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Subject: Re: [OMPI devel] Comm_spawn limits
From: George Bosilca (bosilca_at_[hidden])
Date: 2008-10-22 14:53:27


What's happened if we roll around with the counter ?

   george.

On Oct 22, 2008, at 2:49 PM, Ralph Castain wrote:

> There recently was activity on the mailing lists where someone was
> attempting to call comm_spawn 100,000 times. Setting aside the
> threading issues that were the focus of that exchange, the fact is
> that OMPI currently cannot handle that many comm_spawns.
>
> The ORTE jobid is composed of two elements:
>
> 1. the top 16-bits is an "identifier" for that mpirun
>
> 2. the lower 16-bits is a running counter identifying the specific
> job/launch for those procs.
>
> Thus, we are limited to 64k comm_spawns.
>
> Expanding this would require either revamping the entire way we
> handle jobs (e.g., removing the mpirun identifier - major effort),
> or expanding the orte_jobid_t from its current 32-bits to 64-bits.
>
> Is this a problem we want to address?
> Ralph
>
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