Qt application on Xenomai

Stéphane Ancelot sancelot at numalliance.com
Mon Mar 4 08:55:57 CET 2019


I will share some points from my viewpoint :

The Xenomai impact will depend on the processor architecture selected 
(uniprocessor or multiprocessor).

In uniprocessor context, while your rt application will consume cpu 
time, meanwhile the other scheduled application will be waiting for 
their time slice.

And thus GUI application is interrupted and may be slow in some cases 
(that really depends on the impact of the RT process). In multiprocessor 
context, this becomes no more a problem.

Performance is then dependant on the cpu architecture (x86/x64/arm...) 
and their graphics chip device.

Depending on the graphics chip, the performance needed to drive a 19inch 
size display is not the same as driving a 7inch size display.

There are two kinds of Qt applications these days : Native Qt and QML 

* Qt is native and can use 2D OpenGL or display framebuffer,

* QML is no more than a javascript application layer running in a 
javascript web engine , in this case you will be performance mainly 
impacted by the QML architecture.

If your GUI application fits only few buttons in a display, then, that's 
not a problem.


Stéphane ANCELOT

Le 02/03/2019 à 06:57, Sumitabh Ghosh via Xenomai a écrit :
> Hi Henning,
> Thanks for your confirmation. Just to understand your set up further, does
> the POSIX layer used by QT is of the Xenomai skin ? Is This the way Qt is
> leveraging the rt features ?
> I guess the rendering of graphics is handled through non rt Linux
> framebuffer /opengl apis.
> Let me know if my above understanding is correct.
> Thanks,
> Sumit
> On Fri, Mar 1, 2019, 18:02 Henning Schild <henning.schild at siemens.com>
> wrote:
>> Hi,
>> i am not sure i fully understand the question. In case you are worried
>> about combining Xenomai and Qt, i can assure you that it is possible.
>> We do have big c++/Qt applications running both rt and non-rt on
>> xenomai.
>> regards,
>> Henning
>> Am Fri, 1 Mar 2019 14:10:42 +0530
>> schrieb Sumitabh Ghosh via Xenomai <xenomai at xenomai.org>:
>>> Hi,
>>> I have a generic question not specific to any platform. If I want to
>>> run a small graphics application on Xenomai 3.x what would be the
>>> correct approach. e.g. Qt application framework which needs POSIX
>>> apis and a linux frame buffer to be able to render 2D applications.
>>> Kindly provide me some pointers.
>>> Thanks in advance.
>>> Cheers!
>>> Sumit

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