[mpich-discuss] Example MPICH2 multicore host file?

[Scott Atchley]

On Apr 2, 2009, at 8:10 PM, Steve Smith wrote:

> I am running mpich2 on two multicore machines (linux dual-quad-core  
> and OSX dual-core).

Hopefully, the Mac is x86 and not PPC (endian issues).

> I haven't had any problems with building and running code. However,  
> I've seen some behavior that makes me wonder if data/processing is  
> actually being subdivided between my cores - or whether they are all  
> getting the same data.
>
> I have not seen an example of a working MPICH2 hostfile. Based on  
> the OPENMPI ans MPICH1 examples at http://cs.calvin.edu/curriculum/cs/374/homework/MPI/01/multicoreHostFiles.html 
>  I'm thinking my MPICH2 hostfile should have a different format.
>
> Can anyone point me to a working example MPICH2 multicore hostfile?

The MPICH2 machinefile is the same as MPICH where you use:

<hostname>:<number of cores>

If you are using TCP and you have multiple interfaces, you can specify  
which interface with:

<hostname>:<number of cores> ifhn=<hostname for preferred interface>

For example, if you have an eight core node with two networks and the  
hostnames are foo-int and foo-ext (for internal and external  
interface), you might want to use:

foo-ext:8 ifhn=foo-int

Scott