1/*
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24
25#ifndef SHARE_GC_G1_G1PREDICTIONS_HPP
26#define SHARE_GC_G1_G1PREDICTIONS_HPP
27
28#include "utilities/numberSeq.hpp"
29
30// Utility class containing various helper methods for prediction.
31class G1Predictions {
32 private:
33 double _sigma;
34
35 // This function is used to estimate the stddev of sample sets. There is some
36 // special consideration of small sample sets: the actual stddev for them is
37 // not very useful, so we calculate some value based on the sample average.
38 // Five or more samples yields zero (at that point we use the stddev); fewer
39 // scale the sample set average linearly from two times the average to 0.5 times
40 // it.
41 double stddev_estimate(TruncatedSeq const* seq) const {
42 double estimate = seq->dsd();
43 int const samples = seq->num();
44 if (samples < 5) {
45 estimate = MAX2(seq->davg() * (5 - samples) / 2.0, estimate);
46 }
47 return estimate;
48 }
49 public:
50 G1Predictions(double sigma) : _sigma(sigma) {
51 assert(sigma >= 0.0, "Confidence must be larger than or equal to zero");
52 }
53
54 // Confidence factor.
55 double sigma() const { return _sigma; }
56
57 double get_new_prediction(TruncatedSeq const* seq) const {
58 return seq->davg() + _sigma * stddev_estimate(seq);
59 }
60};
61
62#endif // SHARE_GC_G1_G1PREDICTIONS_HPP
63