I tried with MPI_THREAD_FUNNELED but it still returns MPI_THREAD_SINGLE in "provided". I tried a sample program that has thread_0 doing MPI and thread_1 doing some computation and thread_0 and thread_1 doing some thread synchronization (using pthread condition variables). The program seems to be doing fine and so also the thread synchronization. I think, even if MPI_THREAD_SINGLE is returned in provided, such a design works. Now, since the thread synchronization seems to be fine, I think multiple threads (with only one thread executing MPI calls) works even if "provided" returns MPI_THREAD_SINGLE.
-Thanks and Regards, Sarang. Quoting "Brian W. Barrett" <bbarr...@lanl.gov>: > If only one thread ever makes calls into MPI, you don't actually > need > MPI_THREAD_MULTIPLE but only MPI_THREAD_FUNNELED. Open MPI will > generally > support MPI_THREAD_FUNNELED out of the box (but on certain > configurations, > mainly platforms without threads, will not), so if you request > MPI_THREAD_FUNNELED, it should be returned in provided. > > Good luck, > > Brian > > > Thanks a lot guys for your help. I am also trying a design where I > have > > one thread doing MPI and others doing some computation (non-MPI). > If I > > have only MPI_THREAD_SINGLE enabled for OpenMPI, can I still > implement > > this kind of a design or there would be issues with threads in > OpenMPI. > > > > -Thanks and Regards, > > Sarang. > > > > Quoting "Brian W. Barrett" <bbarr...@lanl.gov>: > > > >> There are two ways you can find out if an Open MPI build has > >> MPI_THREAD_MULTIPLE support: > >> > >> * On the command line: You can run "ompi_info | grep Thread". If > you > >> see > >> mpi: no, the build doesn't support MPI_THREAD_MULTIPLE. If you > see > >> mpi: > >> yes, the build does support MPI_THREAD_MULTIPLE. > >> > >> * At run-time. As mentioned below, if you request > >> MPI_THREAD_MULTIPLE and > >> provided is only MPI_THREAD_SINGLE, then Open MPI does not have > >> MPI_THREAD_MULTIPLE support. > >> > >> > >> Good luck, > >> > >> Brian > >> > >> > You are already there. the fact that MPI_Thread_init only > provide > >> > MPI_THREAD_SINGLE shows that MPI_THREAD_MULTIPLE is NOT enabled > in > >> the > >> > library binary that you're using. Although MPI_THREAD_MULTIPLE > is > >> > implemented in the library source code, it is only lightly > tested, > >> so it > >> > is > >> > not enabled by default. > >> > > >> > To enable MPI_THREAD_MULTIPLE, you need to recompile the library > by > >> first > >> > including --enable-mpi-threads as one of the parameters when you > >> rerun > >> > ./configure as the first step of recompiling the library. > >> > > >> > > >> > > >> > On 5/27/07, smai...@ksu.edu <smai...@ksu.edu> wrote: > >> >> > >> >> Hi, > >> >> I want to use threads with OpenMPI such that the > threads > >> would > >> >> be able to call MPI functions. For this purpose, I am using > >> >> MPI_Init_thread with MPI_THREAD_MULTIPLE option. But this > function > >> call > >> >> returns MPI_THREAD_SINGLE in the "provided" parameter > indicating > >> that > >> >> MPI_THREAD_MULTIPLE is not configured. Somewhere it is > mentioned > >> that > >> >> OpenMPI needs to be configured with --enable-mpi-threads > inorder > >> to use > >> >> MPI_THREAD_MULTIPLE. If true, is it possible to know whether > the > >> >> OpenMPI (1.1.2)which I have already configured, has the option > >> >> "--enable-mpi-threads" already configured or not? Also, how > easy > >> or > >> >> difficult is it to configure --enable-mpi-threads option? > >> >> Please share some information on this. > >> >> > >> >> -Thanks and Regards, > >> >> Sarang. > >> >> > >> >> > >> >> _______________________________________________ > >> >> users mailing list > >> >> us...@open-mpi.org > >> >> http://www.open-mpi.org/mailman/listinfo.cgi/users > >> >> > >> > _______________________________________________ > >> > users mailing list > >> > us...@open-mpi.org > >> > http://www.open-mpi.org/mailman/listinfo.cgi/users > >> > >> _______________________________________________ > >> users mailing list > >> us...@open-mpi.org > >> http://www.open-mpi.org/mailman/listinfo.cgi/users > >> > >> > > > > > > > >
