26 #define SHARE_VM_GC_G1_G1YOUNGREMSETSAMPLINGTHREAD_HPP
  27 
  28 #include "gc/shared/concurrentGCThread.hpp"
  29 
  30 // The G1YoungRemSetSamplingThread is used to re-assess the validity of
  31 // the prediction for the remembered set lengths of the young generation.
  32 //
  33 // At the end of the GC G1 determines the length of the young gen based on
  34 // how much time the next GC can take, and when the next GC may occur
  35 // according to the MMU.
  36 //
  37 // The assumption is that a significant part of the GC is spent on scanning
  38 // the remembered sets (and many other components), so this thread constantly
  39 // reevaluates the prediction for the remembered set scanning costs, and potentially
  40 // G1Policy resizes the young gen. This may do a premature GC or even
  41 // increase the young gen size to keep pause time length goal.
  42 class G1YoungRemSetSamplingThread: public ConcurrentGCThread {
  43 private:
  44   Monitor _monitor;
  45 




  46   void sample_young_list_rs_lengths();
  47 
  48   void run_service();
  49   void stop_service();
  50 
  51   void sleep_before_next_cycle();
  52 
  53   double _vtime_accum;  // Accumulated virtual time.
  54 
  55 public:
  56   G1YoungRemSetSamplingThread();
  57   double vtime_accum() { return _vtime_accum; }
  58 };
  59 
  60 #endif // SHARE_VM_GC_G1_G1YOUNGREMSETSAMPLINGTHREAD_HPP

  26 #define SHARE_VM_GC_G1_G1YOUNGREMSETSAMPLINGTHREAD_HPP
  27 
  28 #include "gc/shared/concurrentGCThread.hpp"
  29 
  30 // The G1YoungRemSetSamplingThread is used to re-assess the validity of
  31 // the prediction for the remembered set lengths of the young generation.
  32 //
  33 // At the end of the GC G1 determines the length of the young gen based on
  34 // how much time the next GC can take, and when the next GC may occur
  35 // according to the MMU.
  36 //
  37 // The assumption is that a significant part of the GC is spent on scanning
  38 // the remembered sets (and many other components), so this thread constantly
  39 // reevaluates the prediction for the remembered set scanning costs, and potentially
  40 // G1Policy resizes the young gen. This may do a premature GC or even
  41 // increase the young gen size to keep pause time length goal.
  42 class G1YoungRemSetSamplingThread: public ConcurrentGCThread {
  43 private:
  44   Monitor _monitor;
  45 
  46   double _last_periodic_gc_attempt_s;
  47 
  48   double _vtime_accum;  // Accumulated virtual time.
  49 
  50   void sample_young_list_rs_lengths();
  51 
  52   void run_service();
  53   void stop_service();
  54 
  55   void sleep_before_next_cycle();
  56 
  57   bool should_start_periodic_gc();
  58 
  59 public:
  60   G1YoungRemSetSamplingThread();
  61   double vtime_accum() { return _vtime_accum; }
  62 };
  63 
  64 #endif // SHARE_VM_GC_G1_G1YOUNGREMSETSAMPLINGTHREAD_HPP