6684579: SoftReference processing can be made more efficient
Summary: For current soft-ref clearing policies, we can decide at marking time if a soft-reference will definitely not be cleared, postponing the decision of whether it will definitely be cleared to the final reference processing phase. This can be especially beneficial in the case of concurrent collectors where the marking is usually concurrent but reference processing is usually not.
Reviewed-by: jmasa
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//
// Defines all globals flags used by the garbage-first compiler.
//
#define G1_FLAGS(develop, develop_pd, product, product_pd, diagnostic, experimental, notproduct, manageable, product_rw) \
\
product(intx, ParallelGCG1AllocBufferSize, 4*K, \
"Size of parallel G1 allocation buffers in to-space.") \
\
product(intx, G1TimeSliceMS, 500, \
"Time slice for MMU specification") \
\
product(intx, G1MaxPauseTimeMS, 200, \
"Max GC time per MMU time slice") \
\
product(intx, G1ConfidencePerc, 50, \
"Confidence level for MMU/pause predictions") \
\
product(intx, G1MarkingOverheadPerc, 0, \
"Overhead of concurrent marking") \
\
product(bool, G1AccountConcurrentOverhead, false, \
"Whether soft real-time compliance in G1 will take into account" \
"concurrent overhead") \
\
product(intx, G1YoungGenSize, 0, \
"Size of the G1 young generation, 0 is the adaptive policy") \
\
product(bool, G1Gen, true, \
"If true, it will enable the generational G1") \
\
develop(intx, G1GCPct, 10, \
"The desired percent time spent on GC") \
\
product(intx, G1PolicyVerbose, 0, \
"The verbosity level on G1 policy decisions") \
\
develop(bool, G1UseHRIntoRS, true, \
"Determines whether the 'advanced' HR Into rem set is used.") \
\
product(bool, G1VerifyRemSet, false, \
"If true, verify the rem set functioning at each GC") \
\
product(bool, G1VerifyConcMark, false, \
"If true, verify the conc marking code at full GC time") \
\
develop(intx, G1MarkingVerboseLevel, 0, \
"Level (0-4) of verboseness of the marking code") \
\
develop(bool, G1VerifyConcMarkPrintReachable, true, \
"If conc mark verification fails, print reachable objects") \
\
develop(bool, G1TraceMarkStackOverflow, false, \
"If true, extra debugging code for CM restart for ovflw.") \
\
product(bool, G1VerifyMarkingInEvac, false, \
"If true, verify marking info during evacuation") \
\
develop(intx, G1PausesBtwnConcMark, -1, \
"If positive, fixed number of pauses between conc markings") \
\
product(intx, G1EfficiencyPctCausesMark, 80, \
"The cum gc efficiency since mark fall-off that causes " \
"new marking") \
\
product(bool, TraceConcurrentMark, false, \
"Trace concurrent mark") \
\
product(bool, SummarizeG1ConcMark, false, \
"Summarize concurrent mark info") \
\
product(bool, SummarizeG1RSStats, false, \
"Summarize remembered set processing info") \
\
product(bool, SummarizeG1ZFStats, false, \
"Summarize zero-filling info") \
\
product(bool, TraceG1Refine, false, \
"Trace G1 concurrent refinement") \
\
develop(bool, G1ConcMark, true, \
"If true, run concurrent marking for G1") \
\
product(intx, G1CMStackSize, 2 * 1024 * 1024, \
"Size of the mark stack for concurrent marking.") \
\
product(intx, G1CMRegionStackSize, 1024 * 1024, \
"Size of the region stack for concurrent marking.") \
\
develop(bool, G1ConcRefine, true, \
"If true, run concurrent rem set refinement for G1") \
\
develop(intx, G1ConcRefineTargTraversals, 4, \
"Number of concurrent refinement we try to achieve") \
\
develop(intx, G1ConcRefineInitialDelta, 4, \
"Number of heap regions of alloc ahead of starting collection " \
"pause to start concurrent refinement (initially)") \
\
product(bool, G1SmoothConcRefine, true, \
"Attempts to smooth out the overhead of concurrent refinement") \
\
develop(bool, G1ConcZeroFill, true, \
"If true, run concurrent zero-filling thread") \
\
develop(intx, G1ConcZFMaxRegions, 1, \
"Stop zero-filling when # of zf'd regions reaches") \
\
product(intx, G1SteadyStateUsed, 90, \
"If non-0, try to maintain 'used' at this pct (of max)") \
\
product(intx, G1SteadyStateUsedDelta, 30, \
"If G1SteadyStateUsed is non-0, then do pause this number of " \
"of percentage points earlier if no marking is in progress.") \
\
develop(bool, G1SATBBarrierPrintNullPreVals, false, \
"If true, count frac of ptr writes with null pre-vals.") \
\
product(intx, G1SATBLogBufferSize, 1*K, \
"Number of entries in an SATB log buffer.") \
\
product(intx, G1SATBProcessCompletedThreshold, 20, \
"Number of completed buffers that triggers log processing.") \
\
develop(intx, G1ExtraRegionSurvRate, 33, \
"If the young survival rate is S, and there's room left in " \
"to-space, we will allow regions whose survival rate is up to " \
"S + (1 - S)*X, where X is this parameter (as a fraction.)") \
\
develop(intx, G1InitYoungSurvRatio, 50, \
"Expected Survival Rate for newly allocated bytes") \
\
develop(bool, G1SATBPrintStubs, false, \
"If true, print generated stubs for the SATB barrier") \
\
product(intx, G1ExpandByPctOfAvail, 20, \
"When expanding, % of uncommitted space to claim.") \
\
develop(bool, G1RSBarrierRegionFilter, true, \
"If true, generate region filtering code in RS barrier") \
\
develop(bool, G1RSBarrierNullFilter, true, \
"If true, generate null-pointer filtering code in RS barrier") \
\
develop(bool, G1PrintCTFilterStats, false, \
"If true, print stats on RS filtering effectiveness") \
\
develop(bool, G1RSBarrierUseQueue, true, \
"If true, use queueing RS barrier") \
\
develop(bool, G1RSLogCheckCardTable, false, \
"If true, verify that no dirty cards remain after RS log " \
"processing.") \
\
product(intx, G1MinPausesBetweenMarks, 2, \
"Number of inefficient pauses necessary to trigger marking.") \
\
product(intx, G1InefficientPausePct, 80, \
"Threshold of an 'inefficient' pauses (as % of cum efficiency.") \
\
product(intx, G1RSPopLimit, 32768, \
"Limit that defines popularity. Should go away! XXX") \
\
develop(bool, G1RSCountHisto, false, \
"If true, print a histogram of RS occupancies after each pause") \
\
product(intx, G1ObjPopLimit, 256, \
"Limit that defines popularity for an object.") \
\
product(bool, G1TraceFileOverwrite, false, \
"Allow the trace file to be overwritten") \
\
develop(intx, G1PrintRegionLivenessInfo, 0, \
"When > 0, print the occupancies of the <n> best and worst" \
"regions.") \
\
develop(bool, G1TracePopularity, false, \
"When true, provide detailed tracing of popularity.") \
\
product(bool, G1SummarizePopularity, false, \
"When true, provide end-of-run-summarization of popularity.") \
\
product(intx, G1NumPopularRegions, 1, \
"Number of regions reserved to hold popular objects. " \
"Should go away later.") \
\
develop(bool, G1PrintParCleanupStats, false, \
"When true, print extra stats about parallel cleanup.") \
\
product(bool, G1DoAgeCohortChecks, false, \
"When true, check well-formedness of age cohort structures.") \
\
develop(bool, G1DisablePreBarrier, false, \
"Disable generation of pre-barrier (i.e., marking barrier) ") \
\
develop(bool, G1DisablePostBarrier, false, \
"Disable generation of post-barrier (i.e., RS barrier) ") \
\
product(intx, G1DirtyCardQueueMax, 30, \
"Maximum number of completed RS buffers before mutator threads " \
"start processing them.") \
\
develop(intx, G1ConcRSLogCacheSize, 10, \
"Log base 2 of the length of conc RS hot-card cache.") \
\
product(bool, G1ConcRSCountTraversals, false, \
"If true, gather data about the number of times CR traverses " \
"cards ") \
\
product(intx, G1ConcRSHotCardLimit, 4, \
"The threshold that defines (>=) a hot card.") \
\
develop(bool, G1PrintOopAppls, false, \
"When true, print applications of closures to external locs.") \
\
product(intx, G1LogRSRegionEntries, 7, \
"Log_2 of max number of regions for which we keep bitmaps.") \
\
develop(bool, G1RecordHRRSOops, false, \
"When true, record recent calls to rem set operations.") \
\
develop(bool, G1RecordHRRSEvents, false, \
"When true, record recent calls to rem set operations.") \
\
develop(intx, G1MaxVerifyFailures, -1, \
"The maximum number of verification failrues to print. " \
"-1 means print all.") \
\
develop(bool, G1ScrubRemSets, true, \
"When true, do RS scrubbing after cleanup.") \
\
develop(bool, G1RSScrubVerbose, false, \
"When true, do RS scrubbing with verbose output.") \
\
develop(bool, G1YoungSurvRateVerbose, false, \
"print out the survival rate of young regions according to age.") \
\
develop(intx, G1YoungSurvRateNumRegionsSummary, 0, \
"the number of regions for which we'll print a surv rate " \
"summary.") \
\
product(bool, G1UseScanOnlyPrefix, false, \
"It determines whether the system will calculate an optimum " \
"scan-only set.") \
\
product(intx, G1MinReservePerc, 10, \
"It determines the minimum reserve we should have in the heap " \
"to minimize the probability of promotion failure.") \
\
product(bool, G1TraceRegions, false, \
"If set G1 will print information on which regions are being " \
"allocated and which are reclaimed.") \
\
develop(bool, G1HRRSUseSparseTable, true, \
"When true, use sparse table to save space.") \
\
develop(bool, G1HRRSFlushLogBuffersOnVerify, false, \
"Forces flushing of log buffers before verification.") \
\
product(intx, G1MaxSurvivorRegions, 0, \
"The maximum number of survivor regions")
G1_FLAGS(DECLARE_DEVELOPER_FLAG, DECLARE_PD_DEVELOPER_FLAG, DECLARE_PRODUCT_FLAG, DECLARE_PD_PRODUCT_FLAG, DECLARE_DIAGNOSTIC_FLAG, DECLARE_EXPERIMENTAL_FLAG, DECLARE_NOTPRODUCT_FLAG, DECLARE_MANAGEABLE_FLAG, DECLARE_PRODUCT_RW_FLAG)