[mpich-discuss] Process Mapping in MPICH2

[Pavan Balaji]

This might answer your questions better.

http://wiki.mcs.anl.gov/mpich2/index.php/Using_the_Hydra_Process_Manager

  -- Pavan

On 02/14/2012 04:29 PM, vaibhav dutt wrote:
> Hi,
>
> I am doing some experiments in quantum chemistry software GAMESS
>   using an old version of MPICH2.
> I was wondering how the process mapping is done in mpich2.
> For example  I have a hostfile which contains hosts like
>
> host1
> host2
> ...
>
> hostn
>
> and each host has 8 cores. When I spawn 32 processes, could you please
> tell me
> what will be the order of ranks spawned. I mean would it be  like
>
> 1) rank 0 to 7 on host 1, rank 8 to 15 on host2 ...
>   or
> 2) rank 0 on host 1, rank 1 on host2......rank n on host n, rank n+1 on
> host 1.
>
>
> Moreover, how can I change the rank mapping within a node , for example
> if I want to
> have certain ranks together on a die of a socket.
>
> Thanks
>
>
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-- 
Pavan Balaji
http://www.mcs.anl.gov/~balaji