1/*
2 * Copyright (c) 2018, 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/g1/g1Arguments.hpp"
28#include "gc/g1/g1CollectedHeap.inline.hpp"
29#include "gc/g1/g1HeapVerifier.hpp"
30#include "gc/g1/heapRegion.hpp"
31#include "gc/g1/heapRegionRemSet.hpp"
32#include "gc/shared/cardTableRS.hpp"
33#include "gc/shared/gcArguments.hpp"
34#include "gc/shared/workerPolicy.hpp"
35#include "runtime/globals.hpp"
36#include "runtime/globals_extension.hpp"
37
38static const double MaxRamFractionForYoung = 0.8;
39size_t G1Arguments::MaxMemoryForYoung;
40
41static size_t calculate_heap_alignment(size_t space_alignment) {
42 size_t card_table_alignment = CardTableRS::ct_max_alignment_constraint();
43 size_t page_size = UseLargePages ? os::large_page_size() : os::vm_page_size();
44 return MAX3(card_table_alignment, space_alignment, page_size);
45}
46
47void G1Arguments::initialize_alignments() {
48 // Set up the region size and associated fields.
49 //
50 // There is a circular dependency here. We base the region size on the heap
51 // size, but the heap size should be aligned with the region size. To get
52 // around this we use the unaligned values for the heap.
53 HeapRegion::setup_heap_region_size(InitialHeapSize, MaxHeapSize);
54 HeapRegionRemSet::setup_remset_size();
55
56 SpaceAlignment = HeapRegion::GrainBytes;
57 HeapAlignment = calculate_heap_alignment(SpaceAlignment);
58}
59
60size_t G1Arguments::conservative_max_heap_alignment() {
61 return HeapRegion::max_region_size();
62}
63
64void G1Arguments::initialize_verification_types() {
65 if (strlen(VerifyGCType) > 0) {
66 const char delimiter[] = " ,\n";
67 size_t length = strlen(VerifyGCType);
68 char* type_list = NEW_C_HEAP_ARRAY(char, length + 1, mtInternal);
69 strncpy(type_list, VerifyGCType, length + 1);
70 char* save_ptr;
71
72 char* token = strtok_r(type_list, delimiter, &save_ptr);
73 while (token != NULL) {
74 parse_verification_type(token);
75 token = strtok_r(NULL, delimiter, &save_ptr);
76 }
77 FREE_C_HEAP_ARRAY(char, type_list);
78 }
79}
80
81void G1Arguments::parse_verification_type(const char* type) {
82 if (strcmp(type, "young-normal") == 0) {
83 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyYoungNormal);
84 } else if (strcmp(type, "concurrent-start") == 0) {
85 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyConcurrentStart);
86 } else if (strcmp(type, "mixed") == 0) {
87 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyMixed);
88 } else if (strcmp(type, "remark") == 0) {
89 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyRemark);
90 } else if (strcmp(type, "cleanup") == 0) {
91 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyCleanup);
92 } else if (strcmp(type, "full") == 0) {
93 G1HeapVerifier::enable_verification_type(G1HeapVerifier::G1VerifyFull);
94 } else {
95 log_warning(gc, verify)("VerifyGCType: '%s' is unknown. Available types are: "
96 "young-normal, concurrent-start, mixed, remark, cleanup and full", type);
97 }
98}
99
100void G1Arguments::initialize() {
101 GCArguments::initialize();
102 assert(UseG1GC, "Error");
103 FLAG_SET_DEFAULT(ParallelGCThreads, WorkerPolicy::parallel_worker_threads());
104 if (ParallelGCThreads == 0) {
105 assert(!FLAG_IS_DEFAULT(ParallelGCThreads), "The default value for ParallelGCThreads should not be 0.");
106 vm_exit_during_initialization("The flag -XX:+UseG1GC can not be combined with -XX:ParallelGCThreads=0", NULL);
107 }
108
109 // When dumping the CDS archive we want to reduce fragmentation by
110 // triggering a full collection. To get as low fragmentation as
111 // possible we only use one worker thread.
112 if (DumpSharedSpaces) {
113 FLAG_SET_ERGO(ParallelGCThreads, 1);
114 }
115
116 if (FLAG_IS_DEFAULT(G1ConcRefinementThreads)) {
117 FLAG_SET_ERGO(G1ConcRefinementThreads, ParallelGCThreads);
118 }
119
120 // MarkStackSize will be set (if it hasn't been set by the user)
121 // when concurrent marking is initialized.
122 // Its value will be based upon the number of parallel marking threads.
123 // But we do set the maximum mark stack size here.
124 if (FLAG_IS_DEFAULT(MarkStackSizeMax)) {
125 FLAG_SET_DEFAULT(MarkStackSizeMax, 128 * TASKQUEUE_SIZE);
126 }
127
128 if (FLAG_IS_DEFAULT(GCTimeRatio) || GCTimeRatio == 0) {
129 // In G1, we want the default GC overhead goal to be higher than
130 // it is for PS, or the heap might be expanded too aggressively.
131 // We set it here to ~8%.
132 FLAG_SET_DEFAULT(GCTimeRatio, 12);
133 }
134
135 // Below, we might need to calculate the pause time interval based on
136 // the pause target. When we do so we are going to give G1 maximum
137 // flexibility and allow it to do pauses when it needs to. So, we'll
138 // arrange that the pause interval to be pause time target + 1 to
139 // ensure that a) the pause time target is maximized with respect to
140 // the pause interval and b) we maintain the invariant that pause
141 // time target < pause interval. If the user does not want this
142 // maximum flexibility, they will have to set the pause interval
143 // explicitly.
144
145 if (FLAG_IS_DEFAULT(MaxGCPauseMillis)) {
146 // The default pause time target in G1 is 200ms
147 FLAG_SET_DEFAULT(MaxGCPauseMillis, 200);
148 }
149
150 // Then, if the interval parameter was not set, set it according to
151 // the pause time target (this will also deal with the case when the
152 // pause time target is the default value).
153 if (FLAG_IS_DEFAULT(GCPauseIntervalMillis)) {
154 FLAG_SET_DEFAULT(GCPauseIntervalMillis, MaxGCPauseMillis + 1);
155 }
156
157 if (FLAG_IS_DEFAULT(ParallelRefProcEnabled) && ParallelGCThreads > 1) {
158 FLAG_SET_DEFAULT(ParallelRefProcEnabled, true);
159 }
160
161 log_trace(gc)("MarkStackSize: %uk MarkStackSizeMax: %uk", (unsigned int) (MarkStackSize / K), (uint) (MarkStackSizeMax / K));
162
163 // By default do not let the target stack size to be more than 1/4 of the entries
164 if (FLAG_IS_DEFAULT(GCDrainStackTargetSize)) {
165 FLAG_SET_ERGO(GCDrainStackTargetSize, MIN2(GCDrainStackTargetSize, (uintx)TASKQUEUE_SIZE / 4));
166 }
167
168#ifdef COMPILER2
169 // Enable loop strip mining to offer better pause time guarantees
170 if (FLAG_IS_DEFAULT(UseCountedLoopSafepoints)) {
171 FLAG_SET_DEFAULT(UseCountedLoopSafepoints, true);
172 if (FLAG_IS_DEFAULT(LoopStripMiningIter)) {
173 FLAG_SET_DEFAULT(LoopStripMiningIter, 1000);
174 }
175 }
176#endif
177
178 initialize_verification_types();
179}
180
181static size_t calculate_reasonable_max_memory_for_young(FormatBuffer<100> &calc_str, double max_ram_fraction_for_young) {
182 julong phys_mem;
183 // If MaxRam is specified, we use that as maximum physical memory available.
184 if (FLAG_IS_DEFAULT(MaxRAM)) {
185 phys_mem = os::physical_memory();
186 calc_str.append("Physical_Memory");
187 } else {
188 phys_mem = (julong)MaxRAM;
189 calc_str.append("MaxRAM");
190 }
191
192 julong reasonable_max = phys_mem;
193
194 // If either MaxRAMFraction or MaxRAMPercentage is specified, we use them to calculate
195 // reasonable max size of young generation.
196 if (!FLAG_IS_DEFAULT(MaxRAMFraction)) {
197 reasonable_max = (julong)(phys_mem / MaxRAMFraction);
198 calc_str.append(" / MaxRAMFraction");
199 } else if (!FLAG_IS_DEFAULT(MaxRAMPercentage)) {
200 reasonable_max = (julong)((phys_mem * MaxRAMPercentage) / 100);
201 calc_str.append(" * MaxRAMPercentage / 100");
202 } else {
203 // We use our own fraction to calculate max size of young generation.
204 reasonable_max = phys_mem * max_ram_fraction_for_young;
205 calc_str.append(" * %0.2f", max_ram_fraction_for_young);
206 }
207
208 return (size_t)reasonable_max;
209}
210
211void G1Arguments::initialize_heap_flags_and_sizes() {
212 if (AllocateOldGenAt != NULL) {
213 initialize_heterogeneous();
214 }
215
216 GCArguments::initialize_heap_flags_and_sizes();
217}
218
219void G1Arguments::initialize_heterogeneous() {
220 FormatBuffer<100> calc_str("");
221
222 MaxMemoryForYoung = calculate_reasonable_max_memory_for_young(calc_str, MaxRamFractionForYoung);
223
224 if (MaxNewSize > MaxMemoryForYoung) {
225 if (FLAG_IS_CMDLINE(MaxNewSize)) {
226 log_warning(gc, ergo)("Setting MaxNewSize to " SIZE_FORMAT " based on dram available (calculation = align(%s))",
227 MaxMemoryForYoung, calc_str.buffer());
228 } else {
229 log_info(gc, ergo)("Setting MaxNewSize to " SIZE_FORMAT " based on dram available (calculation = align(%s)). "
230 "Dram usage can be lowered by setting MaxNewSize to a lower value", MaxMemoryForYoung, calc_str.buffer());
231 }
232 MaxNewSize = MaxMemoryForYoung;
233 }
234 if (NewSize > MaxMemoryForYoung) {
235 if (FLAG_IS_CMDLINE(NewSize)) {
236 log_warning(gc, ergo)("Setting NewSize to " SIZE_FORMAT " based on dram available (calculation = align(%s))",
237 MaxMemoryForYoung, calc_str.buffer());
238 }
239 NewSize = MaxMemoryForYoung;
240 }
241
242}
243
244CollectedHeap* G1Arguments::create_heap() {
245 return new G1CollectedHeap();
246}
247
248bool G1Arguments::is_heterogeneous_heap() {
249 return AllocateOldGenAt != NULL;
250}
251
252size_t G1Arguments::reasonable_max_memory_for_young() {
253 return MaxMemoryForYoung;
254}
255
256size_t G1Arguments::heap_reserved_size_bytes() {
257 return (is_heterogeneous_heap() ? 2 : 1) * MaxHeapSize;
258}
259
260size_t G1Arguments::heap_max_size_bytes() {
261 return MaxHeapSize;
262}