2009/3/6 Gilles Chanteperdrix <[email protected]>: > M. Koehrer wrote: >> Hi everybody, >> >> is it possible to use OpenMP with Xenomai Realtime threads? I have a >> Intel QuadCore CPU running. Currently I use the native skin to create >> multiple threads to run on multiple CPU cores. That works perfectly. >> However for some computations, a more local parallel computation >> could be great. And OpenMP provides exactly the right thing here. My >> question is now: Is it possible to use OpenMP with Xenomai real time >> tasks? How can I define the worker threads of OpenMP to be real time >> threads? What about the priority of these threads? > > I do not know what OpenMP is,
OpenMP is a proposed standard for shared-memory parallel programming: http://openmp.org. The idea is to indicate to the OpenMP-aware compiler which part of your code may be parallelized with #pragma omp <something> those pragma should be ignored by non OpenMP-aware compiler making the parallelized code more portable. GCC 4.2 and up support OpenMP pragma if you use the -fopenmp command line switch. > but if it uses the posix API, the first > step to make it work with Xenomai is to try and compile it with xenomai > posix skin. Then, all threads created by this openmp compiled for > xenomai posix skin will be real-time threads, and the priority of these > threads will be the one chosen by the pthread_att_setschedparam or > pthread_setschedparam services. The OpenMP parallel model concerning threads is a so-called fork/join model. The compiler insert the code that creates the threads (and eventually join them) at appropriate places for you. The work is then distributed to those "worker" threads. The code use to handle those mechanism is NOT under user control, user only insert OpenMP pragmas. In GCC there is a supporting library "libgomp" used: http://gcc.gnu.org/viewcvs/trunk/libgomp/ the lib seems to be using pthread, but this as to be checked carefully. Thus I would bet that somewhere in libgomp you'll find the pthread_xxxx calls corresponding to the OpenMP handled threads. I think in order to make the OpenMP thread Xenomai one's you'll have to find WHERE (in the libgomp code) they are created and may WHEN they are launched, in order to be sure the libgomp created threand will be Xenomai tasks. The solution used by other compiler to support OpenMP may be different, so the Xenomai+OpenMP support may be different for other compiler. -- Erk _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
