1 /*
2 * Copyright (c) 2017, 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/cms/cmsArguments.hpp"
27 #include "gc/cms/cmsHeap.hpp"
28 #include "gc/cms/compactibleFreeListSpace.hpp"
29 #include "gc/shared/cardTableRS.hpp"
30 #include "gc/shared/gcArguments.inline.hpp"
31 #include "gc/shared/genCollectedHeap.hpp"
32 #include "runtime/arguments.hpp"
33 #include "runtime/globals.hpp"
34 #include "runtime/globals_extension.hpp"
35 #include "runtime/vm_version.hpp"
36 #include "utilities/defaultStream.hpp"
37
38 size_t CMSArguments::conservative_max_heap_alignment() {
39 return GenCollectedHeap::conservative_max_heap_alignment();
40 }
41
42 void CMSArguments::set_parnew_gc_flags() {
43 assert(!UseSerialGC && !UseParallelOldGC && !UseParallelGC && !UseG1GC,
44 "control point invariant");
45 assert(UseConcMarkSweepGC, "CMS is expected to be on here");
46
47 if (FLAG_IS_DEFAULT(ParallelGCThreads)) {
48 FLAG_SET_DEFAULT(ParallelGCThreads, Abstract_VM_Version::parallel_worker_threads());
49 assert(ParallelGCThreads > 0, "We should always have at least one thread by default");
50 } else if (ParallelGCThreads == 0) {
51 jio_fprintf(defaultStream::error_stream(),
52 "The ParNew GC can not be combined with -XX:ParallelGCThreads=0\n");
53 vm_exit(1);
54 }
55
56 // By default YoungPLABSize and OldPLABSize are set to 4096 and 1024 respectively,
57 // these settings are default for Parallel Scavenger. For ParNew+Tenured configuration
58 // we set them to 1024 and 1024.
59 // See CR 6362902.
60 if (FLAG_IS_DEFAULT(YoungPLABSize)) {
61 FLAG_SET_DEFAULT(YoungPLABSize, (intx)1024);
62 }
63 if (FLAG_IS_DEFAULT(OldPLABSize)) {
64 FLAG_SET_DEFAULT(OldPLABSize, (intx)1024);
65 }
66
67 // When using compressed oops, we use local overflow stacks,
68 // rather than using a global overflow list chained through
69 // the klass word of the object's pre-image.
70 if (UseCompressedOops && !ParGCUseLocalOverflow) {
71 if (!FLAG_IS_DEFAULT(ParGCUseLocalOverflow)) {
72 warning("Forcing +ParGCUseLocalOverflow: needed if using compressed references");
73 }
74 FLAG_SET_DEFAULT(ParGCUseLocalOverflow, true);
75 }
76 assert(ParGCUseLocalOverflow || !UseCompressedOops, "Error");
77 }
78
79 CMSSettings CMSArguments::initialize_heap_flags() {
80 CMSSettings s;
81
82 GenArguments::initialize_heap_flags(s);
83
84 return s;
85 }
86
87 // Adjust some sizes to suit CMS and/or ParNew needs; these work well on
88 // sparc/solaris for certain applications, but would gain from
89 // further optimization and tuning efforts, and would almost
90 // certainly gain from analysis of platform and environment.
91 void CMSArguments::initialize_flags() {
92 GCArguments::initialize_flags();
93 assert(!UseSerialGC && !UseParallelOldGC && !UseParallelGC, "Error");
94 assert(UseConcMarkSweepGC, "CMS is expected to be on here");
95
96 // Set CMS global values
97 CompactibleFreeListSpace::set_cms_values();
98
99 // Turn off AdaptiveSizePolicy by default for cms until it is complete.
100 disable_adaptive_size_policy("UseConcMarkSweepGC");
101
102 set_parnew_gc_flags();
103
104 size_t max_heap = align_down(MaxHeapSize,
105 CardTableRS::ct_max_alignment_constraint());
106
107 // Now make adjustments for CMS
108 intx tenuring_default = (intx)6;
109 size_t young_gen_per_worker = CMSYoungGenPerWorker;
110
111 // Preferred young gen size for "short" pauses:
112 // upper bound depends on # of threads and NewRatio.
113 const size_t preferred_max_new_size_unaligned =
114 MIN2(max_heap/(NewRatio+1), ScaleForWordSize(young_gen_per_worker * ParallelGCThreads));
115 size_t preferred_max_new_size =
116 align_up(preferred_max_new_size_unaligned, os::vm_page_size());
117
118 // Unless explicitly requested otherwise, size young gen
119 // for "short" pauses ~ CMSYoungGenPerWorker*ParallelGCThreads
120
121 // If either MaxNewSize or NewRatio is set on the command line,
122 // assume the user is trying to set the size of the young gen.
123 if (FLAG_IS_DEFAULT(MaxNewSize) && FLAG_IS_DEFAULT(NewRatio)) {
124
125 // Set MaxNewSize to our calculated preferred_max_new_size unless
126 // NewSize was set on the command line and it is larger than
127 // preferred_max_new_size.
128 if (!FLAG_IS_DEFAULT(NewSize)) { // NewSize explicitly set at command-line
129 FLAG_SET_ERGO(size_t, MaxNewSize, MAX2(NewSize, preferred_max_new_size));
130 } else {
131 FLAG_SET_ERGO(size_t, MaxNewSize, preferred_max_new_size);
132 }
133 log_trace(gc, heap)("CMS ergo set MaxNewSize: " SIZE_FORMAT, MaxNewSize);
134
135 // Code along this path potentially sets NewSize and OldSize
136 log_trace(gc, heap)("CMS set min_heap_size: " SIZE_FORMAT " initial_heap_size: " SIZE_FORMAT " max_heap: " SIZE_FORMAT,
137 Arguments::min_heap_size(), InitialHeapSize, max_heap);
138 size_t min_new = preferred_max_new_size;
139 if (FLAG_IS_CMDLINE(NewSize)) {
140 min_new = NewSize;
141 }
142 if (max_heap > min_new && Arguments::min_heap_size() > min_new) {
143 // Unless explicitly requested otherwise, make young gen
144 // at least min_new, and at most preferred_max_new_size.
145 if (FLAG_IS_DEFAULT(NewSize)) {
146 FLAG_SET_ERGO(size_t, NewSize, MAX2(NewSize, min_new));
147 FLAG_SET_ERGO(size_t, NewSize, MIN2(preferred_max_new_size, NewSize));
148 log_trace(gc, heap)("CMS ergo set NewSize: " SIZE_FORMAT, NewSize);
149 }
150 // Unless explicitly requested otherwise, size old gen
151 // so it's NewRatio x of NewSize.
152 if (FLAG_IS_DEFAULT(OldSize)) {
153 if (max_heap > NewSize) {
154 FLAG_SET_ERGO(size_t, OldSize, MIN2(NewRatio*NewSize, max_heap - NewSize));
155 log_trace(gc, heap)("CMS ergo set OldSize: " SIZE_FORMAT, OldSize);
156 }
157 }
158 }
159 }
160 // Unless explicitly requested otherwise, definitely
161 // promote all objects surviving "tenuring_default" scavenges.
162 if (FLAG_IS_DEFAULT(MaxTenuringThreshold) &&
163 FLAG_IS_DEFAULT(SurvivorRatio)) {
164 FLAG_SET_ERGO(uintx, MaxTenuringThreshold, tenuring_default);
165 }
166 // If we decided above (or user explicitly requested)
167 // `promote all' (via MaxTenuringThreshold := 0),
168 // prefer minuscule survivor spaces so as not to waste
169 // space for (non-existent) survivors
170 if (FLAG_IS_DEFAULT(SurvivorRatio) && MaxTenuringThreshold == 0) {
171 FLAG_SET_ERGO(uintx, SurvivorRatio, MAX2((uintx)1024, SurvivorRatio));
172 }
173
174 // OldPLABSize is interpreted in CMS as not the size of the PLAB in words,
175 // but rather the number of free blocks of a given size that are used when
176 // replenishing the local per-worker free list caches.
177 if (FLAG_IS_DEFAULT(OldPLABSize)) {
178 if (!FLAG_IS_DEFAULT(ResizeOldPLAB) && !ResizeOldPLAB) {
179 // OldPLAB sizing manually turned off: Use a larger default setting,
180 // unless it was manually specified. This is because a too-low value
181 // will slow down scavenges.
182 FLAG_SET_ERGO(size_t, OldPLABSize, CompactibleFreeListSpaceLAB::_default_static_old_plab_size); // default value before 6631166
183 } else {
184 FLAG_SET_DEFAULT(OldPLABSize, CompactibleFreeListSpaceLAB::_default_dynamic_old_plab_size); // old CMSParPromoteBlocksToClaim default
185 }
186 }
187
188 // If either of the static initialization defaults have changed, note this
189 // modification.
190 if (!FLAG_IS_DEFAULT(OldPLABSize) || !FLAG_IS_DEFAULT(OldPLABWeight)) {
191 CompactibleFreeListSpaceLAB::modify_initialization(OldPLABSize, OldPLABWeight);
192 }
193
194 log_trace(gc)("MarkStackSize: %uk MarkStackSizeMax: %uk", (unsigned int) (MarkStackSize / K), (uint) (MarkStackSizeMax / K));
195 }
196
197 void CMSArguments::disable_adaptive_size_policy(const char* collector_name) {
198 if (UseAdaptiveSizePolicy) {
199 if (FLAG_IS_CMDLINE(UseAdaptiveSizePolicy)) {
200 warning("Disabling UseAdaptiveSizePolicy; it is incompatible with %s.",
201 collector_name);
202 }
203 FLAG_SET_DEFAULT(UseAdaptiveSizePolicy, false);
204 }
205 }
206
207 CollectedHeap* CMSArguments::create_heap() {
208 return new CMSHeap(initialize_heap_flags());
209 }