1. 根目录:
2. tools
3. perf
4. util
5. stat.h

#ifndef __PERF_STATS_H
#define __PERF_STATS_H

#include "types.h"

struct stats
{
	double n, mean, M2;
};

void update_stats(struct stats *stats, u64 val);
double avg_stats(struct stats *stats);
double stddev_stats(struct stats *stats);
double rel_stddev_stats(double stddev, double avg);

#endif