Incorrect tail latencies in Histogram report

[gunnarmorling]

Version and Runtime

vegeta -version
Version: v12.12.0
Commit: 03ca49e9b419c106db29d687827c4c823d8b8ece
Runtime: go1.22.5 linux/amd64
Date: 2024-07-29T17:35:40Z+0000

Expected Behaviour

I am running vegeta report -type hdrplot to create an HDR histogram. I'm expecting to see representative tail latencies, as e.g. shown with the red curve here (rendered by feeding Vegeta results fed to HdrHistogram).

Actual Behaviour

It seems that tail latencies > p9999 are calculated incorrectly by Vegeta, see the sharp bump at 99.99% in the blue curve (output of vegeta report), in contrast to the numbers from HdrHistogram. Perhaps the right level of resolution is missing there?

Steps to Reproduce

Create a plot with values showing a range of values in the > p9999 percentiles.

Additional Context

n/a