[mpich-devel] MPI_Dims_create() fails for nproc >1000000

[Jeff Hammond]

I started working on a patch, but I'm not sure if it is the right
thing to just encode a longer static array of primes.

Any suggestions on how to proceed?  Should I generate the array of
primes on-the-fly (once per MPI instance) up to the max possible
amount?

Jeff


---------- Forwarded message ----------
From: Jeff Hammond <jeff.science at gmail.com>
Date: Thu, Dec 19, 2013 at 10:55 AM
Subject: Re: [mpich-discuss] MPI_Dims_create() fails for nproc >1000000
To: discuss at mpich.org


Can you provide a short test that reproduces the issue you are seeing?
 I will add a Trac ticket for it.

Thanks,

Jeff

On Thu, Dec 19, 2013 at 9:49 AM, Andreas Schäfer <gentryx at gmx.de> wrote:
> Hi,
>
> I noticed that MPICH's MPI_Dims_create() fails with a floating point
> exception, if the number of processes is larger than 10^6. Apparently
> the reason is that the prime factors are hard coded into the code and
> are limited to 1000 (or sqrt(10^6)). Open MPI's implementation has no
> such limitation.
>
> Best
> -Andreas
>
>
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--
Jeff Hammond
jeff.science at gmail.com


-- 
Jeff Hammond
jeff.science at gmail.com