[httperf] Statistics

Martin Arlitt arlitt at granite.hpl.hp.com
Tue Jan 30 06:50:38 PST 2007


hi Chris

I'll pass along your suggestion to the development team.

thanks

Martin

On Tue, 30 Jan 2007, Chris Wilson wrote:

> Hi Martin,
>
> On Mon, 29 Jan 2007, Martin Arlitt wrote:
>
> > as you know the true median cannot be higher than the maximum.  however,
> > httperf trades off a small amount of accuracy in order to reduce the
> > memory required.  instead of keeping a list of all the connection times,
> > it keeps a histogram; the median value that is reported is the middle of
> > the bin that contains the median value.  for example, if the bin held
> > all observed values from 4 to 5 ms, then the reported median would be
> > 4.5ms, no matter where the observed values fell within the bin.
>
> Thanks for the explanation. Would it make sense for httperf to report the
> median as "4 ms" or "4.5 +/- 1.0 ms" to avoid giving a false impression of
> the accuracy?
>
> Cheers, Chris
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