ptask

Periodic Real-Time Task interface to pthreads

• Version 0.1, April 2013
• Version 0.2, August 2013
• Version 0.3, September 2015
• Version 0.4, July 2017
• Version 0.5, February 2019

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Authors

• Giorgio Buttazzo (g.buttazzo@sssup.it)
• Giuseppe Lipari (g.lipari@sssup.it)

Contributors

• Alessio Balsini (a.balsini@sssup.it)
• Alexandre Becart and Benoit Delecroix (integrating SCHED_DEADLINE)
• Pierre Caruyer (dline exception)
• Amine El Messaoudi and Flora Dziedzic (ptaskTracer)

License: GPL 3.0

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Introduction

PTASK is a simple wrapper to the pthread library. It is intended for real-time programmers that wish to control the timing behaviour and the synchronisation of threads. It is intended to be minimalistic, yet extensible to more complex usage scenarios.

Currently it provides:

• An API for implementing periodic and aperiodic tasks;
• A simple API for group scheduling and synchronization;
• An API for mode changes.

A manual is available in docs/ptask_manual_x.x.pdf.

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Instructions

Prerequisites

• Allegro 4 libraries
• CMake 3.1+

Compiling

To compile the library the first time, enter the main ptask folder (from now identified with ptask/) and type:

$ mkdir build
$ cd build
$ cmake ..
$ make

this produces the library file ptask/build/src/libptask.a, that must be included into your projects.

This also compiles all the:

• examples (ptask/build/src/examples);
• tests (ptask/build/src/tests).

To compile the examples, use the same procedure in directory examples/. Before doing that, make sure you have already installed the Allegro library, version 4 (http://liballeg.org/download.html). On Ubuntu systems, you can install it with

  sudo apt-get install liballegro4-dev

Once you compiled the sources, remember to become super-user, otherwise Linux will not allow you to create real-time tasks!

To run the tests, execute the script

$ ptask/build/src/tests/runtest.sh

or, from the ptask/build/ directory, run

$ sudo make test

Tracing

You can now visualize the execution trace of the tasks in a PTASK application using ptaskTracer, a library build on top of ltt-ng. ptaskTracer uses ltt-ng to produce an event file, that is then parsed by a Java tool and transformed into a SVG file that can be visualized in any browser.

To use ptaskTracer, you must first install the lttng development library (in Debian, package liblttng-ust-dev), then invoke cmake with option -DTRACE=ON.

Happy programming!