1 /*
   2  * Copyright (c) 1997, 2018, Oracle and/or its affiliates. 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 #ifndef SHARE_GC_SHARED_GC_GLOBALS_HPP
  26 #define SHARE_GC_SHARED_GC_GLOBALS_HPP
  27 
  28 #include "utilities/macros.hpp"
  29 #if INCLUDE_CMSGC
  30 #include "gc/cms/cms_globals.hpp"
  31 #endif
  32 #if INCLUDE_G1GC
  33 #include "gc/g1/g1_globals.hpp"
  34 #endif
  35 #if INCLUDE_PARALLELGC
  36 #include "gc/parallel/parallel_globals.hpp"
  37 #endif
  38 #if INCLUDE_SERIALGC
  39 #include "gc/serial/serial_globals.hpp"
  40 #endif
  41 #if INCLUDE_ZGC
  42 #include "gc/z/z_globals.hpp"
  43 #endif
  44 
  45 #define GC_FLAGS(develop,                                                   \
  46                  develop_pd,                                                \
  47                  product,                                                   \
  48                  product_pd,                                                \
  49                  diagnostic,                                                \
  50                  diagnostic_pd,                                             \
  51                  experimental,                                              \
  52                  notproduct,                                                \
  53                  manageable,                                                \
  54                  product_rw,                                                \
  55                  lp64_product,                                              \
  56                  range,                                                     \
  57                  constraint,                                                \
  58                  writeable)                                                 \
  59                                                                             \
  60   CMSGC_ONLY(GC_CMS_FLAGS(                                                  \
  61     develop,                                                                \
  62     develop_pd,                                                             \
  63     product,                                                                \
  64     product_pd,                                                             \
  65     diagnostic,                                                             \
  66     diagnostic_pd,                                                          \
  67     experimental,                                                           \
  68     notproduct,                                                             \
  69     manageable,                                                             \
  70     product_rw,                                                             \
  71     lp64_product,                                                           \
  72     range,                                                                  \
  73     constraint,                                                             \
  74     writeable))                                                             \
  75                                                                             \
  76   G1GC_ONLY(GC_G1_FLAGS(                                                    \
  77     develop,                                                                \
  78     develop_pd,                                                             \
  79     product,                                                                \
  80     product_pd,                                                             \
  81     diagnostic,                                                             \
  82     diagnostic_pd,                                                          \
  83     experimental,                                                           \
  84     notproduct,                                                             \
  85     manageable,                                                             \
  86     product_rw,                                                             \
  87     lp64_product,                                                           \
  88     range,                                                                  \
  89     constraint,                                                             \
  90     writeable))                                                             \
  91                                                                             \
  92   PARALLELGC_ONLY(GC_PARALLEL_FLAGS(                                        \
  93     develop,                                                                \
  94     develop_pd,                                                             \
  95     product,                                                                \
  96     product_pd,                                                             \
  97     diagnostic,                                                             \
  98     diagnostic_pd,                                                          \
  99     experimental,                                                           \
 100     notproduct,                                                             \
 101     manageable,                                                             \
 102     product_rw,                                                             \
 103     lp64_product,                                                           \
 104     range,                                                                  \
 105     constraint,                                                             \
 106     writeable))                                                             \
 107                                                                             \
 108   SERIALGC_ONLY(GC_SERIAL_FLAGS(                                            \
 109     develop,                                                                \
 110     develop_pd,                                                             \
 111     product,                                                                \
 112     product_pd,                                                             \
 113     diagnostic,                                                             \
 114     diagnostic_pd,                                                          \
 115     experimental,                                                           \
 116     notproduct,                                                             \
 117     manageable,                                                             \
 118     product_rw,                                                             \
 119     lp64_product,                                                           \
 120     range,                                                                  \
 121     constraint,                                                             \
 122     writeable))                                                             \
 123                                                                             \
 124   ZGC_ONLY(GC_Z_FLAGS(                                                      \
 125     develop,                                                                \
 126     develop_pd,                                                             \
 127     product,                                                                \
 128     product_pd,                                                             \
 129     diagnostic,                                                             \
 130     diagnostic_pd,                                                          \
 131     experimental,                                                           \
 132     notproduct,                                                             \
 133     manageable,                                                             \
 134     product_rw,                                                             \
 135     lp64_product,                                                           \
 136     range,                                                                  \
 137     constraint,                                                             \
 138     writeable))                                                             \
 139                                                                             \
 140   /* gc */                                                                  \
 141                                                                             \
 142   product(bool, UseConcMarkSweepGC, false,                                  \
 143           "Use Concurrent Mark-Sweep GC in the old generation")             \
 144                                                                             \
 145   product(bool, UseSerialGC, false,                                         \
 146           "Use the Serial garbage collector")                               \
 147                                                                             \
 148   product(bool, UseG1GC, false,                                             \
 149           "Use the Garbage-First garbage collector")                        \
 150                                                                             \
 151   product(bool, UseParallelGC, false,                                       \
 152           "Use the Parallel Scavenge garbage collector")                    \
 153                                                                             \
 154   product(bool, UseParallelOldGC, false,                                    \
 155           "Use the Parallel Old garbage collector")                         \
 156                                                                             \
 157   experimental(bool, UseZGC, false,                                         \
 158           "Use the Z garbage collector")                                    \
 159                                                                             \
 160   product(uint, ParallelGCThreads, 0,                                       \
 161           "Number of parallel threads parallel gc will use")                \
 162           constraint(ParallelGCThreadsConstraintFunc,AfterErgo)             \
 163                                                                             \
 164   diagnostic(bool, UseSemaphoreGCThreadsSynchronization, true,              \
 165             "Use semaphore synchronization for the GC Threads, "            \
 166             "instead of synchronization based on mutexes")                  \
 167                                                                             \
 168   product(bool, UseDynamicNumberOfGCThreads, true,                          \
 169           "Dynamically choose the number of threads up to a maximum of "    \
 170           "ParallelGCThreads parallel collectors will use for garbage "     \
 171           "collection work")                                                \
 172                                                                             \
 173   diagnostic(bool, InjectGCWorkerCreationFailure, false,                    \
 174              "Inject thread creation failures for "                         \
 175              "UseDynamicNumberOfGCThreads")                                 \
 176                                                                             \
 177   diagnostic(bool, ForceDynamicNumberOfGCThreads, false,                    \
 178           "Force dynamic selection of the number of "                       \
 179           "parallel threads parallel gc will use to aid debugging")         \
 180                                                                             \
 181   product(size_t, HeapSizePerGCThread, ScaleForWordSize(32*M),              \
 182           "Size of heap (bytes) per GC thread used in calculating the "     \
 183           "number of GC threads")                                           \
 184           range((size_t)os::vm_page_size(), (size_t)max_uintx)              \
 185                                                                             \
 186   product(uint, ConcGCThreads, 0,                                           \
 187           "Number of threads concurrent gc will use")                       \
 188           constraint(ConcGCThreadsConstraintFunc,AfterErgo)                 \
 189                                                                             \
 190   product(uint, GCTaskTimeStampEntries, 200,                                \
 191           "Number of time stamp entries per gc worker thread")              \
 192           range(1, max_jint)                                                \
 193                                                                             \
 194   product(bool, AlwaysTenure, false,                                        \
 195           "Always tenure objects in eden (ParallelGC only)")                \
 196                                                                             \
 197   product(bool, NeverTenure, false,                                         \
 198           "Never tenure objects in eden, may tenure on overflow "           \
 199           "(ParallelGC only)")                                              \
 200                                                                             \
 201   product(bool, ScavengeBeforeFullGC, true,                                 \
 202           "Scavenge youngest generation before each full GC.")              \
 203                                                                             \
 204   product(bool, ExplicitGCInvokesConcurrent, false,                         \
 205           "A System.gc() request invokes a concurrent collection; "         \
 206           "(effective only when using concurrent collectors)")              \
 207                                                                             \
 208   product(bool, GCLockerInvokesConcurrent, false,                           \
 209           "The exit of a JNI critical section necessitating a scavenge, "   \
 210           "also kicks off a background concurrent collection")              \
 211                                                                             \
 212   product(uintx, GCLockerEdenExpansionPercent, 5,                           \
 213           "How much the GC can expand the eden by while the GC locker "     \
 214           "is active (as a percentage)")                                    \
 215           range(0, 100)                                                     \
 216                                                                             \
 217   diagnostic(uintx, GCLockerRetryAllocationCount, 2,                        \
 218           "Number of times to retry allocations when "                      \
 219           "blocked by the GC locker")                                       \
 220           range(0, max_uintx)                                               \
 221                                                                             \
 222   product(uintx, ParallelGCBufferWastePct, 10,                              \
 223           "Wasted fraction of parallel allocation buffer")                  \
 224           range(0, 100)                                                     \
 225                                                                             \
 226   product(uintx, TargetPLABWastePct, 10,                                    \
 227           "Target wasted space in last buffer as percent of overall "       \
 228           "allocation")                                                     \
 229           range(1, 100)                                                     \
 230                                                                             \
 231   product(uintx, PLABWeight, 75,                                            \
 232           "Percentage (0-100) used to weight the current sample when "      \
 233           "computing exponentially decaying average for ResizePLAB")        \
 234           range(0, 100)                                                     \
 235                                                                             \
 236   product(bool, ResizePLAB, true,                                           \
 237           "Dynamically resize (survivor space) promotion LAB's")            \
 238                                                                             \
 239   product(int, ParGCArrayScanChunk, 50,                                     \
 240           "Scan a subset of object array and push remainder, if array is "  \
 241           "bigger than this")                                               \
 242           range(1, max_jint/3)                                              \
 243                                                                             \
 244   product(uintx, OldPLABWeight, 50,                                         \
 245           "Percentage (0-100) used to weight the current sample when "      \
 246           "computing exponentially decaying average for resizing "          \
 247           "OldPLABSize")                                                    \
 248           range(0, 100)                                                     \
 249                                                                             \
 250   product(bool, ResizeOldPLAB, true,                                        \
 251           "Dynamically resize (old gen) promotion LAB's")                   \
 252                                                                             \
 253   product(bool, AlwaysPreTouch, false,                                      \
 254           "Force all freshly committed pages to be pre-touched")            \
 255                                                                             \
 256   product(size_t, PreTouchParallelChunkSize, 1 * G,                         \
 257           "Per-thread chunk size for parallel memory pre-touch.")           \
 258           range(1, SIZE_MAX / 2)                                            \
 259                                                                             \
 260   /* where does the range max value of (max_jint - 1) come from? */         \
 261   product(size_t, MarkStackSizeMax, NOT_LP64(4*M) LP64_ONLY(512*M),         \
 262           "Maximum size of marking stack")                                  \
 263           range(1, (max_jint - 1))                                          \
 264                                                                             \
 265   product(size_t, MarkStackSize, NOT_LP64(32*K) LP64_ONLY(4*M),             \
 266           "Size of marking stack")                                          \
 267           constraint(MarkStackSizeConstraintFunc,AfterErgo)                 \
 268                                                                             \
 269   develop(bool, VerifyBlockOffsetArray, false,                              \
 270           "Do (expensive) block offset array verification")                 \
 271                                                                             \
 272   diagnostic(bool, BlockOffsetArrayUseUnallocatedBlock, false,              \
 273           "Maintain _unallocated_block in BlockOffsetArray "                \
 274           "(currently applicable only to CMS collector)")                   \
 275                                                                             \
 276   product(intx, RefDiscoveryPolicy, 0,                                      \
 277           "Select type of reference discovery policy: "                     \
 278           "reference-based(0) or referent-based(1)")                        \
 279           range(ReferenceProcessor::DiscoveryPolicyMin,                     \
 280                 ReferenceProcessor::DiscoveryPolicyMax)                     \
 281                                                                             \
 282   product(bool, ParallelRefProcEnabled, false,                              \
 283           "Enable parallel reference processing whenever possible")         \
 284                                                                             \
 285   product(bool, ParallelRefProcBalancingEnabled, true,                      \
 286           "Enable balancing of reference processing queues")                \
 287                                                                             \
 288   product(uintx, InitiatingHeapOccupancyPercent, 45,                        \
 289           "The percent occupancy (IHOP) of the current old generation "     \
 290           "capacity above which a concurrent mark cycle will be initiated " \
 291           "Its value may change over time if adaptive IHOP is enabled, "    \
 292           "otherwise the value remains constant. "                          \
 293           "In the latter case a value of 0 will result as frequent as "     \
 294           "possible concurrent marking cycles. A value of 100 disables "    \
 295           "concurrent marking. "                                            \
 296           "Fragmentation waste in the old generation is not considered "    \
 297           "free space in this calculation. (G1 collector only)")            \
 298           range(0, 100)                                                     \
 299                                                                             \
 300   notproduct(bool, ScavengeALot, false,                                     \
 301           "Force scavenge at every Nth exit from the runtime system "       \
 302           "(N=ScavengeALotInterval)")                                       \
 303                                                                             \
 304   develop(bool, FullGCALot, false,                                          \
 305           "Force full gc at every Nth exit from the runtime system "        \
 306           "(N=FullGCALotInterval)")                                         \
 307                                                                             \
 308   notproduct(bool, GCALotAtAllSafepoints, false,                            \
 309           "Enforce ScavengeALot/GCALot at all potential safepoints")        \
 310                                                                             \
 311   notproduct(bool, PromotionFailureALot, false,                             \
 312           "Use promotion failure handling on every youngest generation "    \
 313           "collection")                                                     \
 314                                                                             \
 315   develop(uintx, PromotionFailureALotCount, 1000,                           \
 316           "Number of promotion failures occurring at PLAB "                 \
 317           "refill attempts (ParNew) or promotion attempts "                 \
 318           "(other young collectors)")                                       \
 319                                                                             \
 320   develop(uintx, PromotionFailureALotInterval, 5,                           \
 321           "Total collections between promotion failures a lot")             \
 322                                                                             \
 323   experimental(uintx, WorkStealingSleepMillis, 1,                           \
 324           "Sleep time when sleep is used for yields")                       \
 325                                                                             \
 326   experimental(uintx, WorkStealingYieldsBeforeSleep, 5000,                  \
 327           "Number of yields before a sleep is done during work stealing")   \
 328                                                                             \
 329   experimental(uintx, WorkStealingHardSpins, 4096,                          \
 330           "Number of iterations in a spin loop between checks on "          \
 331           "time out of hard spin")                                          \
 332                                                                             \
 333   experimental(uintx, WorkStealingSpinToYieldRatio, 10,                     \
 334           "Ratio of hard spins to calls to yield")                          \
 335                                                                             \
 336   develop(uintx, ObjArrayMarkingStride, 2048,                               \
 337           "Number of object array elements to push onto the marking stack " \
 338           "before pushing a continuation entry")                            \
 339                                                                             \
 340   develop(bool, MetadataAllocationFailALot, false,                          \
 341           "Fail metadata allocations at intervals controlled by "           \
 342           "MetadataAllocationFailALotInterval")                             \
 343                                                                             \
 344   develop(uintx, MetadataAllocationFailALotInterval, 1000,                  \
 345           "Metadata allocation failure a lot interval")                     \
 346                                                                             \
 347   notproduct(bool, ExecuteInternalVMTests, false,                           \
 348           "Enable execution of internal VM tests")                          \
 349                                                                             \
 350   notproduct(bool, VerboseInternalVMTests, false,                           \
 351           "Turn on logging for internal VM tests.")                         \
 352                                                                             \
 353   product(bool, ExecutingUnitTests, false,                                  \
 354           "Whether the JVM is running unit tests or not")                   \
 355                                                                             \
 356   product_pd(bool, UseTLAB, "Use thread-local object allocation")           \
 357                                                                             \
 358   product_pd(bool, ResizeTLAB,                                              \
 359           "Dynamically resize TLAB size for threads")                       \
 360                                                                             \
 361   product(bool, ZeroTLAB, false,                                            \
 362           "Zero out the newly created TLAB")                                \
 363                                                                             \
 364   product(bool, TLABStats, true,                                            \
 365           "Provide more detailed and expensive TLAB statistics.")           \
 366                                                                             \
 367   product_pd(bool, NeverActAsServerClassMachine,                            \
 368           "Never act like a server-class machine")                          \
 369                                                                             \
 370   product(bool, AlwaysActAsServerClassMachine, false,                       \
 371           "Always act like a server-class machine")                         \
 372                                                                             \
 373   product_pd(uint64_t, MaxRAM,                                              \
 374           "Real memory size (in bytes) used to set maximum heap size")      \
 375           range(0, 0XFFFFFFFFFFFFFFFF)                                      \
 376                                                                             \
 377   product(bool, AggressiveHeap, false,                                      \
 378           "Optimize heap options for long-running memory intensive apps")   \
 379                                                                             \
 380   product(size_t, ErgoHeapSizeLimit, 0,                                     \
 381           "Maximum ergonomically set heap size (in bytes); zero means use " \
 382           "MaxRAM * MaxRAMPercentage / 100")                                \
 383           range(0, max_uintx)                                               \
 384                                                                             \
 385   product(uintx, MaxRAMFraction, 4,                                         \
 386           "Maximum fraction (1/n) of real memory used for maximum heap "    \
 387           "size. "                                                          \
 388           "Deprecated, use MaxRAMPercentage instead")                       \
 389           range(1, max_uintx)                                               \
 390                                                                             \
 391   product(uintx, MinRAMFraction, 2,                                         \
 392           "Minimum fraction (1/n) of real memory used for maximum heap "    \
 393           "size on systems with small physical memory size. "               \
 394           "Deprecated, use MinRAMPercentage instead")                       \
 395           range(1, max_uintx)                                               \
 396                                                                             \
 397   product(uintx, InitialRAMFraction, 64,                                    \
 398           "Fraction (1/n) of real memory used for initial heap size. "      \
 399           "Deprecated, use InitialRAMPercentage instead")                   \
 400           range(1, max_uintx)                                               \
 401                                                                             \
 402   product(double, MaxRAMPercentage, 25.0,                                   \
 403           "Maximum percentage of real memory used for maximum heap size")   \
 404           range(0.0, 100.0)                                                 \
 405                                                                             \
 406   product(double, MinRAMPercentage, 50.0,                                   \
 407           "Minimum percentage of real memory used for maximum heap"         \
 408           "size on systems with small physical memory size")                \
 409           range(0.0, 100.0)                                                 \
 410                                                                             \
 411   product(double, InitialRAMPercentage, 1.5625,                             \
 412           "Percentage of real memory used for initial heap size")           \
 413           range(0.0, 100.0)                                                 \
 414                                                                             \
 415   product(int, ActiveProcessorCount, -1,                                    \
 416           "Specify the CPU count the VM should use and report as active")   \
 417                                                                             \
 418   develop(uintx, MaxVirtMemFraction, 2,                                     \
 419           "Maximum fraction (1/n) of virtual memory used for ergonomically "\
 420           "determining maximum heap size")                                  \
 421                                                                             \
 422   product(bool, UseAdaptiveSizePolicy, true,                                \
 423           "Use adaptive generation sizing policies")                        \
 424                                                                             \
 425   product(bool, UsePSAdaptiveSurvivorSizePolicy, true,                      \
 426           "Use adaptive survivor sizing policies")                          \
 427                                                                             \
 428   product(bool, UseAdaptiveGenerationSizePolicyAtMinorCollection, true,     \
 429           "Use adaptive young-old sizing policies at minor collections")    \
 430                                                                             \
 431   product(bool, UseAdaptiveGenerationSizePolicyAtMajorCollection, true,     \
 432           "Use adaptive young-old sizing policies at major collections")    \
 433                                                                             \
 434   product(bool, UseAdaptiveSizePolicyWithSystemGC, false,                   \
 435           "Include statistics from System.gc() for adaptive size policy")   \
 436                                                                             \
 437   product(bool, UseAdaptiveGCBoundary, false,                               \
 438           "Allow young-old boundary to move")                               \
 439                                                                             \
 440   develop(intx, PSAdaptiveSizePolicyResizeVirtualSpaceAlot, -1,             \
 441           "Resize the virtual spaces of the young or old generations")      \
 442           range(-1, 1)                                                      \
 443                                                                             \
 444   product(uintx, AdaptiveSizeThroughPutPolicy, 0,                           \
 445           "Policy for changing generation size for throughput goals")       \
 446           range(0, 1)                                                       \
 447                                                                             \
 448   product(uintx, AdaptiveSizePolicyInitializingSteps, 20,                   \
 449           "Number of steps where heuristics is used before data is used")   \
 450           range(0, max_uintx)                                               \
 451                                                                             \
 452   develop(uintx, AdaptiveSizePolicyReadyThreshold, 5,                       \
 453           "Number of collections before the adaptive sizing is started")    \
 454                                                                             \
 455   product(uintx, AdaptiveSizePolicyOutputInterval, 0,                       \
 456           "Collection interval for printing information; zero means never") \
 457           range(0, max_uintx)                                               \
 458                                                                             \
 459   product(bool, UseAdaptiveSizePolicyFootprintGoal, true,                   \
 460           "Use adaptive minimum footprint as a goal")                       \
 461                                                                             \
 462   product(uintx, AdaptiveSizePolicyWeight, 10,                              \
 463           "Weight given to exponential resizing, between 0 and 100")        \
 464           range(0, 100)                                                     \
 465                                                                             \
 466   product(uintx, AdaptiveTimeWeight,       25,                              \
 467           "Weight given to time in adaptive policy, between 0 and 100")     \
 468           range(0, 100)                                                     \
 469                                                                             \
 470   product(uintx, PausePadding, 1,                                           \
 471           "How much buffer to keep for pause time")                         \
 472           range(0, max_juint)                                               \
 473                                                                             \
 474   product(uintx, PromotedPadding, 3,                                        \
 475           "How much buffer to keep for promotion failure")                  \
 476           range(0, max_juint)                                               \
 477                                                                             \
 478   product(uintx, SurvivorPadding, 3,                                        \
 479           "How much buffer to keep for survivor overflow")                  \
 480           range(0, max_juint)                                               \
 481                                                                             \
 482   product(uintx, ThresholdTolerance, 10,                                    \
 483           "Allowed collection cost difference between generations")         \
 484           range(0, 100)                                                     \
 485                                                                             \
 486   product(uintx, AdaptiveSizePolicyCollectionCostMargin, 50,                \
 487           "If collection costs are within margin, reduce both by full "     \
 488           "delta")                                                          \
 489           range(0, 100)                                                     \
 490                                                                             \
 491   product(uintx, YoungGenerationSizeIncrement, 20,                          \
 492           "Adaptive size percentage change in young generation")            \
 493           range(0, 100)                                                     \
 494                                                                             \
 495   product(uintx, YoungGenerationSizeSupplement, 80,                         \
 496           "Supplement to YoungedGenerationSizeIncrement used at startup")   \
 497           range(0, 100)                                                     \
 498                                                                             \
 499   product(uintx, YoungGenerationSizeSupplementDecay, 8,                     \
 500           "Decay factor to YoungedGenerationSizeSupplement")                \
 501           range(1, max_uintx)                                               \
 502                                                                             \
 503   product(uintx, TenuredGenerationSizeIncrement, 20,                        \
 504           "Adaptive size percentage change in tenured generation")          \
 505           range(0, 100)                                                     \
 506                                                                             \
 507   product(uintx, TenuredGenerationSizeSupplement, 80,                       \
 508           "Supplement to TenuredGenerationSizeIncrement used at startup")   \
 509           range(0, 100)                                                     \
 510                                                                             \
 511   product(uintx, TenuredGenerationSizeSupplementDecay, 2,                   \
 512           "Decay factor to TenuredGenerationSizeIncrement")                 \
 513           range(1, max_uintx)                                               \
 514                                                                             \
 515   product(uintx, MaxGCPauseMillis, max_uintx - 1,                           \
 516           "Adaptive size policy maximum GC pause time goal in millisecond, "\
 517           "or (G1 Only) the maximum GC time per MMU time slice")            \
 518           range(1, max_uintx - 1)                                           \
 519           constraint(MaxGCPauseMillisConstraintFunc,AfterErgo)              \
 520                                                                             \
 521   product(uintx, GCPauseIntervalMillis, 0,                                  \
 522           "Time slice for MMU specification")                               \
 523           constraint(GCPauseIntervalMillisConstraintFunc,AfterErgo)         \
 524                                                                             \
 525   product(uintx, MaxGCMinorPauseMillis, max_uintx,                          \
 526           "Adaptive size policy maximum GC minor pause time goal "          \
 527           "in millisecond")                                                 \
 528           range(0, max_uintx)                                               \
 529                                                                             \
 530   product(uintx, GCTimeRatio, 99,                                           \
 531           "Adaptive size policy application time to GC time ratio")         \
 532           range(0, max_juint)                                               \
 533                                                                             \
 534   product(uintx, AdaptiveSizeDecrementScaleFactor, 4,                       \
 535           "Adaptive size scale down factor for shrinking")                  \
 536           range(1, max_uintx)                                               \
 537                                                                             \
 538   product(bool, UseAdaptiveSizeDecayMajorGCCost, true,                      \
 539           "Adaptive size decays the major cost for long major intervals")   \
 540                                                                             \
 541   product(uintx, AdaptiveSizeMajorGCDecayTimeScale, 10,                     \
 542           "Time scale over which major costs decay")                        \
 543           range(0, max_uintx)                                               \
 544                                                                             \
 545   product(uintx, MinSurvivorRatio, 3,                                       \
 546           "Minimum ratio of young generation/survivor space size")          \
 547           range(3, max_uintx)                                               \
 548                                                                             \
 549   product(uintx, InitialSurvivorRatio, 8,                                   \
 550           "Initial ratio of young generation/survivor space size")          \
 551           range(0, max_uintx)                                               \
 552                                                                             \
 553   product(size_t, BaseFootPrintEstimate, 256*M,                             \
 554           "Estimate of footprint other than Java Heap")                     \
 555           range(0, max_uintx)                                               \
 556                                                                             \
 557   product(bool, UseGCOverheadLimit, true,                                   \
 558           "Use policy to limit of proportion of time spent in GC "          \
 559           "before an OutOfMemory error is thrown")                          \
 560                                                                             \
 561   product(uintx, GCTimeLimit, 98,                                           \
 562           "Limit of the proportion of time spent in GC before "             \
 563           "an OutOfMemoryError is thrown (used with GCHeapFreeLimit)")      \
 564           range(0, 100)                                                     \
 565                                                                             \
 566   product(uintx, GCHeapFreeLimit, 2,                                        \
 567           "Minimum percentage of free space after a full GC before an "     \
 568           "OutOfMemoryError is thrown (used with GCTimeLimit)")             \
 569           range(0, 100)                                                     \
 570                                                                             \
 571   develop(uintx, AdaptiveSizePolicyGCTimeLimitThreshold, 5,                 \
 572           "Number of consecutive collections before gc time limit fires")   \
 573           range(1, max_uintx)                                               \
 574                                                                             \
 575   product(intx, PrefetchCopyIntervalInBytes, -1,                            \
 576           "How far ahead to prefetch destination area (<= 0 means off)")    \
 577           range(-1, max_jint)                                               \
 578                                                                             \
 579   product(intx, PrefetchScanIntervalInBytes, -1,                            \
 580           "How far ahead to prefetch scan area (<= 0 means off)")           \
 581           range(-1, max_jint)                                               \
 582                                                                             \
 583   product(intx, PrefetchFieldsAhead, -1,                                    \
 584           "How many fields ahead to prefetch in oop scan (<= 0 means off)") \
 585           range(-1, max_jint)                                               \
 586                                                                             \
 587   diagnostic(bool, VerifyDuringStartup, false,                              \
 588           "Verify memory system before executing any Java code "            \
 589           "during VM initialization")                                       \
 590                                                                             \
 591   diagnostic(bool, VerifyBeforeExit, trueInDebug,                           \
 592           "Verify system before exiting")                                   \
 593                                                                             \
 594   diagnostic(bool, VerifyBeforeGC, false,                                   \
 595           "Verify memory system before GC")                                 \
 596                                                                             \
 597   diagnostic(bool, VerifyAfterGC, false,                                    \
 598           "Verify memory system after GC")                                  \
 599                                                                             \
 600   diagnostic(bool, VerifyDuringGC, false,                                   \
 601           "Verify memory system during GC (between phases)")                \
 602                                                                             \
 603   diagnostic(ccstrlist, VerifyGCType, "",                                   \
 604              "GC type(s) to verify when Verify*GC is enabled."              \
 605              "Available types are collector specific.")                     \
 606                                                                             \
 607   diagnostic(ccstrlist, VerifySubSet, "",                                   \
 608           "Memory sub-systems to verify when Verify*GC flag(s) "            \
 609           "are enabled. One or more sub-systems can be specified "          \
 610           "in a comma separated string. Sub-systems are: "                  \
 611           "threads, heap, symbol_table, string_table, codecache, "          \
 612           "dictionary, classloader_data_graph, metaspace, jni_handles, "    \
 613           "codecache_oops")                                                 \
 614                                                                             \
 615   diagnostic(bool, GCParallelVerificationEnabled, true,                     \
 616           "Enable parallel memory system verification")                     \
 617                                                                             \
 618   diagnostic(bool, DeferInitialCardMark, false,                             \
 619           "When +ReduceInitialCardMarks, explicitly defer any that "        \
 620           "may arise from new_pre_store_barrier")                           \
 621                                                                             \
 622   product(bool, UseCondCardMark, false,                                     \
 623           "Check for already marked card before updating card table")       \
 624                                                                             \
 625   diagnostic(bool, VerifyRememberedSets, false,                             \
 626           "Verify GC remembered sets")                                      \
 627                                                                             \
 628   diagnostic(bool, VerifyObjectStartArray, true,                            \
 629           "Verify GC object start array if verify before/after")            \
 630                                                                             \
 631   product(bool, DisableExplicitGC, false,                                   \
 632           "Ignore calls to System.gc()")                                    \
 633                                                                             \
 634   product(bool, BindGCTaskThreadsToCPUs, false,                             \
 635           "Bind GCTaskThreads to CPUs if possible")                         \
 636                                                                             \
 637   product(bool, UseGCTaskAffinity, false,                                   \
 638           "Use worker affinity when asking for GCTasks")                    \
 639                                                                             \
 640   product(bool, PrintGC, false,                                             \
 641           "Print message at garbage collection. "                           \
 642           "Deprecated, use -Xlog:gc instead.")                              \
 643                                                                             \
 644   product(bool, PrintGCDetails, false,                                      \
 645           "Print more details at garbage collection. "                      \
 646           "Deprecated, use -Xlog:gc* instead.")                             \
 647                                                                             \
 648   develop(intx, ConcGCYieldTimeout, 0,                                      \
 649           "If non-zero, assert that GC threads yield within this "          \
 650           "number of milliseconds")                                         \
 651           range(0, max_intx)                                                \
 652                                                                             \
 653   notproduct(intx, ScavengeALotInterval,     1,                             \
 654           "Interval between which scavenge will occur with +ScavengeALot")  \
 655                                                                             \
 656   notproduct(intx, FullGCALotInterval,     1,                               \
 657           "Interval between which full gc will occur with +FullGCALot")     \
 658                                                                             \
 659   notproduct(intx, FullGCALotStart,     0,                                  \
 660           "For which invocation to start FullGCAlot")                       \
 661                                                                             \
 662   notproduct(intx, FullGCALotDummies,  32*K,                                \
 663           "Dummy object allocated with +FullGCALot, forcing all objects "   \
 664           "to move")                                                        \
 665                                                                             \
 666   /* gc parameters */                                                       \
 667   product(size_t, InitialHeapSize, 0,                                       \
 668           "Initial heap size (in bytes); zero means use ergonomics")        \
 669           constraint(InitialHeapSizeConstraintFunc,AfterErgo)               \
 670                                                                             \
 671   product(size_t, MaxHeapSize, ScaleForWordSize(96*M),                      \
 672           "Maximum heap size (in bytes)")                                   \
 673           constraint(MaxHeapSizeConstraintFunc,AfterErgo)                   \
 674                                                                             \
 675   product(size_t, OldSize, ScaleForWordSize(4*M),                           \
 676           "Initial tenured generation size (in bytes)")                     \
 677           range(0, max_uintx)                                               \
 678                                                                             \
 679   product(size_t, NewSize, ScaleForWordSize(1*M),                           \
 680           "Initial new generation size (in bytes)")                         \
 681           constraint(NewSizeConstraintFunc,AfterErgo)                       \
 682                                                                             \
 683   product(size_t, MaxNewSize, max_uintx,                                    \
 684           "Maximum new generation size (in bytes), max_uintx means set "    \
 685           "ergonomically")                                                  \
 686           range(0, max_uintx)                                               \
 687                                                                             \
 688   product_pd(size_t, HeapBaseMinAddress,                                    \
 689           "OS specific low limit for heap base address")                    \
 690           constraint(HeapBaseMinAddressConstraintFunc,AfterErgo)            \
 691                                                                             \
 692   product(size_t, PretenureSizeThreshold, 0,                                \
 693           "Maximum size in bytes of objects allocated in DefNew "           \
 694           "generation; zero means no maximum")                              \
 695           range(0, max_uintx)                                               \
 696                                                                             \
 697   product(size_t, MinTLABSize, 2*K,                                         \
 698           "Minimum allowed TLAB size (in bytes)")                           \
 699           range(1, max_uintx/2)                                             \
 700           constraint(MinTLABSizeConstraintFunc,AfterMemoryInit)             \
 701                                                                             \
 702   product(size_t, TLABSize, 0,                                              \
 703           "Starting TLAB size (in bytes); zero means set ergonomically")    \
 704           constraint(TLABSizeConstraintFunc,AfterMemoryInit)                \
 705                                                                             \
 706   product(size_t, YoungPLABSize, 4096,                                      \
 707           "Size of young gen promotion LAB's (in HeapWords)")               \
 708           constraint(YoungPLABSizeConstraintFunc,AfterMemoryInit)           \
 709                                                                             \
 710   product(size_t, OldPLABSize, 1024,                                        \
 711           "Size of old gen promotion LAB's (in HeapWords), or Number "      \
 712           "of blocks to attempt to claim when refilling CMS LAB's")         \
 713           constraint(OldPLABSizeConstraintFunc,AfterMemoryInit)             \
 714                                                                             \
 715   product(uintx, TLABAllocationWeight, 35,                                  \
 716           "Allocation averaging weight")                                    \
 717           range(0, 100)                                                     \
 718                                                                             \
 719   /* Limit the lower bound of this flag to 1 as it is used  */              \
 720   /* in a division expression.                              */              \
 721   product(uintx, TLABWasteTargetPercent, 1,                                 \
 722           "Percentage of Eden that can be wasted")                          \
 723           range(1, 100)                                                     \
 724                                                                             \
 725   product(uintx, TLABRefillWasteFraction,    64,                            \
 726           "Maximum TLAB waste at a refill (internal fragmentation)")        \
 727           range(1, max_juint)                                               \
 728                                                                             \
 729   product(uintx, TLABWasteIncrement,    4,                                  \
 730           "Increment allowed waste at slow allocation")                     \
 731           range(0, max_jint)                                                \
 732           constraint(TLABWasteIncrementConstraintFunc,AfterMemoryInit)      \
 733                                                                             \
 734   product(uintx, SurvivorRatio, 8,                                          \
 735           "Ratio of eden/survivor space size")                              \
 736           range(1, max_uintx-2)                                             \
 737           constraint(SurvivorRatioConstraintFunc,AfterMemoryInit)           \
 738                                                                             \
 739   product(uintx, NewRatio, 2,                                               \
 740           "Ratio of old/new generation sizes")                              \
 741           range(0, max_uintx-1)                                             \
 742                                                                             \
 743   product_pd(size_t, NewSizeThreadIncrease,                                 \
 744           "Additional size added to desired new generation size per "       \
 745           "non-daemon thread (in bytes)")                                   \
 746           range(0, max_uintx)                                               \
 747                                                                             \
 748   product(uintx, QueuedAllocationWarningCount, 0,                           \
 749           "Number of times an allocation that queues behind a GC "          \
 750           "will retry before printing a warning")                           \
 751           range(0, max_uintx)                                               \
 752                                                                             \
 753   diagnostic(uintx, VerifyGCStartAt,   0,                                   \
 754           "GC invoke count where +VerifyBefore/AfterGC kicks in")           \
 755           range(0, max_uintx)                                               \
 756                                                                             \
 757   diagnostic(intx, VerifyGCLevel,     0,                                    \
 758           "Generation level at which to start +VerifyBefore/AfterGC")       \
 759           range(0, 1)                                                       \
 760                                                                             \
 761   product(uintx, MaxTenuringThreshold,    15,                               \
 762           "Maximum value for tenuring threshold")                           \
 763           range(0, markOopDesc::max_age + 1)                                \
 764           constraint(MaxTenuringThresholdConstraintFunc,AfterErgo)          \
 765                                                                             \
 766   product(uintx, InitialTenuringThreshold,    7,                            \
 767           "Initial value for tenuring threshold")                           \
 768           range(0, markOopDesc::max_age + 1)                                \
 769           constraint(InitialTenuringThresholdConstraintFunc,AfterErgo)      \
 770                                                                             \
 771   product(uintx, TargetSurvivorRatio,    50,                                \
 772           "Desired percentage of survivor space used after scavenge")       \
 773           range(0, 100)                                                     \
 774                                                                             \
 775   product(uintx, MarkSweepDeadRatio,     5,                                 \
 776           "Percentage (0-100) of the old gen allowed as dead wood. "        \
 777           "Serial mark sweep treats this as both the minimum and maximum "  \
 778           "value. "                                                         \
 779           "CMS uses this value only if it falls back to mark sweep. "       \
 780           "Par compact uses a variable scale based on the density of the "  \
 781           "generation and treats this as the maximum value when the heap "  \
 782           "is either completely full or completely empty.  Par compact "    \
 783           "also has a smaller default value; see arguments.cpp.")           \
 784           range(0, 100)                                                     \
 785                                                                             \
 786   product(uint, MarkSweepAlwaysCompactCount,     4,                         \
 787           "How often should we fully compact the heap (ignoring the dead "  \
 788           "space parameters)")                                              \
 789           range(1, max_juint)                                               \
 790                                                                             \
 791   develop(uintx, GCExpandToAllocateDelayMillis, 0,                          \
 792           "Delay between expansion and allocation (in milliseconds)")       \
 793                                                                             \
 794   product(uintx, GCDrainStackTargetSize, 64,                                \
 795           "Number of entries we will try to leave on the stack "            \
 796           "during parallel gc")                                             \
 797           range(0, max_juint)
 798 
 799 #endif // SHARE_GC_SHARED_GC_GLOBALS_HPP