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#ifndef SHARE_VM_GC_G1_G1PREDICTIONS_HPP
#define SHARE_VM_GC_G1_G1PREDICTIONS_HPP
#include "utilities/numberSeq.hpp"
// Utility class containing various helper methods for prediction.
class G1Predictions VALUE_OBJ_CLASS_SPEC {
private:
double _sigma;
// This function is used to estimate the stddev of sample sets. There is some
// special consideration of small sample sets: the actual stddev for them is
// not very useful, so we calculate some value based on the sample average.
// Five or more samples yields zero (at that point we use the stddev); fewer
// scale the sample set average linearly from two times the average to 0.5 times
// it.
double stddev_estimate(TruncatedSeq const* seq) const {
double estimate = seq->dsd();
int const samples = seq->num();
if (samples < 5) {
estimate = MAX2(seq->davg() * (5 - samples) / 2.0, estimate);
}
return estimate;
}
public:
G1Predictions(double sigma) : _sigma(sigma) {
assert(sigma >= 0.0, "Confidence must be larger than or equal to zero");
}
// Confidence factor.
double sigma() const { return _sigma; }
double get_new_prediction(TruncatedSeq const* seq) const {
return seq->davg() + _sigma * stddev_estimate(seq);
}
};
#endif // SHARE_VM_GC_G1_G1PREDICTIONS_HPP