Automatically striping large messages across multiple NICs is certainly a very nice feature; I was not aware that OpenMPI does this transparently. (I wonder if other MPI implementations do this or not). However, I have the following concern: Since the communication over an ethernet NIC is most likely over IP, does it take into account the route cost when striping messages? For example, host A and B in the MPD ring might be connected via two NICs, one direct and one via an intermediate router, or one with a large bandwidth and another with a small bandwidth. Does OpenMPI send a smaller chunk of data over a route with a higher cost?
Because of this concern, I think the channel bonding approach someone else suggested is more preferable; all these details will be taken care of at the hardware level instead of at the IP level. Thanks Durga On Dec 6, 2007 9:42 AM, Jeff Squyres <jsquy...@cisco.com> wrote: > Wow, that's quite a .sig. :-) > > Open MPI will automatically stripe large messages across however many > NICs you have. So you shouldn't need to use multiple threads. > > The threading support in the OMPI v1.2 series is broken; it's not > worth using. There's a big warning in configure when you enable it. :-) > > > On Dec 5, 2007, at 9:57 PM, Tee Wen Kai wrote: > > > Hi everyone, > > > > I have installed openmpi-1.2.3. My system has two ethernet ports. > > Thus, I am trying to make use of both ports to speed up the > > communication process by using openmp to split into two threads. > > However, this implementation always cause error. Then I realized > > that I need to build openmpi using --enable-mpi-threads and use > > MPI_Init_thread to initialize. But, the initialization always return > > MPI_THREAD_SINGLE no matter what value I set. Using ompi_info|grep > > Thread, it shows that thread support has already been activated. > > Thus, I seek your help to teach me what other configurations I need > > to set in order to use multi-threads and what are the parameters to > > include in mpirun in order to use the two ethernet ports. > > > > Thank you very much. > > > > Regards, > > Tee > > > > > > > > _________________________________________________ > > > > > > > > Many of us spend our time wishing for things we could have if we > > didn't spend half our time wishing. > > > > Looking for last minute shopping deals? Find them fast with Yahoo! > > Search._______________________________________________ > > users mailing list > > us...@open-mpi.org > > http://www.open-mpi.org/mailman/listinfo.cgi/users > > > -- > Jeff Squyres > Cisco Systems > _______________________________________________ > users mailing list > us...@open-mpi.org > http://www.open-mpi.org/mailman/listinfo.cgi/users > -- Its a battle between humans and communists; Which side are you in? .
