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Subject: Re: [OMPI users] strange IMB runs
From: Michael Di Domenico (mdidomenico4_at_[hidden])
Date: 2009-08-14 11:18:26


> One of the differences among MPI implementations is the default placement of
> processes within the node. E.g., should processes by default be collocated
> on cores of the same socket or on cores of different sockets? I don't know
> if that issue is applicable here (that is, HP MPI vs Open MPI or on
> Superdome architecture), but it's potentially an issue to look at. With HP
> MPI, mpirun has a -cpu_bind switch for controlling placement. With Open
> MPI, mpirun controls placement with -rankfile.
>
> E.g., what happens if you try
>
> % cat rf1
> rank 0=XX slot=0
> rank 1=XX slot=1
> % cat rf2
> rank 0=XX slot=0
> rank 1=XX slot=2
> % cat rf3
> rank 0=XX slot=0
> rank 1=XX slot=3
> [...etc...]
> % mpirun -np 2 --mca btl self,sm --host XX,XX -rf rf1 $PWD/IMB-MPI1 pingpong
> % mpirun -np 2 --mca btl self,sm --host XX,XX -rf rf2 $PWD/IMB-MPI1 pingpong
> % mpirun -np 2 --mca btl self,sm --host XX,XX -rf rf3 $PWD/IMB-MPI1 pingpong
> [...etc...]
>
> where XX is the name of your node and you march through all the cores on
> your Superdome node?

I tried this, but it didn't seem to make a difference either