![Xiao Guangrong](/assets/img/avatar_default.png)
Then, the code can be shared between kvm events and perf stat. Signed-off-by: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com> [ Dong Hao <haodong@linux.vnet.ibm.com>: rebase it on acme's git tree ] Signed-off-by: Dong Hao <haodong@linux.vnet.ibm.com> Cc: Avi Kivity <avi@redhat.com> Cc: David Ahern <dsahern@gmail.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: kvm@vger.kernel.org Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Runzhen Wang <runzhen@linux.vnet.ibm.com> Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com Link: http://lkml.kernel.org/r/1347870675-31495-3-git-send-email-haodong@linux.vnet.ibm.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
58 lines
984 B
C
58 lines
984 B
C
#include <math.h>
|
|
|
|
#include "stat.h"
|
|
|
|
void update_stats(struct stats *stats, u64 val)
|
|
{
|
|
double delta;
|
|
|
|
stats->n++;
|
|
delta = val - stats->mean;
|
|
stats->mean += delta / stats->n;
|
|
stats->M2 += delta*(val - stats->mean);
|
|
}
|
|
|
|
double avg_stats(struct stats *stats)
|
|
{
|
|
return stats->mean;
|
|
}
|
|
|
|
/*
|
|
* http://en.wikipedia.org/wiki/Algorithms_for_calculating_variance
|
|
*
|
|
* (\Sum n_i^2) - ((\Sum n_i)^2)/n
|
|
* s^2 = -------------------------------
|
|
* n - 1
|
|
*
|
|
* http://en.wikipedia.org/wiki/Stddev
|
|
*
|
|
* The std dev of the mean is related to the std dev by:
|
|
*
|
|
* s
|
|
* s_mean = -------
|
|
* sqrt(n)
|
|
*
|
|
*/
|
|
double stddev_stats(struct stats *stats)
|
|
{
|
|
double variance, variance_mean;
|
|
|
|
if (!stats->n)
|
|
return 0.0;
|
|
|
|
variance = stats->M2 / (stats->n - 1);
|
|
variance_mean = variance / stats->n;
|
|
|
|
return sqrt(variance_mean);
|
|
}
|
|
|
|
double rel_stddev_stats(double stddev, double avg)
|
|
{
|
|
double pct = 0.0;
|
|
|
|
if (avg)
|
|
pct = 100.0 * stddev/avg;
|
|
|
|
return pct;
|
|
}
|