.Hi Phiilppe,

No, I did not create this issue.   There is a significant increase in the
accuracy when using "large" window sizes.

Thanks

Malith


On Wed, Nov 29, 2017 at 3:53 AM, Philippe Mouawad <
[email protected]> wrote:

> Hello,
> Any feedback on this ?
> Are you the opener of this ?:
>
> - https://bz.apache.org/bugzilla/show_bug.cgi?id=61725
>
> Thanks
>
> On Thu, Nov 23, 2017 at 11:32 PM, Philippe Mouawad <
> [email protected]> wrote:
>
> > Hello,
> > You can adjust accuracy by setting in user.properties:
> >
> >    - jmeter.reportgenerator.statistic_window = 20000
> >
> > Caution : higher value provides a better accuracy but needs more memory.
> >
> > This is not a bug.
> >
> > We use DescriptiveStatistics from commons-math with a sliding window.
> >
> > So if after modifying this value you still face issue, please report and
> > open a bug at commons-math.
> >
> > Regards
> >
> >
> > On Thu, Nov 23, 2017 at 5:04 AM, Malith Jayasinghe <
> > [email protected]> wrote:
> >
> >> Dear All,
> >>
> >> We have been using JMETER extensively for performance testing.
> >>
> >> All our performance reports are generated using the JMETER Dashboard.
> >>
> >> Recently, we have found out that there is an issue in
> >> the JMETER dashboard's *latency percentile calculation. *
> >>
> >> There is a significant difference in the actual percentile values and
> the
> >> values shown in the dashboard. We have verified this using "R" and in
> >> fact,
> >> the values shown the JMETER aggregate report are correct. The values
> that
> >> appear in the JMETER Dashboard are not.
> >>
> >> We understand that JMETER Dashboard may be using a different algorithm
> >> (approximation) for percentile calculation. However, the problem is that
> >> that latency percentiles values calculated using this algorithm are not
> >> accurate (at least for certain scenarios).
> >>
> >> We have had a case where the Dashboard showing a 95% percentile value
> 1000
> >> ms. However, the correct value was 321 ms.
> >>
> >> The accuracy of percentile values are of utmost importance to us and we
> >> would kindly ask you to look into this issue and release a patch if
> >> possible.
> >>
> >> If you can implement the same algorithm used in the aggregate report
> >> within
> >> the dashboard that will resolve this issue.
> >>
> >>
> >> Thanks
> >>
> >> Malith Jayasinghe
> >>
> >
> >
> >
> > --
> > Cordialement.
> > Philippe Mouawad.
> >
> >
> >
>
>
> --
> Cordialement.
> Philippe Mouawad.
>

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