/*

 * Copyright (c) 2016, 2018, Red Hat, Inc. All rights reserved.

 *

 * This code is free software; you can redistribute it and/or modify it

 * under the terms of the GNU General Public License version 2 only, as

 * published by the Free Software Foundation.

 *

 * This code is distributed in the hope that it will be useful, but WITHOUT

 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

 * version 2 for more details (a copy is included in the LICENSE file that

 * accompanied this code).

 *

 * You should have received a copy of the GNU General Public License version

 * 2 along with this work; if not, write to the Free Software Foundation,

 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

 *

 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

 * or visit www.oracle.com if you need additional information or have any

 * questions.

 *

 */

#ifndef SHARE_GC_SHENANDOAH_SHENANDOAH_GLOBALS_HPP

#define SHARE_GC_SHENANDOAH_SHENANDOAH_GLOBALS_HPP

#define GC_SHENANDOAH_FLAGS(develop,                                        \

                            develop_pd,                                     \

                            product,                                        \

                            product_pd,                                     \

                            diagnostic,                                     \

                            diagnostic_pd,                                  \

                            experimental,                                   \

                            notproduct,                                     \

                            manageable,                                     \

                            product_rw,                                     \

                            lp64_product,                                   \

                            range,                                          \

                            constraint,                                     \

                            writeable)                                      \

                                                                            \

  experimental(size_t, ShenandoahHeapRegionSize, 0,                         \

          "Size of the Shenandoah regions. Set to zero to detect "          \

          "automatically.")                                                 \

                                                                            \

  experimental(size_t, ShenandoahTargetNumRegions, 2048,                    \

          "Target number of regions. We try to get around that many "       \

          "regions, based on Shenandoah{Min,Max}RegionSize.")               \

                                                                            \

  experimental(size_t, ShenandoahMinRegionSize, 256 * K,                    \

          "Minimum Shenandoah heap region size.")                           \

                                                                            \

  experimental(size_t, ShenandoahMaxRegionSize, 32 * M,                     \

          "Maximum Shenandoah heap region size.")                           \

                                                                            \

  experimental(intx, ShenandoahHumongousThreshold, 100,                     \

          "How large should the object be to get allocated in humongous "   \

          "region, in percents of heap region size. This also caps the "    \

          "maximum TLAB size.")                                             \

          range(1, 100)                                                     \

                                                                            \

  experimental(ccstr, ShenandoahGCHeuristics, "adaptive",                   \

          "The heuristics to use in Shenandoah GC. Possible values:"        \

          " *) adaptive - adapt to maintain the given amount of free heap;" \

          " *) static  -  start concurrent GC when static free heap "       \

          "               threshold and static allocation threshold are "   \

          "               tripped;"                                         \

          " *) passive -  do not start concurrent GC, wait for Full GC; "   \

          " *) aggressive - run concurrent GC continuously, evacuate "      \

          "               everything;"                                      \

          " *) compact - run GC with lower footprint target, may end up "   \

          "               doing continuous GC, evacuate lots of live "      \

          "               objects, uncommit heap aggressively;")            \

                                                                            \

  experimental(ccstr, ShenandoahUpdateRefsEarly, "adaptive",                \

          "Run a separate concurrent reference updating phase after"        \

          "concurrent evacuation. Possible values: 'on', 'off', 'adaptive'")\

                                                                            \

  experimental(uintx, ShenandoahRefProcFrequency, 5,                        \

          "How often should (weak, soft, etc) references be processed. "    \

          "References get processed at every Nth GC cycle. Set to zero "    \

          "to disable reference processing.")                               \

                                                                            \

  experimental(uintx, ShenandoahUnloadClassesFrequency, 5,                  \

          "How often should classes get unloaded. "                         \

          "Class unloading is performed at every Nth GC cycle. "            \

          "Set to zero to disable class unloading during concurrent GC.")   \

                                                                            \

  experimental(uintx, ShenandoahGarbageThreshold, 60,                       \

          "Sets the percentage of garbage a region need to contain before " \

          "it can be marked for collection. Does not apply to all "         \

          "heuristics.")                                                    \

          range(0,100)                                                      \

                                                                            \

  experimental(uintx, ShenandoahFreeThreshold, 10,                          \

          "Set the percentage of free heap at which a GC cycle is started. "\

          "Does not apply to all heuristics.")                              \

          range(0,100)                                                      \

                                                                            \

  experimental(uintx, ShenandoahInitFreeThreshold, 70,                      \

          "Initial remaining free heap threshold for learning steps in "    \

          "heuristics. In percents of total heap size. Does not apply to "  \

          "all heuristics.")                                                \

          range(0,100)                                                      \

                                                                            \

  experimental(uintx, ShenandoahMinFreeThreshold, 10,                       \

          "Minimum remaining free space threshold, after which collection " \

          "definitely triggers. Does not apply to all heuristics.")         \

          range(0,100)                                                      \

                                                                            \

  experimental(uintx, ShenandoahAllocationThreshold, 0,                     \

          "Set percentage of memory allocated since last GC cycle before "  \

          "a new GC cycle can be started. Set to zero to effectively "      \

          "disable.")                                                       \

          range(0,100)                                                      \

                                                                            \

  experimental(uintx, ShenandoahLearningSteps, 5,                           \

          "Number of GC cycles to run in order to learn application "       \

          "and GC performance for adaptive heuristics.")                    \

          range(0,100)                                                      \

                                                                            \

  experimental(uintx, ShenandoahImmediateThreshold, 90,                     \

          "If mark identifies more than this much immediate garbage "       \

          "regions, it shall recycle them, and shall not continue the "     \

          "rest of the GC cycle. The value is in percents of total "        \

          "number of candidate regions for collection set. Setting this "   \

          "threshold to 100% effectively disables this shortcut.")          \

          range(0,100)                                                      \

                                                                            \

  experimental(uintx, ShenandoahMergeUpdateRefsMinGap, 100,                 \

          "If GC is currently running in separate update-refs mode "        \

          "this numbers gives the threshold when to switch to "             \

          "merged update-refs mode. Number is percentage relative to"       \

          "duration(marking)+duration(update-refs).")                       \

                                                                            \

  experimental(uintx, ShenandoahMergeUpdateRefsMaxGap, 200,                 \

          "If GC is currently running in merged update-refs mode "          \

          "this numbers gives the threshold when to switch to "             \

          "separate update-refs mode. Number is percentage relative "       \

          "to duration(marking)+duration(update-refs).")                    \

                                                                            \

  experimental(uintx, ShenandoahGuaranteedGCInterval, 5*60*1000,            \

          "Adaptive and dynamic heuristics would guarantee a GC cycle "     \

          "at least with this interval. This is useful when large idle"     \

          " intervals are present, where GC can run without stealing "      \

          "time from active application. Time is in milliseconds.")         \

                                                                            \

  experimental(bool, ShenandoahAlwaysClearSoftRefs, false,                  \

          "Clear soft references always, instead of using any smart "       \

          "cleanup policy. This minimizes footprint at expense of more "    \

          "softref churn in applications.")                                 \

                                                                            \

  experimental(bool, ShenandoahUncommit, true,                              \

          "Allow Shenandoah to uncommit unused memory.")                    \

                                                                            \

  experimental(uintx, ShenandoahUncommitDelay, 5*60*1000,                   \

          "Shenandoah would start to uncommit memory for regions that were" \

          " not used for more than this time. First use after that would "  \

          "incur allocation stalls. Actively used regions would never be "  \

          "uncommitted, because they never decay. Time is in milliseconds." \

          "Setting this delay to 0 effectively makes Shenandoah to "        \

          "uncommit the regions almost immediately.")                       \

                                                                            \

  experimental(bool, ShenandoahRegionSampling, false,                       \

          "Turns on heap region sampling via JVMStat")                      \

                                                                            \

  experimental(int, ShenandoahRegionSamplingRate, 40,                       \

          "Sampling rate for heap region sampling. "                        \

          "Number of milliseconds between samples")                         \

                                                                            \

  experimental(uintx, ShenandoahControlIntervalMin, 1,                      \

          "The minumum sleep interval for control loop that drives "        \

          "the cycles. Lower values would increase GC responsiveness "      \

          "to changing heap conditions, at the expense of higher perf "     \

          "overhead. Time is in milliseconds.")                             \

                                                                            \

  experimental(uintx, ShenandoahControlIntervalMax, 10,                     \

          "The maximum sleep interval for control loop that drives "        \

          "the cycles. Lower values would increase GC responsiveness "      \

          "to changing heap conditions, at the expense of higher perf "     \

          "overhead. Time is in milliseconds.")                             \

                                                                            \

  experimental(uintx, ShenandoahControlIntervalAdjustPeriod, 1000,          \

          "The time period for one step in control loop interval "          \

          "adjustment. Lower values make adjustments faster, at the "       \

          "expense of higher perf overhead. Time is in milliseconds.")      \

                                                                            \

  diagnostic(bool, ShenandoahVerify, false,                                 \

          "Verify the Shenandoah garbage collector")                        \

                                                                            \

  diagnostic(intx, ShenandoahVerifyLevel, 4,                                \

          "Shenandoah verification level: "                                 \

          "0 = basic heap checks; "                                         \

          "1 = previous level, plus basic region checks; "                  \

          "2 = previous level, plus all roots; "                            \

          "3 = previous level, plus all reachable objects; "                \

          "4 = previous level, plus all marked objects")                    \

                                                                            \

  diagnostic(bool, ShenandoahElasticTLAB, true,                             \

          "Use Elastic TLABs with Shenandoah")                              \

                                                                            \

  diagnostic(bool, ShenandoahAllowMixedAllocs, true,                        \

          "Allow mixing mutator and collector allocations in a single "     \

          "region")                                                         \

                                                                            \

  experimental(uintx, ShenandoahAllocSpikeFactor, 5,                        \

          "The amount of heap space to reserve for absorbing the "          \

          "allocation spikes. Larger value wastes more memory in "          \

          "non-emergency cases, but provides more safety in emergency "     \

          "cases. In percents of total heap size.")                         \

          range(0,100)                                                      \

                                                                            \

  experimental(uintx, ShenandoahEvacReserve, 5,                             \

          "Maximum amount of free space to reserve for evacuation. "        \

          "Larger values make GC more aggressive, while leaving less "      \

          "headroom for application to allocate in. "                       \

          "In percents of total heap size.")                                \

          range(1,100)                                                      \

                                                                            \

  experimental(double, ShenandoahEvacWaste, 1.2,                            \

          "How much waste evacuations produce within the reserved "         \

          "space. Larger values make evacuations more resilient "           \

          "against allocation failures, at expense of smaller csets "       \

          "on each cycle.")                                                 \

          range(1.0,100.0)                                                  \

                                                                            \

  experimental(bool, ShenandoahEvacReserveOverflow, true,                   \

          "Allow evacuations to overflow the reserved space. "              \

          "Enabling it will make evacuations more resilient when "          \

          "evacuation reserve/waste is incorrect, at the risk that "        \

          "application allocations run out of memory too early.")           \

                                                                            \

  diagnostic(bool, ShenandoahAllocationTrace, false,                        \

          "Trace allocation latencies and stalls. Can be expensive when "   \

          "lots of allocations happen, and may introduce scalability "      \

          "bottlenecks.")                                                   \

                                                                            \

  diagnostic(intx, ShenandoahAllocationStallThreshold, 10000,               \

          "When allocation tracing is enabled, the allocation stalls "      \

          "larger than this threshold would be reported as warnings. "      \

          "Time is in microseconds.")                                       \

                                                                            \

  experimental(uintx, ShenandoahEvacAssist, 10,                             \

          "How many objects to evacuate on WB assist path. "                \

          "Use zero to disable.")                                           \

                                                                            \

  experimental(bool, ShenandoahPacing, true,                                \

          "Pace application allocations to give GC chance to start "        \

          "and complete before allocation failure is reached.")             \

                                                                            \

  experimental(uintx, ShenandoahPacingMaxDelay, 10,                         \

          "Max delay for pacing application allocations. "                  \

          "Time is in milliseconds.")                                       \

                                                                            \

  experimental(uintx, ShenandoahPacingIdleSlack, 2,                         \

          "Percent of heap counted as non-taxable allocations during idle. "\

          "Larger value makes the pacing milder during idle phases, "       \

          "requiring less rendezvous with control thread. Lower value "     \

          "makes the pacing control less responsive to out-of-cycle allocs.")\

          range(0, 100)                                                     \

                                                                            \

  experimental(uintx, ShenandoahPacingCycleSlack, 10,                       \

          "Percent of free space taken as non-taxable allocations during "  \

          "the GC cycle. Larger value makes the pacing milder at the "      \

          "beginning of the GC cycle. Lower value makes the pacing less "   \

          "uniform during the cycle.")                                      \

          range(0, 100)                                                     \

                                                                            \

  experimental(double, ShenandoahPacingSurcharge, 1.1,                      \

          "Additional pacing tax surcharge to help unclutter the heap. "    \

          "Larger values makes the pacing more aggressive. Lower values "   \

          "risk GC cycles finish with less memory than were available at "  \

          "the beginning of it.")                                           \

          range(1.0, 100.0)                                                 \

                                                                            \

  experimental(uintx, ShenandoahCriticalFreeThreshold, 1,                   \

          "Percent of heap that needs to be free after recovery cycles, "   \

          "either Degenerated or Full GC. If this much space is not "       \

          "available, next recovery step would triggered.")                 \

          range(0, 100)                                                     \

                                                                            \

  diagnostic(bool, ShenandoahDegeneratedGC, true,                           \

          "Use Degenerated GC as the graceful degradation step. Disabling " \

          "this leads to degradation to Full GC")                           \

                                                                            \

  experimental(uintx, ShenandoahFullGCThreshold, 3,                         \

          "How many back-to-back Degenerated GCs to do before triggering "  \

          "a Full GC.")                                                     \

                                                                            \

  experimental(bool, ShenandoahImplicitGCInvokesConcurrent, false,          \

          "Should internally-caused GCs invoke concurrent cycles, or go to" \

          "stop-the-world (degenerated/full)?")                             \

                                                                            \

  experimental(bool, ShenandoahHumongousMoves, true,                        \

          "Allow moving humongous regions. This makes GC more resistant "   \

          "to external fragmentation that may otherwise fail other "        \

          "humongous allocations, at the expense of higher GC copying "     \

          "costs.")                                                         \

                                                                            \

  diagnostic(bool, ShenandoahOOMDuringEvacALot, false,                      \

          "Simulate OOM during evacuation frequently.")                     \

                                                                            \

  diagnostic(bool, ShenandoahAllocFailureALot, false,                       \

          "Make lots of artificial allocation failures.")                   \

                                                                            \

  diagnostic(bool, ShenandoahTerminationTrace, false,                       \

          "Tracing task termination timings")                               \

                                                                            \

  develop(bool, ShenandoahVerifyObjectEquals, false,                        \

          "Verify that == and != are not used on oops. Only in fastdebug")  \

                                                                            \

  diagnostic(bool, ShenandoahAlwaysPreTouch, false,                         \

          "Pre-touch heap memory, overrides global AlwaysPreTouch")         \

                                                                            \

  experimental(intx, ShenandoahMarkScanPrefetch, 32,                        \

          "How many objects to prefetch ahead when traversing mark bitmaps."\

          "Set to 0 to disable prefetching.")                               \

          range(0, 256)                                                     \

                                                                            \

  experimental(uintx, ShenandoahMarkLoopStride, 1000,                       \

          "How many items are processed during one marking step")           \

                                                                            \

  experimental(uintx, ShenandoahParallelRegionStride, 1024,                 \

          "How many regions are processed in one stride during parallel "   \

          "iteration.")                                                     \

                                                                            \

  experimental(size_t, ShenandoahSATBBufferSize, 1 * K,                     \

          "Number of entries in an SATB log buffer.")                       \

          range(1, max_uintx)                                               \

                                                                            \

  experimental(uintx, ShenandoahSATBBufferFlushInterval, 100,               \

          "Forcefully flush non-empty SATB buffers at this interval. "      \

          "Time is in milliseconds.")                                       \

                                                                            \

  experimental(uint, ShenandoahParallelSafepointThreads, 4,                 \

          "Number of parallel threads used for safepoint prolog/epilog")    \

                                                                            \

  experimental(bool, ShenandoahPreclean, true,                              \

          "Do concurrent preclean phase before final mark: process "        \

          "definitely alive references to avoid dealing with them during "  \

          "pause.")                                                         \

                                                                            \

  experimental(bool, ShenandoahSuspendibleWorkers, false,                   \

          "Suspend concurrent GC worker threads at safepoints")             \

                                                                            \

  diagnostic(bool, ShenandoahSATBBarrier, true,                             \

          "Turn on/off SATB barriers in Shenandoah")                        \

                                                                            \

  diagnostic(bool, ShenandoahKeepAliveBarrier, true,                        \

          "Turn on/off keep alive barriers in Shenandoah")                  \

                                                                            \

  diagnostic(bool, ShenandoahWriteBarrier, true,                            \

          "Turn on/off write barriers in Shenandoah")                       \

                                                                            \

  diagnostic(bool, ShenandoahReadBarrier, true,                             \

          "Turn on/off read barriers in Shenandoah")                        \

                                                                            \

  diagnostic(bool, ShenandoahStoreValEnqueueBarrier, false,                 \

          "Turn on/off enqueuing of oops for storeval barriers")            \

                                                                            \

  diagnostic(bool, ShenandoahStoreValReadBarrier, true,                     \

          "Turn on/off store val read barriers in Shenandoah")              \

                                                                            \

  diagnostic(bool, ShenandoahCASBarrier, true,                              \

          "Turn on/off CAS barriers in Shenandoah")                         \

                                                                            \

  diagnostic(bool, ShenandoahAcmpBarrier, true,                             \

          "Turn on/off acmp barriers in Shenandoah")                        \

                                                                            \

  diagnostic(bool, ShenandoahCloneBarrier, true,                            \

          "Turn on/off clone barriers in Shenandoah")                       \

                                                                            \

  diagnostic(bool, ShenandoahStoreCheck, false,                             \

          "Emit additional code that checks objects are written to only"    \

          " in to-space")                                                   \

                                                                            \

  experimental(bool, ShenandoahConcurrentScanCodeRoots, true,               \

          "Scan code roots concurrently, instead of during a pause")        \

                                                                            \

  experimental(uintx, ShenandoahCodeRootsStyle, 2,                          \

          "Use this style to scan code cache:"                              \

          " 0 - sequential iterator;"                                       \

          " 1 - parallel iterator;"                                         \

          " 2 - parallel iterator with cset filters;")                      \

                                                                            \

  experimental(bool, ShenandoahOptimizeStaticFinals, true,                  \

          "Optimize barriers on static final fields. "                      \

          "Turn it off for maximum compatibility with reflection or JNI "   \

          "code that manipulates final fields.")                            \

                                                                            \

  experimental(bool, ShenandoahOptimizeInstanceFinals, false,               \

          "Optimize barriers on final instance fields."                     \

          "Turn it off for maximum compatibility with reflection or JNI "   \

          "code that manipulates final fields.")                            \

                                                                            \

  experimental(bool, ShenandoahOptimizeStableFinals, false,                 \

          "Optimize barriers on stable fields."                             \

          "Turn it off for maximum compatibility with reflection or JNI "   \

          "code that manipulates final fields.")                            \

                                                                            \

  diagnostic(bool, ShenandoahDecreaseRegisterPressure, false,               \

          "Try to reuse after-barrier values to reduce register pressure")  \

                                                                            \

  experimental(bool, ShenandoahCommonGCStateLoads, false,                   \

         "Enable commonming for GC state loads in generated code.")         \

                                                                            \

  develop(bool, ShenandoahVerifyOptoBarriers, false,                        \

          "Verify no missing barriers in C2")                               \

                                                                            \

  experimental(bool, ShenandoahDontIncreaseWBFreq, true,                    \

          "Common 2 WriteBarriers or WriteBarrier and a ReadBarrier only "  \

          "if the resulting WriteBarrier isn't executed more frequently")   \

                                                                            \

  experimental(bool, ShenandoahLoopOptsAfterExpansion, true,                \

          "Attempt more loop opts after write barrier expansion")           \

#endif // SHARE_GC_SHENANDOAH_SHENANDOAH_GLOBALS_HPP