1 /*
   2  * Copyright (c) 1997, 2019, 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 "runtime/globals_shared.hpp"
  29 #include "utilities/macros.hpp"
  30 #if INCLUDE_CMSGC
  31 #include "gc/cms/cms_globals.hpp"
  32 #endif
  33 #if INCLUDE_EPSILONGC
  34 #include "gc/epsilon/epsilon_globals.hpp"
  35 #endif
  36 #if INCLUDE_G1GC
  37 #include "gc/g1/g1_globals.hpp"
  38 #endif
  39 #if INCLUDE_PARALLELGC
  40 #include "gc/parallel/parallel_globals.hpp"
  41 #endif
  42 #if INCLUDE_SERIALGC
  43 #include "gc/serial/serial_globals.hpp"
  44 #endif
  45 #if INCLUDE_SHENANDOAHGC
  46 #include "gc/shenandoah/shenandoah_globals.hpp"
  47 #endif
  48 #if INCLUDE_ZGC
  49 #include "gc/z/z_globals.hpp"
  50 #endif
  51 
  52 #define GC_FLAGS(develop,                                                   \
  53                  develop_pd,                                                \
  54                  product,                                                   \
  55                  product_pd,                                                \
  56                  diagnostic,                                                \
  57                  diagnostic_pd,                                             \
  58                  experimental,                                              \
  59                  notproduct,                                                \
  60                  manageable,                                                \
  61                  product_rw,                                                \
  62                  lp64_product,                                              \
  63                  range,                                                     \
  64                  constraint,                                                \
  65                  writeable)                                                 \
  66                                                                             \
  67   CMSGC_ONLY(GC_CMS_FLAGS(                                                  \
  68     develop,                                                                \
  69     develop_pd,                                                             \
  70     product,                                                                \
  71     product_pd,                                                             \
  72     diagnostic,                                                             \
  73     diagnostic_pd,                                                          \
  74     experimental,                                                           \
  75     notproduct,                                                             \
  76     manageable,                                                             \
  77     product_rw,                                                             \
  78     lp64_product,                                                           \
  79     range,                                                                  \
  80     constraint,                                                             \
  81     writeable))                                                             \
  82                                                                             \
  83   EPSILONGC_ONLY(GC_EPSILON_FLAGS(                                          \
  84     develop,                                                                \
  85     develop_pd,                                                             \
  86     product,                                                                \
  87     product_pd,                                                             \
  88     diagnostic,                                                             \
  89     diagnostic_pd,                                                          \
  90     experimental,                                                           \
  91     notproduct,                                                             \
  92     manageable,                                                             \
  93     product_rw,                                                             \
  94     lp64_product,                                                           \
  95     range,                                                                  \
  96     constraint,                                                             \
  97     writeable))                                                             \
  98                                                                             \
  99   G1GC_ONLY(GC_G1_FLAGS(                                                    \
 100     develop,                                                                \
 101     develop_pd,                                                             \
 102     product,                                                                \
 103     product_pd,                                                             \
 104     diagnostic,                                                             \
 105     diagnostic_pd,                                                          \
 106     experimental,                                                           \
 107     notproduct,                                                             \
 108     manageable,                                                             \
 109     product_rw,                                                             \
 110     lp64_product,                                                           \
 111     range,                                                                  \
 112     constraint,                                                             \
 113     writeable))                                                             \
 114                                                                             \
 115   PARALLELGC_ONLY(GC_PARALLEL_FLAGS(                                        \
 116     develop,                                                                \
 117     develop_pd,                                                             \
 118     product,                                                                \
 119     product_pd,                                                             \
 120     diagnostic,                                                             \
 121     diagnostic_pd,                                                          \
 122     experimental,                                                           \
 123     notproduct,                                                             \
 124     manageable,                                                             \
 125     product_rw,                                                             \
 126     lp64_product,                                                           \
 127     range,                                                                  \
 128     constraint,                                                             \
 129     writeable))                                                             \
 130                                                                             \
 131   SERIALGC_ONLY(GC_SERIAL_FLAGS(                                            \
 132     develop,                                                                \
 133     develop_pd,                                                             \
 134     product,                                                                \
 135     product_pd,                                                             \
 136     diagnostic,                                                             \
 137     diagnostic_pd,                                                          \
 138     experimental,                                                           \
 139     notproduct,                                                             \
 140     manageable,                                                             \
 141     product_rw,                                                             \
 142     lp64_product,                                                           \
 143     range,                                                                  \
 144     constraint,                                                             \
 145     writeable))                                                             \
 146                                                                             \
 147   SHENANDOAHGC_ONLY(GC_SHENANDOAH_FLAGS(                                    \
 148     develop,                                                                \
 149     develop_pd,                                                             \
 150     product,                                                                \
 151     product_pd,                                                             \
 152     diagnostic,                                                             \
 153     diagnostic_pd,                                                          \
 154     experimental,                                                           \
 155     notproduct,                                                             \
 156     manageable,                                                             \
 157     product_rw,                                                             \
 158     lp64_product,                                                           \
 159     range,                                                                  \
 160     constraint,                                                             \
 161     writeable))                                                             \
 162                                                                             \
 163   ZGC_ONLY(GC_Z_FLAGS(                                                      \
 164     develop,                                                                \
 165     develop_pd,                                                             \
 166     product,                                                                \
 167     product_pd,                                                             \
 168     diagnostic,                                                             \
 169     diagnostic_pd,                                                          \
 170     experimental,                                                           \
 171     notproduct,                                                             \
 172     manageable,                                                             \
 173     product_rw,                                                             \
 174     lp64_product,                                                           \
 175     range,                                                                  \
 176     constraint,                                                             \
 177     writeable))                                                             \
 178                                                                             \
 179   /* gc */                                                                  \
 180                                                                             \
 181   product(bool, UseConcMarkSweepGC, false,                                  \
 182           "Use Concurrent Mark-Sweep GC in the old generation")             \
 183                                                                             \
 184   product(bool, UseSerialGC, false,                                         \
 185           "Use the Serial garbage collector")                               \
 186                                                                             \
 187   product(bool, UseG1GC, false,                                             \
 188           "Use the Garbage-First garbage collector")                        \
 189                                                                             \
 190   product(bool, UseParallelGC, false,                                       \
 191           "Use the Parallel Scavenge garbage collector")                    \
 192                                                                             \
 193   product(bool, UseParallelOldGC, false,                                    \
 194           "Use the Parallel Old garbage collector")                         \
 195                                                                             \
 196   experimental(bool, UseEpsilonGC, false,                                   \
 197           "Use the Epsilon (no-op) garbage collector")                      \
 198                                                                             \
 199   experimental(bool, UseZGC, false,                                         \
 200           "Use the Z garbage collector")                                    \
 201                                                                             \
 202   experimental(bool, UseShenandoahGC, false,                                \
 203           "Use the Shenandoah garbage collector")                           \
 204                                                                             \
 205   product(uint, ParallelGCThreads, 0,                                       \
 206           "Number of parallel threads parallel gc will use")                \
 207           constraint(ParallelGCThreadsConstraintFunc,AfterErgo)             \
 208                                                                             \
 209   diagnostic(bool, UseSemaphoreGCThreadsSynchronization, true,              \
 210             "Use semaphore synchronization for the GC Threads, "            \
 211             "instead of synchronization based on mutexes")                  \
 212                                                                             \
 213   product(bool, UseDynamicNumberOfGCThreads, true,                          \
 214           "Dynamically choose the number of threads up to a maximum of "    \
 215           "ParallelGCThreads parallel collectors will use for garbage "     \
 216           "collection work")                                                \
 217                                                                             \
 218   diagnostic(bool, InjectGCWorkerCreationFailure, false,                    \
 219              "Inject thread creation failures for "                         \
 220              "UseDynamicNumberOfGCThreads")                                 \
 221                                                                             \
 222   diagnostic(bool, ForceDynamicNumberOfGCThreads, false,                    \
 223           "Force dynamic selection of the number of "                       \
 224           "parallel threads parallel gc will use to aid debugging")         \
 225                                                                             \
 226   product(size_t, HeapSizePerGCThread, ScaleForWordSize(32*M),              \
 227           "Size of heap (bytes) per GC thread used in calculating the "     \
 228           "number of GC threads")                                           \
 229           range((size_t)os::vm_page_size(), (size_t)max_uintx)              \
 230                                                                             \
 231   product(uint, ConcGCThreads, 0,                                           \
 232           "Number of threads concurrent gc will use")                       \
 233           constraint(ConcGCThreadsConstraintFunc,AfterErgo)                 \
 234                                                                             \
 235   product(uint, GCTaskTimeStampEntries, 200,                                \
 236           "Number of time stamp entries per gc worker thread")              \
 237           range(1, max_jint)                                                \
 238                                                                             \
 239   product(bool, AlwaysTenure, false,                                        \
 240           "Always tenure objects in eden (ParallelGC only)")                \
 241                                                                             \
 242   product(bool, NeverTenure, false,                                         \
 243           "Never tenure objects in eden, may tenure on overflow "           \
 244           "(ParallelGC only)")                                              \
 245                                                                             \
 246   product(bool, ScavengeBeforeFullGC, true,                                 \
 247           "Scavenge youngest generation before each full GC.")              \
 248                                                                             \
 249   product(bool, ExplicitGCInvokesConcurrent, false,                         \
 250           "A System.gc() request invokes a concurrent collection; "         \
 251           "(effective only when using concurrent collectors)")              \
 252                                                                             \
 253   product(bool, GCLockerInvokesConcurrent, false,                           \
 254           "The exit of a JNI critical section necessitating a scavenge, "   \
 255           "also kicks off a background concurrent collection")              \
 256                                                                             \
 257   product(uintx, GCLockerEdenExpansionPercent, 5,                           \
 258           "How much the GC can expand the eden by while the GC locker "     \
 259           "is active (as a percentage)")                                    \
 260           range(0, 100)                                                     \
 261                                                                             \
 262   diagnostic(uintx, GCLockerRetryAllocationCount, 2,                        \
 263           "Number of times to retry allocations when "                      \
 264           "blocked by the GC locker")                                       \
 265           range(0, max_uintx)                                               \
 266                                                                             \
 267   product(uintx, ParallelGCBufferWastePct, 10,                              \
 268           "Wasted fraction of parallel allocation buffer")                  \
 269           range(0, 100)                                                     \
 270                                                                             \
 271   product(uintx, TargetPLABWastePct, 10,                                    \
 272           "Target wasted space in last buffer as percent of overall "       \
 273           "allocation")                                                     \
 274           range(1, 100)                                                     \
 275                                                                             \
 276   product(uintx, PLABWeight, 75,                                            \
 277           "Percentage (0-100) used to weight the current sample when "      \
 278           "computing exponentially decaying average for ResizePLAB")        \
 279           range(0, 100)                                                     \
 280                                                                             \
 281   product(bool, ResizePLAB, true,                                           \
 282           "Dynamically resize (survivor space) promotion LAB's")            \
 283                                                                             \
 284   product(int, ParGCArrayScanChunk, 50,                                     \
 285           "Scan a subset of object array and push remainder, if array is "  \
 286           "bigger than this")                                               \
 287           range(1, max_jint/3)                                              \
 288                                                                             \
 289   product(uintx, OldPLABWeight, 50,                                         \
 290           "Percentage (0-100) used to weight the current sample when "      \
 291           "computing exponentially decaying average for resizing "          \
 292           "OldPLABSize")                                                    \
 293           range(0, 100)                                                     \
 294                                                                             \
 295   product(bool, ResizeOldPLAB, true,                                        \
 296           "Dynamically resize (old gen) promotion LAB's")                   \
 297                                                                             \
 298   product(bool, AlwaysPreTouch, false,                                      \
 299           "Force all freshly committed pages to be pre-touched")            \
 300                                                                             \
 301   product(size_t, PreTouchParallelChunkSize, 1 * G,                         \
 302           "Per-thread chunk size for parallel memory pre-touch.")           \
 303           range(1, SIZE_MAX / 2)                                            \
 304                                                                             \
 305   /* where does the range max value of (max_jint - 1) come from? */         \
 306   product(size_t, MarkStackSizeMax, NOT_LP64(4*M) LP64_ONLY(512*M),         \
 307           "Maximum size of marking stack")                                  \
 308           range(1, (max_jint - 1))                                          \
 309                                                                             \
 310   product(size_t, MarkStackSize, NOT_LP64(32*K) LP64_ONLY(4*M),             \
 311           "Size of marking stack")                                          \
 312           constraint(MarkStackSizeConstraintFunc,AfterErgo)                 \
 313                                                                             \
 314   develop(bool, VerifyBlockOffsetArray, false,                              \
 315           "Do (expensive) block offset array verification")                 \
 316                                                                             \
 317   diagnostic(bool, BlockOffsetArrayUseUnallocatedBlock, false,              \
 318           "Maintain _unallocated_block in BlockOffsetArray "                \
 319           "(currently applicable only to CMS collector)")                   \
 320                                                                             \
 321   product(intx, RefDiscoveryPolicy, 0,                                      \
 322           "Select type of reference discovery policy: "                     \
 323           "reference-based(0) or referent-based(1)")                        \
 324           range(ReferenceProcessor::DiscoveryPolicyMin,                     \
 325                 ReferenceProcessor::DiscoveryPolicyMax)                     \
 326                                                                             \
 327   product(bool, ParallelRefProcEnabled, false,                              \
 328           "Enable parallel reference processing whenever possible")         \
 329                                                                             \
 330   product(bool, ParallelRefProcBalancingEnabled, true,                      \
 331           "Enable balancing of reference processing queues")                \
 332                                                                             \
 333   experimental(size_t, ReferencesPerThread, 1000,                           \
 334                "Ergonomically start one thread for this amount of "         \
 335                "references for reference processing if "                    \
 336                "ParallelRefProcEnabled is true. Specify 0 to disable and "  \
 337                "use all threads.")                                          \
 338                                                                             \
 339   product(uintx, InitiatingHeapOccupancyPercent, 45,                        \
 340           "The percent occupancy (IHOP) of the current old generation "     \
 341           "capacity above which a concurrent mark cycle will be initiated " \
 342           "Its value may change over time if adaptive IHOP is enabled, "    \
 343           "otherwise the value remains constant. "                          \
 344           "In the latter case a value of 0 will result as frequent as "     \
 345           "possible concurrent marking cycles. A value of 100 disables "    \
 346           "concurrent marking. "                                            \
 347           "Fragmentation waste in the old generation is not considered "    \
 348           "free space in this calculation. (G1 collector only)")            \
 349           range(0, 100)                                                     \
 350                                                                             \
 351   notproduct(bool, ScavengeALot, false,                                     \
 352           "Force scavenge at every Nth exit from the runtime system "       \
 353           "(N=ScavengeALotInterval)")                                       \
 354                                                                             \
 355   develop(bool, FullGCALot, false,                                          \
 356           "Force full gc at every Nth exit from the runtime system "        \
 357           "(N=FullGCALotInterval)")                                         \
 358                                                                             \
 359   notproduct(bool, GCALotAtAllSafepoints, false,                            \
 360           "Enforce ScavengeALot/GCALot at all potential safepoints")        \
 361                                                                             \
 362   notproduct(bool, PromotionFailureALot, false,                             \
 363           "Use promotion failure handling on every youngest generation "    \
 364           "collection")                                                     \
 365                                                                             \
 366   develop(uintx, PromotionFailureALotCount, 1000,                           \
 367           "Number of promotion failures occurring at PLAB "                 \
 368           "refill attempts (ParNew) or promotion attempts "                 \
 369           "(other young collectors)")                                       \
 370                                                                             \
 371   develop(uintx, PromotionFailureALotInterval, 5,                           \
 372           "Total collections between promotion failures a lot")             \
 373                                                                             \
 374   diagnostic(bool, UseOWSTTaskTerminator, true,                             \
 375           "Use Optimized Work Stealing Threads task termination "           \
 376           "protocol")                                                       \
 377                                                                             \
 378   experimental(uintx, WorkStealingSleepMillis, 1,                           \
 379           "Sleep time when sleep is used for yields")                       \
 380                                                                             \
 381   experimental(uintx, WorkStealingYieldsBeforeSleep, 5000,                  \
 382           "Number of yields before a sleep is done during work stealing")   \
 383                                                                             \
 384   experimental(uintx, WorkStealingHardSpins, 4096,                          \
 385           "Number of iterations in a spin loop between checks on "          \
 386           "time out of hard spin")                                          \
 387                                                                             \
 388   experimental(uintx, WorkStealingSpinToYieldRatio, 10,                     \
 389           "Ratio of hard spins to calls to yield")                          \
 390                                                                             \
 391   develop(uintx, ObjArrayMarkingStride, 2048,                               \
 392           "Number of object array elements to push onto the marking stack " \
 393           "before pushing a continuation entry")                            \
 394                                                                             \
 395   develop(bool, MetadataAllocationFailALot, false,                          \
 396           "Fail metadata allocations at intervals controlled by "           \
 397           "MetadataAllocationFailALotInterval")                             \
 398                                                                             \
 399   develop(uintx, MetadataAllocationFailALotInterval, 1000,                  \
 400           "Metadata allocation failure a lot interval")                     \
 401                                                                             \
 402   product(bool, ExecutingUnitTests, false,                                  \
 403           "Whether the JVM is running unit tests or not")                   \
 404                                                                             \
 405   product_pd(bool, UseTLAB, "Use thread-local object allocation")           \
 406                                                                             \
 407   product_pd(bool, ResizeTLAB,                                              \
 408           "Dynamically resize TLAB size for threads")                       \
 409                                                                             \
 410   product(bool, ZeroTLAB, false,                                            \
 411           "Zero out the newly created TLAB")                                \
 412                                                                             \
 413   product(bool, TLABStats, true,                                            \
 414           "Provide more detailed and expensive TLAB statistics.")           \
 415                                                                             \
 416   product_pd(bool, NeverActAsServerClassMachine,                            \
 417           "Never act like a server-class machine")                          \
 418                                                                             \
 419   product(bool, AlwaysActAsServerClassMachine, false,                       \
 420           "Always act like a server-class machine")                         \
 421                                                                             \
 422   product_pd(uint64_t, MaxRAM,                                              \
 423           "Real memory size (in bytes) used to set maximum heap size")      \
 424           range(0, 0XFFFFFFFFFFFFFFFF)                                      \
 425                                                                             \
 426   product(bool, AggressiveHeap, false,                                      \
 427           "Optimize heap options for long-running memory intensive apps")   \
 428                                                                             \
 429   product(size_t, ErgoHeapSizeLimit, 0,                                     \
 430           "Maximum ergonomically set heap size (in bytes); zero means use " \
 431           "MaxRAM * MaxRAMPercentage / 100")                                \
 432           range(0, max_uintx)                                               \
 433                                                                             \
 434   product(uintx, MaxRAMFraction, 4,                                         \
 435           "Maximum fraction (1/n) of real memory used for maximum heap "    \
 436           "size. "                                                          \
 437           "Deprecated, use MaxRAMPercentage instead")                       \
 438           range(1, max_uintx)                                               \
 439                                                                             \
 440   product(uintx, MinRAMFraction, 2,                                         \
 441           "Minimum fraction (1/n) of real memory used for maximum heap "    \
 442           "size on systems with small physical memory size. "               \
 443           "Deprecated, use MinRAMPercentage instead")                       \
 444           range(1, max_uintx)                                               \
 445                                                                             \
 446   product(uintx, InitialRAMFraction, 64,                                    \
 447           "Fraction (1/n) of real memory used for initial heap size. "      \
 448           "Deprecated, use InitialRAMPercentage instead")                   \
 449           range(1, max_uintx)                                               \
 450                                                                             \
 451   product(double, MaxRAMPercentage, 25.0,                                   \
 452           "Maximum percentage of real memory used for maximum heap size")   \
 453           range(0.0, 100.0)                                                 \
 454                                                                             \
 455   product(double, MinRAMPercentage, 50.0,                                   \
 456           "Minimum percentage of real memory used for maximum heap"         \
 457           "size on systems with small physical memory size")                \
 458           range(0.0, 100.0)                                                 \
 459                                                                             \
 460   product(double, InitialRAMPercentage, 1.5625,                             \
 461           "Percentage of real memory used for initial heap size")           \
 462           range(0.0, 100.0)                                                 \
 463                                                                             \
 464   product(int, ActiveProcessorCount, -1,                                    \
 465           "Specify the CPU count the VM should use and report as active")   \
 466                                                                             \
 467   develop(uintx, MaxVirtMemFraction, 2,                                     \
 468           "Maximum fraction (1/n) of virtual memory used for ergonomically "\
 469           "determining maximum heap size")                                  \
 470                                                                             \
 471   product(bool, UseAdaptiveSizePolicy, true,                                \
 472           "Use adaptive generation sizing policies")                        \
 473                                                                             \
 474   product(bool, UsePSAdaptiveSurvivorSizePolicy, true,                      \
 475           "Use adaptive survivor sizing policies")                          \
 476                                                                             \
 477   product(bool, UseAdaptiveGenerationSizePolicyAtMinorCollection, true,     \
 478           "Use adaptive young-old sizing policies at minor collections")    \
 479                                                                             \
 480   product(bool, UseAdaptiveGenerationSizePolicyAtMajorCollection, true,     \
 481           "Use adaptive young-old sizing policies at major collections")    \
 482                                                                             \
 483   product(bool, UseAdaptiveSizePolicyWithSystemGC, false,                   \
 484           "Include statistics from System.gc() for adaptive size policy")   \
 485                                                                             \
 486   product(bool, UseAdaptiveGCBoundary, false,                               \
 487           "Allow young-old boundary to move")                               \
 488                                                                             \
 489   develop(intx, PSAdaptiveSizePolicyResizeVirtualSpaceAlot, -1,             \
 490           "Resize the virtual spaces of the young or old generations")      \
 491           range(-1, 1)                                                      \
 492                                                                             \
 493   product(uintx, AdaptiveSizeThroughPutPolicy, 0,                           \
 494           "Policy for changing generation size for throughput goals")       \
 495           range(0, 1)                                                       \
 496                                                                             \
 497   product(uintx, AdaptiveSizePolicyInitializingSteps, 20,                   \
 498           "Number of steps where heuristics is used before data is used")   \
 499           range(0, max_uintx)                                               \
 500                                                                             \
 501   develop(uintx, AdaptiveSizePolicyReadyThreshold, 5,                       \
 502           "Number of collections before the adaptive sizing is started")    \
 503                                                                             \
 504   product(uintx, AdaptiveSizePolicyOutputInterval, 0,                       \
 505           "Collection interval for printing information; zero means never") \
 506           range(0, max_uintx)                                               \
 507                                                                             \
 508   product(bool, UseAdaptiveSizePolicyFootprintGoal, true,                   \
 509           "Use adaptive minimum footprint as a goal")                       \
 510                                                                             \
 511   product(uintx, AdaptiveSizePolicyWeight, 10,                              \
 512           "Weight given to exponential resizing, between 0 and 100")        \
 513           range(0, 100)                                                     \
 514                                                                             \
 515   product(uintx, AdaptiveTimeWeight,       25,                              \
 516           "Weight given to time in adaptive policy, between 0 and 100")     \
 517           range(0, 100)                                                     \
 518                                                                             \
 519   product(uintx, PausePadding, 1,                                           \
 520           "How much buffer to keep for pause time")                         \
 521           range(0, max_juint)                                               \
 522                                                                             \
 523   product(uintx, PromotedPadding, 3,                                        \
 524           "How much buffer to keep for promotion failure")                  \
 525           range(0, max_juint)                                               \
 526                                                                             \
 527   product(uintx, SurvivorPadding, 3,                                        \
 528           "How much buffer to keep for survivor overflow")                  \
 529           range(0, max_juint)                                               \
 530                                                                             \
 531   product(uintx, ThresholdTolerance, 10,                                    \
 532           "Allowed collection cost difference between generations")         \
 533           range(0, 100)                                                     \
 534                                                                             \
 535   product(uintx, AdaptiveSizePolicyCollectionCostMargin, 50,                \
 536           "If collection costs are within margin, reduce both by full "     \
 537           "delta")                                                          \
 538           range(0, 100)                                                     \
 539                                                                             \
 540   product(uintx, YoungGenerationSizeIncrement, 20,                          \
 541           "Adaptive size percentage change in young generation")            \
 542           range(0, 100)                                                     \
 543                                                                             \
 544   product(uintx, YoungGenerationSizeSupplement, 80,                         \
 545           "Supplement to YoungedGenerationSizeIncrement used at startup")   \
 546           range(0, 100)                                                     \
 547                                                                             \
 548   product(uintx, YoungGenerationSizeSupplementDecay, 8,                     \
 549           "Decay factor to YoungedGenerationSizeSupplement")                \
 550           range(1, max_uintx)                                               \
 551                                                                             \
 552   product(uintx, TenuredGenerationSizeIncrement, 20,                        \
 553           "Adaptive size percentage change in tenured generation")          \
 554           range(0, 100)                                                     \
 555                                                                             \
 556   product(uintx, TenuredGenerationSizeSupplement, 80,                       \
 557           "Supplement to TenuredGenerationSizeIncrement used at startup")   \
 558           range(0, 100)                                                     \
 559                                                                             \
 560   product(uintx, TenuredGenerationSizeSupplementDecay, 2,                   \
 561           "Decay factor to TenuredGenerationSizeIncrement")                 \
 562           range(1, max_uintx)                                               \
 563                                                                             \
 564   product(uintx, MaxGCPauseMillis, max_uintx - 1,                           \
 565           "Adaptive size policy maximum GC pause time goal in millisecond, "\
 566           "or (G1 Only) the maximum GC time per MMU time slice")            \
 567           range(1, max_uintx - 1)                                           \
 568           constraint(MaxGCPauseMillisConstraintFunc,AfterErgo)              \
 569                                                                             \
 570   product(uintx, GCPauseIntervalMillis, 0,                                  \
 571           "Time slice for MMU specification")                               \
 572           constraint(GCPauseIntervalMillisConstraintFunc,AfterErgo)         \
 573                                                                             \
 574   product(uintx, MaxGCMinorPauseMillis, max_uintx,                          \
 575           "Adaptive size policy maximum GC minor pause time goal "          \
 576           "in millisecond")                                                 \
 577           range(0, max_uintx)                                               \
 578                                                                             \
 579   product(uintx, GCTimeRatio, 99,                                           \
 580           "Adaptive size policy application time to GC time ratio")         \
 581           range(0, max_juint)                                               \
 582                                                                             \
 583   product(uintx, AdaptiveSizeDecrementScaleFactor, 4,                       \
 584           "Adaptive size scale down factor for shrinking")                  \
 585           range(1, max_uintx)                                               \
 586                                                                             \
 587   product(bool, UseAdaptiveSizeDecayMajorGCCost, true,                      \
 588           "Adaptive size decays the major cost for long major intervals")   \
 589                                                                             \
 590   product(uintx, AdaptiveSizeMajorGCDecayTimeScale, 10,                     \
 591           "Time scale over which major costs decay")                        \
 592           range(0, max_uintx)                                               \
 593                                                                             \
 594   product(uintx, MinSurvivorRatio, 3,                                       \
 595           "Minimum ratio of young generation/survivor space size")          \
 596           range(3, max_uintx)                                               \
 597                                                                             \
 598   product(uintx, InitialSurvivorRatio, 8,                                   \
 599           "Initial ratio of young generation/survivor space size")          \
 600           range(0, max_uintx)                                               \
 601                                                                             \
 602   product(size_t, BaseFootPrintEstimate, 256*M,                             \
 603           "Estimate of footprint other than Java Heap")                     \
 604           range(0, max_uintx)                                               \
 605                                                                             \
 606   product(bool, UseGCOverheadLimit, true,                                   \
 607           "Use policy to limit of proportion of time spent in GC "          \
 608           "before an OutOfMemory error is thrown")                          \
 609                                                                             \
 610   product(uintx, GCTimeLimit, 98,                                           \
 611           "Limit of the proportion of time spent in GC before "             \
 612           "an OutOfMemoryError is thrown (used with GCHeapFreeLimit)")      \
 613           range(0, 100)                                                     \
 614                                                                             \
 615   product(uintx, GCHeapFreeLimit, 2,                                        \
 616           "Minimum percentage of free space after a full GC before an "     \
 617           "OutOfMemoryError is thrown (used with GCTimeLimit)")             \
 618           range(0, 100)                                                     \
 619                                                                             \
 620   develop(uintx, GCOverheadLimitThreshold, 5,                               \
 621           "Number of consecutive collections before gc time limit fires")   \
 622           range(1, max_uintx)                                               \
 623                                                                             \
 624   product(intx, PrefetchCopyIntervalInBytes, -1,                            \
 625           "How far ahead to prefetch destination area (<= 0 means off)")    \
 626           range(-1, max_jint)                                               \
 627                                                                             \
 628   product(intx, PrefetchScanIntervalInBytes, -1,                            \
 629           "How far ahead to prefetch scan area (<= 0 means off)")           \
 630           range(-1, max_jint)                                               \
 631                                                                             \
 632   product(intx, PrefetchFieldsAhead, -1,                                    \
 633           "How many fields ahead to prefetch in oop scan (<= 0 means off)") \
 634           range(-1, max_jint)                                               \
 635                                                                             \
 636   diagnostic(bool, VerifyDuringStartup, false,                              \
 637           "Verify memory system before executing any Java code "            \
 638           "during VM initialization")                                       \
 639                                                                             \
 640   diagnostic(bool, VerifyBeforeExit, trueInDebug,                           \
 641           "Verify system before exiting")                                   \
 642                                                                             \
 643   diagnostic(bool, VerifyBeforeGC, false,                                   \
 644           "Verify memory system before GC")                                 \
 645                                                                             \
 646   diagnostic(bool, VerifyAfterGC, false,                                    \
 647           "Verify memory system after GC")                                  \
 648                                                                             \
 649   diagnostic(bool, VerifyDuringGC, false,                                   \
 650           "Verify memory system during GC (between phases)")                \
 651                                                                             \
 652   diagnostic(ccstrlist, VerifyGCType, "",                                   \
 653              "GC type(s) to verify when Verify*GC is enabled."              \
 654              "Available types are collector specific.")                     \
 655                                                                             \
 656   diagnostic(ccstrlist, VerifySubSet, "",                                   \
 657           "Memory sub-systems to verify when Verify*GC flag(s) "            \
 658           "are enabled. One or more sub-systems can be specified "          \
 659           "in a comma separated string. Sub-systems are: "                  \
 660           "threads, heap, symbol_table, string_table, codecache, "          \
 661           "dictionary, classloader_data_graph, metaspace, jni_handles, "    \
 662           "codecache_oops")                                                 \
 663                                                                             \
 664   diagnostic(bool, GCParallelVerificationEnabled, true,                     \
 665           "Enable parallel memory system verification")                     \
 666                                                                             \
 667   diagnostic(bool, DeferInitialCardMark, false,                             \
 668           "When +ReduceInitialCardMarks, explicitly defer any that "        \
 669           "may arise from new_pre_store_barrier")                           \
 670                                                                             \
 671   product(bool, UseCondCardMark, false,                                     \
 672           "Check for already marked card before updating card table")       \
 673                                                                             \
 674   diagnostic(bool, VerifyRememberedSets, false,                             \
 675           "Verify GC remembered sets")                                      \
 676                                                                             \
 677   diagnostic(bool, VerifyObjectStartArray, true,                            \
 678           "Verify GC object start array if verify before/after")            \
 679                                                                             \
 680   product(bool, DisableExplicitGC, false,                                   \
 681           "Ignore calls to System.gc()")                                    \
 682                                                                             \
 683   product(bool, BindGCTaskThreadsToCPUs, false,                             \
 684           "Bind GCTaskThreads to CPUs if possible")                         \
 685                                                                             \
 686   product(bool, UseGCTaskAffinity, false,                                   \
 687           "Use worker affinity when asking for GCTasks")                    \
 688                                                                             \
 689   product(bool, PrintGC, false,                                             \
 690           "Print message at garbage collection. "                           \
 691           "Deprecated, use -Xlog:gc instead.")                              \
 692                                                                             \
 693   product(bool, PrintGCDetails, false,                                      \
 694           "Print more details at garbage collection. "                      \
 695           "Deprecated, use -Xlog:gc* instead.")                             \
 696                                                                             \
 697   develop(intx, ConcGCYieldTimeout, 0,                                      \
 698           "If non-zero, assert that GC threads yield within this "          \
 699           "number of milliseconds")                                         \
 700           range(0, max_intx)                                                \
 701                                                                             \
 702   notproduct(intx, ScavengeALotInterval,     1,                             \
 703           "Interval between which scavenge will occur with +ScavengeALot")  \
 704                                                                             \
 705   notproduct(intx, FullGCALotInterval,     1,                               \
 706           "Interval between which full gc will occur with +FullGCALot")     \
 707                                                                             \
 708   notproduct(intx, FullGCALotStart,     0,                                  \
 709           "For which invocation to start FullGCAlot")                       \
 710                                                                             \
 711   notproduct(intx, FullGCALotDummies,  32*K,                                \
 712           "Dummy object allocated with +FullGCALot, forcing all objects "   \
 713           "to move")                                                        \
 714                                                                             \
 715   /* gc parameters */                                                       \
 716   product(size_t, MinHeapSize, 0,                                           \
 717           "Minimum heap size (in bytes); zero means use ergonomics")        \
 718           constraint(MinHeapSizeConstraintFunc,AfterErgo)                   \
 719                                                                             \
 720   product(size_t, InitialHeapSize, 0,                                       \
 721           "Initial heap size (in bytes); zero means use ergonomics")        \
 722           constraint(InitialHeapSizeConstraintFunc,AfterErgo)               \
 723                                                                             \
 724   product(size_t, MaxHeapSize, ScaleForWordSize(96*M),                      \
 725           "Maximum heap size (in bytes)")                                   \
 726           constraint(MaxHeapSizeConstraintFunc,AfterErgo)                   \
 727                                                                             \
 728   manageable(size_t, SoftMaxHeapSize, 0,                                    \
 729           "Soft limit for maximum heap size (in bytes)")                    \
 730           constraint(SoftMaxHeapSizeConstraintFunc,AfterMemoryInit)         \
 731                                                                             \
 732   product(size_t, OldSize, ScaleForWordSize(4*M),                           \
 733           "Initial tenured generation size (in bytes)")                     \
 734           range(0, max_uintx)                                               \
 735                                                                             \
 736   product(size_t, NewSize, ScaleForWordSize(1*M),                           \
 737           "Initial new generation size (in bytes)")                         \
 738           constraint(NewSizeConstraintFunc,AfterErgo)                       \
 739                                                                             \
 740   product(size_t, MaxNewSize, max_uintx,                                    \
 741           "Maximum new generation size (in bytes), max_uintx means set "    \
 742           "ergonomically")                                                  \
 743           range(0, max_uintx)                                               \
 744                                                                             \
 745   product_pd(size_t, HeapBaseMinAddress,                                    \
 746           "OS specific low limit for heap base address")                    \
 747           constraint(HeapBaseMinAddressConstraintFunc,AfterErgo)            \
 748                                                                             \
 749   product(size_t, PretenureSizeThreshold, 0,                                \
 750           "Maximum size in bytes of objects allocated in DefNew "           \
 751           "generation; zero means no maximum")                              \
 752           range(0, max_uintx)                                               \
 753                                                                             \
 754   product(size_t, MinTLABSize, 2*K,                                         \
 755           "Minimum allowed TLAB size (in bytes)")                           \
 756           range(1, max_uintx/2)                                             \
 757           constraint(MinTLABSizeConstraintFunc,AfterMemoryInit)             \
 758                                                                             \
 759   product(size_t, TLABSize, 0,                                              \
 760           "Starting TLAB size (in bytes); zero means set ergonomically")    \
 761           constraint(TLABSizeConstraintFunc,AfterMemoryInit)                \
 762                                                                             \
 763   product(size_t, YoungPLABSize, 4096,                                      \
 764           "Size of young gen promotion LAB's (in HeapWords)")               \
 765           constraint(YoungPLABSizeConstraintFunc,AfterMemoryInit)           \
 766                                                                             \
 767   product(size_t, OldPLABSize, 1024,                                        \
 768           "Size of old gen promotion LAB's (in HeapWords), or Number "      \
 769           "of blocks to attempt to claim when refilling CMS LAB's")         \
 770           constraint(OldPLABSizeConstraintFunc,AfterMemoryInit)             \
 771                                                                             \
 772   product(uintx, TLABAllocationWeight, 35,                                  \
 773           "Allocation averaging weight")                                    \
 774           range(0, 100)                                                     \
 775                                                                             \
 776   /* Limit the lower bound of this flag to 1 as it is used  */              \
 777   /* in a division expression.                              */              \
 778   product(uintx, TLABWasteTargetPercent, 1,                                 \
 779           "Percentage of Eden that can be wasted")                          \
 780           range(1, 100)                                                     \
 781                                                                             \
 782   product(uintx, TLABRefillWasteFraction,    64,                            \
 783           "Maximum TLAB waste at a refill (internal fragmentation)")        \
 784           range(1, max_juint)                                               \
 785                                                                             \
 786   product(uintx, TLABWasteIncrement,    4,                                  \
 787           "Increment allowed waste at slow allocation")                     \
 788           range(0, max_jint)                                                \
 789           constraint(TLABWasteIncrementConstraintFunc,AfterMemoryInit)      \
 790                                                                             \
 791   product(uintx, SurvivorRatio, 8,                                          \
 792           "Ratio of eden/survivor space size")                              \
 793           range(1, max_uintx-2)                                             \
 794           constraint(SurvivorRatioConstraintFunc,AfterMemoryInit)           \
 795                                                                             \
 796   product(uintx, NewRatio, 2,                                               \
 797           "Ratio of old/new generation sizes")                              \
 798           range(0, max_uintx-1)                                             \
 799                                                                             \
 800   product_pd(size_t, NewSizeThreadIncrease,                                 \
 801           "Additional size added to desired new generation size per "       \
 802           "non-daemon thread (in bytes)")                                   \
 803           range(0, max_uintx)                                               \
 804                                                                             \
 805   product(uintx, QueuedAllocationWarningCount, 0,                           \
 806           "Number of times an allocation that queues behind a GC "          \
 807           "will retry before printing a warning")                           \
 808           range(0, max_uintx)                                               \
 809                                                                             \
 810   diagnostic(uintx, VerifyGCStartAt,   0,                                   \
 811           "GC invoke count where +VerifyBefore/AfterGC kicks in")           \
 812           range(0, max_uintx)                                               \
 813                                                                             \
 814   diagnostic(intx, VerifyGCLevel,     0,                                    \
 815           "Generation level at which to start +VerifyBefore/AfterGC")       \
 816           range(0, 1)                                                       \
 817                                                                             \
 818   product(uintx, MaxTenuringThreshold,    15,                               \
 819           "Maximum value for tenuring threshold")                           \
 820           range(0, markOopDesc::max_age + 1)                                \
 821           constraint(MaxTenuringThresholdConstraintFunc,AfterErgo)          \
 822                                                                             \
 823   product(uintx, InitialTenuringThreshold,    7,                            \
 824           "Initial value for tenuring threshold")                           \
 825           range(0, markOopDesc::max_age + 1)                                \
 826           constraint(InitialTenuringThresholdConstraintFunc,AfterErgo)      \
 827                                                                             \
 828   product(uintx, TargetSurvivorRatio,    50,                                \
 829           "Desired percentage of survivor space used after scavenge")       \
 830           range(0, 100)                                                     \
 831                                                                             \
 832   product(uintx, MarkSweepDeadRatio,     5,                                 \
 833           "Percentage (0-100) of the old gen allowed as dead wood. "        \
 834           "Serial mark sweep treats this as both the minimum and maximum "  \
 835           "value. "                                                         \
 836           "CMS uses this value only if it falls back to mark sweep. "       \
 837           "Par compact uses a variable scale based on the density of the "  \
 838           "generation and treats this as the maximum value when the heap "  \
 839           "is either completely full or completely empty.  Par compact "    \
 840           "also has a smaller default value; see arguments.cpp.")           \
 841           range(0, 100)                                                     \
 842                                                                             \
 843   product(uint, MarkSweepAlwaysCompactCount,     4,                         \
 844           "How often should we fully compact the heap (ignoring the dead "  \
 845           "space parameters)")                                              \
 846           range(1, max_juint)                                               \
 847                                                                             \
 848   develop(uintx, GCExpandToAllocateDelayMillis, 0,                          \
 849           "Delay between expansion and allocation (in milliseconds)")       \
 850                                                                             \
 851   product(uintx, GCDrainStackTargetSize, 64,                                \
 852           "Number of entries we will try to leave on the stack "            \
 853           "during parallel gc")                                             \
 854           range(0, max_juint)
 855 
 856 #endif // SHARE_GC_SHARED_GC_GLOBALS_HPP