Commit 80d65f95 authored by Tomas Krizek's avatar Tomas Krizek

README: add info about histogram tool

parent 379e3b69
......@@ -14,6 +14,7 @@ Respdiff v2 is conceptually chain of independent tools:
2. orchestrator: send pre-generated wire format to servers and gather answers
3. msgdiff: compare DNS answers
4. diffsum: summarize differences into textual report
5. histogram: plot graph of answer latencies
This split allows us to repeat steps using the same data as necessary,
e.g. run analysis with different parameters without re-querying the
......@@ -78,6 +79,15 @@ with higher granularity, producing stats for each field in DNS message
Ordering and grouping of mismatches is specified in ``[report]`` section of config file.
Histogram
---------
``orchestrator.py`` saves the latency for each answer in LMDB. Afterwards, they
can be used to analyze the performance of the resolver. ``histrogram.py`` generates a
`logarithmic percentile histogram <https://blog.powerdns.com/2017/11/02/dns-performance-metrics-the-logarithmic-percentile-histogram/>`_
from these latencies.
Usage
-----
Please note that this is very basic use-case where nothing is prepared beforehand.
......@@ -105,4 +115,10 @@ Compute differences in responses and generate a text report from them.
$ ./msgdiff.py "${DIR}"
$ ./diffsum.py "${DIR}" > "${DIR}"/"${DIR}".txt
Plot a logarithmic percentile graph of answer latencies.
.. code-block:: console
$ ./histogram.py -o histogram.svg "${DIR}"
You can also re-run ``msgdiff.py`` and ``diffsum.py`` using different configuration.
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