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.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(ShenandoahLoadRefBarrier, false);
49 FLAG_SET_DEFAULT(ShenandoahKeepAliveBarrier, false);
50 FLAG_SET_DEFAULT(ShenandoahStoreValEnqueueBarrier, false);
51 FLAG_SET_DEFAULT(ShenandoahCASBarrier, false);
52 FLAG_SET_DEFAULT(ShenandoahCloneBarrier, false);
53
54 FLAG_SET_DEFAULT(ShenandoahVerifyOptoBarriers, false);
55 #endif
56
57 #ifdef _LP64
58 // The optimized ObjArrayChunkedTask takes some bits away from the full 64 addressable
59 // bits, fail if we ever attempt to address more than we can. Only valid on 64bit.
60 if (MaxHeapSize >= ObjArrayChunkedTask::max_addressable()) {
61 jio_fprintf(defaultStream::error_stream(),
62 "Shenandoah GC cannot address more than " SIZE_FORMAT " bytes, and " SIZE_FORMAT " bytes heap requested.",
63 ObjArrayChunkedTask::max_addressable(), MaxHeapSize);
64 vm_exit(1);
65 }
66 #endif
67
68 if (UseLargePages && (MaxHeapSize / os::large_page_size()) < ShenandoahHeapRegion::MIN_NUM_REGIONS) {
69 warning("Large pages size (" SIZE_FORMAT "K) is too large to afford page-sized regions, disabling uncommit",
70 os::large_page_size() / K);
71 FLAG_SET_DEFAULT(ShenandoahUncommit, false);
72 }
73
74 // Enable NUMA by default. While Shenandoah is not NUMA-aware, enabling NUMA makes
75 // storage allocation code NUMA-aware, and NUMA interleaving makes the storage
76 // allocated in consistent manner (interleaving) to minimize run-to-run variance.
77 if (FLAG_IS_DEFAULT(UseNUMA)) {
78 FLAG_SET_DEFAULT(UseNUMA, true);
79 FLAG_SET_DEFAULT(UseNUMAInterleaving, true);
80 }
81
82 FLAG_SET_DEFAULT(ParallelGCThreads,
83 WorkerPolicy::parallel_worker_threads());
84
85 if (FLAG_IS_DEFAULT(ConcGCThreads)) {
86 uint conc_threads = MAX2((uint) 1, ParallelGCThreads);
87 FLAG_SET_DEFAULT(ConcGCThreads, conc_threads);
88 }
89
90 if (FLAG_IS_DEFAULT(ParallelRefProcEnabled)) {
91 FLAG_SET_DEFAULT(ParallelRefProcEnabled, true);
92 }
93
94 if (ShenandoahRegionSampling && FLAG_IS_DEFAULT(PerfDataMemorySize)) {
95 // When sampling is enabled, max out the PerfData memory to get more
96 // Shenandoah data in, including Matrix.
97 FLAG_SET_DEFAULT(PerfDataMemorySize, 2048*K);
98 }
99
100 #ifdef COMPILER2
101 // Shenandoah cares more about pause times, rather than raw throughput.
102 if (FLAG_IS_DEFAULT(UseCountedLoopSafepoints)) {
103 FLAG_SET_DEFAULT(UseCountedLoopSafepoints, true);
104 if (FLAG_IS_DEFAULT(LoopStripMiningIter)) {
105 FLAG_SET_DEFAULT(LoopStripMiningIter, 1000);
106 }
107 }
108 #ifdef ASSERT
109 // C2 barrier verification is only reliable when all default barriers are enabled
110 if (ShenandoahVerifyOptoBarriers &&
111 (!FLAG_IS_DEFAULT(ShenandoahSATBBarrier) ||
112 !FLAG_IS_DEFAULT(ShenandoahLoadRefBarrier) ||
113 !FLAG_IS_DEFAULT(ShenandoahKeepAliveBarrier) ||
114 !FLAG_IS_DEFAULT(ShenandoahStoreValEnqueueBarrier) ||
115 !FLAG_IS_DEFAULT(ShenandoahCASBarrier) ||
116 !FLAG_IS_DEFAULT(ShenandoahCloneBarrier)
117 )) {
118 warning("Unusual barrier configuration, disabling C2 barrier verification");
119 FLAG_SET_DEFAULT(ShenandoahVerifyOptoBarriers, false);
120 }
121 #else
122 guarantee(!ShenandoahVerifyOptoBarriers, "Should be disabled");
123 #endif // ASSERT
124 #endif // COMPILER2
125
126 if (AlwaysPreTouch) {
127 // Shenandoah handles pre-touch on its own. It does not let the
128 // generic storage code to do the pre-touch before Shenandoah has
129 // a chance to do it on its own.
130 FLAG_SET_DEFAULT(AlwaysPreTouch, false);
131 FLAG_SET_DEFAULT(ShenandoahAlwaysPreTouch, true);
132 }
133
134 // Record more information about previous cycles for improved debugging pleasure
135 if (FLAG_IS_DEFAULT(LogEventsBufferEntries)) {
136 FLAG_SET_DEFAULT(LogEventsBufferEntries, 250);
137 }
138
139 if (ShenandoahAlwaysPreTouch) {
140 if (!FLAG_IS_DEFAULT(ShenandoahUncommit)) {
141 warning("AlwaysPreTouch is enabled, disabling ShenandoahUncommit");
142 }
143 FLAG_SET_DEFAULT(ShenandoahUncommit, false);
144 }
145
146 if ((InitialHeapSize == MaxHeapSize) && ShenandoahUncommit) {
147 log_info(gc)("Min heap equals to max heap, disabling ShenandoahUncommit");
148 FLAG_SET_DEFAULT(ShenandoahUncommit, false);
149 }
150
151 // If class unloading is disabled, no unloading for concurrent cycles as well.
152 // If class unloading is enabled, users should opt-in for unloading during
153 // concurrent cycles.
154 if (!ClassUnloading || !FLAG_IS_CMDLINE(ClassUnloadingWithConcurrentMark)) {
155 log_info(gc)("Consider -XX:+ClassUnloadingWithConcurrentMark if large pause times "
156 "are observed on class-unloading sensitive workloads");
157 FLAG_SET_DEFAULT(ClassUnloadingWithConcurrentMark, false);
158 }
159
160 // AOT is not supported yet
161 if (UseAOT) {
162 if (!FLAG_IS_DEFAULT(UseAOT)) {
163 warning("Shenandoah does not support AOT at this moment, disabling UseAOT");
164 }
165 FLAG_SET_DEFAULT(UseAOT, false);
166 }
167
168 // TLAB sizing policy makes resizing decisions before each GC cycle. It averages
169 // historical data, assigning more recent data the weight according to TLABAllocationWeight.
170 // Current default is good for generational collectors that run frequent young GCs.
171 // With Shenandoah, GC cycles are much less frequent, so we need we need sizing policy
172 // to converge faster over smaller number of resizing decisions.
173 if (FLAG_IS_DEFAULT(TLABAllocationWeight)) {
174 FLAG_SET_DEFAULT(TLABAllocationWeight, 90);
175 }
176
177 // Shenandoah needs more C2 nodes to compile some methods with lots of barriers.
178 // NodeLimitFudgeFactor needs to stay the same relative to MaxNodeLimit.
179 #ifdef COMPILER2
180 if (FLAG_IS_DEFAULT(MaxNodeLimit)) {
181 FLAG_SET_DEFAULT(MaxNodeLimit, MaxNodeLimit * 3);
182 FLAG_SET_DEFAULT(NodeLimitFudgeFactor, NodeLimitFudgeFactor * 3);
183 }
184 #endif
185
186 // Make sure safepoint deadlocks are failing predictably. This sets up VM to report
187 // fatal error after 10 seconds of wait for safepoint syncronization (not the VM
188 // operation itself). There is no good reason why Shenandoah would spend that
189 // much time synchronizing.
190 #ifdef ASSERT
191 FLAG_SET_DEFAULT(SafepointTimeout, true);
192 FLAG_SET_DEFAULT(SafepointTimeoutDelay, 10000);
193 FLAG_SET_DEFAULT(AbortVMOnSafepointTimeout, true);
194 #endif
195 }
196
197 size_t ShenandoahArguments::conservative_max_heap_alignment() {
198 size_t align = ShenandoahMaxRegionSize;
199 if (UseLargePages) {
200 align = MAX2(align, os::large_page_size());
201 }
202 return align;
203 }
204
205 void ShenandoahArguments::initialize_alignments() {
206 // Need to setup sizes early to get correct alignments.
207 ShenandoahHeapRegion::setup_sizes(InitialHeapSize, MaxHeapSize);
208
209 // This is expected by our algorithm for ShenandoahHeap::heap_region_containing().
210 size_t align = ShenandoahHeapRegion::region_size_bytes();
211 if (UseLargePages) {
212 align = MAX2(align, os::large_page_size());
213 }
214 SpaceAlignment = align;
215 HeapAlignment = align;
216 }
217
218 CollectedHeap* ShenandoahArguments::create_heap() {
219 return new ShenandoahHeap(new ShenandoahCollectorPolicy());
220 }