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
|