[Rock-dev] Scheduler warning and realtime

[Alexander Duda]

On 11/08/2012 04:28 PM, Pierre Letier wrote:
> Le 11/8/2012 4:09 PM, Sylvain Joyeux a écrit :
>> On 11/08/2012 03:27 PM, Pierre Letier wrote:
>>> I succeeded to build an application based on Orogen. It is currently
>>> working on a xubuntu 12.04. The application is running correctly but
>>> when I start it, I receive the following warning:
>>>
>>> 0.037 [ Warning][Thread] Lowering scheduler type to SCHED_OTHER for
>>> non-privileged users..
>>> 0.037 [ Warning][Activity] Lowering scheduler type to SCHED_OTHER for
>>> non-privileged users..
>>> Based on a google reserach, I found the following answer on the
>>> Orocos mailing list:
>>> http://www.orocos.org/node/1089
>>>
>>> In summary I need to change my user ulimit to use the real-time
>>> scheduler as a non-priveleged user. This solution works (I don't have
>>> anymore the warning). However, I don't know where, in my Orogen
>>> development, I specify that I want to use the real time sheduler. I
>>> don't define any realtime parameter in the deployment (I use the
>>> "automatic" deployment approach) or any priority. I was thinking that
>>> I was automatically in SCHED_OTHER from OROCOS point of view. Do you
>>> have any idea about that ?
>> In theory, if you don't add the .realtime tag to the deployed task,
>> the warning should not appear. I thought I fixed it a while back. RTT
>> spawns some threads (for isolating CORBA from the task context for
>> instance), and I thought I made sure they would be spawned with the
>> same scheduler than the task ... Will have to check that.
>>> In the future, I would like to port the component in realtime, using
>>> XENOMAI. For that I have the following questions:
>>>
>>> - Any suggestion/advices about the installation/configuration of
>>> XUBUNTU/XENOMAI/Orogen (e.g. kernel configuration). Is there specific
>>> thinks to do with orogen ?
>> In theory, there is nothing special to do with oroGen. In practice, we
>> have not done any Xenomai work in ages, so I don't really know. We
>> moved to using Linux with the RT patchset, which gives good RT
>> performance without the Xenomai caveats (i.e. the normal linux-based
>> monitoring / debugging tools work out of the box)
> Interesting, do you have any documentation / link to do that (I am note
> linked to XENOMAI) (see last question).
>>> - How the orogen codes/component have to be modified/updated to make
>>> them working in the realtime environement (modification of CMAKE ?)
>> orogen should be called with the --target=xenomai flag and RTT should
>> be compiled for both xenomai and gnulinux.
>>
>> The orogen parameter is historical in nature and we should probably
>> make it completely configurable when calling CMake (i.e. cmake
>> -DOROCOS_TARGET=xenomai). Automatically compiling the two
>> configurations for RTT using autoproj is not supported either ... I
>> should have a look at that, since it is also required by
>> cross-compilation setups.
>>> - How the GUI UI have to be managed if developped on the same
>>> computer ? (of course not realtime)
>> I don't really understand that question ...
> I use the Ruby script to call and configure/connect some graphical user
> interface (control buttons, status, plots....). If I use the deployer to
> specify the realtime behavior of some tasks, may I have issues with the
> graphical rendering (I understand it will depend on what I do with the
> realtime tasks) or could the graphical rendering be a problem for the tasks
>>> - is there any documentation/tutorial about developping orogen
>>> components on realtime platforms (like Xenomai)
>> There was not, but now there is. I quickly wrote this without testing,
>> so it might not be as accurate as one might like ;-)
>>
>>     https://rock.opendfki.de/wiki/WikiStart/Toolchain/RTPlatforms

Try the following link instead:
http://rock.opendfki.de/wiki/WikiStart/Toolchain/RTPlatforms

Alex


>>
> The link is password protected.
>
> Thank you
>


-- 
Dipl.-Ing. Alexander Duda
Unterwasserrobotik

DFKI Bremen
Robotics Innovation Center
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E-Mail: alexander.duda at dfki.de

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