Histograms

Motivation

The Linux TSN Testbench keeps track of the round-trip times of each frame. Currently the minimum, maximum and average values are displayed in the log files over the whole application run time. However, it does not show the distribution of the round-trip times. For example, the distribution is of interest to see the relation of outliers in contrast to regular case.

Therefore, the Linux TSN Testbench also includes the possibility to generate a histogram file after a successful run. The histogram itself is a text file which can be easily plotted e.g., with gnuplot.

The histogram functionality is disabled by default. To enable it, apply the following options the configuration file of the reference application.

Configuration parameters

The parameters which affect the histogram integration are presented in the table below:

Features & configure options

Option

Description

StatsHistogramEnabled

Decides whether a histogram is written after successful run or not

StatsHistogramMininumNS

Lower boundary of RTT which is recorded in histogram e.g., 1ms

StatsHistogramMaximumNS

Upper boundary of RTT which is recorded in histogram e.g., 10ms

StatsHistogramFile

Path to file where to store the histogram after run

Example

The example below shows a histogram of tests/profinet. It is plotted using scripts/plot_histogram.pl which requires gnuplot to be installed.

Histogram of tests/profinet