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/cms/cmsArguments.hpp" 28 #include "gc/cms/cmsCollectorPolicy.hpp" 29 #include "gc/cms/cmsHeap.hpp" 30 #include "gc/cms/compactibleFreeListSpace.hpp" 31 #include "gc/shared/gcArguments.inline.hpp" 32 #include "gc/shared/genCollectedHeap.hpp" 33 #include "runtime/arguments.hpp" 34 #include "runtime/globals.hpp" 35 #include "runtime/globals_extension.hpp" 36 #include "runtime/vm_version.hpp" 37 #include "utilities/defaultStream.hpp" 38 39 size_t CMSArguments::conservative_max_heap_alignment() { 40 return GenCollectedHeap::conservative_max_heap_alignment(); 41 } 42 43 void CMSArguments::set_parnew_gc_flags() { 44 assert(!UseSerialGC && !UseParallelOldGC && !UseParallelGC && !UseG1GC, 45 "control point invariant"); 46 assert(UseConcMarkSweepGC, "CMS is expected to be on here"); 47 48 if (FLAG_IS_DEFAULT(ParallelGCThreads)) { 49 FLAG_SET_DEFAULT(ParallelGCThreads, VM_Version::parallel_worker_threads()); 50 assert(ParallelGCThreads > 0, "We should always have at least one thread by default"); 51 } else if (ParallelGCThreads == 0) { 52 jio_fprintf(defaultStream::error_stream(), 53 "The ParNew GC can not be combined with -XX:ParallelGCThreads=0\n"); 54 vm_exit(1); 55 } 56 57 // By default YoungPLABSize and OldPLABSize are set to 4096 and 1024 respectively, 58 // these settings are default for Parallel Scavenger. For ParNew+Tenured configuration 59 // we set them to 1024 and 1024. 60 // See CR 6362902. 61 if (FLAG_IS_DEFAULT(YoungPLABSize)) { 62 FLAG_SET_DEFAULT(YoungPLABSize, (intx)1024); 63 } 64 if (FLAG_IS_DEFAULT(OldPLABSize)) { 65 FLAG_SET_DEFAULT(OldPLABSize, (intx)1024); 66 } 67 68 // When using compressed oops, we use local overflow stacks, 69 // rather than using a global overflow list chained through 70 // the klass word of the object's pre-image. 71 if (UseCompressedOops && !ParGCUseLocalOverflow) { 72 if (!FLAG_IS_DEFAULT(ParGCUseLocalOverflow)) { 73 warning("Forcing +ParGCUseLocalOverflow: needed if using compressed references"); 74 } 75 FLAG_SET_DEFAULT(ParGCUseLocalOverflow, true); 76 } 77 assert(ParGCUseLocalOverflow || !UseCompressedOops, "Error"); 78 } 79 80 // Adjust some sizes to suit CMS and/or ParNew needs; these work well on 81 // sparc/solaris for certain applications, but would gain from 82 // further optimization and tuning efforts, and would almost 83 // certainly gain from analysis of platform and environment. 84 void CMSArguments::initialize() { 85 GCArguments::initialize(); 86 87 assert(!UseSerialGC && !UseParallelOldGC && !UseParallelGC, "Error"); 88 assert(UseConcMarkSweepGC, "CMS is expected to be on here"); 89 90 // CMS space iteration, which FLSVerifyAllHeapreferences entails, 91 // insists that we hold the requisite locks so that the iteration is 92 // MT-safe. For the verification at start-up and shut-down, we don't 93 // yet have a good way of acquiring and releasing these locks, 94 // which are not visible at the CollectedHeap level. We want to 95 // be able to acquire these locks and then do the iteration rather 96 // than just disable the lock verification. This will be fixed under 97 // bug 4788986. 98 if (UseConcMarkSweepGC && FLSVerifyAllHeapReferences) { 99 if (VerifyDuringStartup) { 100 warning("Heap verification at start-up disabled " 101 "(due to current incompatibility with FLSVerifyAllHeapReferences)"); 102 VerifyDuringStartup = false; // Disable verification at start-up 103 } 104 105 if (VerifyBeforeExit) { 106 warning("Heap verification at shutdown disabled " 107 "(due to current incompatibility with FLSVerifyAllHeapReferences)"); 108 VerifyBeforeExit = false; // Disable verification at shutdown 109 } 110 } 111 112 if (!ClassUnloading) { 113 FLAG_SET_CMDLINE(bool, CMSClassUnloadingEnabled, false); 114 } 115 116 // Set CMS global values 117 CompactibleFreeListSpace::set_cms_values(); 118 119 // Turn off AdaptiveSizePolicy by default for cms until it is complete. 120 disable_adaptive_size_policy("UseConcMarkSweepGC"); 121 122 set_parnew_gc_flags(); 123 124 size_t max_heap = align_down(MaxHeapSize, 125 CardTableRS::ct_max_alignment_constraint()); 126 127 // Now make adjustments for CMS 128 intx tenuring_default = (intx)6; 129 size_t young_gen_per_worker = CMSYoungGenPerWorker; 130 131 // Preferred young gen size for "short" pauses: 132 // upper bound depends on # of threads and NewRatio. 133 const size_t preferred_max_new_size_unaligned = 134 MIN2(max_heap/(NewRatio+1), ScaleForWordSize(young_gen_per_worker * ParallelGCThreads)); 135 size_t preferred_max_new_size = 136 align_up(preferred_max_new_size_unaligned, os::vm_page_size()); 137 138 // Unless explicitly requested otherwise, size young gen 139 // for "short" pauses ~ CMSYoungGenPerWorker*ParallelGCThreads 140 141 // If either MaxNewSize or NewRatio is set on the command line, 142 // assume the user is trying to set the size of the young gen. 143 if (FLAG_IS_DEFAULT(MaxNewSize) && FLAG_IS_DEFAULT(NewRatio)) { 144 145 // Set MaxNewSize to our calculated preferred_max_new_size unless 146 // NewSize was set on the command line and it is larger than 147 // preferred_max_new_size. 148 if (!FLAG_IS_DEFAULT(NewSize)) { // NewSize explicitly set at command-line 149 FLAG_SET_ERGO(size_t, MaxNewSize, MAX2(NewSize, preferred_max_new_size)); 150 } else { 151 FLAG_SET_ERGO(size_t, MaxNewSize, preferred_max_new_size); 152 } 153 log_trace(gc, heap)("CMS ergo set MaxNewSize: " SIZE_FORMAT, MaxNewSize); 154 155 // Code along this path potentially sets NewSize and OldSize 156 log_trace(gc, heap)("CMS set min_heap_size: " SIZE_FORMAT " initial_heap_size: " SIZE_FORMAT " max_heap: " SIZE_FORMAT, 157 Arguments::min_heap_size(), InitialHeapSize, max_heap); 158 size_t min_new = preferred_max_new_size; 159 if (FLAG_IS_CMDLINE(NewSize)) { 160 min_new = NewSize; 161 } 162 if (max_heap > min_new && Arguments::min_heap_size() > min_new) { 163 // Unless explicitly requested otherwise, make young gen 164 // at least min_new, and at most preferred_max_new_size. 165 if (FLAG_IS_DEFAULT(NewSize)) { 166 FLAG_SET_ERGO(size_t, NewSize, MAX2(NewSize, min_new)); 167 FLAG_SET_ERGO(size_t, NewSize, MIN2(preferred_max_new_size, NewSize)); 168 log_trace(gc, heap)("CMS ergo set NewSize: " SIZE_FORMAT, NewSize); 169 } 170 // Unless explicitly requested otherwise, size old gen 171 // so it's NewRatio x of NewSize. 172 if (FLAG_IS_DEFAULT(OldSize)) { 173 if (max_heap > NewSize) { 174 FLAG_SET_ERGO(size_t, OldSize, MIN2(NewRatio*NewSize, max_heap - NewSize)); 175 log_trace(gc, heap)("CMS ergo set OldSize: " SIZE_FORMAT, OldSize); 176 } 177 } 178 } 179 } 180 // Unless explicitly requested otherwise, definitely 181 // promote all objects surviving "tenuring_default" scavenges. 182 if (FLAG_IS_DEFAULT(MaxTenuringThreshold) && 183 FLAG_IS_DEFAULT(SurvivorRatio)) { 184 FLAG_SET_ERGO(uintx, MaxTenuringThreshold, tenuring_default); 185 } 186 // If we decided above (or user explicitly requested) 187 // `promote all' (via MaxTenuringThreshold := 0), 188 // prefer minuscule survivor spaces so as not to waste 189 // space for (non-existent) survivors 190 if (FLAG_IS_DEFAULT(SurvivorRatio) && MaxTenuringThreshold == 0) { 191 FLAG_SET_ERGO(uintx, SurvivorRatio, MAX2((uintx)1024, SurvivorRatio)); 192 } 193 194 // OldPLABSize is interpreted in CMS as not the size of the PLAB in words, 195 // but rather the number of free blocks of a given size that are used when 196 // replenishing the local per-worker free list caches. 197 if (FLAG_IS_DEFAULT(OldPLABSize)) { 198 if (!FLAG_IS_DEFAULT(ResizeOldPLAB) && !ResizeOldPLAB) { 199 // OldPLAB sizing manually turned off: Use a larger default setting, 200 // unless it was manually specified. This is because a too-low value 201 // will slow down scavenges. 202 FLAG_SET_ERGO(size_t, OldPLABSize, CompactibleFreeListSpaceLAB::_default_static_old_plab_size); // default value before 6631166 203 } else { 204 FLAG_SET_DEFAULT(OldPLABSize, CompactibleFreeListSpaceLAB::_default_dynamic_old_plab_size); // old CMSParPromoteBlocksToClaim default 205 } 206 } 207 208 // If either of the static initialization defaults have changed, note this 209 // modification. 210 if (!FLAG_IS_DEFAULT(OldPLABSize) || !FLAG_IS_DEFAULT(OldPLABWeight)) { 211 CompactibleFreeListSpaceLAB::modify_initialization(OldPLABSize, OldPLABWeight); 212 } 213 214 log_trace(gc)("MarkStackSize: %uk MarkStackSizeMax: %uk", (unsigned int) (MarkStackSize / K), (uint) (MarkStackSizeMax / K)); 215 } 216 217 void CMSArguments::disable_adaptive_size_policy(const char* collector_name) { 218 if (UseAdaptiveSizePolicy) { 219 if (FLAG_IS_CMDLINE(UseAdaptiveSizePolicy)) { 220 warning("Disabling UseAdaptiveSizePolicy; it is incompatible with %s.", 221 collector_name); 222 } 223 FLAG_SET_DEFAULT(UseAdaptiveSizePolicy, false); 224 } 225 } 226 227 CollectedHeap* CMSArguments::create_heap() { 228 return create_heap_with_policy<CMSHeap, ConcurrentMarkSweepPolicy>(); 229 }