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src/hotspot/share/gc/shenandoah/heuristics/shenandoahAdaptiveHeuristics.cpp

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  24 #include "precompiled.hpp"
  25 
  26 #include "gc/shenandoah/heuristics/shenandoahAdaptiveHeuristics.hpp"
  27 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
  28 #include "gc/shenandoah/shenandoahFreeSet.hpp"
  29 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
  30 #include "logging/log.hpp"
  31 #include "logging/logTag.hpp"
  32 #include "utilities/quickSort.hpp"
  33 
  34 ShenandoahAdaptiveHeuristics::ShenandoahAdaptiveHeuristics() :
  35   ShenandoahHeuristics(),
  36   _cycle_gap_history(new TruncatedSeq(5)),
  37   _conc_mark_duration_history(new TruncatedSeq(5)),
  38   _conc_uprefs_duration_history(new TruncatedSeq(5)) {
  39 
  40   SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
  41   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
  42 
  43   // Final configuration checks

  44   SHENANDOAH_CHECK_FLAG_SET(ShenandoahSATBBarrier);
  45   SHENANDOAH_CHECK_FLAG_SET(ShenandoahReadBarrier);
  46   SHENANDOAH_CHECK_FLAG_SET(ShenandoahWriteBarrier);
  47   SHENANDOAH_CHECK_FLAG_SET(ShenandoahStoreValReadBarrier);
  48   SHENANDOAH_CHECK_FLAG_SET(ShenandoahKeepAliveBarrier);
  49   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCASBarrier);
  50   SHENANDOAH_CHECK_FLAG_SET(ShenandoahAcmpBarrier);
  51   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCloneBarrier);
  52 }
  53 
  54 ShenandoahAdaptiveHeuristics::~ShenandoahAdaptiveHeuristics() {}
  55 
  56 void ShenandoahAdaptiveHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
  57                                                                          RegionData* data, size_t size,
  58                                                                          size_t actual_free) {
  59   size_t garbage_threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
  60 
  61   // The logic for cset selection in adaptive is as follows:
  62   //
  63   //   1. We cannot get cset larger than available free space. Otherwise we guarantee OOME
  64   //      during evacuation, and thus guarantee full GC. In practice, we also want to let
  65   //      application to allocate something. This is why we limit CSet to some fraction of
  66   //      available space. In non-overloaded heap, max_cset would contain all plausible candidates
  67   //      over garbage threshold.
  68   //
  69   //   2. We should not get cset too low so that free threshold would not be met right
  70   //      after the cycle. Otherwise we get back-to-back cycles for no reason if heap is




  24 #include "precompiled.hpp"
  25 
  26 #include "gc/shenandoah/heuristics/shenandoahAdaptiveHeuristics.hpp"
  27 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
  28 #include "gc/shenandoah/shenandoahFreeSet.hpp"
  29 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
  30 #include "logging/log.hpp"
  31 #include "logging/logTag.hpp"
  32 #include "utilities/quickSort.hpp"
  33 
  34 ShenandoahAdaptiveHeuristics::ShenandoahAdaptiveHeuristics() :
  35   ShenandoahHeuristics(),
  36   _cycle_gap_history(new TruncatedSeq(5)),
  37   _conc_mark_duration_history(new TruncatedSeq(5)),
  38   _conc_uprefs_duration_history(new TruncatedSeq(5)) {
  39 
  40   SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
  41   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
  42 
  43   // Final configuration checks
  44   SHENANDOAH_CHECK_FLAG_SET(ShenandoahLoadRefBarrier);
  45   SHENANDOAH_CHECK_FLAG_SET(ShenandoahSATBBarrier);



  46   SHENANDOAH_CHECK_FLAG_SET(ShenandoahKeepAliveBarrier);
  47   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCASBarrier);

  48   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCloneBarrier);
  49 }
  50 
  51 ShenandoahAdaptiveHeuristics::~ShenandoahAdaptiveHeuristics() {}
  52 
  53 void ShenandoahAdaptiveHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
  54                                                                          RegionData* data, size_t size,
  55                                                                          size_t actual_free) {
  56   size_t garbage_threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
  57 
  58   // The logic for cset selection in adaptive is as follows:
  59   //
  60   //   1. We cannot get cset larger than available free space. Otherwise we guarantee OOME
  61   //      during evacuation, and thus guarantee full GC. In practice, we also want to let
  62   //      application to allocate something. This is why we limit CSet to some fraction of
  63   //      available space. In non-overloaded heap, max_cset would contain all plausible candidates
  64   //      over garbage threshold.
  65   //
  66   //   2. We should not get cset too low so that free threshold would not be met right
  67   //      after the cycle. Otherwise we get back-to-back cycles for no reason if heap is


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