// the find
brendangregg/HeatMap
Heat map generation tools
A Perl script from Brendan Gregg that converts per-event latency traces into interactive SVG heat maps. It's a focused single-purpose tool aimed at performance engineers doing latency analysis — particularly useful if you're already collecting DTrace or similar trace data.
The SVG output is interactive with mouse-over stats (count, percentile, accumulated percentage), which is genuinely useful for spotting latency distribution patterns that averages hide. Gregg's DTrace pedigree means the tool reflects real production use cases, not toy examples. The --maxlat/--minlat clipping options are the right design: outliers get their own pass rather than squashing the interesting bulk of the distribution.
It's a 3-hour Perl script by the author's own admission, last touched in 2021, with minimal input validation. The input format is completely rigid — two whitespace-separated numeric columns, no headers, no flexibility. It's DTrace-centric in its documentation and examples, so if you're on Linux with perf or eBPF you're mostly on your own for generating compatible trace files. No tests, no packaging, and 328 stars over 12+ years signals this is a grab-and-use utility, not a maintained library.