Mark Dixon via users <users@lists.open-mpi.org> writes: > But remember that IMB-IO doesn't cover everything.
I don't know what useful operations it omits, but it was the obvious thing to run, that should show up pathology, with simple things first. It does at least run, which was the first concern. > For example, hdf5's > t_bigio parallel test appears to be a pathological case and OMPIO is 2 > orders of magnitude slower on a Lustre filesystem: > > - OMPI's default MPI-IO implementation on Lustre (ROMIO): 21 seconds > - OMPI's alternative MPI-IO implementation on Lustre (OMPIO): 2554 seconds It's less dramatic in the case I ran, but there's clearly something badly wrong which needs profiling. It's probably useful to know how many ranks that's with, and whether it's the default striping. (I assume with default ompio fs parameters.) > End users seem to have the choice of: > > - use openmpi 4.x and have some things broken (romio) > - use openmpi 4.x and have some things slow (ompio) > - use openmpi 3.x and everything works I can have a look with the current or older romio, unless someone else is going to; we should sort this. > My concern is that openmpi 3.x is near, or at, end of life. 'Twas ever thus, but if it works? [Posted in case it's useful, rather than discussing more locally.]
