[Rtai] About RTAI suppport for ARM(AT91SAM9263)

[Torsten Koschorrek]

Hello,

付言华 wrote:
> Dear Sir,
> 
>        I knew of the information  related to latency  of rtai on ARM from
> the below, which comes from
>  http://mail.rtai.org/pipermail/rtai/2007-July/017689.html<http://mail.rtai.org/pipermail/rtai/2007-July/017689.html>
>        Hence, I want to confirm that from you. That is, how is the rea-time
> of RTAI on AT91sam926x no, and can it be used in real time application?
> 

The cited mail was the first release of the patch. The rtai version was 
3.5cv IIRC and the kernel 2.6.20. The latest is kernel-2.6.20.13 and 
rtai-3.7.1. So there might be some enhancements in performance (might 
be, because I can't say for sure, I don't have any at91 hardware).

I suggest to give it a try and do some performance measurements yourself 
(from ml I see, you're already trying). It depends on your needs if it's 
usable or not.

Torsten


>  //////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
> 
> *2007/7/16, Gregory CLEMENT <  <mailto:**gclement00 at
> gmail.com*<http://mail.rtai.org/cgi-bin/mailman/listinfo/rtai>
> *> **gclement00 at
> gmail.com*<http://mail.rtai.org/cgi-bin/mailman/listinfo/rtai>
> *>:
> 
> Hello RTAI list,
> 
> We are really proud to send you our first version of support for RTAI
> on ARM for recent kernel (2.6.20) for AT91 boards.
> The good news:
> - it compiles
> - it runs  ( without any crash) on AT91 board
> - it had already good latency with no load ( max latency around 60us,
> and average latency around 15us, for information on Xenomai we have
> 70us for max latency and around 15us for average latency in the same
> condition)
> The bad new:
> -it had very poor latency under load ( max latency is over 20ms and
> average latency is meaningless for information on Xenomai we have
> 100us for max latency and around 15us for average latency in the same
> condition), hence it is not yet usable for real time application
> 
> We hope this big latency are made by a newbie error on our porting
> that you will be able to find easily
> 
> Two patch are joined :
> hal patch for 2.6.20 kernel patched with to apply on
> adeos-ipipe-2.6.20-arm-1.7-03.patch :
> hal-adeos-ipipe-2.6.20-arm-AT91.patch
> RTAI patch to apply on RTAI magma of 11/07/2007:
> RTAI-magma-AT91.patch
> 
> I want to thank our intern Alexandre BOUIN for his work on this porting.
> 
> 
> --
> Gregory CLEMENT
> Adeneo
> 2, chemin du Ruisseau - BP21
> 69136 Ecully Cedex
> France
> Tel : +33-4 72 18 08 40
> *
> //////////////////////////////////////////////////////////////////////////////////////////////////////////////////
> 
> 
> 
> 2009/12/2 Torsten Koschorrek <devel at koschorrek.com>
> 
>> Hello,
>>
>>
>> 付言华 wrote:
>>
>>> Hi developers of RTAI for ARM,
>>>        I am planning to port RTAI on ARM of AT91sam9263. I need your help
>>> for some questions:
>>>       1, I know that the early version support for RTAI on ARM(at91) had
>>> very poor latency under load. So I want to know  if there is improvement
>>> in
>>> latency, now ? And now, if it is able for real time application ?
>>>
>> What do you mean by early version? Can you give us some more information
>>  related to latency (maybe test results), please?
>>
>>
>>       2, If yes, how can I get it?
>>>           If no, are you plan to realize that, and when?
>>>
>> Patches are in <rtai-dir>/base/arch/arm/patches/ or at
>> https://www.rtai.org/RTAICONTRIB/ . AT91 is supported in 3.7.x although I
>> don't have feedback if the integration from magma-patch into 3.7.x done by
>> me was successful (I don't have AT91 myself).
>>
>>
>>        Thank you very much.
>>> Best regards,
>>> Yanhua Fu,
>>>
>>>
>> Torsten
>>
>