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Subject: Re: [hwloc-users] MPI + threads parallelization
From: Brice Goglin (Brice.Goglin_at_[hidden])
Date: 2010-10-01 05:02:42


Le 01/10/2010 10:56, Ondrej Marsalek a écrit :
> Hi again,
>
> I have a question regarding parallelization using both MPI and threads
> in a NUMA setup. I would like to be able to use one MPI process per
> socket or NUMA node and use threads within each MPI process to use all
> the cores. Can I use hwloc to put and keep all of these in the right
> places?
>
> Thanks,
> Ondrej
>

It mostly depends on the MPI implementation. Several of them are
switching to hwloc for binding, so you will likely have a mpiexec option
to do so.

Otherwise, assuming mpiexec does not bind anything and you have 4 numa
nodes, you can do it manually with something like:
  mpiexec --np 1 hwloc-bind node:0 myprog : -np 1 hwloc-bind node:1
myrog : -np 2 hwloc-bind node:2 myprog : -np 3 hwloc-bind node:3 myprog
which runs 4 instances of "myprog" and bind them on different numa nodes.

Brice