Hi everybody, I am using Xenomai for a high performance real time simulation system. All of the simulation code is executed within user space. One application is running that consists of several Xenomai real time threads. For performance reasons I am always using the latest PC technology available (which is currently Pentium D or Core2Duo PCs, we are thinking even of using quad-core CPUs). There has to be a kind of thread synchronisation e.g. when accessing shared data. Hardware I/O is done via rtnet or via PCI I/O boards that work in user space aswell (PCI memory mapped into the user space). This is done e.g. by using semaphores, mutexes et.c I like the Xenomai-native skin as it provides a very clear API that is easy to use. However, for a user space only application it is a performance killer, that all API calls lead to a mode switch from user to kernel space. Each API call takes about 1-2 microseconds (us) on my PC which is really expensive. Especially when inter process communication is used to protect the access to shared data it is mostly the case that the calling thread does not have to wait. In this situation there is no need for a context switch. The API call did not lead to a rescheduling of the available tasks. And for this the required 1-2 us do really hurt.
Thus my question/proposal is if there is a plan to use a "variant" of the native API that is optimized for user space only applications. In this case e.g. futexes can be used. If there is a need to reschedule to another task it is fine to "invest" the 2us but it can be avoided mostly which should increase the overall performance dramatically. This would lead to a library where a big part of the functionality is handled directly in the library (in user space). Currently the skin passes the (user space) API call via a Xenomai System call to the kernel space to execute there the actual functionality. Thanks for any feedback on this proposal. Regards Mathias -- Mathias Koehrer [EMAIL PROTECTED] Viel oder wenig? Schnell oder langsam? Unbegrenzt surfen + telefonieren ohne Zeit- und Volumenbegrenzung? DAS TOP ANGEBOT JETZT bei Arcor: günstig und schnell mit DSL - das All-Inclusive-Paket für clevere Doppel-Sparer, nur 39,85 inkl. DSL- und ISDN-Grundgebühr! http://www.arcor.de/rd/emf-dsl-2 _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
