream.hpp"
34 #include "utilities/macros.hpp"
35
36 size_t HeapAlignment = 0;
37 size_t SpaceAlignment = 0;
38
39 void GCArguments::initialize() {
40 if (FullGCALot && FLAG_IS_DEFAULT(MarkSweepAlwaysCompactCount)) {
41 MarkSweepAlwaysCompactCount = 1; // Move objects every gc.
42 }
43
44 if (!UseParallelGC && FLAG_IS_DEFAULT(ScavengeBeforeFullGC)) {
45 FLAG_SET_DEFAULT(ScavengeBeforeFullGC, false);
46 }
47
48 if (GCTimeLimit == 100) {
49 // Turn off gc-overhead-limit-exceeded checks
50 FLAG_SET_DEFAULT(UseGCOverheadLimit, false);
51 }
52
53 if (MinHeapFreeRatio == 100) {
54 // Keeping the heap 100% free is hard ;-) so limit it to 99%.
55 FLAG_SET_ERGO(MinHeapFreeRatio, 99);
56 }
57
58 if (!ClassUnloading) {
59 // If class unloading is disabled, also disable concurrent class unloading.
60 FLAG_SET_CMDLINE(ClassUnloadingWithConcurrentMark, false);
61 }
62
63 if (!FLAG_IS_DEFAULT(AllocateOldGenAt)) {
64 // CompressedOops not supported when AllocateOldGenAt is set.
65 LP64_ONLY(FLAG_SET_DEFAULT(UseCompressedOops, false));
66 LP64_ONLY(FLAG_SET_DEFAULT(UseCompressedClassPointers, false));
67 // When AllocateOldGenAt is set, we cannot use largepages for entire heap memory.
68 // Only young gen which is allocated in dram can use large pages, but we currently don't support that.
69 FLAG_SET_DEFAULT(UseLargePages, false);
70 }
71 }
72
73 void GCArguments::initialize_heap_sizes() {
74 initialize_alignments();
75 initialize_heap_flags_and_sizes();
76 initialize_size_info();
77 }
78
79 size_t GCArguments::compute_heap_alignment() {
80 // The card marking array and the offset arrays for old generations are
81 // committed in os pages as well. Make sure they are entirely full (to
82 // avoid partial page problems), e.g. if 512 bytes heap corresponds to 1
83 // byte entry and the os page size is 4096, the maximum heap size should
84 // be 512*4096 = 2MB aligned.
85
86 size_t alignment = CardTableRS::ct_max_alignment_constraint();
87
88 if (UseLargePages) {
89 // In presence of large pages we have to make sure that our
90 // alignment is large page aware.
91 alignment = lcm(os::large_page_size(), alignment);
92 }
93
94 return alignment;
95 }
96
97 bool GCArguments::check_args_consistency() {
98 bool status = true;
99 if (!FLAG_IS_DEFAULT(AllocateHeapAt) && !FLAG_IS_DEFAULT(AllocateOldGenAt)) {
100 jio_fprintf(defaultStream::error_stream(),
101 "AllocateHeapAt and AllocateOldGenAt cannot be used together.\n");
102 status = false;
103 }
104 if (!FLAG_IS_DEFAULT(AllocateHeapAt) && UseLargePages) {105 jio_fprintf(defaultStream::error_stream(),106 "AllocateHeapAt and UseLargePages cannot be used together.\n");107 status = false;108 }
109 if (!FLAG_IS_DEFAULT(AllocateOldGenAt) && (UseSerialGC || UseEpsilonGC || UseZGC)) {
110 jio_fprintf(defaultStream::error_stream(),
111 "AllocateOldGenAt is not supported for selected GC.\n");
112 status = false;
113 }
114 return status;
115 }
116
117 #ifdef ASSERT
118 void GCArguments::assert_flags() {
119 assert(InitialHeapSize <= MaxHeapSize, "Ergonomics decided on incompatible initial and maximum heap sizes");
120 assert(InitialHeapSize % HeapAlignment == 0, "InitialHeapSize alignment");
121 assert(MaxHeapSize % HeapAlignment == 0, "MaxHeapSize alignment");
122 }
123
124 void GCArguments::assert_size_info() {
125 assert(MaxHeapSize >= MinHeapSize, "Ergonomics decided on incompatible minimum and maximum heap sizes");
126 assert(InitialHeapSize >= MinHeapSize, "Ergonomics decided on incompatible initial and minimum heap sizes");
127 assert(MaxHeapSize >= InitialHeapSize, "Ergonomics decided on incompatible initial and maximum heap sizes");
128 assert(MinHeapSize % HeapAlignment == 0, "MinHeapSize alignment");
129 assert(InitialHeapSize % HeapAlignment == 0, "InitialHeapSize alignment");
130 assert(MaxHeapSize % HeapAlignment == 0, "MaxHeapSize alignment");
131 }
132 #endif // ASSERT
133
134 void GCArguments::initialize_size_info() {
135 log_debug(gc, heap)("Minimum heap " SIZE_FORMAT " Initial heap " SIZE_FORMAT " Maximum heap " SIZE_FORMAT,
136 MinHeapSize, InitialHeapSize, MaxHeapSize);
137
138 DEBUG_ONLY(assert_size_info();)
139 }
140
141 void GCArguments::initialize_heap_flags_and_sizes() {
142 assert(SpaceAlignment != 0, "Space alignment not set up properly");
143 assert(HeapAlignment != 0, "Heap alignment not set up properly");
144 assert(HeapAlignment >= SpaceAlignment,
145 "HeapAlignment: " SIZE_FORMAT " less than SpaceAlignment: " SIZE_FORMAT,
146 HeapAlignment, SpaceAlignment);
147 assert(HeapAlignment % SpaceAlignment == 0,
148 "HeapAlignment: " SIZE_FORMAT " not aligned by SpaceAlignment: " SIZE_FORMAT,
149 HeapAlignment, SpaceAlignment);
150
151 if (FLAG_IS_CMDLINE(MaxHeapSize)) {
152 if (FLAG_IS_CMDLINE(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {
153 vm_exit_during_initialization("Initial heap size set to a larger value than the maximum heap size");
154 }
155 if (FLAG_IS_CMDLINE(MinHeapSize) && MaxHeapSize < MinHeapSize) {
156 vm_exit_during_initialization("Incompatible minimum and maximum heap sizes specified");
157 }
158 }
159
160 // Check heap parameter properties
161 if (MaxHeapSize < 2 * M) {
162 vm_exit_during_initialization("Too small maximum heap");
163 }
164 if (InitialHeapSize < M) {
165 vm_exit_during_initialization("Too small initial heap");
166 }
167 if (MinHeapSize < M) {
168 vm_exit_during_initialization("Too small minimum heap");
169 }
170
171 // User inputs from -Xmx and -Xms must be aligned
172 // Write back to flags if the values changed
173 if (!is_aligned(MinHeapSize, HeapAlignment)) {
174 FLAG_SET_ERGO(MinHeapSize, align_up(MinHeapSize, HeapAlignment));
175 }
176 if (!is_aligned(InitialHeapSize, HeapAlignment)) {
177 FLAG_SET_ERGO(InitialHeapSize, align_up(InitialHeapSize, HeapAlignment));
178 }
179 if (!is_aligned(MaxHeapSize, HeapAlignment)) {
180 FLAG_SET_ERGO(MaxHeapSize, align_up(MaxHeapSize, HeapAlignment));
181 }
182
183 if (FLAG_IS_CMDLINE(InitialHeapSize) && FLAG_IS_CMDLINE(MinHeapSize) &&
184 InitialHeapSize < MinHeapSize) {
185 vm_exit_during_initialization("Incompatible minimum and initial heap sizes specified");
186 }
187
188 if (!FLAG_IS_DEFAULT(InitialHeapSize) && InitialHeapSize > MaxHeapSize) {
189 FLAG_SET_ERGO(MaxHeapSize, InitialHeapSize);
190 } else if (!FLAG_IS_DEFAULT(MaxHeapSize) && InitialHeapSize > MaxHeapSize) {
191 FLAG_SET_ERGO(InitialHeapSize, MaxHeapSize);
192 if (InitialHeapSize < MinHeapSize) {
193 FLAG_SET_ERGO(MinHeapSize, InitialHeapSize);
194 }
195 }
196
197 if (FLAG_IS_DEFAULT(SoftMaxHeapSize)) {
198 FLAG_SET_ERGO(SoftMaxHeapSize, MaxHeapSize);
199 }
200
201 FLAG_SET_ERGO(MinHeapDeltaBytes, align_up(MinHeapDeltaBytes, SpaceAlignment));
202
203 DEBUG_ONLY(assert_flags();)
204 }
--- EOF ---