[lttng-dev] Non-Preempt Test v1.01

[Raphaël Beamonte]

Hi all !

I just released the Non-Preempt Test (npt) version 1.01 which is
available here: http://git.dorsal.polymtl.ca/?p=npt.git

The purpose of this tool is to simulate a small real-time system that
runs with a high priority without being stopped or preempted. To do so,
it first sets its environment (cpu affinity, RT scheduler, memory locked
into RAM with mlockall) and can optionally disable the local IRQs if
compiled with the right options (not defined by default).

The core of the application is a loop that calculates the time gap
between the start of two consecutive loops using the rdtsc asm
instruction, thus a similarity with the hwlat_detector kernel module for
kernel analysis. At the end of its execution, npt computes latencies
statistics for each loop and generates a histogram showing the different
latencies reached and the number of time it reached each one.

This tool can be used to analyse and identify overhead of different
realtime applications as we can compare the latencies in each loops and
thus identify the added latency from a "blank" run. It is released
LTTng-ready and can thus be easily traced. Next versions could include
other userspace tracers ability.

Feedback, collaborations and contributions are welcome!

Regards,
Raphaël Beamonte

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