[Rtai] About RTAI suppport for ARM(AT91SAM9263)
devel at koschorrek.com
Thu Dec 3 15:18:12 CET 2009
> Dear Sir,
> I knew of the information related to latency of rtai on ARM from
> the below, which comes from
> 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-188.8.131.52 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.
> *2007/7/16, Gregory CLEMENT < <mailto:**gclement00 at
> *> **gclement00 at
> 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
> 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 :
> RTAI patch to apply on RTAI magma of 11/07/2007:
> I want to thank our intern Alexandre BOUIN for his work on this porting.
> Gregory CLEMENT
> 2, chemin du Ruisseau - BP21
> 69136 Ecully Cedex
> Tel : +33-4 72 18 08 40
> 2009/12/2 Torsten Koschorrek <devel at koschorrek.com>
>> 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
>>> 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,
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