NGUYEN Laurent wrote:
Hello,

I'm trying to understand the difference between theses two options:

" --mca mpi_paffinity_alone 1 "
and
" --bind-to-core "

To me, it's the same thing (may be paffinity have maffinity in addition) but the purpose af theses options is to bind MPI process to processors. Which is the best to obtain performances?

They are essentially the same thing.  The history is that mpi_paffinity_alone came first.  Then a group of us decided that we wanted to be able to do more than just core binding (like bind-to-socket and eventually others) so we decided a more descriptive name made sense.  I would suggest sticking with --bind-to-core just so thinks look clear in your mpirun command.  That and the possibility that one day mpi_paffinity_alone is deprecated.
I have another question about processes bindings: I use rankfiles to have a precise binding of my process on processor or socket (it useful for hybrid computing like pthread or OpenMP). I read you don't want to maintain this feature: how can I substitute it?
IMO, I say we do support it and will until we find a suitable replacement (there is a proposal that Jeff and I have bounced around to each other intermittently but have not brought it to the community).   There have been discussion about lack of testing of rankfiles and other binding related items making it hard for some to feel comfortable about putting code back that may have side negative side affects.  But I don't equate that to mean we will not support or take bug reports on the rankfile feature.

--
Oracle
Terry D. Dontje | Principal Software Engineer
Developer Tools Engineering | +1.650.633.7054
Oracle - Performance Technologies
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Email terry.dontje@oracle.com