1 /*
2 * Copyright (c) 2018, Red Hat, Inc. and/or its affiliates.
3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
4 *
5 * This code is free software; you can redistribute it and/or modify it
6 * under the terms of the GNU General Public License version 2 only, as
7 * published by the Free Software Foundation.
8 *
9 * This code is distributed in the hope that it will be useful, but WITHOUT
10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
12 * version 2 for more details (a copy is included in the LICENSE file that
13 * accompanied this code).
14 *
15 * You should have received a copy of the GNU General Public License version
16 * 2 along with this work; if not, write to the Free Software Foundation,
17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
18 *
19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
20 * or visit www.oracle.com if you need additional information or have any
21 * questions.
22 *
23 */
24
25 #include "precompiled.hpp"
26 #include "gc/shared/gcArguments.inline.hpp"
27 #include "gc/shared/taskqueue.hpp"
28 #include "gc/shenandoah/shenandoahArguments.hpp"
29 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
30 #include "gc/shenandoah/shenandoahHeap.hpp"
31 #include "utilities/defaultStream.hpp"
32
33 void ShenandoahArguments::initialize() {
34
35 #if !(defined AARCH64 || defined AMD64 || defined IA32)
36 vm_exit_during_initialization("Shenandoah GC is not supported on this platform.");
37 #endif
38
39 #ifdef IA32
40 log_warning(gc)("Shenandoah GC is not fully supported on this platform:");
41 log_warning(gc)(" concurrent modes are not supported, only STW cycles are enabled;");
42 log_warning(gc)(" arch-specific barrier code is not implemented, disabling barriers;");
43
44 FLAG_SET_DEFAULT(ShenandoahGCHeuristics, "passive");
45
46 FLAG_SET_DEFAULT(ShenandoahSATBBarrier, false);
47 FLAG_SET_DEFAULT(ShenandoahConditionalSATBBarrier, false);
48 FLAG_SET_DEFAULT(ShenandoahKeepAliveBarrier, false);
49 FLAG_SET_DEFAULT(ShenandoahWriteBarrier, false);
50 FLAG_SET_DEFAULT(ShenandoahReadBarrier, false);
51 FLAG_SET_DEFAULT(ShenandoahStoreValEnqueueBarrier, false);
52 FLAG_SET_DEFAULT(ShenandoahStoreValWriteBarrier, false);
53 FLAG_SET_DEFAULT(ShenandoahStoreValReadBarrier, false);
54 FLAG_SET_DEFAULT(ShenandoahCASBarrier, false);
55 FLAG_SET_DEFAULT(ShenandoahAcmpBarrier, false);
56 FLAG_SET_DEFAULT(ShenandoahCloneBarrier, false);
57 FLAG_SET_DEFAULT(UseShenandoahMatrix, false);
58 #endif
59
60 #ifdef _LP64
61 // The optimized ObjArrayChunkedTask takes some bits away from the full 64 addressable
62 // bits, fail if we ever attempt to address more than we can. Only valid on 64bit.
63 if (MaxHeapSize >= ObjArrayChunkedTask::max_addressable()) {
64 jio_fprintf(defaultStream::error_stream(),
65 "Shenandoah GC cannot address more than " SIZE_FORMAT " bytes, and " SIZE_FORMAT " bytes heap requested.",
66 ObjArrayChunkedTask::max_addressable(), MaxHeapSize);
67 vm_exit(1);
68 }
69 #endif
70
71 FLAG_SET_DEFAULT(ParallelGCThreads,
72 Abstract_VM_Version::parallel_worker_threads());
73
74 if (FLAG_IS_DEFAULT(ConcGCThreads)) {
75 uint conc_threads = MAX2((uint) 1, ParallelGCThreads);
76 FLAG_SET_DEFAULT(ConcGCThreads, conc_threads);
77 }
78
79 if (FLAG_IS_DEFAULT(ParallelRefProcEnabled)) {
80 FLAG_SET_DEFAULT(ParallelRefProcEnabled, true);
81 }
82
83 if (ShenandoahRegionSampling && FLAG_IS_DEFAULT(PerfDataMemorySize)) {
84 // When sampling is enabled, max out the PerfData memory to get more
85 // Shenandoah data in, including Matrix.
86 FLAG_SET_DEFAULT(PerfDataMemorySize, 2048*K);
87 }
88
89 #ifdef COMPILER2
90 // Shenandoah cares more about pause times, rather than raw throughput.
91 if (FLAG_IS_DEFAULT(UseCountedLoopSafepoints)) {
92 FLAG_SET_DEFAULT(UseCountedLoopSafepoints, true);
93 if (FLAG_IS_DEFAULT(LoopStripMiningIter)) {
94 FLAG_SET_DEFAULT(LoopStripMiningIter, 1000);
95 }
96 }
97 #ifdef ASSERT
98 // C2 barrier verification is only reliable when all default barriers are enabled
99 if (ShenandoahVerifyOptoBarriers &&
100 (!FLAG_IS_DEFAULT(ShenandoahSATBBarrier) ||
101 !FLAG_IS_DEFAULT(ShenandoahKeepAliveBarrier) ||
102 !FLAG_IS_DEFAULT(ShenandoahWriteBarrier) ||
103 !FLAG_IS_DEFAULT(ShenandoahReadBarrier) ||
104 !FLAG_IS_DEFAULT(ShenandoahStoreValEnqueueBarrier) ||
105 !FLAG_IS_DEFAULT(ShenandoahStoreValReadBarrier) ||
106 !FLAG_IS_DEFAULT(ShenandoahCASBarrier) ||
107 !FLAG_IS_DEFAULT(ShenandoahAcmpBarrier) ||
108 !FLAG_IS_DEFAULT(ShenandoahCloneBarrier)
109 )) {
110 warning("Unusual barrier configuration, disabling C2 barrier verification");
111 FLAG_SET_DEFAULT(ShenandoahVerifyOptoBarriers, false);
112 }
113 #else
114 guarantee(!ShenandoahVerifyOptoBarriers, "Should be disabled");
115 #endif // ASSERT
116 #endif // COMPILER2
117
118 if (AlwaysPreTouch) {
119 // Shenandoah handles pre-touch on its own. It does not let the
120 // generic storage code to do the pre-touch before Shenandoah has
121 // a chance to do it on its own.
122 FLAG_SET_DEFAULT(AlwaysPreTouch, false);
123 FLAG_SET_DEFAULT(ShenandoahAlwaysPreTouch, true);
124 }
125
126 // Shenandoah C2 optimizations apparently dislike the shape of thread-local handshakes.
127 // Disable it by default, unless we enable it specifically for debugging.
128 if (FLAG_IS_DEFAULT(ThreadLocalHandshakes)) {
129 if (ThreadLocalHandshakes) {
130 FLAG_SET_DEFAULT(ThreadLocalHandshakes, false);
131 }
132 } else {
133 if (ThreadLocalHandshakes) {
134 warning("Thread-local handshakes are not working correctly with Shenandoah at the moment. Enable at your own risk.");
135 }
136 }
137
138 // Record more information about previous cycles for improved debugging pleasure
139 if (FLAG_IS_DEFAULT(LogEventsBufferEntries)) {
140 FLAG_SET_DEFAULT(LogEventsBufferEntries, 250);
141 }
142
143 if (ShenandoahConcurrentEvacCodeRoots) {
144 if (!ShenandoahBarriersForConst) {
145 if (FLAG_IS_DEFAULT(ShenandoahBarriersForConst)) {
146 warning("Concurrent code cache evacuation is enabled, enabling barriers for constants.");
147 FLAG_SET_DEFAULT(ShenandoahBarriersForConst, true);
148 } else {
149 warning("Concurrent code cache evacuation is enabled, but barriers for constants are disabled. "
150 "This may lead to surprising crashes.");
151 }
152 }
153 } else {
154 if (ShenandoahBarriersForConst) {
155 if (FLAG_IS_DEFAULT(ShenandoahBarriersForConst)) {
156 warning("Concurrent code cache evacuation is disabled, disabling barriers for constants.");
157 FLAG_SET_DEFAULT(ShenandoahBarriersForConst, false);
158 }
159 }
160 }
161
162 if (ShenandoahAlwaysPreTouch) {
163 if (!FLAG_IS_DEFAULT(ShenandoahUncommit)) {
164 warning("AlwaysPreTouch is enabled, disabling ShenandoahUncommit");
165 }
166 FLAG_SET_DEFAULT(ShenandoahUncommit, false);
167 }
168 }
169
170 size_t ShenandoahArguments::conservative_max_heap_alignment() {
171 return ShenandoahMaxRegionSize;
172 }
173
174 CollectedHeap* ShenandoahArguments::create_heap() {
175 return create_heap_with_policy<ShenandoahHeap, ShenandoahCollectorPolicy>();
176 }