[mpich-discuss] mpiexec and -n option

[Pavan Balaji]

The default value is the total number of processes specified by the user 
(in the host file) or by the resource manager. In this case, it looks 
like that's 4.

  -- Pavan

On 08/15/2011 01:52 PM, Jain, Rohit wrote:
> I am running mpiexec in following format without any binding:
>
> mpiexec a1.out : a2.out : a3.out
>
> I was expecting that hydra would launch only 3 processes. But, I am
> seeing it is launching 12 processes (4 each). Isn’t default value of –n
> is 1?
>
> -verbose option shows following output which confirms my suspicion:
>
> # --version 1.5a1 --iface-ip-env-name MPICH_INTERFACE_HOSTNAME
> --hostname dxyv117 --global-core-map 0,4,0 --filler-process-map 0,4,0
> --global-process-count 12 --auto-cleanup 1 --pmi-rank -1 --pmi-kvsname
> kvs_61149_0 --pmi-process-mapping (vector,(0,1,4)) --ckpoint-num -1
>
> What is causing this behavior?
>
> Regards,
>
> Rohit
>
>
>
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-- 
Pavan Balaji
http://www.mcs.anl.gov/~balaji