1 /*
2 * Copyright (c) 2018, 2019, Red Hat, Inc. All rights reserved.
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/workerPolicy.hpp"
28 #include "gc/shenandoah/shenandoahArguments.hpp"
29 #include "gc/shenandoah/shenandoahCollectorPolicy.hpp"
30 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
31 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
32 #include "gc/shenandoah/shenandoahTaskqueue.hpp"
33 #include "utilities/defaultStream.hpp"
34
35 void ShenandoahArguments::initialize() {
36 #if !(defined AARCH64 || defined AMD64 || defined IA32)
37 vm_exit_during_initialization("Shenandoah GC is not supported on this platform.");
38 #endif
39
40 #ifdef IA32
41 log_warning(gc)("Shenandoah GC is not fully supported on this platform:");
42 log_warning(gc)(" concurrent modes are not supported, only STW cycles are enabled;");
43 log_warning(gc)(" arch-specific barrier code is not implemented, disabling barriers;");
44
45 FLAG_SET_DEFAULT(ShenandoahGCHeuristics, "passive");
46
47 FLAG_SET_DEFAULT(ShenandoahSATBBarrier, false);
48 FLAG_SET_DEFAULT(ShenandoahKeepAliveBarrier, false);
49 FLAG_SET_DEFAULT(ShenandoahStoreValEnqueueBarrier, false);
50 FLAG_SET_DEFAULT(ShenandoahCASBarrier, false);
51 FLAG_SET_DEFAULT(ShenandoahCloneBarrier, false);
52 #endif
53
54 #ifdef _LP64
55 // The optimized ObjArrayChunkedTask takes some bits away from the full 64 addressable
56 // bits, fail if we ever attempt to address more than we can. Only valid on 64bit.
57 if (MaxHeapSize >= ObjArrayChunkedTask::max_addressable()) {
58 jio_fprintf(defaultStream::error_stream(),
59 "Shenandoah GC cannot address more than " SIZE_FORMAT " bytes, and " SIZE_FORMAT " bytes heap requested.",
60 ObjArrayChunkedTask::max_addressable(), MaxHeapSize);
61 vm_exit(1);
62 }
63 #endif
64
65 if (UseLargePages && (MaxHeapSize / os::large_page_size()) < ShenandoahHeapRegion::MIN_NUM_REGIONS) {
66 warning("Large pages size (" SIZE_FORMAT "K) is too large to afford page-sized regions, disabling uncommit",
67 os::large_page_size() / K);
68 FLAG_SET_DEFAULT(ShenandoahUncommit, false);
69 }
70
71 // Enable NUMA by default. While Shenandoah is not NUMA-aware, enabling NUMA makes
72 // storage allocation code NUMA-aware, and NUMA interleaving makes the storage
73 // allocated in consistent manner (interleaving) to minimize run-to-run variance.
74 if (FLAG_IS_DEFAULT(UseNUMA)) {
75 FLAG_SET_DEFAULT(UseNUMA, true);
76 FLAG_SET_DEFAULT(UseNUMAInterleaving, true);
77 }
78
79 FLAG_SET_DEFAULT(ParallelGCThreads,
80 WorkerPolicy::parallel_worker_threads());
81
82 if (FLAG_IS_DEFAULT(ConcGCThreads)) {
83 uint conc_threads = MAX2((uint) 1, ParallelGCThreads);
84 FLAG_SET_DEFAULT(ConcGCThreads, conc_threads);
85 }
86
87 if (FLAG_IS_DEFAULT(ParallelRefProcEnabled)) {
88 FLAG_SET_DEFAULT(ParallelRefProcEnabled, true);
89 }
90
91 if (ShenandoahRegionSampling && FLAG_IS_DEFAULT(PerfDataMemorySize)) {
92 // When sampling is enabled, max out the PerfData memory to get more
93 // Shenandoah data in, including Matrix.
94 FLAG_SET_DEFAULT(PerfDataMemorySize, 2048*K);
95 }
96
97 #ifdef COMPILER2
98 // Shenandoah cares more about pause times, rather than raw throughput.
99 if (FLAG_IS_DEFAULT(UseCountedLoopSafepoints)) {
100 FLAG_SET_DEFAULT(UseCountedLoopSafepoints, true);
101 if (FLAG_IS_DEFAULT(LoopStripMiningIter)) {
102 FLAG_SET_DEFAULT(LoopStripMiningIter, 1000);
103 }
104 }
105 #ifdef ASSERT
106 // C2 barrier verification is only reliable when all default barriers are enabled
107 if (ShenandoahVerifyOptoBarriers &&
108 (!FLAG_IS_DEFAULT(ShenandoahSATBBarrier) ||
109 !FLAG_IS_DEFAULT(ShenandoahKeepAliveBarrier) ||
110 !FLAG_IS_DEFAULT(ShenandoahStoreValEnqueueBarrier) ||
111 !FLAG_IS_DEFAULT(ShenandoahCASBarrier) ||
112 !FLAG_IS_DEFAULT(ShenandoahCloneBarrier)
113 )) {
114 warning("Unusual barrier configuration, disabling C2 barrier verification");
115 FLAG_SET_DEFAULT(ShenandoahVerifyOptoBarriers, false);
116 }
117 #else
118 guarantee(!ShenandoahVerifyOptoBarriers, "Should be disabled");
119 #endif // ASSERT
120 #endif // COMPILER2
121
122 if (AlwaysPreTouch) {
123 // Shenandoah handles pre-touch on its own. It does not let the
124 // generic storage code to do the pre-touch before Shenandoah has
125 // a chance to do it on its own.
126 FLAG_SET_DEFAULT(AlwaysPreTouch, false);
127 FLAG_SET_DEFAULT(ShenandoahAlwaysPreTouch, true);
128 }
129
130 // Record more information about previous cycles for improved debugging pleasure
131 if (FLAG_IS_DEFAULT(LogEventsBufferEntries)) {
132 FLAG_SET_DEFAULT(LogEventsBufferEntries, 250);
133 }
134
135 if (ShenandoahAlwaysPreTouch) {
136 if (!FLAG_IS_DEFAULT(ShenandoahUncommit)) {
137 warning("AlwaysPreTouch is enabled, disabling ShenandoahUncommit");
138 }
139 FLAG_SET_DEFAULT(ShenandoahUncommit, false);
140 }
141
142 // If class unloading is disabled, no unloading for concurrent cycles as well.
143 // If class unloading is enabled, users should opt-in for unloading during
144 // concurrent cycles.
145 if (!ClassUnloading || !FLAG_IS_CMDLINE(ClassUnloadingWithConcurrentMark)) {
146 log_info(gc)("Consider -XX:+ClassUnloadingWithConcurrentMark if large pause times "
147 "are observed on class-unloading sensitive workloads");
148 FLAG_SET_DEFAULT(ClassUnloadingWithConcurrentMark, false);
149 }
150
151 // AOT is not supported yet
152 if (UseAOT) {
153 if (!FLAG_IS_DEFAULT(UseAOT)) {
154 warning("Shenandoah does not support AOT at this moment, disabling UseAOT");
155 }
156 FLAG_SET_DEFAULT(UseAOT, false);
157 }
158
159 // TLAB sizing policy makes resizing decisions before each GC cycle. It averages
160 // historical data, assigning more recent data the weight according to TLABAllocationWeight.
161 // Current default is good for generational collectors that run frequent young GCs.
162 // With Shenandoah, GC cycles are much less frequent, so we need we need sizing policy
163 // to converge faster over smaller number of resizing decisions.
164 if (FLAG_IS_DEFAULT(TLABAllocationWeight)) {
165 FLAG_SET_DEFAULT(TLABAllocationWeight, 90);
166 }
167
168 // Shenandoah needs more C2 nodes to compile some methods with lots of barriers.
169 // NodeLimitFudgeFactor needs to stay the same relative to MaxNodeLimit.
170 #ifdef COMPILER2
171 if (FLAG_IS_DEFAULT(MaxNodeLimit)) {
172 FLAG_SET_DEFAULT(MaxNodeLimit, MaxNodeLimit * 3);
173 FLAG_SET_DEFAULT(NodeLimitFudgeFactor, NodeLimitFudgeFactor * 3);
174 }
175 #endif
176
177 // Make sure safepoint deadlocks are failing predictably. This sets up VM to report
178 // fatal error after 10 seconds of wait for safepoint syncronization (not the VM
179 // operation itself). There is no good reason why Shenandoah would spend that
180 // much time synchronizing.
181 #ifdef ASSERT
182 FLAG_SET_DEFAULT(SafepointTimeout, true);
183 FLAG_SET_DEFAULT(SafepointTimeoutDelay, 10000);
184 FLAG_SET_DEFAULT(AbortVMOnSafepointTimeout, true);
185 #endif
186 }
187
188 size_t ShenandoahArguments::conservative_max_heap_alignment() {
189 size_t align = ShenandoahMaxRegionSize;
190 if (UseLargePages) {
191 align = MAX2(align, os::large_page_size());
192 }
193 return align;
194 }
195
196 CollectedHeap* ShenandoahArguments::create_heap() {
197 return create_heap_with_policy<ShenandoahHeap, ShenandoahCollectorPolicy>();
198 }