I assume UCX is https://www.openucx.org? (Google found several things called UCX when I searched, but that seemed the right one.) I will try installing it and then reinstall OpenMPI. Hopefully it will then choose between network transports automatically based on what's available. I'll also look at the slides and see if I can make sense of them. Thanks.
.. Lana (lana.de...@gmail.com) On Sat, Jul 18, 2020 at 9:41 AM Jeff Squyres (jsquyres) <jsquy...@cisco.com> wrote: > On Jul 16, 2020, at 2:56 PM, Lana Deere via users < > users@lists.open-mpi.org> wrote: > > > I am new to open mpi. I built 4.0.4 on a CentOS7 machine and tried doing > an mpirun of a small program compiled against openmpi. It seems to have > failed because my host does not have infiniband. I can't seem to figure > out how I should configure when I build so it will do what I want, namely > use infiniband if there are IB HCAs on the system and otherwise use the > ethernet on the system. > > > UCX is the underlying library that Mellanox/Nvidia prefers these days for > use with MPI and InfiniBand. > > Meaning: you should first install UCX and then build Open MPI with > --with-ucx=/directory/of/ucx/installation. > > We just hosted parts 1 and 2 of a seminar entitled "The ABCs of Open MPI" > that covered topics like this. Check out: > > https://www.open-mpi.org/video/?category=general#abcs-of-open-mpi-part-1 > and > https://www.open-mpi.org/video/?category=general#abcs-of-open-mpi-part-2 > > In particular, you might want to look at slides 28-42 in part 2 for a > bunch of discussion about how Open MPI (by default) picks the underlying > network / APIs to use, and then how you can override that if you want to. > > -- > Jeff Squyres > jsquy...@cisco.com > >
