1 /*
  2  * Copyright (c) 1997, 2020, 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_EPSILONGC
 31 #include "gc/epsilon/epsilon_globals.hpp"
 32 #endif
 33 #if INCLUDE_G1GC
 34 #include "gc/g1/g1_globals.hpp"
 35 #endif
 36 #if INCLUDE_PARALLELGC
 37 #include "gc/parallel/parallel_globals.hpp"
 38 #endif
 39 #if INCLUDE_SERIALGC
 40 #include "gc/serial/serial_globals.hpp"
 41 #endif
 42 #if INCLUDE_SHENANDOAHGC
 43 #include "gc/shenandoah/shenandoah_globals.hpp"
 44 #endif
 45 #if INCLUDE_ZGC
 46 #include "gc/z/z_globals.hpp"
 47 #endif
 48 
 49 #define GC_FLAGS(develop,                                                   \
 50                  develop_pd,                                                \
 51                  product,                                                   \
 52                  product_pd,                                                \
 53                  notproduct,                                                \
 54                  range,                                                     \
 55                  constraint)                                                \
 56                                                                             \
 57   EPSILONGC_ONLY(GC_EPSILON_FLAGS(                                          \
 58     develop,                                                                \
 59     develop_pd,                                                             \
 60     product,                                                                \
 61     product_pd,                                                             \
 62     notproduct,                                                             \
 63     range,                                                                  \
 64     constraint))                                                            \
 65                                                                             \
 66   G1GC_ONLY(GC_G1_FLAGS(                                                    \
 67     develop,                                                                \
 68     develop_pd,                                                             \
 69     product,                                                                \
 70     product_pd,                                                             \
 71     notproduct,                                                             \
 72     range,                                                                  \
 73     constraint))                                                            \
 74                                                                             \
 75   PARALLELGC_ONLY(GC_PARALLEL_FLAGS(                                        \
 76     develop,                                                                \
 77     develop_pd,                                                             \
 78     product,                                                                \
 79     product_pd,                                                             \
 80     notproduct,                                                             \
 81     range,                                                                  \
 82     constraint))                                                            \
 83                                                                             \
 84   SERIALGC_ONLY(GC_SERIAL_FLAGS(                                            \
 85     develop,                                                                \
 86     develop_pd,                                                             \
 87     product,                                                                \
 88     product_pd,                                                             \
 89     notproduct,                                                             \
 90     range,                                                                  \
 91     constraint))                                                            \
 92                                                                             \
 93   SHENANDOAHGC_ONLY(GC_SHENANDOAH_FLAGS(                                    \
 94     develop,                                                                \
 95     develop_pd,                                                             \
 96     product,                                                                \
 97     product_pd,                                                             \
 98     notproduct,                                                             \
 99     range,                                                                  \
100     constraint))                                                            \
101                                                                             \
102   ZGC_ONLY(GC_Z_FLAGS(                                                      \
103     develop,                                                                \
104     develop_pd,                                                             \
105     product,                                                                \
106     product_pd,                                                             \
107     notproduct,                                                             \
108     range,                                                                  \
109     constraint))                                                            \
110                                                                             \
111   /* gc */                                                                  \
112                                                                             \
113   product(bool, UseSerialGC, false,                                         \
114           "Use the Serial garbage collector")                               \
115                                                                             \
116   product(bool, UseG1GC, false,                                             \
117           "Use the Garbage-First garbage collector")                        \
118                                                                             \
119   product(bool, UseParallelGC, false,                                       \
120           "Use the Parallel garbage collector.")                            \
121                                                                             \
122   product(bool, UseEpsilonGC, false, EXPERIMENTAL,                          \
123           "Use the Epsilon (no-op) garbage collector")                      \
124                                                                             \
125   product(bool, UseZGC, false,                                              \
126           "Use the Z garbage collector")                                    \
127                                                                             \
128   product(bool, UseShenandoahGC, false,                                     \
129           "Use the Shenandoah garbage collector")                           \
130                                                                             \
131   product(uint, ParallelGCThreads, 0,                                       \
132           "Number of parallel threads parallel gc will use")                \
133           constraint(ParallelGCThreadsConstraintFunc,AfterErgo)             \
134                                                                             \
135   product(bool, UseDynamicNumberOfGCThreads, true,                          \
136           "Dynamically choose the number of threads up to a maximum of "    \
137           "ParallelGCThreads parallel collectors will use for garbage "     \
138           "collection work")                                                \
139                                                                             \
140   product(bool, InjectGCWorkerCreationFailure, false, DIAGNOSTIC,           \
141              "Inject thread creation failures for "                         \
142              "UseDynamicNumberOfGCThreads")                                 \
143                                                                             \
144   product(size_t, HeapSizePerGCThread, ScaleForWordSize(32*M),              \
145           "Size of heap (bytes) per GC thread used in calculating the "     \
146           "number of GC threads")                                           \
147           constraint(VMPageSizeConstraintFunc, AtParse)                     \
148                                                                             \
149   product(uint, ConcGCThreads, 0,                                           \
150           "Number of threads concurrent gc will use")                       \
151           constraint(ConcGCThreadsConstraintFunc,AfterErgo)                 \
152                                                                             \
153   product(bool, AlwaysTenure, false,                                        \
154           "Always tenure objects in eden (ParallelGC only)")                \
155                                                                             \
156   product(bool, NeverTenure, false,                                         \
157           "Never tenure objects in eden, may tenure on overflow "           \
158           "(ParallelGC only)")                                              \
159                                                                             \
160   product(bool, ScavengeBeforeFullGC, true,                                 \
161           "Scavenge youngest generation before each full GC.")              \
162                                                                             \
163   product(bool, ExplicitGCInvokesConcurrent, false,                         \
164           "A System.gc() request invokes a concurrent collection; "         \
165           "(effective only when using concurrent collectors)")              \
166                                                                             \
167   product(uintx, GCLockerEdenExpansionPercent, 5,                           \
168           "How much the GC can expand the eden by while the GC locker "     \
169           "is active (as a percentage)")                                    \
170           range(0, 100)                                                     \
171                                                                             \
172   product(uintx, GCLockerRetryAllocationCount, 2, DIAGNOSTIC,               \
173           "Number of times to retry allocations when "                      \
174           "blocked by the GC locker")                                       \
175           range(0, max_uintx)                                               \
176                                                                             \
177   product(uintx, ParallelGCBufferWastePct, 10,                              \
178           "Wasted fraction of parallel allocation buffer")                  \
179           range(0, 100)                                                     \
180                                                                             \
181   product(uintx, TargetPLABWastePct, 10,                                    \
182           "Target wasted space in last buffer as percent of overall "       \
183           "allocation")                                                     \
184           range(1, 100)                                                     \
185                                                                             \
186   product(uintx, PLABWeight, 75,                                            \
187           "Percentage (0-100) used to weight the current sample when "      \
188           "computing exponentially decaying average for ResizePLAB")        \
189           range(0, 100)                                                     \
190                                                                             \
191   product(bool, ResizePLAB, true,                                           \
192           "Dynamically resize (survivor space) promotion LAB's")            \
193                                                                             \
194   product(int, ParGCArrayScanChunk, 50,                                     \
195           "Scan a subset of object array and push remainder, if array is "  \
196           "bigger than this")                                               \
197           range(1, max_jint/3)                                              \
198                                                                             \
199                                                                             \
200   product(bool, AlwaysPreTouch, false,                                      \
201           "Force all freshly committed pages to be pre-touched")            \
202                                                                             \
203   product(size_t, PreTouchParallelChunkSize, 1 * G,                         \
204           "Per-thread chunk size for parallel memory pre-touch.")           \
205           range(1, SIZE_MAX / 2)                                            \
206                                                                             \
207   /* where does the range max value of (max_jint - 1) come from? */         \
208   product(size_t, MarkStackSizeMax, NOT_LP64(4*M) LP64_ONLY(512*M),         \
209           "Maximum size of marking stack")                                  \
210           range(1, (max_jint - 1))                                          \
211                                                                             \
212   product(size_t, MarkStackSize, NOT_LP64(32*K) LP64_ONLY(4*M),             \
213           "Size of marking stack")                                          \
214           constraint(MarkStackSizeConstraintFunc,AfterErgo)                 \
215           range(1, (max_jint - 1))                                          \
216                                                                             \
217   product(intx, RefDiscoveryPolicy, 0,                                      \
218           "Select type of reference discovery policy: "                     \
219           "reference-based(0) or referent-based(1)")                        \
220           range(ReferenceProcessor::DiscoveryPolicyMin,                     \
221                 ReferenceProcessor::DiscoveryPolicyMax)                     \
222                                                                             \
223   product(bool, ParallelRefProcEnabled, false,                              \
224           "Enable parallel reference processing whenever possible")         \
225                                                                             \
226   product(bool, ParallelRefProcBalancingEnabled, true,                      \
227           "Enable balancing of reference processing queues")                \
228                                                                             \
229   product(size_t, ReferencesPerThread, 1000, EXPERIMENTAL,                  \
230                "Ergonomically start one thread for this amount of "         \
231                "references for reference processing if "                    \
232                "ParallelRefProcEnabled is true. Specify 0 to disable and "  \
233                "use all threads.")                                          \
234                                                                             \
235   product(uintx, InitiatingHeapOccupancyPercent, 45,                        \
236           "The percent occupancy (IHOP) of the current old generation "     \
237           "capacity above which a concurrent mark cycle will be initiated " \
238           "Its value may change over time if adaptive IHOP is enabled, "    \
239           "otherwise the value remains constant. "                          \
240           "In the latter case a value of 0 will result as frequent as "     \
241           "possible concurrent marking cycles. A value of 100 disables "    \
242           "concurrent marking. "                                            \
243           "Fragmentation waste in the old generation is not considered "    \
244           "free space in this calculation. (G1 collector only)")            \
245           range(0, 100)                                                     \
246                                                                             \
247   notproduct(bool, ScavengeALot, false,                                     \
248           "Force scavenge at every Nth exit from the runtime system "       \
249           "(N=ScavengeALotInterval)")                                       \
250                                                                             \
251   develop(bool, FullGCALot, false,                                          \
252           "Force full gc at every Nth exit from the runtime system "        \
253           "(N=FullGCALotInterval)")                                         \
254                                                                             \
255   notproduct(bool, GCALotAtAllSafepoints, false,                            \
256           "Enforce ScavengeALot/GCALot at all potential safepoints")        \
257                                                                             \
258   notproduct(bool, PromotionFailureALot, false,                             \
259           "Use promotion failure handling on every youngest generation "    \
260           "collection")                                                     \
261                                                                             \
262   develop(uintx, PromotionFailureALotCount, 1000,                           \
263           "Number of promotion failures occurring at PLAB promotion "       \
264           "attempts at young collectors")                                   \
265                                                                             \
266   develop(uintx, PromotionFailureALotInterval, 5,                           \
267           "Total collections between promotion failures a lot")             \
268                                                                             \
269   product(uintx, WorkStealingSleepMillis, 1, EXPERIMENTAL,                  \
270           "Sleep time when sleep is used for yields")                       \
271                                                                             \
272   product(uintx, WorkStealingYieldsBeforeSleep, 5000, EXPERIMENTAL,         \
273           "Number of yields before a sleep is done during work stealing")   \
274                                                                             \
275   product(uintx, WorkStealingHardSpins, 4096, EXPERIMENTAL,                 \
276           "Number of iterations in a spin loop between checks on "          \
277           "time out of hard spin")                                          \
278                                                                             \
279   product(uintx, WorkStealingSpinToYieldRatio, 10, EXPERIMENTAL,            \
280           "Ratio of hard spins to calls to yield")                          \
281                                                                             \
282   develop(uintx, ObjArrayMarkingStride, 2048,                               \
283           "Number of object array elements to push onto the marking stack " \
284           "before pushing a continuation entry")                            \
285                                                                             \
286   develop(bool, MetadataAllocationFailALot, false,                          \
287           "Fail metadata allocations at intervals controlled by "           \
288           "MetadataAllocationFailALotInterval")                             \
289                                                                             \
290   develop(uintx, MetadataAllocationFailALotInterval, 1000,                  \
291           "Metadata allocation failure a lot interval")                     \
292                                                                             \
293   product(bool, ExecutingUnitTests, false,                                  \
294           "Whether the JVM is running unit tests or not")                   \
295                                                                             \
296   product_pd(bool, UseTLAB, "Use thread-local object allocation")           \
297                                                                             \
298   product_pd(bool, ResizeTLAB,                                              \
299           "Dynamically resize TLAB size for threads")                       \
300                                                                             \
301   product(bool, ZeroTLAB, false,                                            \
302           "Zero out the newly created TLAB")                                \
303                                                                             \
304   product(bool, TLABStats, true,                                            \
305           "Provide more detailed and expensive TLAB statistics.")           \
306                                                                             \
307   product_pd(bool, NeverActAsServerClassMachine,                            \
308           "Never act like a server-class machine")                          \
309                                                                             \
310   product(bool, AlwaysActAsServerClassMachine, false,                       \
311           "Always act like a server-class machine")                         \
312                                                                             \
313   product_pd(uint64_t, MaxRAM,                                              \
314           "Real memory size (in bytes) used to set maximum heap size")      \
315           range(0, 0XFFFFFFFFFFFFFFFF)                                      \
316                                                                             \
317   product(bool, AggressiveHeap, false,                                      \
318           "Optimize heap options for long-running memory intensive apps")   \
319                                                                             \
320   product(size_t, ErgoHeapSizeLimit, 0,                                     \
321           "Maximum ergonomically set heap size (in bytes); zero means use " \
322           "MaxRAM * MaxRAMPercentage / 100")                                \
323           range(0, max_uintx)                                               \
324                                                                             \
325   product(uintx, MaxRAMFraction, 4,                                         \
326           "Maximum fraction (1/n) of real memory used for maximum heap "    \
327           "size. "                                                          \
328           "Deprecated, use MaxRAMPercentage instead")                       \
329           range(1, max_uintx)                                               \
330                                                                             \
331   product(uintx, MinRAMFraction, 2,                                         \
332           "Minimum fraction (1/n) of real memory used for maximum heap "    \
333           "size on systems with small physical memory size. "               \
334           "Deprecated, use MinRAMPercentage instead")                       \
335           range(1, max_uintx)                                               \
336                                                                             \
337   product(uintx, InitialRAMFraction, 64,                                    \
338           "Fraction (1/n) of real memory used for initial heap size. "      \
339           "Deprecated, use InitialRAMPercentage instead")                   \
340           range(1, max_uintx)                                               \
341                                                                             \
342   product(double, MaxRAMPercentage, 25.0,                                   \
343           "Maximum percentage of real memory used for maximum heap size")   \
344           range(0.0, 100.0)                                                 \
345                                                                             \
346   product(double, MinRAMPercentage, 50.0,                                   \
347           "Minimum percentage of real memory used for maximum heap"         \
348           "size on systems with small physical memory size")                \
349           range(0.0, 100.0)                                                 \
350                                                                             \
351   product(double, InitialRAMPercentage, 1.5625,                             \
352           "Percentage of real memory used for initial heap size")           \
353           range(0.0, 100.0)                                                 \
354                                                                             \
355   product(int, ActiveProcessorCount, -1,                                    \
356           "Specify the CPU count the VM should use and report as active")   \
357                                                                             \
358   develop(uintx, MaxVirtMemFraction, 2,                                     \
359           "Maximum fraction (1/n) of virtual memory used for ergonomically "\
360           "determining maximum heap size")                                  \
361                                                                             \
362   product(bool, UseAdaptiveSizePolicy, true,                                \
363           "Use adaptive generation sizing policies")                        \
364                                                                             \
365   product(bool, UsePSAdaptiveSurvivorSizePolicy, true,                      \
366           "Use adaptive survivor sizing policies")                          \
367                                                                             \
368   product(bool, UseAdaptiveGenerationSizePolicyAtMinorCollection, true,     \
369           "Use adaptive young-old sizing policies at minor collections")    \
370                                                                             \
371   product(bool, UseAdaptiveGenerationSizePolicyAtMajorCollection, true,     \
372           "Use adaptive young-old sizing policies at major collections")    \
373                                                                             \
374   product(bool, UseAdaptiveSizePolicyWithSystemGC, false,                   \
375           "Include statistics from System.gc() for adaptive size policy")   \
376                                                                             \
377   develop(intx, PSAdaptiveSizePolicyResizeVirtualSpaceAlot, -1,             \
378           "Resize the virtual spaces of the young or old generations")      \
379           range(-1, 1)                                                      \
380                                                                             \
381   product(uintx, AdaptiveSizeThroughPutPolicy, 0,                           \
382           "Policy for changing generation size for throughput goals")       \
383           range(0, 1)                                                       \
384                                                                             \
385   product(uintx, AdaptiveSizePolicyInitializingSteps, 20,                   \
386           "Number of steps where heuristics is used before data is used")   \
387           range(0, max_uintx)                                               \
388                                                                             \
389   develop(uintx, AdaptiveSizePolicyReadyThreshold, 5,                       \
390           "Number of collections before the adaptive sizing is started")    \
391                                                                             \
392   product(uintx, AdaptiveSizePolicyOutputInterval, 0,                       \
393           "Collection interval for printing information; zero means never") \
394           range(0, max_uintx)                                               \
395                                                                             \
396   product(bool, UseAdaptiveSizePolicyFootprintGoal, true,                   \
397           "Use adaptive minimum footprint as a goal")                       \
398                                                                             \
399   product(uintx, AdaptiveSizePolicyWeight, 10,                              \
400           "Weight given to exponential resizing, between 0 and 100")        \
401           range(0, 100)                                                     \
402                                                                             \
403   product(uintx, AdaptiveTimeWeight,       25,                              \
404           "Weight given to time in adaptive policy, between 0 and 100")     \
405           range(0, 100)                                                     \
406                                                                             \
407   product(uintx, PausePadding, 1,                                           \
408           "How much buffer to keep for pause time")                         \
409           range(0, max_juint)                                               \
410                                                                             \
411   product(uintx, PromotedPadding, 3,                                        \
412           "How much buffer to keep for promotion failure")                  \
413           range(0, max_juint)                                               \
414                                                                             \
415   product(uintx, SurvivorPadding, 3,                                        \
416           "How much buffer to keep for survivor overflow")                  \
417           range(0, max_juint)                                               \
418                                                                             \
419   product(uintx, ThresholdTolerance, 10,                                    \
420           "Allowed collection cost difference between generations")         \
421           range(0, 100)                                                     \
422                                                                             \
423   product(uintx, AdaptiveSizePolicyCollectionCostMargin, 50,                \
424           "If collection costs are within margin, reduce both by full "     \
425           "delta")                                                          \
426           range(0, 100)                                                     \
427                                                                             \
428   product(uintx, YoungGenerationSizeIncrement, 20,                          \
429           "Adaptive size percentage change in young generation")            \
430           range(0, 100)                                                     \
431                                                                             \
432   product(uintx, YoungGenerationSizeSupplement, 80,                         \
433           "Supplement to YoungedGenerationSizeIncrement used at startup")   \
434           range(0, 100)                                                     \
435                                                                             \
436   product(uintx, YoungGenerationSizeSupplementDecay, 8,                     \
437           "Decay factor to YoungedGenerationSizeSupplement")                \
438           range(1, max_uintx)                                               \
439                                                                             \
440   product(uintx, TenuredGenerationSizeIncrement, 20,                        \
441           "Adaptive size percentage change in tenured generation")          \
442           range(0, 100)                                                     \
443                                                                             \
444   product(uintx, TenuredGenerationSizeSupplement, 80,                       \
445           "Supplement to TenuredGenerationSizeIncrement used at startup")   \
446           range(0, 100)                                                     \
447                                                                             \
448   product(uintx, TenuredGenerationSizeSupplementDecay, 2,                   \
449           "Decay factor to TenuredGenerationSizeIncrement")                 \
450           range(1, max_uintx)                                               \
451                                                                             \
452   product(uintx, MaxGCPauseMillis, max_uintx - 1,                           \
453           "Adaptive size policy maximum GC pause time goal in millisecond, "\
454           "or (G1 Only) the maximum GC time per MMU time slice")            \
455           range(1, max_uintx - 1)                                           \
456           constraint(MaxGCPauseMillisConstraintFunc,AfterErgo)              \
457                                                                             \
458   product(uintx, GCPauseIntervalMillis, 0,                                  \
459           "Time slice for MMU specification")                               \
460           constraint(GCPauseIntervalMillisConstraintFunc,AfterErgo)         \
461                                                                             \
462   product(uintx, MaxGCMinorPauseMillis, max_uintx,                          \
463           "Adaptive size policy maximum GC minor pause time goal "          \
464           "in millisecond")                                                 \
465           range(0, max_uintx)                                               \
466                                                                             \
467   product(uintx, GCTimeRatio, 99,                                           \
468           "Adaptive size policy application time to GC time ratio")         \
469           range(0, max_juint)                                               \
470                                                                             \
471   product(uintx, AdaptiveSizeDecrementScaleFactor, 4,                       \
472           "Adaptive size scale down factor for shrinking")                  \
473           range(1, max_uintx)                                               \
474                                                                             \
475   product(bool, UseAdaptiveSizeDecayMajorGCCost, true,                      \
476           "Adaptive size decays the major cost for long major intervals")   \
477                                                                             \
478   product(uintx, AdaptiveSizeMajorGCDecayTimeScale, 10,                     \
479           "Time scale over which major costs decay")                        \
480           range(0, max_uintx)                                               \
481                                                                             \
482   product(uintx, MinSurvivorRatio, 3,                                       \
483           "Minimum ratio of young generation/survivor space size")          \
484           range(3, max_uintx)                                               \
485                                                                             \
486   product(uintx, InitialSurvivorRatio, 8,                                   \
487           "Initial ratio of young generation/survivor space size")          \
488           range(0, max_uintx)                                               \
489                                                                             \
490   product(size_t, BaseFootPrintEstimate, 256*M,                             \
491           "Estimate of footprint other than Java Heap")                     \
492           range(0, max_uintx)                                               \
493                                                                             \
494   product(bool, UseGCOverheadLimit, true,                                   \
495           "Use policy to limit of proportion of time spent in GC "          \
496           "before an OutOfMemory error is thrown")                          \
497                                                                             \
498   product(uintx, GCTimeLimit, 98,                                           \
499           "Limit of the proportion of time spent in GC before "             \
500           "an OutOfMemoryError is thrown (used with GCHeapFreeLimit)")      \
501           range(0, 100)                                                     \
502                                                                             \
503   product(uintx, GCHeapFreeLimit, 2,                                        \
504           "Minimum percentage of free space after a full GC before an "     \
505           "OutOfMemoryError is thrown (used with GCTimeLimit)")             \
506           range(0, 100)                                                     \
507                                                                             \
508   develop(uintx, GCOverheadLimitThreshold, 5,                               \
509           "Number of consecutive collections before gc time limit fires")   \
510           range(1, max_uintx)                                               \
511                                                                             \
512   product(intx, PrefetchCopyIntervalInBytes, -1,                            \
513           "How far ahead to prefetch destination area (<= 0 means off)")    \
514           range(-1, max_jint)                                               \
515                                                                             \
516   product(intx, PrefetchScanIntervalInBytes, -1,                            \
517           "How far ahead to prefetch scan area (<= 0 means off)")           \
518           range(-1, max_jint)                                               \
519                                                                             \
520   product(intx, PrefetchFieldsAhead, -1,                                    \
521           "How many fields ahead to prefetch in oop scan (<= 0 means off)") \
522           range(-1, max_jint)                                               \
523                                                                             \
524   product(bool, VerifyDuringStartup, false, DIAGNOSTIC,                     \
525           "Verify memory system before executing any Java code "            \
526           "during VM initialization")                                       \
527                                                                             \
528   product(bool, VerifyBeforeExit, trueInDebug, DIAGNOSTIC,                  \
529           "Verify system before exiting")                                   \
530                                                                             \
531   product(bool, VerifyBeforeGC, false, DIAGNOSTIC,                          \
532           "Verify memory system before GC")                                 \
533                                                                             \
534   product(bool, VerifyAfterGC, false, DIAGNOSTIC,                           \
535           "Verify memory system after GC")                                  \
536                                                                             \
537   product(bool, VerifyDuringGC, false, DIAGNOSTIC,                          \
538           "Verify memory system during GC (between phases)")                \
539                                                                             \
540   product(bool, VerifyArchivedFields, trueInDebug, DIAGNOSTIC,              \
541           "Verify memory when archived oop fields are loaded from CDS)")    \
542                                                                             \
543   product(ccstrlist, VerifyGCType, "", DIAGNOSTIC,                          \
544              "GC type(s) to verify when Verify*GC is enabled."              \
545              "Available types are collector specific.")                     \
546                                                                             \
547   product(ccstrlist, VerifySubSet, "", DIAGNOSTIC,                          \
548           "Memory sub-systems to verify when Verify*GC flag(s) "            \
549           "are enabled. One or more sub-systems can be specified "          \
550           "in a comma separated string. Sub-systems are: "                  \
551           "threads, heap, symbol_table, string_table, codecache, "          \
552           "dictionary, classloader_data_graph, metaspace, jni_handles, "    \
553           "codecache_oops")                                                 \
554                                                                             \
555   product(bool, GCParallelVerificationEnabled, true, DIAGNOSTIC,            \
556           "Enable parallel memory system verification")                     \
557                                                                             \
558   product(bool, DeferInitialCardMark, false, DIAGNOSTIC,                    \
559           "When +ReduceInitialCardMarks, explicitly defer any that "        \
560           "may arise from new_pre_store_barrier")                           \
561                                                                             \
562   product(bool, UseCondCardMark, false,                                     \
563           "Check for already marked card before updating card table")       \
564                                                                             \
565   product(bool, VerifyRememberedSets, false, DIAGNOSTIC,                    \
566           "Verify GC remembered sets")                                      \
567                                                                             \
568   product(bool, VerifyObjectStartArray, true, DIAGNOSTIC,                   \
569           "Verify GC object start array if verify before/after")            \
570                                                                             \
571   product(bool, DisableExplicitGC, false,                                   \
572           "Ignore calls to System.gc()")                                    \
573                                                                             \
574   product(bool, PrintGC, false,                                             \
575           "Print message at garbage collection. "                           \
576           "Deprecated, use -Xlog:gc instead.")                              \
577                                                                             \
578   product(bool, PrintGCDetails, false,                                      \
579           "Print more details at garbage collection. "                      \
580           "Deprecated, use -Xlog:gc* instead.")                             \
581                                                                             \
582   develop(intx, ConcGCYieldTimeout, 0,                                      \
583           "If non-zero, assert that GC threads yield within this "          \
584           "number of milliseconds")                                         \
585           range(0, max_intx)                                                \
586                                                                             \
587   notproduct(intx, ScavengeALotInterval,     1,                             \
588           "Interval between which scavenge will occur with +ScavengeALot")  \
589                                                                             \
590   notproduct(intx, FullGCALotInterval,     1,                               \
591           "Interval between which full gc will occur with +FullGCALot")     \
592                                                                             \
593   notproduct(intx, FullGCALotStart,     0,                                  \
594           "For which invocation to start FullGCAlot")                       \
595                                                                             \
596   notproduct(intx, FullGCALotDummies,  32*K,                                \
597           "Dummy object allocated with +FullGCALot, forcing all objects "   \
598           "to move")                                                        \
599                                                                             \
600   /* gc parameters */                                                       \
601   product(size_t, MinHeapSize, 0,                                           \
602           "Minimum heap size (in bytes); zero means use ergonomics")        \
603           constraint(MinHeapSizeConstraintFunc,AfterErgo)                   \
604                                                                             \
605   product(size_t, InitialHeapSize, 0,                                       \
606           "Initial heap size (in bytes); zero means use ergonomics")        \
607           constraint(InitialHeapSizeConstraintFunc,AfterErgo)               \
608                                                                             \
609   product(size_t, MaxHeapSize, ScaleForWordSize(96*M),                      \
610           "Maximum heap size (in bytes)")                                   \
611           constraint(MaxHeapSizeConstraintFunc,AfterErgo)                   \
612                                                                             \
613   product(size_t, SoftMaxHeapSize, 0, MANAGEABLE,                           \
614           "Soft limit for maximum heap size (in bytes)")                    \
615           constraint(SoftMaxHeapSizeConstraintFunc,AfterMemoryInit)         \
616                                                                             \
617   product(size_t, OldSize, ScaleForWordSize(4*M),                           \
618           "Initial tenured generation size (in bytes)")                     \
619           range(0, max_uintx)                                               \
620                                                                             \
621   product(size_t, NewSize, ScaleForWordSize(1*M),                           \
622           "Initial new generation size (in bytes)")                         \
623           constraint(NewSizeConstraintFunc,AfterErgo)                       \
624                                                                             \
625   product(size_t, MaxNewSize, max_uintx,                                    \
626           "Maximum new generation size (in bytes), max_uintx means set "    \
627           "ergonomically")                                                  \
628           range(0, max_uintx)                                               \
629                                                                             \
630   product_pd(size_t, HeapBaseMinAddress,                                    \
631           "OS specific low limit for heap base address")                    \
632           constraint(HeapBaseMinAddressConstraintFunc,AfterErgo)            \
633                                                                             \
634   product(size_t, PretenureSizeThreshold, 0,                                \
635           "Maximum size in bytes of objects allocated in DefNew "           \
636           "generation; zero means no maximum")                              \
637           range(0, max_uintx)                                               \
638                                                                             \
639   product(size_t, MinTLABSize, 2*K,                                         \
640           "Minimum allowed TLAB size (in bytes)")                           \
641           range(1, max_uintx/2)                                             \
642           constraint(MinTLABSizeConstraintFunc,AfterMemoryInit)             \
643                                                                             \
644   product(size_t, TLABSize, 0,                                              \
645           "Starting TLAB size (in bytes); zero means set ergonomically")    \
646           constraint(TLABSizeConstraintFunc,AfterMemoryInit)                \
647                                                                             \
648   product(size_t, YoungPLABSize, 4096,                                      \
649           "Size of young gen promotion LAB's (in HeapWords)")               \
650           constraint(YoungPLABSizeConstraintFunc,AfterMemoryInit)           \
651                                                                             \
652   product(size_t, OldPLABSize, 1024,                                        \
653           "Size of old gen promotion LAB's (in HeapWords)")                 \
654           constraint(OldPLABSizeConstraintFunc,AfterMemoryInit)             \
655                                                                             \
656   product(uintx, TLABAllocationWeight, 35,                                  \
657           "Allocation averaging weight")                                    \
658           range(0, 100)                                                     \
659                                                                             \
660   /* Limit the lower bound of this flag to 1 as it is used  */              \
661   /* in a division expression.                              */              \
662   product(uintx, TLABWasteTargetPercent, 1,                                 \
663           "Percentage of Eden that can be wasted")                          \
664           range(1, 100)                                                     \
665                                                                             \
666   product(uintx, TLABRefillWasteFraction,    64,                            \
667           "Maximum TLAB waste at a refill (internal fragmentation)")        \
668           range(1, max_juint)                                               \
669                                                                             \
670   product(uintx, TLABWasteIncrement,    4,                                  \
671           "Increment allowed waste at slow allocation")                     \
672           range(0, max_jint)                                                \
673           constraint(TLABWasteIncrementConstraintFunc,AfterMemoryInit)      \
674                                                                             \
675   product(uintx, SurvivorRatio, 8,                                          \
676           "Ratio of eden/survivor space size")                              \
677           range(1, max_uintx-2)                                             \
678           constraint(SurvivorRatioConstraintFunc,AfterMemoryInit)           \
679                                                                             \
680   product(uintx, NewRatio, 2,                                               \
681           "Ratio of old/new generation sizes")                              \
682           range(0, max_uintx-1)                                             \
683                                                                             \
684   product_pd(size_t, NewSizeThreadIncrease,                                 \
685           "Additional size added to desired new generation size per "       \
686           "non-daemon thread (in bytes)")                                   \
687           range(0, max_uintx)                                               \
688                                                                             \
689   product(uintx, QueuedAllocationWarningCount, 0,                           \
690           "Number of times an allocation that queues behind a GC "          \
691           "will retry before printing a warning")                           \
692           range(0, max_uintx)                                               \
693                                                                             \
694   product(uintx, VerifyGCStartAt,   0, DIAGNOSTIC,                          \
695           "GC invoke count where +VerifyBefore/AfterGC kicks in")           \
696           range(0, max_uintx)                                               \
697                                                                             \
698   product(intx, VerifyGCLevel,     0, DIAGNOSTIC,                           \
699           "Generation level at which to start +VerifyBefore/AfterGC")       \
700           range(0, 1)                                                       \
701                                                                             \
702   product(uintx, MaxTenuringThreshold,    15,                               \
703           "Maximum value for tenuring threshold")                           \
704           range(0, markWord::max_age + 1)                                   \
705           constraint(MaxTenuringThresholdConstraintFunc,AfterErgo)          \
706                                                                             \
707   product(uintx, InitialTenuringThreshold,    7,                            \
708           "Initial value for tenuring threshold")                           \
709           range(0, markWord::max_age + 1)                                   \
710           constraint(InitialTenuringThresholdConstraintFunc,AfterErgo)      \
711                                                                             \
712   product(uintx, TargetSurvivorRatio,    50,                                \
713           "Desired percentage of survivor space used after scavenge")       \
714           range(0, 100)                                                     \
715                                                                             \
716   product(uintx, MarkSweepDeadRatio,     5,                                 \
717           "Percentage (0-100) of the old gen allowed as dead wood. "        \
718           "Serial mark sweep treats this as both the minimum and maximum "  \
719           "value. "                                                         \
720           "Par compact uses a variable scale based on the density of the "  \
721           "generation and treats this as the maximum value when the heap "  \
722           "is either completely full or completely empty.  Par compact "    \
723           "also has a smaller default value; see arguments.cpp.")           \
724           range(0, 100)                                                     \
725                                                                             \
726   product(uint, MarkSweepAlwaysCompactCount,     4,                         \
727           "How often should we fully compact the heap (ignoring the dead "  \
728           "space parameters)")                                              \
729           range(1, max_juint)                                               \
730                                                                             \
731   develop(uintx, GCExpandToAllocateDelayMillis, 0,                          \
732           "Delay between expansion and allocation (in milliseconds)")       \
733                                                                             \
734   product(uintx, GCDrainStackTargetSize, 64,                                \
735           "Number of entries we will try to leave on the stack "            \
736           "during parallel gc")                                             \
737           range(0, max_juint)
738 
739 // end of GC_FLAGS
740 
741 #endif // SHARE_GC_SHARED_GC_GLOBALS_HPP