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Subject: Re: [OMPI users] mpirun self,sm
From: Ralph Castain (rhc_at_[hidden])
Date: 2009-04-09 04:16:08


hostname never calls MPI_Init, and therefore never initializes the BTL
subsystem. Therefore, hostname will always run correctly.

mpirun is not an MPI process, nor are the daemons used by OMPI to
launch the MPI job. Thus, they also do not call MPI_Init, and
therefore do not see the BTL subsystem.

So this example will run just fine. You need to run an MPI application
to cause it to fail.

Ralph

On Apr 8, 2009, at 10:15 PM, Robert Kubrick wrote:

> How is this possible?
>
> dx:~> mpirun -v -np 2 --mca btl self,sm --host dx,sx hostname
> dx
> sx
>
> dx:~> netstat -i
> Kernel Interface table
> Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP
> TX-OVR Flg
> eth0 1500 0 998755 0 0 0 1070323 0
> 0 0 BMRU
> eth1 1500 0 85352 0 0 0 379993 0
> 0 0 BMRU
> ib0 65520 0 204 0 0 0 155 0
> 5 0 BMRU
> lo 16436 0 1648874 0 0 0 1648874 0
> 0 0 LRU
>
> I want to force an error with the first command above to make sure
> that my btl parameters are used correctly, but it looks like ompi
> runs hostname on the remote machine regardless.
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