Re: [Xenomai-core] RTOS porting on ARM

[Jan Kiszka <jan.kiszka@domain.hid>]

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[Switching the account to underline again that this is my personal POV.]

Gregory CLEMENT wrote:
> 2007/10/9, Jan Kiszka <jan.kiszka@domain.hid>:
>> Gregory CLEMENT wrote:
>>> 2007/10/9, Jan Kiszka <jan.kiszka@domain.hid>:
>>>> Gilles Chanteperdrix wrote:
>>>>> gclement00 at gmail.com (Gregory CLEMENT) wrote:
>>>>>  >
>>>>>  > For RTAI we have now a working systeme with have better max latency
>>>>>  > than Xenomai ( 50us instead of around 100us for Xenomai). I plan to
>>>>>  > update the patches on our site with this new version and communicate
>>>>>  > on it on RTAI list as soon as I have some free time.
>>>>>
>>>>> A good place for discussing about these figures would have been Xenomai
>>>>> mailing list, a place where we could have answered you immediately. Are
>>>>> you sure you are not comparing Xenomai user-space scheduling latency
>>>>> with RTAI kernel-space scheduling latency ?
>>>> Me too asked Gregory for some discussion on this long ago but received
>>>> no response.
>>>>
>>>> Anyway, the critical thing beyond latencies remains *maintenance*. If
>>>> someone decides to apply I-pipe on RTAI *and* doesn't forget to
>>>> contribute to the mandatory bits of the Adeos project, work actively
>>>> within that community (test new versions and report results, track down
>>>> bugs, port to new kernels releases, etc.), anyone would benefit in the
>>>> end. BTW, that would surely stimulate discussions about differing
>>>> numbers on both sides as well.
>>> And you think we didn't contribute to adeos projects, test new version
>>> and report result???
>>> Because it is exactly what we have done.
>> You did this for the startup of this port, and it is highly appreciated.
>> But such things require lasting effort. Probably I'm just so sceptical
>> because there have been many people before posting patches once and then
>> never again. Just look at RTAI's ARM history of the last, mmh, 4 years.
>> I'm always happy being proved wrong regarding such scepticisms of mine!
> 
> There is no more post on adeos mailing list just because we didn't
> change it, since our last post.
> As I mentioned earlier we just set dbgu priority level at a different
> level, it is not a big change, but I will post the patch for it.

Tiny change, but probably significant impact. Every generic improvement
is worth posting. You will help others to exploit it, and you will also
allow other professionals to give you feedback on the changes. The old
story of open source.

>>> Our result on RTAI are pretty recent, and the lack of discussion on it
>>> is only a lack of time and not a lack of wiling.
>> Then I'm looking forward to have this now, e.g. backed up with tracer
>> outputs of both variants.
> 
> As I mentionned, that for now, I am deep under load ? Because I am,
> and so I will do my best but time is not extensible unforutnately.

I understand that (as long as you do not spread half-explained
benchmarks at the same time). Well, maybe you then recall even better
the concerns I sent you earlier about required future maintenance
efforts vs. available time...

Jan


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