Also, loop back interface is somehow special. though all nodes do have the same ip 127.0.0.1, this interface cannot be used for inter node communication.
On Saturday, March 12, 2016, Jeff Squyres (jsquyres) <jsquy...@cisco.com> wrote: > 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 > <javascript:;>> 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 <javascript:;>> 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 > <javascript:;>> 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 <javascript:;> > > 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 <javascript:;> > > 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 <javascript:;> > For corporate legal information go to: > http://www.cisco.com/web/about/doing_business/legal/cri/ > > _______________________________________________ > users mailing list > us...@open-mpi.org <javascript:;> > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/users > Link to this post: > http://www.open-mpi.org/community/lists/users/2016/03/28689.php
