Gilles Chanteperdrix wrote: > Wolfgang Mauerer wrote: >> Hi, >> >> On 03.12.2009, at 14:14, Gilles Chanteperdrix >> <gilles.chanteperd...@xenomai.org >> > wrote: >> >>> Wolfgang Mauerer wrote: >>>> Hi, >>>> >>>> Gilles Chanteperdrix wrote: >>>>> Wolfgang Mauerer wrote: >>>>>> So that means, in essence, that you would accept probabilistic >>>>>> algorithms in realtime context? >>>>> Ah, today's troll! >>>> though it seems that I have to replace Jan this time ;-) >>>>> As I think I explained, the use of a seqlock in real-time context >>>>> when >>>>> the seqlock writer only happens in linux context is not >>>>> probabilistic. >>>>> It will work every time the first pass. >>>> I still don't see why it should succeed every time: What about >>>> the case that the Linux kernel on CPU0 updates the data, while >>>> Xenomai accesses them on another CPU? This can lead to >>>> inconsistent data, and they must be reread on the Xenomai side. >>> Yeah, right. I was not thinking about SMP. But admit that in this >>> case, >>> there will be only one retry, there is nothing pathological.
that's right. Which makes it bounded again, so it's maybe the best way to go. >>> >>>> I'm asking because if this case can not happen, then there's >>>> nothing left to to as I have the code already at hand. >>> You have reworked the nucleus timers handling to adapt to this new >>> real-time clock ? >> Nope. Sorry, I was a bit unclear: I'm just referring to the gtod >> syscall that does the timer handling, Not any other adaptions. > > Ok, but what good is the gtod syscall if you can not use it as a time > reference for other timing related services? it suffices for our project's current purposes ;-) But it's certainly not the full solution. Before, we should have a decision wrt. the design issues, but I won't be able to continue working on this before mid of next week to look at the changed required for timer handling and come up with code. Cheers, Wolfgang _______________________________________________ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
