Hi Darren, thanks for the response. You are right, I should clarify the needs I have... I have two real time applications (two processes), each running a few real time threads. For inter process communication I want to exchange data between the two applications. For this I want to use two queues - one for direction A->B and one for B->A. Now I have the situation that one thread in B that handles the A->B queue is waiting for data from A. Whenever A has the data available, it writes the data into the A->B queue. Immediately after receiving data from A, B unblocks and computes some answer data that is written into the B->A queue. The time between sending the data in A and getting the data back from B should be as low as possible (real time requirements: at max tens of microseconds...). The functionality of mq_send, mq_receive looks suitable. However I am not sure if this can fulfil my performance needs... Perhaps I still have the "Xenomai" thinking which means that only some special API functions are real time capable all others are not... With the RT_PREEMPT patch this seems to be much easier as I can use all suitable functionality (or did I miss some important thing here?!?). Regards Mathias > > Hi all, > > > > I am about to switch an realtime application from Xenomai to the > RT_PREEMPTION patch. > > Everything works really smooth, however I have one question. > > With my Xenomai application I use the message queue which combine transfer > (including queuing) > > of data with activation of the thread. > > In my Xenomai application I use this feature quite frequently. Now, I am > not sure how to do an equivalent > > with the RT_PREEMPT patch. > > (see > http://www.xenomai.org/documentation/xenomai-2.4/html/api/group__native__que > ue.html) > > Of course I could use condition variables and a struct or array to hold > the data I want to pass with the activation > > of a thread. However, using this approach I do not have the queuing (which > is some extra effort I could spent...). > > Another idea I have: I could use sockets which realize the queuing but the > overhead is too high. > > > > Is there any suitable way to implement a message queue like approach using > RT_PREEMPT patch? > > I am running x86 (Dual/Quad Cores). > > I don't if we have many xenomai experts on this list. It would help to > understand which aspects of the Xenomai message queue are important to > you (other than the ability to block on a queue and wake when a message > is available). For a basic message queueing system with the ability to > prioritize messages, you can look to the POSIX.4 Message Queues. A > google search will provide plenty of howto's, and the API appears at > least similar to what you were using with Xenomai. > > I haven't looked, but I don't think Linux supports message driven > Priority Inheritance > (http://www.qnx.com/developers/docs/6.3.2/neutrino/sys_arch/kernel.html#Prio > rity_inheritance_messages). > > -- -- Mathias Koehrer mathias_koehrer@xxxxxxxx Immer auf dem Laufenden! Sport, Auto, Reise, Politik und Promis. Von uns für Sie: der neue Arcor.de-Newsletter! Jetzt anmelden und einfach alles wissen: http://www.arcor.de/rd/footer.newsletter -- To unsubscribe from this list: send the line "unsubscribe linux-rt-users" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
