It's set by default in btl_tcp_if_exclude (because in most cases, you *do* want to exclude the loopback interface -- it's much slower than other shared memory types of scenarios). But this value can certainly be overridden:
mpirun --mca btl_tcp_if_exclude '' .... > On Mar 11, 2016, at 11:15 AM, dpchoudh . <dpcho...@gmail.com> wrote: > > Hello all > > From a user standpoint, that does not seem right to me. Why should one need > any kind of network at all if one is entirely dealing with a single node? Is > there any particular reason OpenMPI does not/cannot use the lo (loopback) > interface? I'd think it is there for exactly this kind of situation. > > Thanks > Durga > > Life is complex. It has real and imaginary parts. > > On Fri, Mar 11, 2016 at 6:08 AM, Gilles Gouaillardet > <gilles.gouaillar...@gmail.com> wrote: > Spawned tasks cannot use the sm nor vader btl so you need an other one (tcp, > openib, ...) > self btl is only to send/recvcount with oneself (e.g. it does not work for > inter process and intra node communications. > > I am pretty sure the lo interface is always discarded by openmpi, so I have > no solution on top of my head that involves openmpi. > maybe your bed bet is to use a "dummy" interface, for example tan or tun or > even a bridge. > > Cheers, > > Gilles > > > > On Friday, March 11, 2016, Rémy Grünblatt <remy.grunbl...@ens-lyon.fr> wrote: > Hello, > I'm having communications problem between two processes (with one being > spawned by the other, on the *same* physical machine). Everything works > as expected when I have network interface such as eth0 or wlo1 up, but > as soon as they are down, I get errors (such as « At least one pair of > MPI processes are unable to reach each other for MPI communications […] »). > I tried to specify a set of mca parameters including the btl "self" > parameter and including the lo interface in btl_tcp_if_include list, as > advised by https://www.open-mpi.org/faq/?category=tcp but I didn't reach > any working state for this code with "external" network interface down. > > Got any idea about what I might do wrong ? > > Example code that triggers the problem: https://ptpb.pw/YOjr.tar.gz > Ompi_info: https://ptpb.pw/Vt_V.txt > Full log: https://ptpb.pw/JCXn.txt > > Rémy > > > > _______________________________________________ > users mailing list > us...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > Link to this post: > http://www.open-mpi.org/community/lists/users/2016/03/28684.php > > _______________________________________________ > users mailing list > us...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > Link to this post: > http://www.open-mpi.org/community/lists/users/2016/03/28687.php -- Jeff Squyres jsquy...@cisco.com For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
