Thanks a lot Brian. -Regards, Sarang.
Quoting "Brian W. Barrett" <bbarr...@lanl.gov>: > You're right, in v1.2 it will return MPI_THREAD_SINGLE (although it > really > shouldn't). Some MPI implementations may do something different if > you > request MPI_THREAD_FUNNELED instead of MPI_THREAD_SINGLE, so you > should > continue to do that. A future version of Open MPI will return the > provided as MPI_THREAD_FUNNELED in that case instead of > MPI_THREAD_SINGLE. > But you can safely use two threads as you describe even with the > provided > of MPI_THREAD_SINGLE. > > Brian > > > 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 > >> >> > >> >> > >> > > >> > > >> > > >> > >> > > > > > > > >
